281

JOURNAL OF THE SCIENTIFIC AGRICULTURAL SOCIETY OF FINLAND
Maataloustieteellinen Aikakauskirja

Vol. 52:281-330. 1980

Growth factors and management technique used in relation
to the developmental rhythm and yield formation
pattern of a pure grass stand

Seppo Pulli
University of Helsinki, Department of Plant Husbandry, 00710, Helsinki 71

Abstract. The investigation of meadow fescue as a forage crop was carried out at
the University of Helsinki in Viikki in 1975 78. The main objective was to study
the rhythm of the growth and yield formation pattern of a stand and the relationship
between growth pattern and growth factors during different phases of the growing
season. The management techniquesstudied were the number of cuttings, use of nitrogen,
requirements of population density and the relationships of management factors to the
changes in the quantity and quality of forage yield.

The most important growth factors in the seeding year spring and autumn devel-
opment were the temperature sum and the total radiation available to the plant and
nitrogen fertilization beyond the temperature sum range of E 500° C, respectively.

During the production years the most important variables in the spring growth
were the growing time, the temperature sum and the total radiation. The midsummer
and autumn growth were mostly influenced by the total precipitation, amount of ni-
trogen for the cut and the precipitation during the week before the prior cut.

For spring, summer and autumn growth one unit increase in LAI created a DM
yield increase of 715, 500 and 315 ha-1 respectively.

Increasing the cutting frequency from two to four decreased the total DM yield
2 527 kg ha-1. The protein content and DM cellulase digestibility increased 4.8 and
13.3 % units respectively. Increasing nitrogen from 130 to 260 kg N ha-1 raised DM
and protein yields 1 110 and 485 kg ha-1

,
the protein content and DM cellulase digest-

ibility 4.2 and 1.4 % units. The seeding rate requirements for the maximum DM yield
were 60 kg ha-1 in the seeding year, 15 —3O kg ha-1 in the second year and 15 kg ha-1

in the third year.
The management system involving a seed rate of 30 kg ha-1

,
3 4 cuts and 260 kg

N ha-1 is recommended.

1. Introduction

The growth and development of a forage crop follows a S-shaped growth
pattern. The shape of the growth curve is defined by the growth factors,
the management technique used and the utilization of the crop. A plant’s
growth and development are dependent on the environmental factors sur-
rounding the crop. Of these factors, the most important are the growth



medium’s characteristics, the amount of light, temperature, the amount of
available water and the availability of nutrients. The most effective utilization
of the feeding material in order to meet economic constraints and forage feeding
standard requirements is achieved through proper management techniques.
It is important to know the quantity and quality changes connected to the
plant’s stage of development. These factors, combined with the intended use
of the forage, determine its cutting schedule. Although many previous in-
vestigators (Huokuna 1964, Raininko 1968, Poutiainen and Rinne 1971,
Syrjälä 1973 7B, Salo et ai. 1975, Rinne 1977, Hakkola 1978) have fun-
damentally described the relationships between growth stage and the cuttings
schedule, the relationships between growth stage and growth factors demand
more investigation. In addition, while energy prices continue to rise, the
quantity of the nitrogen fertilizer and the time of its application during the
growing season are becoming increasingly more important factors affecting
the economic gains of forage production.

When establishing a stand without a companion crop, and the stand will
be harvested in the year of seeding, the seeding rate needs to be taken into
consideration, even more so than when using a companion crop. The obser-
vation is supported by the fact that since the studies during the 1940’s and
1950’s (Pohjakallio 1941, Salonen 1951, Paatela 1953, Laine 1955 and
1958) relatively few studies have been conducted in Finland dealing with
seeding rates and crop establishment techniques related to the population
density.

In this investigation the primary aim was to study the effects of cutting
frequency, nitrogen fertilization and seed rates on the growth, development
and yield formation of a forage stand. The investigation’s second objective
was to study the relationships between the crop’s development and harvest
rhythm and their relationships to the growth factors at different phases
throughout the growing season. The growth analysis studies by the means of
regression models has first used in Finland by Brummer (1961). The investiga-
tions were conducted in 1975 78.

2. Material and methods
Experimental design

The field trials were established on the Helsinki University farm in Viikki in 1975. The
plots were organized in the following ways:

Experimental design: Split-plot
Main plot: Cutting treatments

Sub-plot:

1. 2-cut
2. 3-cut
3. 4-cut

Nitrogen fertilization
1. 130 kg N ha-1

2. 260 kg N ha' 1

282



283

Sub-sub-plot; Seeding densities
1. 325 seeds nr2 ( 7.5 kg ha-1)

2. 650 seeds m“ 2 (15 kg ha" 1)

3. 1 300 seeds m-2 (30 kg ha-1)

4. 2 600 seeds m-2 (60 kg ha-1 )

ThreePeps

The plots were established on an eastward facing slope. The soil type was fine sand and the
variety was Tammisto meadow fescue.

Fertilization and plant protection
In the spring of the seeding year the basic amount of commercial fertilizer mixture was

675 kg ha" 1 NPK (15 —25 15), which represents 100 kg N ha-1 .

After the first cut a higher nitrogen level was used. The 1975 nitrogen levels were:

100 N = 100 kg N ha-1

200 N = 200 kg N ha' 1

In the spring of 1976 and 1977 the basic application of commercial fertilizer mixture was

1 000 kg PK ha*1 (2 —l5 15). The amount of nitrogen per cut was applied as follows
(Nos = 27-0-0):

2-cut system: 130 N 260N
In spring 200 kg Nos ha-1 435 kg Nos ha" 1

After Ist cut 200 kg Nos ha-1 435 kg Nos ha-1

3-cut system: 130 N 260N

In spring 100 kg Nos ha-1 270 kg Nos ha" 1

After Ist, 2nd cuts 150 kg Nos ha' 1 300 kg Nos ha' 1

4-cut system: 130 N 260N

In spring 100 kg Nos ha" 1 220 kg Nos ha* 1

After Ist, 2nd, 3rd
cuts 100 kg Nos ha-1 220 kg Nos ha -1

To study the management effects in 1978 all of the treatments received 500 kg ha-1 (15 —l5
15) which represented 75 kg N ha-1 . A herbicide (dinoseb, 1.6 kg ha-1 ) was applied to control

broadleaf weeds and a watering schedule of 4 X 30 mm was followed to ensure germination after
seeding.

Cutting and yield procedure
During the seeding year the plots were cut twice:

First cut 8 August
Second cut —29 September.

For the actual production years 1976—77 the cutting schedule was as follows:

1976 19772-cut system:
Ist cut 2 July 27 June
2nd cut 27 September 27 September

3-cut system
Ist cut 18 June
2nd cut 27 July

13 June
28 July

3rd cut 27 September 27 September
4-cut system:

Ist cut 4 June
2nd cut 8 July
3rd cut 10 August
4th cut 27 September

2 June
6 July

18 August
27 September



284

In order to investigate the management post effects the stand was harvested on 19 June
1978.

Two 200 g samples of chopped forage material were taken and dried for 24 —36 h at 100° C.
The raw protein and digestibility samples were taken and dried for 24 —36 h at 70° C.

The raw protein content of the dried and ground samples was determined according to the
Kjeldahl method. For determining the digestibility of DM, the one-stage chemical method of
Jones and Hayward (1973) was employed (Pulli 1976).

Crop growth and yield analyses
The leaf area index (LAI) and the overall height of the crop were measured weekly during

the seeding year throughout the growing season. In 1976—77 both the LAI and height of the
crop were determined weekly in the spring and in the summer and fall cuttings.

Leaf area was measured with leaf planimeter, an optical instrument model Kj designed
and built by the Technical university of Helsinki.

During 1976 the raw protein content and the cellulase digestibility of dry matter were
measured weekly throughout the spring, summer and autumn. In 1977 over the same time
period also the development of the dry matter content was recorded in addition to the raw
protein and digestibility factors.

3. Weather conditions
The average temperatures and amount of precipitation for 1975—77 and the

long term average are presented in Table 1. The temperature sum in degree days
(E >o° C) and the total amount of solar radiation (i7Wh cm" 2) from the
seeding day in 1975 and from the beginning of the 1976—77 growing season
to the last cutting day are shown in Fig. 1. The meteorological data was
obtained from the Malmi airport station 1.5 km from the experimental fields.
On the average, summer 1975 was warmer and drier than the long-term average.
The mean temperature of June fell slightly below the long-term average and
precipitation was exceptionally low from June to August.

Table 1. Average temperatures (°C) and precipitation (mm) May—Sept. in 1975 —77 at
Malmi airport.

■»» , Temperature °C Precipitation mm
1975 1976 1977 1931-60 1975 1976 1977 1931-60

May 11.7 10.7 9.4 8.4 38 27 22 41
June 13.7 13.0 14.4 14.1 12 42 36 47
July 18.0 15.9 14.7 17.2 26 52 122 68
Aug. 16.6 15.2 14.5 15.6 29 45 47 70
Sept. 13.3 8.1 8.3 10.5 53 48 73 66
Avg 14.7 12.6 12.3 13.2 27 158 214 300 292

In 1976, May was, on the average, warmer and less rainy. From June to
the end of July the weather was cool and drier than the long-term average.
The rains in August were concentrated in the beginning of the month. September
was cool. The radiation energy conditions were comparable to those for 1975.



285

The 1977 growing season wound up being cooler than the long-term average.
The greatest negative deviation from the average occurred in July, September
was even cooler than in 1976. May, June and August were, under the conditions,
somewhat drier, but July was very wet and September matched the long-term
average. In 1977 the total radiation decidedly fell below the 1975—76 sum
especially in July, which was exceptionally cloudy and rainy.

4. Results and discussion

4. 1. Development and Growth of Seeding Year Stand
4. 1. 1. Population density

Numerous investigations have shown that an individual plant’s development
is not affected by the stand density as long as the plant’s space requirements
are met. As soon as the space limit is reached and exceeded, then the interplant
competition, by reducing the rate of plant growth, brings about a smaller
plant size. The reduction in growth rate occurs earlier and more strongly
the denser the stand is (Donald 1951 and 1963, Baeumer 1964, Murtagh

and Gross 1966). Increasing density reduces the amount of individual plants
already in the germination stage (Braun-Blanquet 1964, Norrington-

Davies and Harries 1977), but even more so as the stand develops under

Fig. 1. Total amount of radiation {2 Wh cm-2) and temperature in degree
days (2t > 0° C) in the experimental area during 1975 77.



286

particularly dense conditions. In a well spaced stand changes in the number
of plants are few. However, over time the number of individuals associated
with different population densities turn out to be the same because a perennial
forage crop has the tendency, under prevailing competition and constant growing
conditions, to gradually reach an adjusted population density (Donald 1951,
Harper and Gaijic 1961). In addition to the intraspecific competition also,
the management technique, crop’s age and, especially under Finnish growing
conditions, wintering affect the population density and the yield of the
invidual plant. Baker (1957) and Baker and Garwood (1959) oberved in a
stand that was cut frequently a considerably larger amount of individuals at
the end of the growing season than in a nonmowed stand.

Results
The established stand emerged 12 days after seeding at all of the seeding

densities. The first growing density measurements were taken three weeks
after establishment (29 May) and the second set was taken on 3 July, eight
weeks after establisment. The results are presented in Table 2.

Table 2. Stand density development in the seeding year in 1975.

Seeding rate Density June 10 Density July 3
Kg ha" 1 Seeds m- 2 Plants m" 2 % Plants m" 2 %

7.5 325 109 33.5 202 62.2
15 650 207 31.9 239 37.8
30 1 300 405 31.2 414 31.9
60 2 600 959 36.9 386 14.9

Avg. 420 33.4 310 36.7

Despite relatively good soil conditions emergence was only 33.4 %. At
the time of emergence there were no significant differences in the percentages
of emergence between densities. Severe competition factors developed in
June and the stand with the greatest density experienced considerable
thinning in July. The greatest plant density was achieved with the seeding
rate of 30 kg ha"1 The final emergence percentage dropped very sharply with
increasing seeding rate (Table 2).

4. 1. 2. Development of LAI and plant height
In a young forage stand the assimilated LAI is directly proportional to

the population density. At the early stage of development the crop’s growth
is much more rapid under dense condititions than those of more space, resulting
in the occurrence of an optimum LAI first in the dense stands (Davidson
and Donald 1958, Donald 1963).

Along with the seeding density the LAI is affected also by the number of
shoots. According to Huokuna (1966) grass produces shoots more abundantly
at low seeding rates rather than at high ones, but the differences in the number



287

of shoots affecting yield level have major importance only during the three
first months after seeding.

Under spaced conditions a crop in the early stages of development produces
noticeably more leaves than under dense conditions (Thomas 1974). Scaris-
brick and Ivins (1970) point out that frequent cutting significantly reduces
both the number of shoots and the number of leaves per shoot in all cuttings.

As the growing density increases the net assimilation rate (NAR) tends to
decrease. If the competition for light is severe, the decrease is relatively rapid
(Blackman 1968, Kvet et al. 1971). Nishimura and Nitta (1974) observed
the net assimilation rate and cross growth rate (CGR) to be higher in well
spaced stands than in dense ones, irregardless of similar LAI values.

With nitrogen fertilization it is possble to obtain the proper LAI optimal
for high production and to maintain it (Donald and Black 1958).

The effect of nitrogen on the leaf area has good duration throughout the
entire growing season (Watson 1956). Phosphorus increses leaf area only in
early stages of development and later, during ripening, it hastens the reduction
of the LAI. Potassium, on the other hand, when applied in the later stages of
growth is an effective agent for reducing the phosphorus influence (Watson
1956).

The height increase of a forage crop follows a sigmoidal curve. In the early
stages of development there are relatively little height growth and leaf size
increases. During stem development height growth is the greatest. Maximum
height is attained in the stage of flowering. Of the factors influencing height
growth, temperature accounts for 75—96 % of the result (Hari and Leikola
1974). According to Mitchell (1956) the optimal temperature for leaf growth

of a forage crop in cool areas is 18—2l° C, resulting in daily increases of I—s
cm for various grasses.

A reduction in the amount of light results in intense competition for light
and height growth of the stand increases (Han et al. 1977). Height growth will
continue to increase until the light intensity reaches 50 % of full daylight.
Any further reduction in light intensity causes a reduction in height growth
because the shading becomes too great (Kamel 1959). This has a significant
influence, particularly on fall plant growth (Pohjonen and Hari 1973).

Results
For all seeding densities the initial increases in LAI and height growth

were similar in the early stages of the seeding year. Only for the density of
325 seeds m-2 was the LAI constantly below the values by a slight amount
(Fig- 2).

The early phase of the seeding year LAI and height growth were best
described by the following regression equations (Fig. 3):
a) Growing days = X

LAI: Y = -1.0429 + 0.116769 X - 0.002755X2 + 0.000024X3 (R = .9923***)
cm: Y = -5.57404 + 0.501106 X - 0.00349X2 + 0.000035X3 (R = .9972***)

b) Temperature sum Z °C = X
LAI: Y = -0.444758 + 0.00325 X - 0.0000037X 2 + 0.0000000028X 3 (R = .9923***)
cm; Y = -6.51441 -f- 0.041844 X - 0.000019X2 + 0.0000000078X 3 (R = .9967***)



For the multiple regression analysis the variables of temperature sum in
degree days (E° C) and the total radiation sum (JSAVhcm" 2 ) clearly proved to be
the most important ones for early development of the seeding year’s LAI and
height growth. Other growth factors had statistically significant correlations
as well (Table 3). The regression equation of Y = 0.33481 -f 0.01744Xx
0.35620X2 where X x =S°C and X 2 = iTWhcnr 2 accounted for 99.1 %

Table 3. The correlation coefficients between growth factors and LAI and plant height in the
seeding year development of the stand.

Factors LAI Height

Growing time .959»»»
.965»»»
.934»»
.868»

.993»*»

.993»»»

.982»»»
.928**

27 > 0° C (temp.)
27 Whcm-2 (rad.)
27 mm (prec.)

Fig. 2. Height and LAI de-
velopment of the seeding year
stand at four different popu-
lation densities.

288



(F-value = 224.8***) of the LAI increase. For height growth, temperature
accounted for 98.5 % (F-value 338.5***), no other factors fit into the regression
model. The seeding year’s height growth regression equation was Y—-
0.40726 + 0.00281 X.

After the first cutting of the seeding year the autumn growth model changed
noticeably. LAI correlated very weakly to growing days or temperature sum.
In addition, nitrogen fertilizer influenced the height growth.

The dependence of crop height on growing time or temperature sum
followed the following regression equations for 100 kg and 200kg annual nitrogen
levels (Fig. 4):

Fig 3. The relationship of
plant height and LAI devel-
opment to the growing time
and to the temperature in
degree days in the seeding
year early growth.

289



a) Growing days = X
100 N ;Y = 5.08354 + 1.76477X - 0.030251X2 + 0.00015X3 (R = .985***)
200 N :Y = 4.34552 + 2.92151X - 0.092640X2 + 0.00103X3 (R = .982***)

b) Temperature sum (£ °C) = X
100 N :Y = 5.03977 + 0.109555 X - 0.000105X2 + 0.000000019X3 (R = .985***)
200 N :Y = 4.41792 + 0.191482 X - 0.000415X2 + 0.000000327X 3 (R = .978***)

From late summer height growth it can be observed that, nitrogen fertilizer
begins to have an influence after the 500° C temperature sum has been reached.
The crop with the lowest nitrogen level (nitrogen fertilization only in the
spring) apparently stopped height growth after the depletion of the nitrogen
in the soil (Fig. 4).

Fig. 4. The relationship of
plant height development to
the growing days and to the
temperature conditions in de-
gree days at two nitrogen
levels in the fall growth
after the first cut in the seeding
year.

290



291

4. 1.3. Seeding year yields
The seeding year yield at the beginning of the growing season is proportional

to the seeding density and the maximum yields are achieved by using greater
seeding rates (Donald 1951, Baeumer 1964, Baeumer and de Wit 1968).
According to Huokuna (1966) the amount of the yield from a forage crop with
no companion crop depends on the seeding rate, provided that the field is
harvested 70 —BO days after seeding or when it is in the pasture stage. In such
a way then, a 10 kg increase in seed per hectare will provide an increase in dry
matter yield of 60—430 kg ha’ 1.

With the progression of growth the maximum yield can be achieved from a
fluctuating density harvested at a later stage of development. Cutting in the
middle of the growing phase provides a bigger yield the denser the crop is
because the plant competition has not yet noticeably reduced plant growth
(Donald 1951).

Competition for light while increasing the growing density also influences
the quality of the forage (van Burg 1962). Those plant parts left in shadow
begin to form mechanical tissue; in other words, plant tissue with more fibers
and less proteins and the result is forage of lower quality.

Results
The greatest dry matter yield of the seeding year stand at either of the

nitrogen levels in the first cutting and in the overall total of the year were
achieved with a sowing density of 30 kg ha’ 1 (Table 4). In the second cutting
the yield differences between seeding densities at both nitrogen levels were
not significantly different despite the fact that for all seeding densities up to
the greatest the yield mildly rose. The seeding density did not affect the dry
matter content of the yield (Table 4). Nitrogen fertilizer had the greatest
influence on the dry matter content. In the second cutting, the stand which
received an additional 100 kg N ha’1 contained 3.2 % units less dry matter
than the stand with 100 kg N ha' 1 applied only in the springtime. Also the
dry matter content of the total yield fertilized with 200 kg N ha’ 1 was signif-
icantly less than the one with 100 kg ha.’ 1

.

In the first harvest the raw protein content of the dry matter was highest
among the two lowest seeding densities. However, the maximum protein
yield was achieved with a seeding rate of 60 kg ha- 1 (Table 5). At both levels
of nitrogen the highest raw protein content for the second cutting and for
the total yield was obtained when the growing density was lowest. Still, the
highest protein yield was obtained when the density was highest.



Table 4. Dry matter yields (DM kg ha" 1) and dry matter content (DM %) of seeding year
stand at two levels of nitrogen cut twice in the seeding year.

Seedingrate Cut 1 Cut 2 Totals
kg ha- 1 100 N 200 N 100 N 200 N Avg.

DM kg ha" 1

7.5 1 759 a 1 387 a 2 205 a 3 054 a 4 054 a 3 554 a
15 2 297 b 1 567 a 2 353 a 3 856ab 4 658ab 4 257 b
30 2 698bc 1571 a 2 580 a 4 188bc 5 359bc 4 774 c
60 2 975 c 1 654 a 2 639 a 4 678 c 5 565 c 5 123 d

Avg. 2 432 1 545 A 2 4448 3 944 A 4 9098 4 427
Cuts N-Fert. Density CxN CxD NxD CxNxD

F-value NS xx xxx NS NS NS NS
LSD. 05 168 kg 233 kg

DM%
7.5 26.1a 27.3a 24.7a 26.7a 25.2a 26.0a

15 26.1a 26.1a 27.8a 27.3a 24.7a 26.0a
30 25.4a 27.7a 24.3a 26.5a 24.7a 25.6a
60 25.6a 27.7a 24.4a 26.5a 24.8a 25.7a

Avg. 25.8 27. 28 25. 3 A 26.8824.9 A 25.9
Cuts N-Fert. Density CxN CxD NxD CxNxD

F-value NS xxx NS xx NS NS NS
LSD 05 0.6 % 0.8 %

Table 5. Protein content (% in DM) and protein yield (kg ha-1 ) of seeding year stand at two
levels of nitrogen and cut twice in the seeding year.

Seeding rate Cut 1 Cut 2 Totals
kg ha" 1 100 N 200 N 10ON 200 N Avg.

Protein %

7.5 17.6 b 15.4 c 20.8 c 16.6 c 19.3 b 18.0 c
15 17.4 b 13.8 a 18.6 a 15.9 b 18.0 a 17.0 b
30 16.4 a 13.3 a 19.8 b 15.2 a 18.0 a 16.6 a
60 16.1 a 14.8 b 20.1 b 15.6 b 18.0 a 16.8ab

Avg. 16.9 14.3 A 19.88 15.8 A 18.38 17.1
Cuts N-Fert. Density CxN CxD NxD CxNxD

F-value NS xx xxx xxx xxx xxx xxx
LSD. 05 0.2 % 0.3 % 0.2 % 0.4 % 0.4 % 0.6 %

Protein kg ha" 1

7.5 310 a 214 a 446 a 508 a 771 a 640 a
15 400 b 216 a 453 a 614 b 854 b 734 b
30 443 c 219 a 511 b 648 b 967 c 806 b
60 479 d 245 a 530 b 732 c 1 001 c 867 c

Avg. 408 224 A 4858 626 A 8998 763

Cuts N-Fert. Density CxN CxD NxD CxNxD
F-value NS xxx NS xx NS NS NS
LSD. 05 0.6 % 0.8 %

292



293

4. 1,4. Discussion
Despite good growing conditions the overall average emergence percentage

was 33.4. The growth density was directly related to the seeding density.
Under dry conditions the competition became so severe, that almost from the
beginning of July differences could be distinquished between different seeding
densities. In addition, the final percentage of emergence followed, to a great
extent, the model of Norrington-Davies and Harries (1977).

Initial growth in a young stand is faster under dense than spaced conditions.
At this time LAI is directly proportional to the growing density and a dense
stand reaches the optimum LAI sooner (Davidson and Donald 1958, Donald
1963). Also height growth is faster under dense than spaced conditions because
competition for light stimulates leaf growth (Alberda 1965 a and b). The
fact that in this investigation, during the early development stage, the lowest
seeding density (7.5 kg ha" 1 325 seeds m" 2 ) produced the lowest LAI and
height growth lends support to Alberda’s statement. In contrast to this, at
sowing densities of 15 kg ha- 1 (650 seeds m" 2 ) there were no decisive differences
between the different seeding rates LATs and heights. In addition, the LAI
for the lowest seeding density remained less than the others throughout the
growing season and continued to grow when the LAI increase for the larger
densities had already ceased. Differences in height growth of the seeding
densities evened out before the first cutting. In this investigation it was
observed, as in many other investigations (Donald 1951, 1956, Baumer and
de Wit 1968), that during the seeding year it is possible to raise the dry matter
yield through increased population density. The growing density influenced
the quality of the seeding year yield only in that the raw protein content of
DM in the first harvest was reduced. Donald (1951) observed similar results
in his investigation. On the basis of the results of this investigation the nitrogen
treatment of 200 kg N ha" 1 was detrimental during the seeding year and could
cause poor wintering.

4. 2. Development and Growth of Stand after Seeding Year

Developmental rhythm of forage stand
The dry matter yield of a hay crop increases as the stand becomes older

(Poijärvi 1931, Agerberg 1943, Huokuna 1960 b, Kivimäe 1965, Hernes
1972, Sau and Viiralt 1974, Pestalozzi and Qyen 1977) and its growth follows
a sigmoidal curve. In general the spring growth of a hay crop varies from 150
kg ha"1 to 300 kg ha" 1 of dry matter a day (Rinne 1977). According to Teitti-
nen (1959) and Raininko (1968) the greatest possible total dry matter yield
can be obtained by harvesting twice during the growing season and, putting
off the second cutting for as long as possible because the differences in the
regrowth are smaller than in the main yield. Protein production is strongest
in the early development stages of the plant. Later the protein content de-
creases as protein production slackens, irregardless of the fact that the amount
of dry matter is still increasing strongly. The fastest production of protein
occurs in spring growth when the decrease in protein content is the greatest.



294

In later growth phases changes happen more slowly, and during autumn
growth the protein yield remains lower than what it was in the early summer
(Sau and Viiralt 1974).

Changes in quality as the stand ages are associated with the leave/stem
relationship and development within the cells (Olofsson 1962). According
to Terry and Tilley (1964) and Guequen and Faconneau (1960) the most
decisive factor is stem development, because changes in the composition of
different plant parts occur in a different way as the stand ages. It is significant
that the chemical composition of a plant for a particular development stage
is the same during different years under the same growing conditions (Pou-
tiainen and Rinne 1971).

The dry matter content is lower in the spring yield than in later yields
(Sullivan et al. 1956). Salo et al. (1975) observed a decrease in the dry matter
content of timothy and meadow fescue during the spring until the leave/stem
ratio fell to 1.0—0.8. The dry matter content was 15.4—16.8%. After this
low point, the dry matter content began to rise.

With favorable weather in the spring the reduction in protein content is
rapid. In Finnish investigations the spring decrease in protein content has
been 0.4—1.0 % units a day (Huokuna 1971 b, Poutiainen and Rinne 1971,
Mela and Poutiainen 1975, Antila 1975, Rinne 1977). In the regrowth
the decrease in protein content slows down the closer the end of the growing
season approaches (Sau and Viiralt 1974). In the autumn the protein content
usually surpasses those of the spring and summer yields (Sullivan et al. 1956,
Winkler et al. 1961, Rinne 1976).

The stems of young forage are more digestible than the leaves up until
flowering (Movat et al. 1965). After this point the digestibility reduces faster
in the stems than in the leaves. On the whole, the digestibliity of forage drops
sharply with the advent of flowering (Terry and Tilley 1964). An earlier in-
vestigation (Poutiainen and Rinne 1971) showed that the in vitro digestibility
of organic matter of a timothy-fescue mixture at 20 % flowering decreased by
0.47 % units a day. Following this flowering percentage the digestibility
dropped by 1.0 unit a day. The lignin content, which increases in the later
development stages, reduces forage digestibility relatively linearly even though
the fiber content does not increase anymore (Agerberg 1956, Salo et al. 1975).

Nitrogen and yielding ability of a forage stand

In studies on the affect of nitrogen fertilization on silage stands (Laine
1966, Giöbel and Steen 1960 and 1965) it has been observed that, the dry
matter yield of forage increases linearly up to a fertilization level of 40 kg N
ha" 1 per cutting. Beyond this level nitrogen provides a still smaller increase
in the yield. Beyond a level of 300 kg N ha" 1 per season a stand does not
produce any further significant increase in the growth of dry matter (Laine
1954, Jäntti and Köylijärvi 1964, Steen 1968, Rinne 1971, Huokuna
1973, Hunt et al. 1975, Baerung 1977 a). According to Giöbel and Steen
(1965) protein production is linear up to a level of 60 kg N ha" 1 per cutting.
Beyond this level the protein yield increase begins slowly to become smaller.



295

Hiivola et ai. (1974) suggest that the largest practical amount of nitrogen
for protein yield is also 300 kg N ha"1 per season. In late summer and with
aging crops the fertilizer optimum becomes less and less. Nitrogen fertilizer
reduces the forage’s dry matter content in all growth stages (Anttinen 1961,
Steen 1968, Huokuna 1973, Baerung 1977 b). Steen (1968) found with
pasture studies that the dry matter content dropped with nitrogen fertilizer
applications of up to 375 kg N ha"1

. Applications above this amount encouraged
the dry matter content to rise again.

Giöbel and Steen (1965) showed forage protein content to rise almost
linearly up to a nitrogen level of 240 kg N ha"1

. Hiivola et al. (1974) and
Rinne et ai. (1976) found with silage forage cut three times during the summer
that in the spring growth the protein content rose linearly at nitrogen levels up
to 200 kg N ha" 1

. For the second and third cuttings the increase in protein
content became slower at the highest levels of nitrogen. The greatest rise in
protein content, 4.2 % units, was obtained by applying from 50 to 100 kg N ha'1
per cut (Rinne et ai. 1976).

The minimum allowable protein content for cattle feed, 16—18% of the
dry matter, can be achieved by cutting the crop three times and applying
nitrogen 250-300 kg N ha' 1 (Huokuna 1970, 1971 b, 1973, 1976).

The decrease in hay digestibility because of stand ageing cannot be com-
pensated for by applying more nitrogen fertilizer (Steen 1968, Willman
1975). Poutiainen and Rinne (1976) showed that of silage forage components,

only protein digestibility improved from nitrogen application. The effect of
nitrogen on the digestibility of the other components was not statistically
significant.

Population density in relation to the growth and development of the stand
Wilson (1960) stressed that stand height depends on the competition within

the stand for light. Regarding the utilization of light, it is important that
the crop’s assimilated surface be evenly distributed along the vertical axis.
In this manner each part of the stand receives a balanced amount of light
and even with a small LAI a great amount of growth can be obtained. According
to Kelly (1958) the stand’s height and stem formation greatly affect the
spring growth because the greatest amount of the shoots are generative. In
midsummer a plant usually forms new shoots, which means that the stand
height alone does not determine the yield. In the autumn neither of the afore-
mentioned factors prevail, they both influnce the yield. The use of light
related to the effective height growth in late stages of development is rather
limited because of the decrease in the assimilation rate. Such factors related
to the decrease are canopy formation, cessation of shooting and the influence
of increasing shadow on the acceleration of old leaf withering (Michell and
Calder 1958).

According to Brown and Blazer (1968) the maximum crop yield can be
achieved by maintaining the optimal LAI which is related to the desired
growth rate as compared to a momentarily high one. However, during the
growing season there may be various optimum LAl’s. The lowest LATs



296

promote shooting. On the other hand, the biggest LAI values may be needed
for production of dry hay or pasturing frequently. The maximum seeding
year yields are obtained by making good use of LAI in connection with a large
population density. Over successive growing seasons, however, the stand
conforms to its environment. In regard to competition, the crop becomes
dense or thins to achieve a balanced state (Donald 1956). As the stand ages
there are accompanying changes in the population density such that the less
dense stands produce greater yields (Laine 1958, Nishimura and Nitta 1974).
The effect of applying fertilizer is that for each level of nitrogen a charac-
teristic maximum yield is obtained with increasing population densities (Donald
1951, Norrington-Davies and Growley 1969).

Population density increases competition for light which in turn encourages
lengthwise growth in the leaves. This has the effect of influencing a color
change in the leaves to light green and etiolating the internodes (Alberda
1965 b). An increase in population density lowers the plant’s nitrogen content
(Donald 1951) and the plant parts left in the shade begin to produce me-
chanical tissue which reduces the quality of the forage.

4.2. 7. Spring growth and development
In the actual production years 1976—77, the spring growth comprised the

first cut of the 2-, 3 and 4-cut systems. The spring growth had the characteristic
that each of the influencing growth and development factors individually
increased LAI, dry matter content and yield while at the same time reduced

Table 6. The correlation coefficients between growth factors and some parameters describing
the development of spring growth of the stand.

LAI DM % DM yield Prot. % Cell. dig. %

Crowing days 625* .730** .994*** -.740** -.967***
S > 0° C (temp.) 354 .893*** .945*** -.B4l*** -.953***
ZWhcm-2 (rad.) 247 .909*** .895*** -.B69*** -.93o***
£mm (prec.) 651* .725** .977*** -.658* -.9o9***
kg N ha" 1 300 .602* .552 -.187 -.379*

the protein content and cellulase digestibility of dry matter. Of the influencing
factors on spring growth, the one with the smallest correlation to the yield
was nitrogen fertilization (Table 6). The LAI for spring growth had the highest
correlation with the precipitation of the growing period. Nevertheless, the
highest determination coefficient for spring growth LAI, 81,6 % (F-value =

19.945***), was given by the regression model : Y = —3.1572 + 0.3971 X!
0.0218 X 2
where Xj = growing days

X 2 = temperature sum in degree days (Z > 0° C)

Spring growth’s dry matter content correlated best with the spring radia-
tion energy sum. In the selective regression analysis the dry matter content



297

depended so heavily on the radiation energy sum that no other factors within
the given limits (P = .90) fit into the model
Y = 13.248 + 0.457 X (R 2 = 82.6 %, F-value = 47.4***)

The spring growth dry matter yield had the best correlation with
growing days (R = .994***). The regression model for dry matter yield
was Y = 3198.031 + 115.3085 Xr - 6.1056 X 2 + 1.8524 X 3 + 16.0215 X 4
(R 2 = 99.9 %, F-value = 1245.13***)
where X 4 = growing days

X 2 = nitrogen fertilization for the cut (kg N ha" 1)

X 3 = temperature sum in degree days (27 > 0 °C)
X 4 = precipitation (27mm)

The spring growth’s protein content correlated strongest with the growing
period’s radiation energy sum (R = —.B69***). The highest determination
coefficient 93.0 % (F-value = 59.757***), for protein content was provided
by the regression model Y = 26.2261 0.6595 X, + 0.061 X 2
where X 4 = total radiation (27Wh cm -2)

X 2 = nitrogen fertilization for the cut (kg N ha'1)

The DM cellulase digestibility of the s
the growing days (R = —.967***). The re
Y = 136.9089 - 1.3114 X 4 - 0.6540 X 2 -

(R 2 = 99.1 %, F-value = 188.703***)

spring growth correlated best with
regression model was

8.7564 X 3 + 0.456 X*

where X 4 = growing days
X 2 = precipitation (27ram)
X 3 = total radiation (27Wh cm -2 )

X 4 = temperature sum in degree days (27 > 0° C)

4. 2. 2. Summer growth and development
Midsummer temperature and radiation intensities are high and most often

there is a prevailing scarcity of water. Summer growth comprised the second
cut in the 3- and 4-cut systems as well as the third cut in the 4-cut system.

The midsummer changes in crop growth were noticeably more irregular than
during the spring. Only five statistically significant correlations were ob-
served between the factors describing the yield and the growth factors (Table 7).

Table 7. The correlation coefficients between growth factors and some parameters describing
the development of the summer growth of the stand.

LAI DM % DM yield Prot. % Cell, dig %

Growing days 220 -.670* .345 —.160 —.397
27 > 0 °C (temp.) 186 -.559 .120 0 -.104
27 Whcm'2 (rad.) -.081 -.156 ,055 .048 -.775**
27mm (prec.) 340 -.589* .341 .120 -.297
2mm 1) (prec.) 198 -.448 .360 -.331 .324
kg ha"1 2) -.011 -.199 -.021 .045 -.530
kg N ha'1 635* -.380 .199 ,716** -.120

*) Precipitation mm during one week before previous cut
2 ) yield kg ha-1 in the earlier cut.



298

In the selective regression model only nitrogen fertilization had statistically
significant influence on LAI development. The model was
Y = 1.5133 + 0.0364 X (R a = 40.4 %, F-value 6.773*)

The dry matter content had a strong correlation (R = —.670*) to the
midsummer growing days. The regression model which gave the best deter-
mination coefficient (80.8 %, F-value = 7.358*) was
Y = 44.0798 - 0.5364 X x + 0.0024 X 2 - 0.0497 X 3 - 0.0405 X 4
where Xx = growing days

X 2 = previous cut’s yield (kg ha' 1 )

X 3 = nitrogen fertilization for the cut (kg N ha' 1)

X 4 = precipitation (£mm)

All of the growth influencing factors investigated poorly described the
development of the dry matter yield. In the selective regression analysis all
variables remained below the given limits (P = .90).

Nitrogen fertilizer was the factor affecting the protein content development
the most (R = .716**). The following regression model gave the highest
coefficient of determination (85.6 %, F-value = 10.389**)
Y = 22.39065 + 0.1416 Xj - 1.1480 X 2 + 0.0448 X 3 + 0.0392 X 4
where X x = nitrogen fertilization for the cut (kg N ha' 1)

Z 2 = growing days
X 3 = temperature sum in degree days (if> O°C)
X 4 = precipitation (Zrnm)

Concerning the DM cellulase digestibility of the summer growth, the
following regression model gave the highest coefficient of determination
(97.8 %, F-value = 79.308***)
Y = 83.0525 + 0.2060 X x + 0.1308 X 2 - 2.7610 X 3 + 0.0262 X 4
where Xx = precipitation during the week before the previous cut (£ mm)

X 2 - temperature sum in degree days (£ >o° C)
X 3 = growing days
X 4 = nitrogen fertilization for the cut (kg N ha' 1)

4. 2. 3. Fall growth and development
In late summer the day length shortens, daytime and especially nighttime

temperatures drop and the radiation intensity in particular decreases. On the
other hand, rainfall is abundant and this abundance is not a limiting growth factor
at this time as it was in midsummer. Also the autumn growth changes are more
irregular than those of the spring but are not as irregular as the summer ones. All
of the final cuts of the various cutting systems are categorized under fall cuttings.

Growth factor influence on fall growth LAI was not determined because
the autumn LAI was recoredd only for 1976.

The highest coefficient of determination for fall growth’s dry matter content
(95.1 %, F-value = 33.837***) was obtained with the following regression
model Y = 22.531 + 0.50428 X x - 0.05237 X 2 - 0.00101 X 3 - 0.11299 X 4
where Xj = total radiation (IWh cm." 2)

X 2 = nitrogen fertilization for the cut (kg N ha' 1 )

X 3 = previous cut’s yield (DM kg ha' 1)

X 4 = precipitation during the week before the previous cut (S mm)



299

Table 8. The correlation coefficients between growth factors and some parameters describing
the development of the fall growth of the stand.

DM % DM yield Prot. % Cell. dig. %

Growing days .550 .760** -.504 -.788**
E > O°C (temp.) .605* .716** -.487 -.737**
ZWhcm"2 (rad.) .663* .631* -.443 -.637*
2mm (prec.) .277 .828*** -.508 -.B62***
mm1) (prec.) —.331 .215 -.205 -.285
kg ha" 1 2) .248 .638* -.321 -.670*
kg N ma" 1 -.037 .782** .294 -.319

') Precipitation mm during one week before previous cut.
a) yield kg ha-1 in the earlier cut.

DM % DM yield Prot. % Cell. dig. %

Whereas the dry matter yield of the summer growth did not correlate with
any of the growth factors, the yield from the fall growth was found to correlate
with the precipitation measured during the week before the previous cut
(Table 8). The best regression model for the dry matter yield was (R 2 = 93.9 %,

F-value =40.720***)
Y = -1249.79 + 13.7815 Xi + 19.6328 X 2 + 53.190 X 3
where Xj = precipitation (Z mm)

X 2 = nitrogen fertilization for the cut (kg N ha' 1)

X 3 = precipitation during the week before the previous cut (Z mm)

The dependence of the fall growth’s protein content on one separate growth
factor turned out to be low. The protein content development was best de-
scribed by the following regression model (R 2 = 93.1 %, F-value = 36.253***)
Y = 18.4625 - 0.0195 X 3 + 0.1029 X 2 - 0.1470 X 3
where Xj = precipitation [Z mm)

X 2 = nitrogen fertilization for the cut (kg N ha' 1 )

X 3 = growing days

For depicting the cellulase digestibility of the fall growth the following
regression model was used Y = 70.4166 0.1010 X t 0.2720 X 2
where Xj = precipitation [E mm)

X 2 = precipitation during the week before the previous cut (E mm)

The coefficient of determination for changes in the DM cellulase digest-
ibility was 86.8 % (F-value = 29.496***).

4. 2.4. Growing time and temperature relations to growth and development
characters of a forage stand

The growing days and the temperature sum in degree days are the most
important factors upon which the descriptive factors of spring, summer and
fall growth depend. These two factors are basic growing conditions for forage
crops in Finland.



Spring growth
In general, all of the investigated characters related to the yield of spring

growth showed relatively strong changes. All regression equations were of the
third degree which had very high statistical significance. The independent
variables in the regression equations were either growing time (a) or temperature
sum in degree days (b). The regression equations were as follows (Fig. 5).

1. LAI

a) Y = 0.009661 - 0.054069 X + 0.007144 X 2 - 0.000074 Xs (R = .876»*»)
b) Y = 0.043788 + 0.006107 X + 0.000033 X 2 - 0.00000004 X 3 (R = .836***)

2. Stand height
a) Y = 0.532344 + 0.255315 X + 0.033959 X 2 - 0.000230 X 3 (R = .988***)
b) Y = 0.759275 + 0.077105 X + 0.000295 X 2 - 0.00000031 X 3 (R = .995***)

Fig. 5. Spring development and
growth of the fesque stand after
seeding year in relation to the
growing days and to the tempera-
ture conditions in degree days.

300



301

3. Dry matter content
a) y = -36,474 + 3.74591 X - 0.08198 Xs + 0.000615 X 3 (R = .868***)
b) Y = -12.4056 + 0.21366 X - 0.044399 X 2 + 0.000031 X 3 (R = .973***)

4. Dry matter yield
a) Y = 0.792528 - 65.7417 X + 4.21189 X 2 - 0.026107 X 3 (R = .998***)
b) Y = 5.75349 - 1.65495 X + 0.027957 X 2 - 0.00007 X 3 (R = .977***)

5. Protein content
a) Y = 33 6065 - 0.013368 X - 0.018151 X 2 + 0.000204 X 3 (H = .917•••)
b) Y = 52.1947 - 0,167158 X + 0.000254 X 2 - 0.00000014 X 3 (R = .952»*«)

6. Cellulase content

a) Y = 51.0319 + 2.36978 X - 0.06537 X 2 + 0.000431 X 3 (R = .955»**)
b) Y = 60.1753 + 0.150145 X - 0.000428 X 2 + 0.00000028 X 3 (R = .966*»*)

Summer growth
The correlation of midsummer growth to growing days and temperature

sum in degree days was less and noticeably less, respectively, than for spring

Fig. 6. Summer development
and growth of the fesque stand
after seeding year in relation
to the growing days and to the
temperature conditions in de-
gree days.



302

growth. In particular, midsummer growth had especially slow changes in the
dry matter and protein contents. Also, the cellulase digestibility of dry matter
dropped relatively slowly and linearly. The independent variables for mid-
summer growth were either growing time (a) or temperature sum in degree
days (b). The regression equations were as follows (Fig. 6):
1. LAI
a) Y = -0.025061 + 0 183391 X + 0.00389 X 2 - 0.000039 X 3 (R = .853***)
b) Y = -0.029375 + 0.012003 X - 0.0000155 X 2 + 0.000000009 X 3 (R - .850***)

2. Stand height
a) Y = 5.14303 + 1.28261 X + 0.073425 X 2 - 0.0016839 X 3 (R = .992***)
b) Y = 4.98153 + 0.146748 X - 0.0000223 X 2 - 0.00000011 X 3 (R = .988***)

3. Dry matter content
a) Y = 24.5757 - 0.624244 X + 0.03392 X 2 - 0.0004598 X 3 (R = .486**)
b) Y = 18.1263 + 0.009892 X + 0.000026 X 2 - 0.00000004 X 3 (R = .505**)

4. Dry matter yield
a) Y = 4.591 + 42.442 X + 0.15536 X 2
b) Y = 20.4374 + 4.79395 X - 0.27944 X 2

(R= .822***)
(R= .791***)

5. Protein content

a) Y = 16.3465 + 0.89533 X - 0.04697 X 2 + 0.00059 X 3 (R = .626***)
b) Y = 23.6649 - 0.018688 X + 0.0000091 X 2 - 0.000000001 X 3 (R- .598***)

6. Cellulase digestibility %

a) Y = 89.0095 - 0.945977 X + 0.002175 X 2
b) Y = 70.6825 - 0.02441 X

(R = .702*»)
(r = .381 NS)

Fall growth
The changes in dry matter and protein contents occurred relatively slowly

also during late summer, LAI did not reach its maximum in the autumn despite
a growing period of 90 days in the 2-cut system. The regression equations
for late summer growth with the independent variables of either growing period
(a) or temperature sum in degree days (b) were as follows (Fig. 7):

1. LAI
a) Y = -0.104588 + 0.109084 X - 0.000270 X 2
b) Y = -0.129214 + 0.908704 X - 0.0247926 X 2
2. Dry matter content

(R = .853**)
(R= .853**)

a) Y = 22.1133 - 0.251295 X + 0.005943 X 2 - 0.0000258 X 3 (R = .638»**)
b) Y = 16.2234 + 0.020281 X - 0.000035 X 2 + 0.00000002 X 3 (R = .566***)

3. Dry matter yield
a) Y = -8.71256 - 10,0924 X + 1.15345 X 2 - 0.006842 X 2 (R = .877***)
b) Y = 13.8027 - 0.988314 X + 0.0083108 X 2 - 0.0000044 X 3 (R = .863***)

4. Protein content

a) Y = 23.0423 + 0.06078 X - 0.006185 X 2 + 0.000046 X 3 (R = .808»**)
b) Y = 24.6414 - 0.006555 X - 0.000012 X 2 + 0.000000008 X 3 (R = .746***)

5. Cellulase digestibility %

a) Y = 75.4445 - 0.36397 X + 0.000866 X 2
b) Y = 73.084 - 0.027699 X + 0.0000077 X 2

(R= .806**)
(R = .743**)



303

For the 1976—77 cuttings also the relationships between LAI and dry
matter yield were determined (Fig. 8). During spring growth the dry matter
yield increased rather sharply as LAI increased. However, as LAI increased
over the growing period the resulting increase in yield slowly decreased, but
at the same time significance of the liner regression line improved.

4. 2. 5. Discussion
The growing conditions under which forage yield development is the most

effective in Finland, occur in early summer. Because of long days there is
abundant light, the radiant intensity is high, temperatures are relatively high
and the amount of water for plant utilization in the soil is sufficient. How-
ever, a scarcity of water can limit the benefits of the other aforementioned
conditions. In the autumn there is abundant water for plants, but light and
temperature become the limiting factors. In addition, growth slows down
anyway in the autumn because the plant gradually starts to prepare for win-
tering (Rappe 1948).

The regression models describing the yield show that the yield forming
characteristics of spring growth experienced faster changes than the yield

Fig. 7. Autumn development
and growth of the fesque stand
after seeding year in relation
to the growing days and to the
temperature conditions in de-
gree days.



304

quality characters of mid and late summer growth. These results agreed with
those of many previous investigations (Huokuna 1964 and 1973, Poutiainen
and Rinne 1971, Syrjälä 1973 and 1974, Hiivola et al. 1974, Salo et ai.
1975, Rinne 1977). The growth factors which best described the spring growth
DM yield were growing days, temperature sum in degree days and total radia-
tion.

Midsummer growth is most often limited by a shortage of water. By ap-
plying nitrogen fertilizer it is possible, in part, to overcome the effect of drought
(Mela 1974), and therefore the fertilizer displays a more noticeable influence
on midsummer growth than spring growth. An important factor to ensure
establishment of a sufficient assimilative surface is enough water immediatly
after cutting. In the midsummer regression model the most important variables
affecting the yield were the amount of nitrogen applied precipitation, and the
precipitation during the week before the prior cutting. What is particularly
worth considering is the low coefficient of determination in the selective
regression model, while in the descriptive parabola for the dry matter yield
both the growing time and the temperature sum in degree days were sta-
tistically highly significant.

Not including the dry matter content, in the regression model for fall growth
the factor which best described crop growth was the late summer precipitation.
The regression model for the fall DM yield surprisingly set the precipitation, the

Fig. 8. The relationship between the dry matter yield (DM kg ha-1 ) and
leaf area index (LAI) in spring, summer and autumn growth.



305

amount of nitrogen applied and the precipitation during the week before the
prior cutting as the most determining factors; presumably due to the dominant
weather conditions. During the investigation years, August remained notice-
ably below the long-term average and, the abundant September rains could not
counteract the stop in growth which occurred in August because the other
growth factors decreased at the same time. According to the regression model,
precipitation reduces the protein content and cellulase digestibility of the DM
yield. Olofsson (1962) and Salo et ai. (1975) suggest that in grasses ample
moisture easily increases the amount of mechanical tissue at the expense of
digestible material.

LAI and dry matter yield had extremely statistically significant corre-
lations with spring, summer and fall growth. The significance was lowest in the
spring when stem formation was strongest and the highest for the leafy autumn
yield.

During spring growth an increase in LAI of one LAI-unit increased the
yield by 710 kg ha' 1. The maximum LAI of 8.5 was reached 50—60 days after
the initiation of growth in the spring, at which time it began to decrease but
the stand’s height still increased. The maximum LAI for spring growth was
achieved with a temperature sum of 550° C (i7> 0° C).

The reduction in LAI at the end of the spring growth shows that a crop
left growing longer would have gone beyond the optimum cutting time as
determined with the aid of LAI (Brown and Blaser 1968) even though the
height was still increasing. The LAl’s determined in this investigation cor-
responded with those of previous studies (Brougham 1958, Evans 1964,
Raininko 1968).

The protein content dropped sharply in the temperature range of 150
350° C, where a rise in cumulative temperature sum of 10° C induced a 0.17 %

units deci'ease in protein content. At the same time, every 10° C increase
caused a 0.4 % units increase in dry matter content. The second intensive
increase in dry matter content begins during the growth stage where LAI
reaches its maximum. The digestibility of dry matter improves in the spring
and then begins to decrease a little bit later than the protein content does.
Cellulase digestibility of dry matter declines in the temperature lange of
250 650° C, where a 10° C rise reduces digestibility by abount 0.6 % units.

In 45 growing days the midsumer LAI reached a value of 4, and an one
LAI-unit rise corresponded to an increase in dry matter yield of 500 kg/ha.
In contrast to the spring LAI, the midsummer LAI had not reached its maxi-
mum whereas in the span of 35 days and with the temperature sum = 600° C,
the crop reached its maximum height. Both the protein content and DM
cellulase digestibility reductions were steady during summer growth.

In the temperature range of 200—400° C every 10° C increase in cumulative
temperature sum brought about a 0.1 % unit and 0.4 % units reduction in *he
protein content and cellulase digestibility respectively. At the same time each
10° C rise increased the dry matter content by 0.1 %.

The autumn LAI was initially almost as vigorous as the midsummer LAI
in regard to growing period or temperature sum in degree days. In the 92 day
growing period the autumn LAI approached a value of 8. Usually in the autumn



306

the LAI remains less than the early and late summer ones (Anslow 1965 a
and b). For fall growth an increase of LAI unit increased the dry matter
yield by 315 kg ha' 1

.

4. 3. Forage Yields and Quality

4. 3. 7. Dry matter content
The total DM yield’s dry matter content was, on the average, significantly

higher during the production years for the 2-cut system than for the 3- and
4-cut systems (Table 9, Fig. 9). There were no significant differences between
individual cuttings in regard to the dry matter contents for any of the cutting
systems over the two year average (Fig. 10). Nitrogen fertilization decreased
the DM yield’s dry matter contents, even though a statistically significant
difference was recorded actually for only the first production year. By checking
each cutting system it was found that nitrogen reduced the dry matter content
by a statistically significant amount only in the 4-cut system (Fig. 9). Nitrogen
also had an effect on the individual cuttings’ dry matter content only in the
4-cut system which had the most significant differences in its late summer
cuttings (Fig. 10).

Seeding rate was significant at a low nitrogen level in the 2-cut system
during the first actual production year in such a way than an increase in the
seeding rate significantly increased the dry matter content (Table 9). The
reason for this was the overdelayed cutting time resulting in overmaturity
and a decrease in quality. The dry matter content proved to significantly
decrease also when using the 4-cut system at a low level of nitrogen combined
with the highest seeding rate (Fig. 10).

Fig. 9. Average dry matter content (% DM) of three cutting systems at four population
densities and two levels of nitrogen.



307

Table
9.

Dry
matter
content
(%)

of
the
stand
in

1976
and

1977.

Seeding
rate

2-cut

3-cut

4-cut

Cuts
avg.

kg
ha"
1

130N 260NAvg.

130N 260NAvg.

130N 260NAvg.

130N 260NAvg.

1976

7.5

29.2a 30.4a 29.8a 25.6a 25.2a 25.4a 25.3b 24.5a 24.9a 26.7a 26.7a 26.7
a

15

30.9ab
30.7a 30.8a 26.0a 25.7a 25.9a 25.9b 24.1a 25.0a 27.5a 26.7a 27.1

a

30

31.3bc
30.2a 30.8a 25.9a 25.1a 25.5a 25.7b 24.1a 24.9a 27.6a 26.5a 27.1

a

60

32.1c 29.4a 30.8a 24.9a 24.7a 24.8a 24.2a 23.9a 24.1a 27.1a 26.0a 26.6
a

Avg.
30.9a 30.2a 30.68

25.6a 25.2a 25.4A 25.3b 24.2a 24.8a 27.2b 26.5a 26.9

1977

7.5

26.8a 27.4a 27.1a 23.5a 21.5a 22.5a 23.0a 20.9a 22.0a 24.4a 23.3a 23.9
a

15

27.4a 27.1a 27.3a 23.7a 21.1a 22.4a 23.0a 20.9a 22.0a 24.7a 23.0a 23.9
a

30

27.7a 26.8a 27.3a 23.5a 21.6a 22.5a 22.9a 21.0a 22.0a 24.7a 23.1a 23.9
a

60

27.2a 27.5a 27.4a 23.0a 21.0a 22.0a 22.3a 20.9a 21.6a 24.2a 23.1a 23.7
a

Avg.
27.3a 27.2a 27.38

23.4a 21.3a 22.4A 22.9a 20.9a 21.8A 24.5a 23.1a 23
8

Cuts

N-fert.
Density

CxN
CxD
NxD
CxNxD

1976
F-value

xxx
x

NS

NS

NS

NS

NS

LSD.
05

1.1
%

0.6
%

1977
F-value

xxx
x

NS

NS

NS

NS

NS

LSD.
05

1.5%
1.3%

F-years
xxx,

LSD
05

0.8
%



4. 3. 2. Dry matter yields
The dry matter yields for the seeding year average 4.4 tons ha' 1

, and for
the two following production years 6.7 and 9.2 tons ha' 1 respectively. The
greatest dry matter yield was obtained by cutting twice and the smallest by
cutting four times (Table 10). The differences between cutting systems were
statistically significant for 1976 and 1977 (Table 10) and on the average for
1976—77 (Fig. 11). In the grand total yield for 1976—77 (Fig. 13) the yield
level of the 4-cut system was significantly lower than yield level of the other
cutting systems.

During the first cut of the 2-cut system two-thirds of the total yield tor
the growing period were obtained (Table 11). The 3-cut system produced the
largest yields in the first cut and the smallest in the second in midsummer
(Fig. 12). In the 4-cut system the smallest yield was obtained in the last cut
(Table 11). On the average for 1976—77 the largest part of the total yield
came from the second cut of the 4-cut system, followed by the first and third
cuts respectively. However, the cuttings did not statistically differ from
each other (Fig. 12).

Nitrogen increased the dry matter yield significantly for all the cutting
systems for 1976—77. The average increase in the grand total yield for 1976
77, based on the nitrogen fertilizer change of 130 kg ha'1 —260 kg ha' 1

, was
2 271 kg ha' 1 (Fig. 13). Adding nitrogen had the tendency of evening out the
yield differences between cuttings in each cutting system. What was significant
was that in the first cuttings there were no statistically significant differences
such as those which showed up in later cuttings (Table 11, Fig. 12).

Fig. 10. Average dry matter content (% DM) of individual cuts in three cutting systems
seeded at four population densities and ferilized at two levels of nitrogen.

308



309

Table
10.

Dry
matter

yields
(DM,
kg
ha"
1
)

of
the
stand
in

1976
and

1977.

Seeding

2-cut

3-cut

4-cut

Cuts
avg.

rate
kg
ha"
1

130N 260NAvg.

130N 260NAvg.

130N 260NAvg.

130N 260NAvg.

1976

7.5

7
278a 8240a 7759a 5992a 6213a 6102a 4873a 5017a 4945a 6048a 6490a 6269

a

15

7
671a 8354a 8013ab

6
132a 7142b 6637ab

4
931ab
5
234ab
5
083ab
6
245ab
6
910ab
6
578
b

30

7
915ab
8

414a 8164ab
6

606a 7621b 7114b 5218ab
5
931bc
5
573bc
6
580bc
7
322bc
6
951bc

60

8
430b 8777a 8604b 6464a 7365b 6915b 5661b 6229c5945c6852c7457c7155

c

Avg.
7

824a 8446b 8135C6299a 7085b 66928
5

171a 5603b5387A

6
437a 7045b 6738

1977

7.5

9
123a 10
497a 9810a 7911a 9651a 8781a 6698a 8559a 7629a 7911a 9569a 8740

a

15

9
865ab

11412a 10
639b7963a 9773 ab

8
868ab
7

021a 9147ab
8
084ab
8
283 ab
10

lllab
9

197
b

30

9
810ab
10

896a 10
353b8548a 10

039ab
9
294ab
6

985a 9130ab
8
058ab
8
448 ab
10

022ab
9
235
b

60

10
468b 10
762a 10
615b8606a 10
408b9507b7111a9731b8421b8728b 10
300b9514

b

Avg.
9

816a 10
891b 10
355C8258a9968b91138

6
954a9142b8048

A

8
343a 10
001b9172

Cuts
N-fert.

Density
CxN

CxD

NxD
CxNxD

1976
F-value

xxx
xxx
xxx

NS

NS

NS

NS

LSD.QS
621

218

307

1977
F-value

xxx
xx

x

NS

NS

NS

NS

LSD.
0ä

540

590

370

F-years*,
LSD.

05
=

545



310

The yield level rose slightly with increases in the seeding rate from 7.5 kg
ha"1 to the highest one of 60 kg ha"1 (Fig. 9). However, the statistical maximum
yield for the 2-cut system in both production years and, on the average, was
achieved with the seeding rate of 15 kg ha" 1

. At the higher nitrogen level the
lowest seeding rate (7.5 kg ha' 1) was enough to obtain the statistical maximum
yield, but on the average at the lower nitrogen level the highest seeding rate
(60 kg ha" 1) was needed (Fig. 11).

Table 11. The relative proportions (%) of individual cuts in the total dry matter yields in
1976-77.

Cuttings % o£ total y ield
130 N 260 N Avg.

2-cut Cut 1. 69.8 59.9 64.6
Cut 2. 30.2 40.1 35.4

3-cut Cut 1. 54.1 42.0 47.6
Cut 2. 20.3 27.1 21.0
Cut 3. 25.6 36.3 31.4

4 cut Cut 1. 31.9 24.4 27.8
Cut 2. 36.0 30.1 32.8
Cut 3. 20.5 28.7 25.0
Cut 4. 11.6 16.8 14.4

Fig. 11. Average dry matter yields (DM tons ha-1) of three cutting systems at four popula-
tion densities and two levels of nitrogen.



311

Table
12.

Raw
protein
content
(%)

in
dry

matter
in

1976
and

1977.

Seeding

2-cut

3-cut

4
cut

Cuts
avg.

rate
kg
ha"
1

130N 260NAvg.

130N 260NAvg.

130N 260NAvg.

130N 260NAvg.

1976

7.5

9.1a 12.5a 10.8a 10.8a 14.4a 12.6a 14.6a 18.7a 16.7a 11.5b 15.2a 13.4
a

15

9.2a 13.1a 11.2a 10.8a 14.8a 12.9a 14.8a 19.2a 17.0a 11.6b 15.7a 13.6
a

30

9.0a 12.8a 10.9a 10.6a 14.4a 12.5a 13.6a 18.7a 16.2a 11.
lab

15.3a 13.2
a

60

B.la
12.9a 10.5a 10.1a 14.8a 12.5a 13.7a 19.1a 16.4a 10.6a 15.6a 13.2

a

Avg.
8.9a 12.9b 10.9A 10.6a 14.6b 12.6A 14.2a 18.9b 16.68

11.2a 15.5b 13.4

1977

7.5

9.9a 13.2a 11.6a 12.6a 17.0a 14.8a 13.7
a

17.5a 15.6a 12.1a 15.9a 14.0
a

15

9.8a 13.7a 11.8a 12.2a 17.7a 15.0a 13.8a 17.5a 15.7a 11.9a 16.3a 14.1
a

30

9.7a 13.5a 11.6a 12.0a 16.4a 14.2a 13.9a 17.3a 15.6a 11.9a 15.7a 13.8
a

60

9.5a 13.6a 11.6a 11.9a 16.1a 14.0a 13.6a 17.2a 15.3a 11.7a 15.6a 13.7
a

Avg.
9.7a 13.5b 11.6A 12.2a 16.8b 14.58

13.8a 17.4b 15.68

11.9a 15.9b 13.9

Cuts
N-fert.

Density

CxN

CxD
NxD
CxNxD

1976
F-value
x

xxx
NS

x

NS

NS

NS

LSD.
05

1.9
%

0.2
%

1977
F-value
x

xxx
NS

NS

NS

NS

NS

LSD.
05

1.8
%

0.3
%

F-years*,
LSD.

05
=

0.5
%



For the 3-cut system the statistical maximum yield in both production
years at the higher nitrogen level was got with the seeding rate of 15 kg ha" 1

(Table 10). At the lower nitrogen level the lowest seeding rate was sufficient
for maximum yield. However, on the average the rate of 30 kg ha" 1 was
required for the statistical maximum yield in production years 1976 77.

In the 4-cut system the seeding rate had an especially significant influence
on the yield. For the maximum yield in 1976 at the low level of nitrogen
the seeding rate of 15 kg ha" 1 was needed and at the high level, 30 kg ha" 1

.

In the following year to achieve the coinciding maximum yield levels the
seeding rates needed were: 7.5 kg ha" 1 and 15 kg ha"1 (Table 10). On the average,
the maximum yield for these years at the low level of nitrogen was reached
with the seeding rate of 15 kg ha"1

, and at the high level with 30 kg ha" 1

(Fig. 11).

4. 3. 3. Raw protein content of dry matter
The protein content of the total dry matter yields was highest in both

years in the 4-cut system and lowest in the 2-cut one (Table 12). On the average
for 1976—77 the differences in protein content between all cutting systems were
statistically significant (Fig. 14).

In 1976—77 the differences between cuttings regarding protein content
in the 2-cut system favored the fall cutting by 1.3 % units. The difference
was not statistically significant (Fig. 15). In the 3-cut system the highest
protein content was obtained in the second cutting and the lowest in the fall
cutting. However, the differences were not statistically significant. There
were no statistical differences between the cuttings of the 4-cut system during
1976—77, although, if ranked according to results they would be first, third,
fourth and second cutting.

Fig. 12. Average dry matter yields (DM tons ha"1 ) of individual cuts in three cutting systems
seeded at four population densities and two levels of nitrogen

312



313

Nitrogen fertilizer raised the protein content by 4.1 percentage units on ihe
average: a very significant amount. The addition of nitrogen fertilizer produced
average increases of 3.9, 4.3 and 4.2 percentage units in the 2-, 3- and 4-cut
systems respectively.

For 1976 it was observed that the fertilizer’s and cuttings’ combined effect
was such that additional nitrogen increased the protein content in the second
cutting of the 2-cut system and in the third cuttings of both the 3- and 4-cut
systems. The seeding rate had very little significance for the protein content
of the dry matter yield.

4. 3. 4. Raw protein yields
In 1976 (the year after seeding), all three cutting systems produced close

to the same amount of protein per unit of surface area. In 1977 statistically
significant differences occurred between all of the cutting systems. On the
average for 1976 77, protein yield differences were not observed, 2-cut system,
1 052 kg ha" 1

, 3-cut system, 1 097 kg ha"1
, 4-cut system, 1 086 kg ha" 1 (Table

13). Also in the grand total yield for 1976—77 there were no statistically signifi-
cant differences between the cutting systems (Fig. 16).

Nitrogen fertilizer increased the protein yield by an average of 364, 608
and 486 kg ha-1 for 1976, 1977 and 1976—77 respectively. The amount of the
1976—77 combined protein yield was influenced very significantly (P = 0.001)
by the nitrogen fertilizer.

Fig. 13. Total dry matter yields (DM tons ha-1 ) in 1976 —77 of three cutting
systems seeded at four population densities and fertilized at two levels of
nitrogen.



314

Table
13.

Raw
protein
yields
(kg
ha-1
)

in
1976

and
1977.

Seeding

2-cut

3-cut

4-cut

Cuts
avg.

rate
kg
ha"
1

130N 260NAvg.

130N 260NAvg.

130N 260NAvg.

130N 260NAvg.

1976

7.5

666a 1032a 849a 648a 894a 771a 710a 938a 824a 675a 956a 816
a

15

703a 1115ab
909a 668a 1056b 862b 730a 1OOlab

866ab

700a 1057b 879
b

30

714a 1073ab
894a 698a 1093b 896b 709a 1109bc

909bc

707a 1092bc
900bc

60

685a 1140b 913a 654a 1091b 873b 778a 1188c 983c706a 1140c 923
c

Avg.
692a 1090b 891

A

667a 1034b 851
A

732a 1059b 896A 697a 1061b 879

1977

7.5

901a 1389a 1145a 996a 1644a 1320a 918a 1499a 1209a 938a 1511a 1225
a

15

966a 1560b1263b 975a 1731a 1353a 972a 1603 ab
1

289 ab

971a 1631b1301
b

30

949a 1475b1212b1029a 1649a 1339a 970a 1584ab
1

277ab

983a 1569b1276
b

60

990a 1469b1230b1026a1677a1351a 970a1676b1323b 995

1
607b1301

b

Avg.
952a1473b1213A1007a1675b1341C 958a1591b12758

972a1580b1276

Cuts
N-fert

Density

CxN
CxD
NxD
CxNxD

1976
F-value

NS

xxx
xxx

NS

NS

xx

NS

L
D.

05

33
kg

40
kg

57
kg

1977
F-value

x

x

xx

NS

NS

NS

NS

L
D.

05

60
kg

107
kg

49
kg

F-years**,
LSD.

05
=

215
kg



315

Fig. 14. Average protein content (prot. % in DM) of three cutting systems at four popula-
tion densities and two levels of nitrogen.

Fig. 15. Average protein content (prot. % in DM) of individual cuts in three cutting systems
seeded at four population densities and fertilized at two levels of nitrogen.



Table
14.

Cellulase
digestibility
of
dry
matter
in

1976
and

1977.

Seeding

2-cut

3-cut

4-cut

Cuts
avg.

rate
kg
ha"
1

130N 260NAvg.

130N 260NAvg.

130N 260NAvg.

130N 260NAvg.

1976

7.5

51.4a 53.5a 52.5a 55.1a 57.5a 56.3a 63.3a 63.3a 63.2a 56.6a 58.1a 57.4
a

15

51.2a 53.4a 52.3a 54.7a 57.4a 56.1a 63.8a 64.6a 64.2a 56.6a 58.5a 57.6
a

30

50.9a 51.0a 51.0a 56.5a 58.3a 57.4a 64.6a 65.2a 64.9a 57.3a 58.2a 57.8
a

60

50.9a 51.3a 51.1a 57.1a 58.2a 57.7a 64.2a 66.2a 65.4a 57.4a 58.6a 58.0
a

Avg.
51.1a 52.3a 51.8A 55.9a 57.9a 56.9A8
64.0a 64.8a 64.48

57.0a 58.4a 57.7

1977

7.5

46.9a 47.8a 47.4a 53.5a 56.9a 55.2a 60.8a 61.4a 61.1a 53.7a 55.4a 54.6
a

15

46.2a 48.2a 47.2a 55.2a 56.6a 55.9a 61.1a 62.9a 62.0a 54.2a 55.8a 55.0
a

30

45.4a 48.4a 46.9a 56.6a 55.5a 56.1a 60.5a 61.4a 61.0a 54.2a 55.1a 54.7
a

60

45.4a 48.3a 46.8a 55.3a 54.5a 54.9a 59.6a 60.5a 60.1a 53.4a 54.4a 53.9
a

Avg.
46.0a 48.2b 47.

1A

55.2a 55.9a 55.58

60.5a 61.6a 61.
1C

53.9a 55.2b 54.6

Avg.
years

7.5

49.1a 50.7a 49.9a 54.3a 57.2a 55.8a 62.1a 62.3a 62.2a 55.2a 56.8a 56.0
a

15

48.7a 50.8a 49.8a 55.0a 57.0a 56.0a 62.5a 63.8a 63.2a 55.4a 57.2a 56.3
a

30

48.2a 49.7a 49.0a 56.6a 56.9a 56.8a 62.6a 63.3a 63.0a 55.8a 56.7a 56.3
a

60

48.2a 49.8a 49.0a 56.2a 56.4a 56.3a 61.9a 63.3a 62.6a 55.4a 56.5a 56.0
a

Avg.
48.6a 50.3a 49.5A 55.5a 56.9a 56.28

62.3a 63.2a 62.8C 55.4a 56.8a 56.2

Cuts

N-fert.
Density

CxN

CxD
NxD
CxNxD

years

1976
F-value

x

NS

NS

NS

NS

NS

NS

LSD.
05

9.9
%

1977
F-value

xxx
x

NS

x

NS

NS

x

LSD.
oä

1.0
%

0.7
%

1976-77
F-value

xxx
NS

NS

NS

NS

NS

x

xxx

LSD.
05

0.8
%

2
1

%

0.4
%

316



Table
15.

Wintering
ability
of
the
stand
under

different
management

practices
in

1976
77

(Scale:
10
=

no
damage,
0

=

completely
disappeared).

Seeding
rate

After
first
winter

After
second
winter

kg
ha"
1

100N 200NAvg.

2-cut

3-cut

4-cut

Sits
avg.

130N 260NAvg.

130N 260NAvg.

130N 260NAvg.

130N 260NAvg.

7.5

9.4

7.8

8.6

9.3

9.0

9.1

9.4

8.5

9.0

9.6

9.6

9.6

9.4

9.0

0.2

15

9.2

7.6

8.4

9.6

9.0

9.3

9.8

9.2

9.5

9.8

9.8

9.8

9.7

9.3

9.5

30

9.6

8.1

8.8

9.8

9.3

9.5

9.8

9.7

9.8

9.8

9.8

9.8

9.8

9.6

9.7

60

9.6

8.4

9.0

9.9

9.3

9.6

9.6

9.2

9.4

10.0
9.8

9.8

9.8

9.4

9.6

9.5

8.0

8.7

9.7

9.2

9.4

9.7

9.2

9.4

9.8

9.8

9.8

9.7

9.3

9.5

Cuts
N-fert.

Density
CxN

CxD
NxD
CxNxD

F-value First
winter

xxx
NS

NS

Second
winter

NS

xx

xxx
NS

NS

NS

NS

317



318

In 1976 the maximum protein yield was achieved with a seeding rate of
30 kg ha’1

, and in 1977 with 15 kg ha’ 1 (Table 13). At the low nitrogen level
the seeding rate had no effect on the protein yield in any of the cutting systems.
At the high nitrogen level the minimum seeding rate was not sufficient for
reaching the maximum protein yield in the 2- and 4-cut systems. This same
trend was found for all cutting systems at the high nitrogen level in the grand
total yield (Fig. 16).

4. 3. 5. Cellulase digestibility of dry matter
The highest DM cellulase digestibility in both years was in the 4-cut system

and the lowest in the 2-cut system. During 1976—77 all of the cutting systems
differed from each other with very high significance (Table 14).

Differences between the invidual cuts of the cutting systems were found
only in the 4-cut system (Fig. 17), where the highest digestibility in both years
was in the first cutting and the lowest in the second.

Nitrogen fertilizer raised the dry matter’s digestibility in 1976 and 1977,
but a significant change was registered only for 1977. In 1977 also the combined
effect (CxN) was significant, where the nitrogen fertilizer significantly raised
the cellulase digestibility in the 2-cut system, but not in the 3- or 4-cut systems.

On the whole, the seeding rate had no statistically significant influence on
the dry matter’s cellulase digestibility in either year. From forage samples
a part of the dry matter’s digestibility in vitro was also determined. There was
a very significant correlation between the cellulase digestibility and the in
vitro digestibility (Fig. 18). The dependence between cellulase and in vitro
digestibility determined for fescue corresponds well to correlations for clover-
grass mixture and coach grass (Pulli 1976).

Fig. 16. Total protein yields (prot. tons ha" 1) in 1976 —77 of three cutting
systems seeded at four population densities and fertilized at two levels of
nitrogen.



4. 3. 6. Discussion
Number of cuttings

An increase in the number of cuttings means a per cutting and per growing
season decrease in dry matter yield (Carter and Law 1948, Huokuna 1957,
Brougham 1959, Heinrichs and Crark 1961, Laine 1965, Anslow 1967,
Frame and Hunt 1971, Pedersen et al. 1974, Wolton 1976).

In this investigation significantly larger yields were gained with two
cuttings as compared to three or four. A reduction in the number of cuttings,
however, meant a noticeable drop in the quality of the yield, as described by
high dry matter content, low protein content and low cellulase DM digestibility.

Instead, the number of cuttings showed, as in prior investigations (Sag-
lamtimur and Bogdan 1970, Lawrence et al. 1971), that it had little influence
on the protein yield per unit of area.

Diffirences in quality between cuttings were least in the 2- and 3-cut systems.
The highest protein content and digestibility were with the 4-cut system,
which also provided the most balanced yield per cutting because the early
summer’s rapid growth covered two cuttings. Dividing the fast growth phase
between two cuttings means a reduction in the total yield (Huokuna 1964).
The amount of the yield and its quality are tied by correlations to the different
cutting systems. The distribution of the yields between different cuttings as is
done in the cutting systems, affects the forage quality the most decisively.

Nitrogen fertilization
The increasing application of nitrogen fertilizer from 130 to 260 kg ha' 1

raised the dry matter yield by an average of 1 110 kg ha'1 in 1976—77. One
kilogram of nitrogen between the range 130 260 kg N ha' 1 produced a dry

Fig. 17. Dry matter cellulase digestibility (%) of individual cuts in three cutting systems
seeded at four population densities and fertilized at two levels of nitrogen.

319



320

matter yield increase of 8.5 kg. The yield increases obtained corresponded with
previous investigations (Laine 1966, Hiivola et al. 1974, Rinne 1971).

Nitrogen fertilization improves the quality of the yield. The fertilizer
reduced the dry matter content in all cutting systems, but only significantly
in 4-cut system. Increasing the nitrogen from 130 kg to 260 ha"1 correspondingly
raised the forage's protein content by 4.2 percentage units, or in other words
an average of 0.3 percentage units for every 10 kg N ha" 1 increase. The corres
pondent increase in protein yield was 485 ha' 1

, which agrees with Hiivola
et al. (1974).

At the low nitrogen level the protein yield ranged from 667 kg to 1 007 kg,
and at the high level from 1 034 kg to 1 675 kg for all cutting systems. On the
average the low nitrogen level produced 835 kg ha" 1 of protein and the high
level 1 320 kg ha" 1

, resulting in 3.7 kg of protein for every kg of nitrogen between
the nitrogen levels of 130—260 kg N ha' 1

.

Nitrogen had the least effect on the dry matter digestibility in the 4"cut
system and the best in the 2-cut system. The N-fertilizer raised the dry matter
cellulase digestibility an average of 1.4 percentage units. According to Steen
(1972), nitrogen fertilizer improves mostly protein digestibility.

Population density effects
During the first year the densest stand is the most productive, but in the

following years the highest yields are obtained from the less dense stands
(Donald 1956). A corresponding phenomena was observed in this investiga-
tion. In the seeding year the greatest yield was achieved with the seeding rate
of 60 kg ha" 1 (2 600 seeds m" 2). During the first actual production year the
statistical maximum was achieved with the rate of 30 kg ha' 1 (1 300 seeds m" 2)

at both nitrogen levels. In the second production year the maximum yield
required only a seeding rate of 15 kg ha"1 (650 seeds m" 2 ). These results agree

Fig. 18. The relationship be-
tween the dry matter cel-
lulase digestibility and the
dry matter in vitro digestibility
of meadow fesque (Festuca
pratensis) stand at different
stages of maturity.



321

well with the results of Laine (1958) and Järvi (1977). As Laine (1958) showed,
the third year’s statistical maximum yield was achieved with the rate of 7.5 kg
ha'1 (Fig. 19). In general it was so that with an increase in the number of
cuttings the statistical maximum yield required a slightly larger rate of seeding.
The exception was the 2-cut system, where delaying the first cutting created
competition at high growing densities which in turn raised the dry matter

Fig. 19. The management post effects on the total and pure
meadow fesque yield three years after seeding.



322

content so much that the yield level sharply climbed all the way to the levels
characteristic for the highest seeding rates. This phenomena was noticeable
particularly at the low level of nitrogen. Applying nitrogen as experienced by
Donald (1951) and Norrington and Davies (1969) increased the seeding
rate requirements for the maximum yield.

The seeding rate had very little influence on the quality of the yield, and
did not affect either dry matter content or cellulase digestibility at all. In-
creasing the seeding rate reduced the protein content very little as compared
to the findings of van Burg (1962) and Alberda (1965 a).

4. 4. Management Post Effects

4. 4. 1. Wintering
The seeding rate and the nitrogen fertilizer applied in the seeding year

influenced the wintering that followed the seeding year. In spring 1977 an
influencing factor, in addition to the previous factors, was also the cutting
frequency.

Obervations showed (Table 15) that the nitrogen fertilization had the
greatest effect on wintering in both years. The application of 100 kg N ha" 1

did not thin the crop at all, whereas the application of 200 kg N ha" 1 thinned
the stands at all densities. The most severe decrease in plant density occurred
in the stand with the lower seeding rate. The influence of nitrogen fertilizer
during the second winter was less than that for the seeding year, but still sta-
tistically significant. The stand was thinned most when cut twice at the high
level of nitrogen. When cutting four times, the nitrogen fertilizer had the least
negative effect on wintering. A statistically significant combined effect (CxN)
was not observed.

4. 4. 2. Productivity
To establish the post effects of the treatments, all plots received 75 kg N

ha"1 and were cut at the same time in the spring of 1978.
At the low level of nitrogen the total dry matter yield decreased with an

increase in the number of cuttings (Fig. 19). At the high levels of nitrogen this
trend was milder. The lower nitrogen level produced 253 kg ha" 1 more dry
matter than the high one. More regrowth, in addition, was found if the cutting
frequency or nitrogen level was raised with one exeption being the 2-cut system
with the low level of nitrogen. In the 4-cut system fescue comprised 93.7 %

of the total yield and in the 2-cut system only 56.2 %. The most stressing
treatment was the 2-cut system at a high level of nitrogen and at low rate of
seeding.

4. 4. 3. Discussion
The disruptive effects of a high level of nitrogen begin to manifest themselves

in the yield development and in the wintering of the stand (Huokuna and
Hiivola 1974). According to this investigation the application of 100 kg N
ha" 1 in the second cutting during the seeding year damaged wintering stands.



323

During the second winter the nitrogen fertilizer did not have a decisive effect
in any of the cutting systems. It can be seen from the regrowth, however, that
in the 2-cut system the 130 kg N ha" 1 application per cutting was too much for
fescue survival. In accordance with previous studies (Huokuna 1974, Hakkola
1978) when increasing the cutting frequency at a certain level of nitrogen, the

amount of nitrogen per cutting decreases and the stand survival improves.

5. Summary and conclusions

The investigation of meadow fescue was carried out at the University of
Helsinki in Viikki in 1975—78. The main objective was to study the rhythm
of the growth and yield formation pattern of a forage crop and the relationship
between growth pattern and growth factors during different phases of the
growing season. The management techniques studied were the number of
cuttings, use of nitrogen, requirements of population density and the relation-
ships of management factors to the changes in the quantity and quality of
forage yield. The following results have been drawn:

1. The most important factors concerning the LAI and height increase
of spring growth in the seeding year were the temperature sum in degree days
and the total radiation. The seeding year’s fall LAI and height correlated
weakly to the growing time and temperature sum. The late summer height
growth during the seeding year was significantly influenced by nitrogen
fertilizer beyond the temperature sum range of 500° C.

2. Differences in growing densities based on seeding rates disappeared in
the dry growing conditions eight weeks after seeding. However the seeding
year yield level can be raised with increasing population density.

3. During the production years after the seeding year the most important
yield formation variables during spring growth were the growing time, the
temperature sum in degree days and the total radiation. For midsummer and
fall growth the following determinants described growth the best; precipitation,
amount of nitrogen for the cut and the precipitation during the week before
the prior cut.

4. During spring growth at a temperature sum of 750° C the yield level
obtained was 6 tons ha" 1 with the following quality characteristics: dry matter
content 30 %, protein content 10 % and cellulase digestibility of dry matter
50 %. The summer growth yield level at a temperature sum of 700° C was 4
tons ha" 1 with the characteristics: dry matter content 22 %, protein content
17.5 % and cellulase digestibility of dry matter 55 %. The fall growth tempera-
ture sum contains the second cutting of the 2-cut system. For the fall growth
with the temperature sum of 1 200° C the obtained dry matter yield was 3.5
tons ha"1 and had quality characteristics of: dry matter content 29 %, protein
content 12 % and cellulase digestibility of dry matter 50 %.

5. During midsummer and fall the crop’s development was noticeably
slower than in the spring. At this time the quality of the yield remained
considerably steady, as the dry matter increase and the protein content decrease



324

were slight. For spring growth the dry matter content rise and protein content
decrease were sharp in the temperature sum range of 150—350° C. The decrease
in cellulase digestibility was strongest in the temperature sum range of 250
650° C.

6. A very significant correlation between dry matter yield and LAI existed
throughout the growing period. The spring growth’s maximum LAI was 8.5,
which represents a temperature sum of 550° C. The summer and fall growths’
LAI value of 7.5 represents temperature sums of 700 and 1 200° respectively.
For spring, summer and fall growth a one unit increase in LAI created a dry
matter yield increase of 715, 500 and 315 kg ha' 1 respectively. The corre-
sponding heights for the spring and summer periods were 85 sm, 60 cm. Because
of height growth differences a smaller and smaller dry matter yield is obtained
in the autumn at the same LAI value.

7. An increase in the number of cuttings signifies a smaller yield per
cutting and per growing season but a considerable improvement in the quality
of the yield. Increasing the number of cuttings from two to four decreased the
yield by and average of 2 527 kg ha" 1

. At the same time the protein content
and dry matter cellulase digestibility increased an average of 4.8 and 13.3
percentage units respectively.

8. Increasing the nitrogen fertilizer applications from 130 to 260 kg N ha" 1

raised the dry matter yield by 1 110 kg ha" 1
, the protein yield by 485 kg ha"1

,

the protein content by 4.2 percentage units and the cellulase digestibility by
1.4 units.

9. The influence of growing density on yield formation was more significant
the more often the crop was cut. The seeding year’s greatest dry matter yield
was obtained with a seeding rate of 60 kg ha" 1 . During the following growing
season 15 kg ha"1 were needed to produce the greatest yield in the 2- and 3-
cut systems and 30 kg ha"1 for the 4-cut system. In the third growing season
15 kg ha' 1 produced the maximum dry matter yield in all cutting systems.

To achieve the maximum yield a higher population density is needed if nitrogen
fertilizer and the number of cuttings are increased. Not including the seeding
year, the seeding rate had little effect on the yield’s quality. In the fourth
growing season the seeding rate had no statistical effect.

10. In the seeding year’s fall growth and in the 2-cut system, 100 and
130 kg N ha"1 respectively were too stressing for the stands. In regard to
preservation of the crop’s productivity, the yield quantity and quality, a
management system involving a seed amount of 30 kg ha" 1

, 3—4 cuttings
per growing season and a fertilization level of 260 kg N ha" 1 is recommended
as the best.



325

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Ms received February 8, 1980.

SELOSTUS

Viljelytoimenpiteiden ja kasvutekijödein
kasvuun ja kehitykseen.

vaikutus nurminadan

Seppo Pulli
Helsingin yliopisto, Kasvinviljelytieteen laitos, 00710 Helsinki 71.

Helsingin yliopiston Kasvinviljelytieteen laitoksella tutkittiin vuosina 1975 —7B niittojen,
N-lannoituksen ja kasvutiheyden vaikutusta nurminadan sadonmuodostukseen sekä kasvun ja
kehityksen suhdetta kasvutekijöihin kasvukauden eri ajankohtina. Tutkimuksista voidaan
vetää seuraavat johtopäätökset:

Kylvövuoden kevätkasvun tärkeimmät LAI:ä ja pituuskasvua selittävät muuttujat olivat
kasvuajan lämpösumma ja säteilysumma. Kylvövuoden syyskasvun LAI ja pituus korreloi-
vat heikosti kasvupäiviin ja lämpösummaan. Kylvövuoden loppukesä pituuskasvuun N-lan-
noitus vaikutti vasta, kun lämpötilasumma oli saavuttanut arvon 500° C.

Erot kylvömäärien välisissä kasvutiheyksissä hävisivät kuivissa olosuhteissa ankaran kil-
pailun vallitessa jo kahdeksan viikon kuluttua kylvöstä. Kuitenkin kylvövuonna on mahdol-
lista kohottaa satotasoa lisäämällä kasvutiheyttä.

Kylvövuoden jälkeen nurmen kevätkasvussa tärkeimmät sadonmuodostusta selittävät
muuttujat olivat kasvuaika ja kasvuajan lämpötilasumma ja säteilysumma. Keskikesällä ja
syyskesällä parhaiten nurmen kasvua selittivät kasvuajan sademäärä, sadolle annettu
N-lannotus sekä viikon aikana ennen edellistä niittoa saatu sade.

Kevätkasvussa lämpösummalla 750° C saavutettiin satotaso 6tn ka. ha- 1 . Kevätsadon laa-
tuominaisuudet olivat: ka-pitoisuus 30 %, rv-pitoisuus 10 % ja ka-sellulaasisulavuus 50 %.

Kesäkasvussa lämpötilasummalla 700° C saavutettiin satotaso 4tn ka. ha~ l . Kesäsadon laa-

tuominaisuudet olivat: ka-pitoisuus 22 %, rv-pitoisuus 17.5 % ja ka-sellulaasisulavuus 55 %.

Syyskasvussa lämpötilasummalla 1 200° C saavutettiin kuiva-ainesato 3.5 tn ha-1 . Syyssadon
laatuominaisuudet olivat: ka-pitoisuus 29 %, rv-pitoisuus 12 % ja ka-sellulaasisulavuus 50 %.

Keski- ja syyskesällä nurmen kehitys oli huomattavasti kevätkasvua hitaampi. Tällöin
myös sadon laatu pysyi pitkään tasaisena, sillä ka-pitoisuuden kohoaminen ja rv-pitoisuuden
aleneminen olivat vähäisiä. Kevätkasvussa kuiva-ainepitoisuuden nousu ja raakavalkuaispi-
toisuuden lasku olivat voimakkaimpia lämpösumraa-alueella 150 300° C. Sellulaasisulavuuden
lasku oli voimakkain lämpösumma-alueella 250 550° C.

Kuiva-ainesadon ja LAI:n välillä vallitsi koko kasvukauden erittäin merkitsevä korre-

laatio. Kevätkasvussa LAI:n maksimi saavutettiin arvolla 8.5, joka edustaa lämpösummaa
550° C. Kesäkasvun ja syyskasvun LAI:-arvot 7.5 edustivat lämpösummia 700° C ja 1 200° O
Kevät-, kesä- ja syyskasvussa yhdellä LAI-yksikön lisäyksellä saavutettiin lisäkasvut 715,
500 ja 315 kg ka. ha-1 . Kevät- ja kesäsadon pituudet olivat 85 ja 60 cm. Pituuskasvueroista
johtuen samalla LAI-arvolla saadaan syksyä kohti yhä pienempi ka-sato.



330

Niittojen lukumäärän lisääminen merkitsee niittoa ja kasvukautta kohti pienempää sato-
tasoa, mutta sadon laadun huomattavaa paranemista. Niittojen lukumäärän lisääminen kahdesta
neljään alensi satotasoa keskimäärin 2 527 kg ka ha" l . Samanaikaisesti rv-pitoisuus ja kuiva-
aineen sellulaasisulavuus paranivat keskimäärin 4.8 ja 13.3 %-yksikköä.

Typpilannoituksen lisääminen 130 kg:stä 260 kg:aan hehtaarilla kohotti kuiva-ainesatoa
1 110 kg ha' 1 . Sama typpilannoituksen lisäys nosti raakavalkuaissatoa 485 kg sekä sadon
raakavalkuaispitoisuutta ja sellulaasisulavuutta 4.2 ja 1.4 %-yksikköä.

Kasvutiheyden vaikutus nurmen sadonmuodostukseen oli sitä merkittävämpi mitä useam-
min niitettiin.

Kylvövuoden suurin ka-sato saavutettiin kylvötiheydellä 60 kg ha- 1 . Kylvövuotta seuraa-
vana kasvukautena suurimpaan satoon 2- ja 3-niittosysteemeissä tarvittiin siemenmäärä 15
kg ha" 1 ja 4-niittosysteemissä 30 kg ha' 1. Kolmantena kasvukautena kuiva-ainesadon maksimi
saavutettiin kaikissa niittosysteemeissä kylvömäärällä 15 kg ha" 1 . Maksimisatotasoon tarvit-
tiin suurempi kasvutiheys, jos N-lannoitusta ja niittokertoja lisättiin. Sadon laatuun kylvö-
tiheydellä oli kylvövuotta lukuunottamatta erittäin vähäinen merkitys. Jälkisadoissa neljän-
tenä kasvukautena ei kylvötiheyksillä ollut tilastollisia eroja.

Kylvövuoden syyskasvulle 100 kg N ha-1 ja 2-niittosysteemissä 130 kg N ha-1 /nutto olivat
kasvustoa liiaksi stressaavia. Nurmen tuottokyvyn säilymisen sekä nurmen määrän ja laadun
kannalta parhaimmaksi viljely teknilliseksi vaihtoehdoksi saatiin menetelmä, jossa nurmi*
natanurmi perustettiin kylvömäärällä 30 kg ha -1, niitettiin 3—4 kertaa kasvukaudessa ja lan-
noitettiin 260 kg ha"1.