JOURNAL OF THE SCIENTIFIC AGRICULTURAL SOCIETY OF FINLAND

296

Maataloustieteellinen Aikakauskirja
Voi. 49: 296-314, 1977

Effect of added magnesium, potassium, lime and nitrogen
on oats 11. Nutrient contents, cation ratios and
magnesium uptake

Raili Jokinen
Agricultural Research Centre, Department of Agricultural Chemistry and Physics
01300 Vantaa 30, Finland

Abstract. In a pot experiment on sphagnum peat soil the magnesium fertilization in-
creased significantly the magnesium content of the grains and the straws of oats. The
addition of potassium fertilization decreased the magnesium content when the plants
received a magnesium fertilization. Without magnesium the rate of potassium fertiliza-
tion did not have an effect on the magnesium content of the straws. The increase in the
equivalent ratio of the three potassium rates and the two magnesium rates decreased the
magnesium content of both the grains and the straws. Along with the magnesium fertiliza-
tion the addition of lime decreased the magnesium content of the grains and increased
that of the straws. Doubling the amount of the nitrogen fertilization with the magnesium
fertilizer increased the magnesium content of the grains and the straws. In the case of
magnesium deficiency the addition of lime or nitrogen did not have an effect on the mag-
nesium content of the yields.

The rate of magnesium, potassium, lime and nitrogen did not have an effect on the
potassium content of the grains. The potassium content of the straws increased with the
addition of potassium. Without the magnesium fertilization the potassium content,
as well as, the ratios K/Mg and K/(Ca + Mg) in the grains and the straws were high.
A part of the missing magnesium had, perhaps, been substituted for by potassium.

The calcium content of the grains and the straws obtained without magnesium fer-
tilization was significantly higher than the calcium content with magnesium fertilization.
The oats substituted possibly in part also calcium for the missing magnesium.

The effect of added magnesium, potassium, lime and nitrogen on the magnesium uptake
by oats was discussed.

Introduction

The positive effect on the magnesium content of the grains of cereals caused
by magnesium fertilization has been rather slight both in pot experiments
and in field experiments (Lehne and Koepke 1962, Jokinen and Simojoki
1975, Jorgensen 1976). The advantageous effect of the magnesium fertili-
zation has been greater on the magnesium content of cereal shoots harvested
before the heading (Jerlström 1975) as well as on that of the straws (Jor-
gensen 1976) than on the magnesium content of the grains.

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297

It has been proposed that the decrease in the magnesium content or in
the magnesium uptake by plants due to potassium fertilization is caused by
the antagonism between potassium and magnesium (Welte and Werner
1963, Alston 1966 b). On the other hand, it has been observed that the
shortage of a certain cation causes an increase in the uptake of other cations
(Grimme et al. 1974, Mengel et al. 1976). According to Terman et al. (1975)
it is possible to obtain definite information about the antagonism between
cations only if the addition of the nutrients does not have an effect on the yield.

In a pot experiment on a mineral soil the use of lime lowered the magne-
sium content of barley harvested before heading (Jerlström 1975). The com-
petition between calcium and magnesium in oat shoots was not strong
(Alston 1966 a, 1966 b). In solution-culture experiments (Falade 1973) an
increase in the magnesium content of a nutrient solution caused a decrease
in the calcium content of corn shoots.

The total quantity of cations taken up by plants increases as a result of
the extent of nitrogen fertilization increasing, and nitrogen in nitrate form
raises the quantity of the cations more clearly than the nitrogen in am-
monium form (Hansen 1972). In rield experiments the addition of nitrogen
fertilizer promoted the uptake of potassium, calcium and magnesium into
green oats (Häland 1971).

The purpose of this experiment is to clarify the effect of magnesium, potas-
sium and nitrogen fertilization, as well as that of lime supply, on the nut-
rient content and on the magnesium uptake of oat grains and straws thus
treated. The significance of the combination effects of the nutrients will also
be studied.

Material and methods

In a pot experiment, carried out in factorial design, were studied the effects
of three different rates of magnesium (Mg0

= 0, Mg1 = 200 and Mg2
= 400

mg/pot Mg), of three rates of potassium (K x = 415, K 2 = 830 and K 4 =

1660 mg/pot K), two of lime (Cax = 2400 and Ca3 = 7200 mg/pot Ca) and
of two of nitrogen (N x = 1000 and N 2 2000 mg/pot N) on the nutrient
contents, the cationic ratios and the magnesium uptake of the grain and
the straw yields of oats during three seasons. As the growth base in 5 liters
Mitscherlich-pots was used 250 g of air-dry Sphagnum-peat 4.2).
A more detailed description of the experiment has been presented previously
(Jokinen 1977).

The total nitrogen was determined for the grain and straw samples by
means of the Kjeldal-method. The magnesium, potassium and calcium con-
tents of the plant samples were determined by means ot atomic absorption
spectrophotometry from ash obtained by dry ashing (500° C) and extracting
into 0.1 N hydrochloric acid. In the calcium and magnesium determinations
the interferences were eliminated by using 5 % La-solution. The nutrient
contents are expressed as mg/g dry-matter.

In the statistical treatment of the data the same methods were used as
in the testing of the yields.



298

Results
Magnesium content of grains and straws

Magnesium fertilization increased in all the years significantly the magne-
sium content of both the grains and the straws regardless of the rate of
liming, and potassium and nitrogen fertilization (Table 1). The magnesium
content of the yields increased as the rate of magnesium fertilization was
increased.

The magnesium content of the grains received with the magnesium fertili-
zation remained almost constant from year to year, even though the fertili-
zation was reneved yearly. The coefficient of variation in all the data was
0.21 for the magnesium content of the grains and 0.58 for the magnesium con-
tent of the straws.

The effect of the three different potassium rates used in the experiment
did not differ from each other as far as the effect on the magnesium content
of the grains was concerned, when there was no magnesium fertilization. The
magnesium content of the straws, on the other hand, decreased due to the
effect of the potassium fertilization in the first and the second years in yields
which had received an abundant nitrogen fertilization and liming. Quantities
of potassium fertilizer supplied along with the magnesium fertilization did
not alter the magnesium content of the grains, either. The magnesium con-
tent of the corresponding straw yields decreased year by year, and the dif-
ference in the magnesium content with the greatest potassium rate and with
the smallest one was significant.

The equivalent ratios between the three rates of potassium (415 mg =

10.6 me, 830 mg = 21.2 me and 1660 mg = 42.5 me) and the two rates of
magnesium (200 mg =16.5 me and 400 mg = 32.9 me) in the annual fer-
tilization were 0.32, 0.65, 1.29 and 2.58. The magnesium content of the grains
and the straws of oats depended on the variations of the ratio K/Mg in all
the data on the average as follows:

K/Mg in the fertilization
0.32 0.65 1.29 2.58

Mg rag/g
Grains 1.5d 1.4' 1.3» 1.2»
Straws 2.6d 2.0 C 1.7b 1.2»

An increase of the ratio from 0.32 to 2.58 decreased the magnesium content
of the grains by 20 % and that of the straws by 54 %. The differences between
the magnesium contents in the grains on one hand, and in the straws on the
other hand, obtained with all the different values of the ratio, were significant.

Tripling the rate of lime had in some cases a slight positive effect on the
magnesium content of the grains (the first year), while in other cases (the
third year) the effect was negative. The magnesium content of the straws
increased significantly in the first two years as lime was added, and most
clearly at the low potassium level. In the third year also the magnesium
content of the straws was depressed as the lime rate was increased at the
highest potassium rate.



299

Table 1. Magnesium content of grains and straws (Mg mg/g dry matter).

V h I j V/d n

Ki K, Kj K; K, K 4

Grains
Ist year

Nx Mg0 1.0» 1.0" 0.9" 1.1» 0.9» I.o*
Mg x 1.30 1.21 l.lc 1.3e l.2 d I.2<i
Mg2 1.4' 1.30 1.2* 1.4' 1.30 1.30

N, Mg0 I.o* 0.9" 0.9» 1.2* I.o* l.C*
Mg! 1.301.2d 1.30 1.4' 1.301.3 e
Mga 1.4' 1.4' 1.4' 1.5» 1.5* 1.4'

2nd year

Nj Mg0 o.B»*° 0.7 a* 0.6a 0.8 abc o.Ba *o 0.7"*
Mgj 1.4«hl I.3'e* l.lior I.2etg I.2efg l.l*e'
Mg, I.6'i I.5*U 1.2«'« 1.3'8* I.2<='K l.ldef

N, Mg 0 0.9*c* l.Ooie 0.7 a 1.l*et 0.9*0 0.9*0
Mg x 1.48* I.3's* 1.2e'« I.4s*i 1.3'8* 1.2e'B
Mg, 1.71 I.5*U I.5*H 1.6U 1.3'8* 1.48*1

3rd year

Ni Mg0 0.9* 0.9* 0.7» I.l* I.o° -

Mgl 1.48 1.3' 1.48 1.3( 1.20 1.2«
Mg, 1.61 1.5h 1.7J 1.48 1.48 1.3'

Straws
Ist year

Ni Mg0 o.6a *° 0.6a 0.4a o.B*o 0.7a *o 0.7 a*c

Mg x I.3c'Bh I.2def« 0.904 I.7Uk I.7Hk 1.4'8*1
Mg, 1.58*U I.6*U 1.2dorg 2.1*» 2.0klm 1.81"

N, Mg0 0.7a*° 0.6a*o 0.5 a* I.2iotg o.9c * 0.7 a*°

Mgj 1.6*11 1.7H I.3e'«w 2.0«m 2.1 lm 1.81"
Mg, 2.3 mn 2.3 mn 1.81" 2.7» 2.6"° 2.3"">

2nd year

Ni Mg0 0.4a*o 0.3»* 0.2» 0.3a* 0.2» 0.2»
Mg, 1.6hH I.2e' 0.6° 2.0"" I.Bl* 1.1»
Mg, 2.2"» I.Bl* l.le 2.6n 2.2 m 1.30'g

N, Mg0 0.4»*0 0.5*0 0.5*0 0.81 0.601 0.5*0
Mgx 1.4'8* 1.2 e' o.B* 2.2 m 1.4'8* 1.3 e'B
Mg, 2.1!°» 1.7H 1.58*1 3.30 2.0"™ 2.l*°

3rd year
Nx Mg0 0.5» 0.5» 0.4» 0.5» 0.5» 0.3»

Mg x 2.6* 1.8» 1.5*0 2.7* 2.0° I.l*
Mg, 3.30' 2.5* . 2.6* 3.7' 2.9*» 1.6*0

The results of the same year do not differ statistically sigcificantly if the same index letter
appears.



300

Grains obtained by an ample nitrogen fertilization have seldom a signi-
ficantly higher magnesium content than by using a small rate of nitrogen.
Doubling the nitrogen fertilization rate increased the magnesium content
of the straws in the first year regardless of the rate of lime, and magnesium
and potassium fertilization. An increase in the nitrogen fertilization rate did
not any longer have a clear positive effect on the magnesium content of
the second year straw yields as it had done in the first year.

Potassium content of grains and straws
The potassium content of the grains did not depend in the first year sig-

nificantly on the studied variables (Table 2). The following year the potas-
sium content of grains obtained without any magnesium fertilization and with
an abundant nitrogen fertilization was higher than the potassium content
of the other corresponding grains obtained by magnesium fertilization. The
same was observed to be also true of the grains of the third year. An increase
in the potassium rate increased the potassium content of the grains only when
there was no magnesium fertilization.

The potassium content of the straws increased sharply as the rate of potas-
sium fertilization was increased, and the increase was independent of the
amount of lime, and magnesium and nitrogen fertilization. As was the case
with the grains, the potassium content of the straws was also in the second
year significantly higher with the high nitrogen rate than the potassium con-
tent of the straws obtained by magnesium fertilization.

Tripling the rate of lime depressed in the first year the potassium content
of the straws. Doubling the nitrogen fertilization rate also affected negatively
the potassium content of the straws, through only in the second year.

Calcium content of grains and straws
The calcium content of the grains was every year somewhat higher without

magnesium fertilization than with magnesium (Table 3). The difference in the
calcium contents was most pronounced with the abundant rate of lime app-
lication. Quadrupling the potassium rate depressed the calcium content of the
grains in the first year at both levels of nitrogen fertilization and lime app-
lication, but in the second year only with the abundant lime rate.

Tripling the rate of lime application increased significantly the calcium
content of the straws in the first year regardless of the rate of potassium, mag-
nesium and nitrogen fertilization. In the third year increasing the rate of lime
increased the calcium content of the straws only if there was no magnesium
fertilization or a slight rate of potassium application.

The magnesium fertilization and a quadrupled potassium fertilization both
depressed the calcium content of the straws regardless of the rates of liming
and nitrogen fertilization. In all the years the calcium content of the straws
was at its maximum when they had received no magnesium fertilization, but
had received abundantly lime and nitrogen as well as a slight rate of potas-
sium.



301

Table 2. Potassium content of grains and straws (K/mg/g dry matter).

Ca x Ca 3

Kj Kj Kj K, K, K 4
Grains

Ist year
N, Mg0 5.4»" 5.4»» 5.6abcd 5.9bcde s.9»cde 5.4 a»

Mg, 5.3»» 5.4»» 5.7 abcd 5.7 abcd 5.4»b 5.5»bc

Mg, 5.2» s.s ab<> 5.7a »cd 5.4 ab 5.3 ab 5.5»be

N 2 Mg0 5.8 abcd 5.9 bcde 6.1 cd <> 6.4 e 6.2 de 6.2 dl>

Mg, s.s abc s.9b cle 5 gbcde 5 gbcde 6.1 cde 6.0 cde

Mg 2 5.8 abcd 5.5»»c s.B abcd s.6abcd 5.8»»cd 6.1 cde

2nd year
Nx Mg„ 6.9ab 7.l a»<= 7.5»c 7.0 abc 6.9 ab 6.5 ab

Mg x 6.2ab 6.7 ab 6.B ab 6.0» 6.0» 6.2 ab

Mg, 6.3ab 6.4ab 6.6ab 6.4 ab 5.7a 6.1 a
N, Mg„ 6.4ab 8.4" 13.1« 9.2 d 14.2» 9.7 d

Mgi 5.8 a 5.7 a 6.2ab 5.8» 6.2 ab 6.2 ab

Mg, 6.1» 5.6» 6.1» 5.9» 5.9» 6.2»b

3rd year
Nx Mg0 6.9ab 7.7»<= 8.6« i 9.2d 9.9 d

Mgx 6.8 ab 6.2» 7.1 ab 6.6» b 6.0» 5.9»
Mg, 7.1» b 6.5» b 7.4»b 6.7»" 6.4»" 6.0»

Straws
Ist year

Nx Mg0 4.8»" 10.2'«h 21.5lm s.o** B.4<= 18.2k

Mg x 4.9» b 9.5'k 22.1 mn 4.1» 9.7'e» 17.7 k
Mg, 4.4» 10.5«h 22.9" 4.6a» 10.0'eh 18.2k

N, Mg0 5.6»c 9.9's>> 18.0" 7.3 d 10.6»i 15.91
Mg x 5.5»° 11.4' 20.81 5.6» 9.5'* 17.5*
Mg, 6.5cd 11.5* 22.3 mn 6.2° 9.3' 15.01

2nd year

Nx Mg0 9.0 ab° 15.3«ie 39.8» 8.0a »° 12.3a »° 33.4» 1

Mg, 6.9»» 14.2° d° 32.7bl 5.9» 12.7a »° d 30.2»
Mg, 5.8» 15.0° d° 33.9"1 5.7» 13.7 b ° d 28.9k»

N, Mg0 11.2ab° 24.7'k 48.01 11.3ab ° 20.9°' 48.91
Mg, 5.8» 6.4» b 19.4d°r 5.1» 8.6 ab ° 20.9°'
Mg, 4.8» 8.7»»° 22.1°' 5.3» 9.8 ab ° 20.9°'

3rd year

Nx Mg0 15.7» 36.4»»° d 48.5»° d 19.8» 63.5 d 65.2 d
Mg x 11.3» 20.9» b 53.0° d 15.8» 27.2»»° 52.3»°
Mg, 9.9» 20.4» 51.6»°d 15.1» 27.4a»° 59.5 d

Meaning of index letters same as in Table 1.



Table 3. Calcium content of grains and straws (Ca mg/g dry matter).

K, K 2 K t K a K 2 K 4

Grains
Ist year

Nx Mg„ 2.o de 1.9de 1.4»b 2.0 de 1.7cd 1.4»"
Mg x 1.7cd 1.5»bc 1.3" 1.7 cd 1.5»b<= 1.3»
Mg 2 1.7 cd 1.4»" 1.2» 1.8»« 1.4»» 1.2»

N 2 Mg0 2.0 de 1.8cd 1.5»b » 2.2<» 2.0 de 1.8»d

Mg x 1.9 d« 1.5»bc 1.3» 2.1» 1.6bc 1.4»b

Mg 2 1.7» 1.4»b 1.2» 2.1» 1.6bc 1.4»

2nd year
N, Mg0 1.0bc I.l° 0.8» b 1.2 c 1.0bc 0.8» b

Mg t 0.8» bo 0.8»b 0.7» b 0.9» bc 0.8» b 0.6»
Mg2 0.8» b 0.8»b 0.6»» 1.0be 0.7» b 0.6»

N 2 Mg0 1.0bc 1.0bo 1.9 d 2.4 e 2.6<> 1.7 d

Mg t I.o b ° 0.9»b « 0.7» b 1.1» 1.0bo 0.8» b

Mg 2 1.0b<! 0.7»b 0.7» b 1.3° 0.9» bc 0.7» b

3rd year
Nj Mg0 0.8» 1.0» 2.4» 5.9 b 2.2»

Mg x 0.8» 0.8» 1.0» 1.0» 0.8» 0.8»
Mg2 0.9» 0.9» 1.2» 1.0» 0.9» 0.7»

Straws
Ist year

Nx Mg0 13.2cdefghi n.4abcdef g.7» b 20.2klm IS.SWi H.labcder
Mgx 12.5b cdergh 10.4abcde 7,7 a 16.4ghijk 14 sefghl H.3abcdct
Mg !X.4abcdet 9.4abcd 8.5» b 16.5Shi Jk 13.4defghl H.labcdef

N 2 Mg0 17.0h »J k i 16.6gbI ikl i2.2»b »de'K 28.8° 23.4™"» 17.6'JkI

Mgx 17.6'Jkl 16.4«blJkl H.2«b <:def 24.7 mn 21.1 lm 15.5'gb'J

Mg2 17.3Ukl l4.9erghi] n.2abcdef 27.3" 19.2*kl 14.5 et «hl

2nd year

Nj Mg0 B.B er& h 6.4bcd 5.0» 13.6 J 9.5bl 5.9» bcd

Mgj 6.9bcde 5.0» bc 3.6» 10.3bI 7.8 de,« 5.0»bc

Mg 2 6.5 b«> e 5.2» bc 3.6» 9.3 fg 7.0" def 5.0» bc

N 2 Mg0 7.8 det« B.l detgh 7.1 cdef 28.1 m 23.61 11.11

Mgj 7.0 cder 6.2»i>cd 4.2» b 15.3Jk 10.9hI 7.5 de'«

Mg 2 7.2cdef 5.9»bcd 4.8» bc 17.lk 10.6bI 7.6 dc'«

3rd year
Nx Mg0 8.1» 7.5» 6.6» 26.9 d 19.5" 14.7b

Mg x 6.6» 5.3» 5.1» 12.7b 7.4» 5.0»
Mg 2 5.8» 4.5» 5.7» 11.8 b 7.5» 5.0»

Meaning of index letters same as in Table 1.

302



303

Table 4. Nitrogen content of grains and straws {N mg/g dry matter).

K! K 2 K 4 K, K 2 K 4

Ist year
Nj Mg0 16.8»» 14.8» 14.8» 15.7»» 13.7» 14.0»

Mg x 16.0»" 14.5» 14.8» 15.2» 14.4» 14.0»
Mg, 16.4»» 13.8» 14.7» 16.5»" 15.9»* 13.7»

N 2 Mg 0 24.5*° 20.5»°* 22.2°*° 31.9» 23.6°*° i9.3bc
Mg! 29.2'* 24.3*° 23.4°*° 29.4f* 23.6°* e 20.3»°*
Mg, 31.2» 26.5°' 25.5°' 30.3* 23.9°*° 20.3»°*

2nd year

N, Mg 0 23.1»» 17.0»" 19.2»" 17.3»» 15.7»" 14.5»
Mgj 17.0»» 15.9»» 17.0»» 15.4»" 14.8» 14.1»
Mg 2 16.5»b 17.3»" 18.6»» 15.3»» 15.0» 13.4»

N, Mg, 33.7»° 31.4»° - 45.1= 43.5°
Mg! 30.6» 23.3»» 24.0»» 25.6»» 20.9»» 21.2»»
Mg 2 30.6» 24.0»» 25.0»» 28.5» 23.9»» 22.0»»

3rd, year

N, Mg„ 42.8» 21.6»» -
-

Mg x 27.6°* 25.2»° 31.5* 20.3» 19.9» 21.2»»
Mg 2 24.7»° 25.9» 27.8°* 19.7» 20.3» 21.3»»

Straws
Ist year

Nj Mg 0 s.B»°* 4.9»»° 5.6»°* 5.6»°* 4.4»» 3.5»
Mgx 5.3»»c* 4.1»» 4.5»» 5.8»c * 3.9»» 3.1»
Mg 2 5.7»c * 4.7»»° 4.3»» 4.9abc 3.9»» 3.4»

N 2 Mg„ 12.0» 7.2*° 6.s°*° 15.1» 9.8' 6.6°*°
Mgl 12.38 8.3" 7.2*° 13.85» 7.6*° 5.7»°*
Mg2 12.4» 8.2" 7.l*° 13.68» 7.9ef 5.6»cd

2ad year

N x Mg0 11.2°* 6.7»» 7.0»» 6.7»» 5.4»» 4.8»
Mg t 7.4»» 5.9»» 5.0»» 6.0»» 4.5»» 4.3»»
Mg, 6.9»» 5.7»» 4.5»» 5.6»» 4.3»» 3.9»

N, Mg„ 22.5° 31.8' 32.8' 30.8' 31.6' 38.3*
Mgj 13.3* 7.3»» 6.7»» 12.4°* 7.1»» 7.3»»
Mg, 12.6* 7.8»» 7.6»» 11.8°* 8.5»° 6.0»»

3rd year
N x Mg 0 23.8*° 25.8*°' 28.6°' 21.4* 30.6' 37.1*

Mgi 11.6»° 10.5»»° 12.9° 9.4abc 5.7 a 6.6»»
Mg, 10.7»»° 9.5»»° 14.6° 9.0»»° 6.8»» 5.5»

Meaning of index letters same as in Table 1.



304

Nitrogen content of grains and straws
The effect of the magnesium fertilization on the nitrogen content of the

grains was slight during the whole experiment at all the rates of potassium
and nitrogen fertilization and at all the rates of lime application (Table 4).
Exceptions were the increase, caused by the magnesium fertilization, in the
nitrogen content in the first year in the grains, and the depression of the
nitrogen content in the second and the third years. Doubling the rate of
nitrogen fertilization increased significantly the nitrogen content of the grains
of the first year regardless of the rate of magnesium and potassium fertili-
zation and the rate of lime application.

The plants which had received an abundant nitrogen and potassium fer-
tilization developed in the second year so few grains that there was not
enough for nitrogen content determinations. In the third year it was pos-
sible to determine the nitrogen content of the grains at the two smallest
rates of potassium application at the level of low lime application.

The nitrogen content of the straws decreased as the rate of potassium ferti-
lization was increased. In all the years the differences were the most pronoun-
ced for the yields which had received a magnesium fertilization as well as
abundant nitrogen fertilization and liming. Without the magnesium fertili-
zation the straws contained in the second year more nitrogen with an abun-
dant rate of nitrogen application than the yields that had been obtained
by using magnesium fertilization.

Interdependence of cation contents in grains and straws
In the grains there was between the magnesium and calcium content or

the magnesium and potassium content no significant correlation. In the straws
the magnesium content was depressed as the potassium content increased.
Within the data of this experiment the correlation coefficients between the
cation contents were as follows:

Mg mg/g
Grains Straws

r
Ca mg/g -0.075 -0.020
K mg/g -0.127 -0.295**

Potassium to magnesium ratio (K/Mg) in grains and straws
In all the years the annually renewed magnesium fertilization decreased

the ratio K/Mg in grains (Table 5). The two rates of magnesium application
showed no difference in this respect. An inrease in the rate of potassium fer-
tilization increased the ratio only in the grains obtained without magnesium
fertilization.

In the straws the ratio K/Mg likewise decreased significantly every year
as a result of the magnesium fertilization. An increase in the rate of potas-
sium application increased the ratio K/Mg very clearly without the magnesium
fertilization. The increase in the value of the ratio was greater at the low level
of nitrogen application than at the high level of nitrogen application. Tripling
the rate of lime application decreased the ratio K/Mg at the highest rate of



305

potassium fertilization irrespective of the rate of magnesium in the first year.
In the following years an increase in the rate of lime application at the low
rate of nitrogen and the highest rate of potassium application increased the
ratio.

An increase in the ratio of potassium to magnesium in fertilization, increa-
sed significantly the ratio of the same cations in the grains and the straws.
In all the data from the three years the results were as follows:

K/Mg in fertilization

0.32 0.65 1.29 2.58

K/Mg in yields
Grains 1.3» 1.4" I.s<= 1.6"
Straws 0.8» 1.6b 4.1c 8.3 d

The increase in the ratio K/Mg was greater in the straws than in the
grains. The two rates of magnesium or the three of potassium fertilization
both altered the potassium to magnesium ratio in the yields less than the
cation ratios in the fertilization.

Ratio of potassium to the sum of calcium and magnesium (Kj (Ca + Mg) ) in
grains and straws

The magnesium fertilization depressed in the second and the third years
the ratio K/ (Ca + Mg) in the grains irrespective of the rate of nitrogen and
potassium fertilization and the rate of liming (Table 6). The two rates of
magnesium application did not show a significant difference in the results.
Neither an increase in the rate of liming nor one in nitrogen fertilization
produced an effect on the ratio in the grains. The increase in the ratio caused
by quadrupling the rate of potassium fertilization in grains produced without
magnesium fertilization was significant from the second year on.

Upon increasing the rate of potassium fertilization the ratio K/ (Ca + Mg)
in the straws increased every year. The increase in the ratio caused by potas-
sium fertilization was smaller at the rate of tripled lime application than at
the rate of slight lime application. Also, doubling the rate of nitrogen fertili-
zation retarded the increase of the ratio in the first two years.

Magnesium uptake
The amount of magnesium taken up by the grains depended more clearly

on the amount of the yield than on the magnesium content. With the straws,
on the other hand, the significance of the magnesium content was greater than
that of the yield. The changes in the amount of magnesium taken up by the
whole yield followed the changes in the uptake of magnesium by the straws.

The amount of magnesium taken up by the grains and the straws increased
significantly every year upon increasing the rate of magnesium fertilization,
and independent of other tested nutrients (Table 7). Only in the third year
did the yields which had received small amounts of calcium and the two
greatest rates of potassium take up equal amounts of magnesium when using
two different rates of magnesium fertilizer.



Table 5. Potassium to magnesium ratio (K/Mg) in grains and straws.

K, K, K, K, K«
Grains

Ist year
Nj Mg0 1.7c "e 1.8de ' I.9°'* I.7°<>° 2.o'k 1.8 d°'

Mgx 1.3»" 1.4»» 1.6° d 1.4»* 1.4»" 1.4»»
Mg, 1.2» 1.3»" I.s*° 1.2» 1.3»» I.s*°

N 2 Mg0 I.B<ier 2.o'k 2.1» I.B*°' I.9etg 2.1b
Mgi 1.3»" 1.5"» 1.5"° 1.3»" I.s*° 1.4»*
Mg2 1.3»* 1.2» 1.3»* 1.2» 1.2» 1.3»

2nd year

Ni Mg„ 2.6* 3.3°d 3.7» 2.B*° 2.B*° 3.o*°
Mgi 1.4» 1.7» 2.0» 1.5» 1.6» 1.8»
Mg2 1.2» 1.4» 1.7» 1.5» 1.4» 1.7»

N 2 Mg„ 2.3* 2.9*° 5.9' 2.6* 5.0° 3.4°<»
Mgi 1.3» 1.4» 1.6» 1.3» 1.5» 1.6»
Mg 2 1.2» 1.2» 1.3» 1.2» 1.4» 1.4»

3rd year
N, Mg0 2.4* 2.8* 3.8° 2.9* 1.6»

Mgj 1.5» 1.5» 1.6» 1.7» 1.5» 1.6»
Mg 2 1.4» 1.3» 1.4» 1.5» 1.5» 1.5»

Straws
Ist year

Ni Mg„ 2.5°* 5.2' 15.9" 2.0° 3.6° 8.2»
Mgi 1.2»* 2.5° d B.o*' 0.8» I.7*° 4.0°
Mg 2 0.9»* 2.0° 6.0* 0.7» I.s»*° 3.2 d

N 2 Mg0 2.4° 5.0' 11.81 1.9° 3.7° 7.3*
Mgi 1.1»* 2.1° 5.1' 0.9»* I.4»*° 3.0°"
Mg2 0.9»* I.6*° 3.8° 0.7» 1.1»* 2.1°

2nd year
Nj Mg0 7.9defg is.oh 37.5J 9.3fg 16.2* 53.9k

Mgj 1.4»* 3.B»"°*°' 16.1* 0.9»* 2.3»*° a « 8.7'»
Mg2 0.8» 2.6»*°*° 9.3'* 0.7» 2.0»*° d 6.8* cde '

N 2 Mg0 B.2°'» 15.8* 30.4' 4.2»"cdet 13.6*" 30.0'
Mgx 1.3»* I.7»*° 7.5 o<le' 0.7» 1.9»"° s.o»*caef
Mg2 0.7» I.6»*° s.o»"cdef 0.5» 1.5»* 3.labcde

3rd year
Nj Mg0 10.2»* 22.2*° 36.0° d 12.4» 43.9a 57.1°

Mgi 1.4» 3.6» 11.1»* 1.8» 4.2» 14.3»*
Mg2 0.9» 2.6» 6.5» 1.3» 2.9» 11.7»*

Meaning of index letters same as in Table 1.

306



307

Table 6. Ratio of potassium to the sum of calcium and magnesium (K/(Ca + Mg)) in grains
and straws.

Ca x Cas

Ki Kj Ki Ki Kj K 4
Grains

Ist year

N t Mg0 0.8»" 0.8"° I.o* 0.8"° 0.8°" o.9°*
Mg! 0.7*" 0.8"° 0.9 cd 0.8"° 0.8"° 0.9° d

Mg 2 0.7»" 0.8"° o.9° d 0.7»" 0.8"° 0.9°"

N a Mg0 0.8"° 0.9° d I.o* 0.8"° 0.9°d 1.0d

Mg t 0.7»" 0.9° d 0.9cd 0.7»" 0.8"° 0.9° d

Mg2 0.7»" 0.8"° o.9° d 0.6» 0.8"° 0.9° d

2nd year
N x Mg0 1.5cd ° 1.7de 2.2' 1.4°d 1.6d° I.B°

Mgj l.l ab° 1.2»" 1.4cd l.la "° l.l a"° 1.3"°d

Mg 2 1.0»" 1.0a " 1.3" l.la "° l.l a"° ].3"°d

Nj Mg0 1.3"°d I.B° 2.3' 1.1»"° I.B° 1.6d°

Mg! 0.9a " 1.0a " 1.2»"° 0.9»" 1.1»" 1.1»"°
Mg2 0.8» 0.9»" 1.0»" 0.8» 1.0»" 1.1»"°

3rd year
N x Mg0 1.5°d 1.6d I.3"° d 0.8» 1.3"cd -

Mgj 1.1»" 1.1»" 1.1»" 1.1»" l.l»b 1.2»"°
Mg 2 1.0»" 1.0»" 1.0»" 1.1»" 1.1»" 1.1»"

Straws
Ist year

N x Mg0 0.2" 0.4d 1.21 0.1» 0.3° o.B*
Mgt 0.2" 0.4d 1.31 0.1» 0.3° 0.7'
Mg2 0.2" 0.5° 1.1" 0.1» 0.3° 0.7'

N 2 Mg0 0.2" 0.3° 0.7' 0.1» 0.2" 0.4 d

Mgj 0.1» 0.3° O.BK 0.1» 0.2" 0.5°
Mg 2 0.2" 0.3° o.B* 0.1» 0.2" 0.4 d

2nd year

Ni Mg0 0.5»" I.l* 3.8 J 0.3»" 0.7"° 2.8"
Mgx 0.4»" 1.0d 3.71 0.2» 0.6"° 2.3*
Mg 2 0.3»" 0.9° 3.2* 0.2» 0.7"° 2.1»

N 2 Mg„ 0.7"° 1.4° 3.0" 1 0.2» 0.6"° 2.1*
Mgi 0.3»" 0.4»" I.B' 0.1» 0.3»" l.l d

Mg 2 0.2» 0.5»" I.6°' 0.1» 0.4»" I.o d

3rd year

N, Mg0 0.9»" 2.2"°d 3.4d° 0.4» 1.7»"° 2.1"° d

Mgx 0.5» 1.3»" 3.7 d° 0.5» 1.3»" 3.9 e

Mgs 0.5» 1.2»" 2.B°d° 0.4» 1.1»" 4.0°

Meaning of index letters same as in Table 1.



308

Table 7. Magnesium uptake (Mg mg/pot, grains + straws).

Ca! Ca3

Kj K 2 K 4 Kx K 2 K 4
Ist year

Nt Mg„ 62» 73abcd 70»bc 82»°"°' 91'*» 100*»'!
Mg x 98'*» 1 1153 98tghi 132 k 158'm 148klm

Mga 1151 136k 1161 150mn 176° 175n°

N 2 Mg, 67»» 90°'*» 88<icrg 85°d°'* 104"'J 113*1
Mgj 110'i 152lm 152lm 143" 193 p 2134
Mg2 147* 189°p 180°p 176» 232' 2678

2ad year
Nx Mg0 27»"° 31»° 25»"° 28»»° 36° 36°

Mgt 87° 89° 66* 122'* 128h| l 100°'
Mg 2 124*hI 120*hI 87° 148kl 148kl 115'*»

N 2 Mg„ 25»»° 18»» 11» 30»»° 15» 13»
Mgl 92° 129hU 109'* 1421" 148kI 168m

Mg 2 130hi J 159lm 134*» 195" 173™ 222°

3rd year

N t Mg„ 10» 9» 3» 8» 3» 1»
Mg t 87° 79° 43» 99°"e 1091° 82°
Mg 2 115° 94°d 52» 143' 141' 101°d°

Meaning of index letters same as in Table 1.

The increase in the rate of potassium fertilization from K x to K 2 increased
significantly the magnesium uptake of yields in the first year at all rates of
magnesium fertilization, since the grain and the straw yields increased and
the changes in the magnesium content were slight. The uptake of magnesium
by the crops which had been produced with the two greatest amounts of
potassium varied. In the second and the third years the greatest rate of
potassium application depressed the uptake of magnesium with respect to
that with the medium rate of potassium, when the plants received a magnesium
fertilization. Without the magnesium fertilization the potassium quantities
did not affect the uptake of magnesium by the second and the third years’
yields.

The increase of the ratio potassium to magnesium in the fertilization depres-
sed significantly the uptake of magnesium by the straws. The amount of
magnesium possessed by the grains did not depend equally evidently on the
K/Mg ratio in the fertilizer. In all the data the results are the following:

K/Mg in fertilization
K./Mg, Kj/Mgj K 2 /Mg 2 K 2/Mgl K 4/Mg2 K 4/

0.32 0.65 0.65 1.29 1.29 2.58

Mg mg/pot
Grains 48»» 42» 59» 56" 62» 58b
Straws 98" 69» 98" 74» 83»» 60"
Total 146»° 111» 157° 130»» 145»° 118»»



309

Tripling the rate of lime application increased significantly the uptake of
magnesium in the first year at all the levels of magnesium, potassium and nit-
rogen fertilization. In the second and the third years an increase in liming
did not affect the magnesium uptake by yields obtained without magnesium.
Also an increase in the rate of nitrogen fertilization advanced the uptake of
magnesium by plants which had received a magnesium fertilization.

During three years (at the Njdevel) the yields of oats took up a total of
98—137 mg/pot of magnesium from the peat itself, and correspondingly during
two years (at the N2-level) 92 126 mg/pot. These quantities correspond to
40—55 and 37—50 mg magnesium with respect to 100 g of air-dry peat.
The peat used in the experiment contained 50 mg/100 g of exchangeable
magnesium. Since the peat contained at the end of the test B—l 7 mg/100 g
of exchangeable magnesium, the plants had taken up also »nonexchangeable»
magnesium. The effects of the lime application and the potassium fertilization
on the consequent reduction of the »nonexchangeable» reserve of magnesium
in the peat were small, as the following results indicate;

Cat
K 2 k 2 k 4

Ca3
Kj K 2 K 4

Mg mg/100 g of air-dry peat
Uptake in 3 years 40 45 39 47 52 55
Exchangeable in peat after

cropping 17 18 17 10 10 8
Released from »nonexchange-

able» 7 13 6 7 12 13

Uptake in 2 years 37 43 40 46 48 50
Exchangeable in peat after

cropping 16 16 15 11 10 10
Released from »nonexchange-

able» 3 9 5 7 8 10

The crops which had been produced by abundant nitrogen fertilization
took up from the peat in two years almost as much magnesium as the crops
produced by small amounts of nitrogen did in three years. Also, the consump-
tion of the »nonexchangeable» magnesium reserves was almost equal at both
rates of nitrogen fertilization.

Uptake of the fertilizer magnesium
In general, the oats took up the more fertilizer magnesium (Mgx —Mg0,

Mgj—Mg0) the more magnesium fertilizer had been supplied (Table 8). There
was, however, no significant difference in the magnesium contents of the yields
which had received two different rates of magnesium fertilization with a low
rate of lime application, a small rate of nitrogen, and an abundant rate of
potassium fertilization.

The oats took up less magnesium supplied in the fertilizer at the greatest
rate of potassium than at the intermediate rate of fertilization. At the rate



310

Table 8. Fertilizer magnesium uptake (mg/pot and %, grains + straws).

Kj K 2 K 4 Kj K 2 K 4

In 3 years Mg mg/pot
Nj Mg x 174 170 110 227 265 194

Mg2 253 242 157 387 334 253

In 2 years

N 2 Mgl 110 173 165 181 220 257
Mg 2 185 242 214 257 286 360

In 3 years %

Nx Mg x 29 28 18 38 44 32
Mg2 21 20 13 32 28 20

In 2 years

N 2 Mg! 28 43 41 45 55 64
Mg 2 23 30 27 32 36 45

The total amount of fertilizer magnesium supply (Mg mg/pot):
Mg! Mg 2

In 3 years 600 1200
In 2 years 400 800

of abundant liming and of abundant nitrogen fertilization the uptake of mag-
nesium increased upon increasing the rate of potassium fertilization.

A tripled rate of lime application enhanced the utilization of the fertili-
zer magnesium at the rate of abundant nitrogen fertilization. Similarly, an
increase in the nitrogen fertilization increased the amount of magnesium taken
up from the fertilizer at all the rates of potassium and magnesium fertilization
and of liming.

Of the annually suplied 200 mg of fertilizer magnesium the oats took up
45—64 % at the abundant rate of liming and of nitrogen fertilization. Of the
double rate of magnesium fertilizer supply the oats took up correspondingly
32-45 %.

Discussion
The magnesium content of the oat grains obtained in this pot experiment

was nearly the same as the magnesium content of oat grains obtained in other
pot (Sorteberg 1974) or field (Jokinen and Simojoki 1975) experiments.
The variation in the magnesium content was small. A 0.1 mg/g change in the
magnesium content, caused by the magnesium fertilization, was already
statistically significant. This result indicates that the magnesium content of
grains varies generally within narrow limits (Jokinen and Simojoki 1975).



311

The magnesium treatments caused more readily a change in the magnesium
content than in the crop yield. Only a very low magnesium content in the
growth base limited the yield (Jokinen 1977). In several experiments (Vi-
gerust 1966, Birch et al. 1966, Sorteberg 1975) the conclusion has been
reached that magnesium fertilization does not affect the yield of cereals, but
increases the magnesium content of the plants. In these experiments, carried
out on mineral and peat soils, the magnesium content of the growth base was
probably not so low as to retard the growth of the crop.

Upon increasing the rate of magnesium fertilizer the yield of the crop rea-
ched its maximum at a lower rate of magnesium application than the mag-
nesium content of the grains and the straws. The same has been noted by,
among others, Alston (1966 b) and Jacques et al. (1975).

Upon increasing the rate of magnesium fertilization the magnesium content
of the straws increased even after the maximum yield has been reached. Even
though Benko and Fecenko (1970) used in their solution-culture experi-
ments nutrient solutions of magnesium contents varying in the range of o—lo
me/1 the increase in the magnesium content of 30 days old barley shoots did
not stop. The positive effect which magnesium fertilization has on increasing
the magnesium content of stalks and leaves of plants is of advantage when
cultivating grasses for animal forage. The low magnesium content or too high
a value of the ratio K/ (Ca -f Mg) in the forage have been mentioned as some
of the causes of grass tetany in livestock (Kemp and CHart 1957).

The potassium and the calcium contents of yields (grains, straws) obtained
without magnesium fertilization were higher than the corresponding contents
of crops that had received a magnesium fertilization. Similarly, the ratios
K/Mg and K/ (Ca + Mg) were high in grains as well as in the straws without
magnesium fertilization. Causes of the high potassium and calcium contents
were probably the insufficiency of the magnesium reserves available to the
plants and the consequent substitution of the missing magnesium by the potas-
sium and the calcium (Grimme et al. 1974, Terman et al. 1975). The substitu-
tion was at its strongest in the second and the third years when there was
little magnesium avaliable to the oats. Jerlström (1975) noted in his pot
experiments that also deficient potassium was substituted for by magnesium,
among other cations. Nothing corresponding was noted in the present data.

The interdepandence between the potassium and magnesium contents in the
grains was not significant. Apparently potassium does not hinder the move-
ment of magnesium in the plants from the stalks and the leaves to the grains.
The same conclusion is suggested by the fact that the amount of magnesium
taken up by the grains did not depend on the rate of potassium fertilization
nor the ratio of potassium to magnesium supplied in the fertilizers.

The rate of potassium given along with the magnesium fertilization in-
creased the straw yield and the potassium content of the straws, but depressed
the magnesium content. The decrease in the magnesium content may, in part
(at the K x and K 2 rates), be caused by the same amount of magnesium
having been taken up by plants of low or high yield; i.e., by the relative
dilution of the yield (Jansson 1971, Grimme et al. 1974). Upon adding potas-
sium fertilizer from K a to K 4 the quantity of magnesium taken up by the



312

straws was diminished. Thus, an ample potassium fertilization impeded the
uptake of magnesium by the oats. Falade (1973) and Terman et al. (1975)
also noted in their experiments that the antagonism between potassium and
magnesium has a significant role only when an abundant potassium fertili-
zation was being used. The significant negative correlation between the potas-
sium and magnesium contents in straws, and the negative effect which an
increase in the ratio of potassium to magnesium in fertilization has on the
magnesium content of the straws and on the uptake of magnesium by straw
crop, further show that the antagonism between potassium and magnesium
has as its only real consequence in oats changes in the nutrient contents and
in the nutrient uptakes of straws.

Calcium moves with difficulty in plants from the stalks and leaves to the
grains (Jacques et al. 1975). Therefore, tripling the rate of liming did not
increase significantly the calcium content of the grains. When there was an
insufficiency of magnesium a part of the missing magnesium had been
substituted by calcium. In other instances these nutrients did not affect each
others’ translocation into the grains. An addition of lime promoted the up-
take of magnesium by oat straws (Falade 1973), and advanced the fertilizer
magnesium uptake. This is understandable since the growth base was acid.

An increase in the rate of nitrogen fertilization increased the amount of
magnesium taken up by the straws, and promoted the uptake of fertilizer
magnesium. The potassium content of the straws, on the other hand, decreased,
and concomitantly the potassium to magnesium ratio (K/Mg) and the ratio
KI (Ca + Mg) decreased. Mäntylahti, and Marjanen (1971) noted that
adding to the nitrogen fertilization lowered the last mentioned ratio of cations
in grass harvested for silage.

REFERENCES

Alston, A. M. 1966a. The influence of N and Mg fertilizer and CaCOa on the absorption of Mg
by oats. J. Agric. Sci. 66; 61 66.

» 1966 b. The effects of limestone. N, K and Mg fertilizers on Mg absorption by oats and
barley. J. Agric. Sci. 67: I—6.

Benko, V. & Fecenko, J. 1970. Effect of various K: Mg ratios upon the formation of dry mat-
ter and the uptake of nutrients by spring barley. Acta Fytotechnica 21: 91 104.

Birch, J. A., Devine, J. R. & Holmes, M. R. J. 1966. Field experiments on the magnesium
requirements of cereals, potatoes and sugar beet in relation to nitrogen and potassium
application. J. Sci. Food Agric. 17: 76 81.

Falade, J. A. 1973. Interrelationships between potassium, calcium and magnesium nutrition
of Zea mays L. Ann. Bot. 37: 345—353.

Ghimme, H., Braunschweig, L. C. von & Nämeth, K. 1974. Beziehungen zwischen Kalium,
Calcium und Magnesium bei Aufnahme und Ertragsbildung. Landw. Forsch. Sonderh.
30/11:93-100.

Hansen, E. M, 1972. Studies on the chemical composition of isolated soil solution and the cation
absorption by plants I. Relationship between form and amount of added nitrogen and
absorption of N, K, Na, Ca and Mg by barley. Plant Soil 37: 589—607.

Häland, A. 1971. Verknad av kalium, magnesium, kalk og nitrogen in markforsok i sorvest
Norge. Forsk. Fors. Landbr. 22: I—2o.



313

Jacques, G. L., Vanderlip, R. L. & Whitney, D. A. 1975. Growth and nutrient accumulation
and distribution in grain sorghum I. Dry matter production and Ca and Mg uptake and
distribution. Agron. J. 67:607 616.

Jansson, S. L. 1971. Naturalness of commercial fertilizers. An ecological treatise. Acta Agr.
Fenn. 123:173-185.

Jerlström, H.-G. 1975. Studies over möjligheterna att med växt- och jordanalyser beskriva
magnesiumsituationen i svensk växtodling. Diss. 175 p. Uppsala.

Jokinen, R. 1977. Effect of added magnesium, potassium, lime and nitrogen on oats I. Yields.

J. Scient. Agric. Soc. Finl. 49: 283 295.
» & Simojoki, P. 1975. Magnesiumlannoitus viljanviljelyssä. Referat: Magnesiuragödsling

vid spannmälsodling. Kehittyvä Maatalous 27; 22—29.
Jorgensen, I. 1976. Kvaelstof, fosfor, kalium og magnesium til Lammefjordens inadaemmede

arealer. Tidsskrift Planteavl 80: 713 741.
Kemp, A. & I'Hart, M. L. 1957. Grass tetany in grazing milking cows. Neth. J. Agric. Sci.

5:4-17.
Lehne, I. & Koepke, V. 1962. Die Wirkung verschiedener Stickstoffformen auf magnesiumar-

men Sandboden. Albrecht-Thaer-Archiv 6: 269 276.
Mengel, K., Viro, M. & Hehl, G. 1976. Effect of potassium on uptake and incorporation of

ammonium-nitrogen of rice plants. Plant Soil 44: 547 558.
Mäntylahti, V. & Marjanen, H. 1971. Tuorerehunurmen lannoitus. Summary; Fertilization

of leys for silage. Ann. Agric. Fenn. 10; 153 173.
Sorteberg, A. 1974. Virkning av magnesium pä avlingsstorrelse og magnesiuminnhold ved

ulike kalking og ulike nitrogenforbindelser. Forsk. Fors. Landbr. 25: 537 558.
Terman, G. L., Allen, S. E. & Bradford, B. N. 1975. Nutrient dilution-antagonism effects

in corn and snap beans in relation to rate and source of applied potassium. Soil Sci.
Soc. Amer. Proc. 39: 680 685.

Welte, E. & Werner, W. 1963. Potassium-magnesium antagonism in soils and crops. J. Sci.
Food Agric. 14: 180 186.

Vigerust, E. 1966. Noen gjadselvirkninger pä jord og plantevekst i rammeforsok. Forsk. Fors.
Landbr. 17; 195-207.

Ms received November 9, 1977

SELOSTUS

Magnesium-, kalium- ja typpilannoituksen sekä kalkituksen vaikutus 11.
Kauran ravinnepitoisuuksiin, kationien suhteeseen ja magnesiumin ottoon
Raili Jokinen
Maatalouden tutkimuskeskus, Maanviljelyskemian ja -fysiikan laitos, 01300 Vantaa 30.

Kolme kasvukautta jatkuneessa astiakokeessa rahkaturve kasvualustana magnesiumlannoi-
tus (0, 200 ja 400 mg Mg/5 1 astia) kohotti merkitsevästi kauran jyvien ja olkien magnesiumpitoi-
suutta. Kaliumlannoituksen lisäys (415, 830 ja 1660 mg/ast K) pienensi merkitsevästi olkien
magnesiumpitoisuutta, kun kasvit saivat magnesiumlannoituksen. Magnesiumin puutteessa
kaliumlannoitemäärät eivät vaikuttaneet olkien magnesiumpitoisuuteen. Lannoituksena annet-
tujen kolmen kalium- ja kahden magnesiummäärän ekvivalenttien suhteen nousu (0.32, 0.65,
1.29 ja 2.58) pienensi sekä jyvien että olkien magnesiumpitoisuutta. Magnesiumlannoituksen
ohella annetun kalkin lisäys (2400 ja 7200 mg/ast Ca) pienensi jyvien mutta kohotti olkien mag-
nesiumpitoisuutta. Typpilannoituksen lisäys kaksinkertaiseksi (1000 ja 2000 mg/ast N) kohotti
jyvien ja olkien magnesiumpitoisuutta, jos kasvit saivat magnesiumlannoituksen. Magnesiumin
puutteessa kalkin tai typen lisäys ei vaikuttanut satojen magnesiumpitoisuuteen.

Tutkimuksessa käytetyt magnesium-, kalium- ja typpimäärät eivät vaikuttaneet kauran jy-
vien kaliumpitoisuuteen. Olkien kaliumpitoisuus nousi kaliummäärää lisättäessä. Ilman magne-



314

siumlannoitusta kauran jyvien ja olkien kaliumpitoisuus sekä suhteiden K/Mg ja K/{Ca 4- Mg)
arvot olivat korkeat. Osa puuttuvasta magnesiumista oli ehkä korvautunut kaliumilla.

Ilman magnesiumlannoitusta saatujen jyvien ja olkien kalsiumpitoisuus oli merkitsevästi
korkeampi kuin magnesiumlannoituksella saatujen satojen kalsiumpitoisuus. Kaura otti puut-
tuvan magnesiumin tilalle osittain ehkä myös kalsiumia. Kaliumlannoituksen lisäys pienensi
kalsiumpitoisuutta, mutta kalkki- tai typpimäärän lisäys kohotti sitä.

Kauran jyvien typpipitoisuus kohosi typpilannoituksen määrää lisättäessä ja pieneni ka-
liumin määrää lisättäessä. Ilman magnesiumia oljet sisälsivät runsaammin typpeä kuin mag-
nesiumlannoituksen saaneet oljet, koska satojen tuleentuminen viivästyi magnesiumin puutteen
vuoksi.

Jyväsadon ottama magnesiummäärä (mg/ast Mg) oli korkeimmillaankin vain noin puolet
koko sadon ottamasta rnagnesiummäärästä. Kalium-, kalkki- ja typpimäärät tai lannoituksena
annettujen kaliumin ja magnesiumin suhde eivät vaikuttaneet jyväsadon magnesiumin ottoon.
Olkisadon ottama magnesiummäärä lisääntyi magnesiumin, kalkin tai typen määrää lisättäessä,
mutta väheni runsasta kaliumlannoitusta käytettäessä, jos kalkitus ja typpilannoitus olivat niu-
kat. Kalkin ja typpilannoituksen lisäys tehostivat kumpikin lannoituksena annetun magnesiu-
min hyväksikäyttöä. Vuosittain annetusta 200 mg:sta magnesiumia kaura käytti hyväkseen
runsaan kalkituksen ja typpilannoituksen tasolla 45 —64 %.