JOURNAL OF THE SCIENTIFIC AGRICULTURAL SOCIETY OF FINLAND
Maataloustieteellinen A ikakauskirja

317

Vol. 50:317-334, 1978

Effects of some heavy metals on oats in pot experiments
with three different soil types.

Asbjgrn Sorteberg

Department of Soil Fertility and Management, Agricultural University of
Norway, 1432 Äs-NLH, Norway

Abstract. An account is given of two pot experiments, of which one has included
all combinations of 5 heavy metals (cadmium, cobalt, lead, mercury and nickel), 3 rates
of each metal, 2 rates of lime, and 3 types of soil (clay soil, peat soil and sandy soil).
The experiment has run for 4 years (1973 1976). Two parallels have been used for
each treatment. A third parallel without crop has been used for soil sampling only.
The second experiment has run for 3 years (1974 1976), and has included the same soil
types and lime rates, but only cadmium and mercury of the metals. The crop grown
in all years has been oats.

250 mg/pot of all metals except lead have had a distinct yield reducing effect. In
the case of mercury, the reducing effect ceases from the third year. It decreases grad-
ually after nickel throughout the experimental period, but not after cadmium and co-
balt. Heavy liming (pH 6 7) has almost eliminated the yield reduction after nickel,
and has considerably reduced it after cobalt.

The contents of cadmium, nickel, cobalt, and mercury in the yield have been mul-
tiplied with the application of 250 mg/pot of the metals mentioned. Application of
even 0.5 mg/pot of cadmium resulted in a distinct increase of content both in grain
and straw. 0.5 and smg mercury, however, had only slight effect. The content of the
metals decreased throughout the experimental period. The effect of mercury in the
fourth year has been minimal, even after the highest application rate. Lead application
led to only moderate increase in the content of the yield.

Roughly 45 —55 percent of the added rates of cadmium, nickel and cobalt, as a mean
value for the soil series, has been recovered as AL-soluble at light liming with pH app-
roximately 5. Heavy liming has reduced the uptake by 3—7 percent for cadmium,
by 16—2O percent for nickel, and by 22 —24 percent for cobalt. Generally, the amounts
of AL-soluble metal in soils have decreased in the order: series peat > sand > clay.

Introduction

An account has been given in a previous publication (Sorteberg 1974)
of a pot experiment in 1973 with heavy metals in oats. The experiment in-
cluded three types of soil (clay soil, peat soil and sandy soil), two rates of
lime, five heavy metals (cadmium, cobalt, lead, mercury and nickel), and
three rates of each metal (0, 50, and 250 mg/pot of five litres) applied in the
form of chlorides. Each series has included two parallels. An additional

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318

parallel without plants has been conducted for each series with the purpose
of providing soil samiples.

The report presents the results from the subsequent years, 1974 76, of
the same experiment. 1973 yields are also included, as well as a supplemen-
tary experiment (Exp. 74) with cadmium and mercury at 0, 0.5 and 5 mg/pot
and the same soil types and lime rates as before. The crop throughout the
experiments has been oats.

Crop yields

Exp. 73
Table 1 shows relative yields of sum grain + straw pertaining to the

highest metalrate. Neither yielded crops nor diagnostic signs observed hrough-
out the growth season indicated that the lowest rate of any metal in question
had notably influenced the size of the yield. Yield figures for those rates have
therefore been excluded. As each treatment has had only two parallels, the
yield results have not been subjected to statistical analysis. However, for
most of the treatments there has only been a slight difference in yield between
the two parallels.

As a supplement to the yield figures in Table 1, the following observations
made during the growth season concerning the effects of the highest metal
application have been noteworthy;

Table 1. Exp. 73. Oats, relative yield of dry matter (grain + straw) for 250 mg metal per
5 litre pot.
Without metal = 100. L.l. = Light liming. H.l. = Heavy liming.
Series I = Clay soil. Series V = Peat soil. Series VI = Sandy soil.

Heavy Soil 1973 1974 1975 1976 Means
metals series L.l. H.l. L.l. H.l. L.l. H.l. L.l. H.l. L.l. H.l.

I 96 89 84 94 92 96 66 78 84 89
Cd V 84 83 97 88 82 30 73 104 84 76

VI 97 102 91 97 97 69 78 62 91 83

I 41 100 51 103 55 98 78 97 56 99
Ni V 27 86 48 103 88 98 81 115 61 101

VI 37 107 58 101 77 82 81 98 63 97

I 78 95 114 120 109 102 101 99 101 104
Hg V 79 70 116 106 101 103 94 95 98 94

VI 6 6 0 114 134 95 98 93 59 77

I 99 98 115 104 98 100 97 92 102 99
Pb V 101 101 113 101 103 106 91 123 102 108

VI 103 104 98 102 93 90 98 96 98 98

I 65 77 70 100 64 95 86 94 71 91
Co V 82 87 93 92 78 100 68 94 80 93

VI 85 105 90 106 72 101 69 96 79 102



319

Cd.
Obvious growth retardation in all treatments, most pronounced at low

lime rate. Ripening nearly a week delayed. In 1975 and 1976 evident Mn-
deficiency at highest lime rate, causing reduced growth.

Ni.
Severly reduced growth at low lime rate. Only slight effect at highest

lime rate. Specific symptoms of Ni deficiency observed in all soil series, prob-
ably also induced iron deficiency. Ripening delayed from a few days to three
weeks. Moderate Mn deficiency in 1975 at heavy lime application.

Hg.
In the sandy soil series (Series I) definite crop failure occurred at both

lime levels in 1973 and at lowest lime rate in 1974. Normal development in
1975 and 1976. The high yield at low lime rate in 1975 must be regarded
against the background of the considerably reduced nutrition uptake during
the two preceding years.

Pb.
Nothing abnormal in any year, except for a moderate Mn dificiency in

1975 and 1976 at highest lime rate.

Co.
Reduced growth in all treatments, particularly at low lime rate. Series V,

low lime rate, showed interveinal chlorosis, probably caused by induced iron
deficiency. Partly delayed ripening.

Relative yields have been calculated throughout the experimental period
for the highest rate of cadmium and nickel at low lime rates and for cobalt
at both lime rates. Cadmium at high lime rate has been eliminated because
of severe manganese deficiency during the third and fourth years. The presen-
tation below shows mean values (in percent) for all three soil series compared
to no heavy metal applied:

1973 1974 1975 1976

Cadmium, low lime rate 92 91 90 72
Nickel * » » 35 52 73 80
Cobalt » » » 77 84 71 74
Cobalt, high lime rate 90 99 99 95

The detrimental effect of heavy nickel application has clearly decreased
throughout the experimental period. The figures for cadmium and cobalt
showed no such trend. It is difficult to determine whether the final year’s
increased yield reduction for cadmium is accidental.

Exp. 74
The low rates of cadmium and mercury applied have not influenced the

crop yield, and the figures concerned are not reported.



320

Heavy metals in the crops
The content of all heavy metals concerned has been determined in crop from

the control pots. Apart from the control, the chemical analyses comprised
nothing but the single metal applied. The chemical analyses have been
carried out by two laboratories (laboratory A 1 and laboratory B 2).

The analytical methods used have been described previously (Sorteberg
1974). Laboratory A is responsible for the results of Exp. 73 in 1973 and 1975,
and for Exp. 74 in 1975. Laboratory B is responsible for all the other crop
analyses.

Table 2 shows the cadmium, nickel, lead and cobalt contents in grain and
straw for Exp. 73. From a relatively large recorded material only the mean
values of soil and year have been given. The statistical material shows wide
variation.

Cd.
Without application, the cadmium content is somewhat higher in straw

than in grains. Increasing cadmium application leads to a heavy increase,
especially in straw. After application the cadmium content in straw is ap-
preciably higher in the peat soil series (Series V) than in the mineral soil ones
(I and VI). The difference is less pronounced in grains, but probably real, as
it appears in practically every single year. The content from the untreated
pots is highest in Series VI for all comparisons. The cadmium content is
clearly reduced both in grains and in straw after heavy liming.

After application, the cadmium content decreases through the experimental
period in every case up to the third year.

For some reason, hitherto unknown, the cadmium content in straw ap-
peared exceptionally low in the fourth year. However, since cadmium ana-
lyses from straw in the fifth year do not in any way confirm this finding, the
cadmium content in straw for the fourth year has not been included in Table 2.

The contents from the untreated pots for each respective year suggest
that a higher cadmium value has been found, at low levels, by laboratory B
than by laboratory A. (Probably because of the balance on the detection
units.)

Ni.
The content of the crop rises sharply with increasing application. Par»

ticularly in the treatments with nickel application the content proves to be
much higher in grains than in straw. This seems to be a characteristic feature
of oats among the grain crops, as previously shown by Andersson and
Nilsson (1975) and by Sorteberg (1974). At application, the content is higher
both in grains and straw in the peat soil series than in the two mineral soil
ones, despite the fact that the content after no application is lowest in the
peat soil series. Increased liming has reduced the nickel uptake considerably.

J) The Central Institute for Industrial Research, Oslo.
2) Chemical Research Laboratory, Agricultural University of Norway.



321

Table 2. Exp. 73, 1973 76. Heavy metals in oats, mg/kg dry matter.

Grain Straw
P u m Light liming Heavy liming Light liming Heavy liming

4-< CS . . .
.

m fli
*, • ■ AJJ 11

_
1

_
/ r 1 j

\S “ 3 u Added heavy metals, mg per pot (5 Itr.)
0 50 250 0 50 250 0 50 250 0 50 250

I 0,09 5.4 9,9 0,07 2,3 5,4 0,20 9,3 31 0,17 2,5 9,1
*** V 0,07 8,3 16 0,03 4,9 8,4 0,15 30 93 0,15 17 43

VI 0,20 6.3 14 0,11 2,4 6,6 0,22 12 55 0,19 3.4 13

Cd
1. 0,11 7.9 18 0,07 3,9 9,0 0,18 25 94 0,14 14 42
2. 0,19 7,4 13 0,11 3,4 6,7 0,29 17 52 0,23 5,2 14
3. ***** 0,06 4,6 9,0 0,03 2,3 4,8 0,11 8,8 34 0,15 3,8 9,0
4. 0,15 2.8 6.0 0,12 2.3 4,9

I 3,3 20 59 0,98 3.4 11 0,66 2,7 24 0,78 0,64 1,2
*�** V 0,97 63 110 0,25 30 72 0,67 19 69 0,54 6,6 23

VI 1.3 24 89 0,71 8,2 33 o,Bo* 4,6 61 o,Bo* 0,65* 7,5
Ni

1. 1,4 42 110 0,73 19 45 0,22** 12 80 0,20** 5,5** 18
2. 2,6 42 92 1,0 16 47 1,3 10 61 1,6 2,9 15
3. ***** 1,6 34 74 0,29 12 35 0,33 7.6 40 0,20 1,6 10
4. 1,6 25 58 0,54 7,2 27 0,77 4,9 23 0,70 2,1 7,5

I 0,21 0,33 0,39 0,34 0,31 0,28 2,1 2.1 2,8 2,1 2,3 2,5
•*• V 0,30 0,52 2,6 0,26 0,33 0,58 1,3 4,3 15 1,5 2.0 5,0

VI 0,27 0,30 0,51 0,23 0,34 0,43 1,7 21 2,9 1,8 2,0 2,2
Pb

1. 0,23 0,37 0,87 0,30 0,27 0,50 1,5 2,7 6,5 1,7 2,2 4,5
2. 0,37 0,68 1.8 0,46 0,63 0,82 2,5 3,8 7,8 2,2 2,6 3,6
3. ***** 0,18 0,29 1,2 0,17 0,12 0,14 1,6 2,5 6,8 2,0 1.7 2,3
4. 0,24 0,36 0,76 0,17 0,28 0,26 1.2 2,2 5,7 1,3 2.1 2,6

I 0,6 1,7 7,1 0,6 0,42 1,4 0,46 5.5 24 0,50 0,92 2,8
•** V 0,6 3,9 17 0,3 1,9 7,7 0,32 17 71 0,37 8,7 32

VI 0,6 1,4 9.4 0,6 0,58 1,8 0,52* 6,2 33 0,50* 1,9 6,4
Co

1. <o,lo** 3,5 17 <o,l** 1,7 5,8 0,14** 18 79 < o,l** 8.1 27
2. 0,6 2.4 10 0,6 0,97 3,1 0,63 9,4 42 0,84 3,8 13
3. ***** 0,1 1,8 8.7 0,1 0,50 2,4 0,26 5.8 25 0,2 1,7 7,8
4. 0,28 1,7 8,0 0,3 0,64 3,3 0,57 4,1 20 0,59 1,8 7,5

• 1. year omitted
*• Series VI omitted

*** Mean 1.-3. year
**•� Mean 1.—4. year

•*••• Mean all series



322

Table3. Exp, 73. Soil series 111, 1975. Ni content in different parts of plants, mg/kg dry matter.

Kernel Glumes Straw

Added Ni Light Heavy Light Heavy Light Heavy
mg/pot liming liming liming liming liming liming

O 4.20.87 0.650.43 0.850.64
50 34 2.73.9 0.653.4 0.63

250 96 9.9 21 1.5 40 1.8

The nickel content shows obvious reduction in the course of time after
application date.

In order to find out more accurately about the distribution of nickel in the
yields, some supplementary analyses have been performed from treatments in
Series 111, 1975. The soil in this series is a compound of 50 volume percent
clay soil and 50 volume percent peat soil. The results from this series have
not been considered in the report. The nickel content was determined for
these treatments in straw, kernels and glumes (Table 3). At heavy liming the
content of the glumes corresponds well with that in straw. At light liming
however, the content of the glumes is considerably lower than in the straw
at the heaviest nickel application. The high nickel content in the grain of
oats cannot, in any case, be explained by high content in the glumes.

Pb.
In the mineral soil series even the highest amount of lead has led to a mod-

erate increase in the crop, the content being approximately doubled at heav-
iest application. In the peat soil series, however, the content has been multi-
plied. Liming had little effect on the lead uptake in mineral soils. In the peat
soil series the uptake has been strongly reduced, particularly at the highest
lead level. The lead content shows several times higher values in straw than in
grains with application as well as without.

The lead content in the yield from year to year does not present an ex-
plicit pattern. The analysis results may also in this case suggest that the
figures from laboratory B range higher than those from laboratory A at low
levels.

Co.
The cobalt content in the yield increases considerably at cobalt application.

The content of the untreated pots is generally lower in the peat soil series
than in the mineral soils, though it increases a great deal more after
application. Increased liming has had no effect on the cobalt content of the
untreated pots but has reduced the content markedly after cobalt application.
In all series with cobalt application, the content decreases notably from the
first to the third year of the experiment.

Hg.
The mercury content is presented in Table 4. In and after the second

year of the experiment the mercury content, with and without application,



Exp. 73. Hg in dry matter of oats, Mg/kg.

Grain Straw
Soil Light liming Heavy liming Light liming Heavy liming
series Year Added Hg, mg per pot (5 Itr.)

0 50 250 0 50 250 0 50 250 0 50 250

11. 5 x 260 8 32 53 32 95 1 300 83 130 1 000
4. 10 9 9 10 10 15 22 25 26 20 32 21

V 1. 45 180 630 43 270 310 110 740 8 600 58 710 8 400
4. < 4 9 10 < 4 5 9 14 56 30 18 39 28

VI 1. <2O 150 xx 25 140 xx 110 3 400 99 000 26 1 700 39 000
4. < 4 8 9 < 4 11 <5 21 26 22 24 20 32

x) Inaccurate result
xx) No yield

has at times been below the detection limits of the laboratories. The table,
therefore, only presents the yield contents for the first and the fourth experi-
mental years. An almost total crop failure in the first year at the highest
mercury amounts in series VI has of course been strongly contributory to the
exceptionally high content in straw this year. It is partly the case also for
Series I and V. Even with the slightly reduced yield taken into account, the
increase in these two series still appears extremely high for straw at the highest
mercury level. In Series VI it is also very high at the lowest level. The mercury
content is, particularly after application, notably less in the grains than in the
straw. This property has not been influenced by liming. In the fourth experi-
mental year, the effect of the mercury application can still be detected in crop
grown in the peat soil, whereas on the mineral soils it no longer had any effect.

Exp. 74
This experiment with cadmium and mercury applications only, has run

for a three year period. The contents of these metals in the yield are given in
Table 5.

Cd.
The small rate of 0.5 mg/pot (0.2 kg/hectare) has increased the content

notably in all soil series, mostly in Series V. At 5 mg/pot the content has
increased strongly. The increase in grains shows a falling trend from the first
to the third year of the experiment. The figures of the analyses for straw are
omitted for the third year for the same reason as those given for the forth
experimental year of Exp. 73. Liming has distinctly reduced the cadmium
content in grains as well as in straw.

Hg.
The content in grain has for most treatments been too low for determi-

nation, and figures representing the content have therefore been excluded from
the table. The content in straw shows moderate increase after mercury appli-

Table 4,

323



324

Table 5. Exp. 74, 1974 76. Heavy metals in oats, mg/kg dry matter for Cd and Mg/kg dry matter for Hg.

Grain Straw
Heavy Soil Light liming Heavy liming Light liming Heavy liming
metals Year series Added heavy metals, mg per pot (5 Itr.)

0 0.5 5 0 0.5 5 0 0,5 5 0 0,5 5

I <0,05 0,11 0,68 <0,05 0,07 0,40 0,09 0,18 0,64 <0,05 0,10 0,26
xx V 0,09 0,39 2,7 <0,05 0,31 2,2 0,14 0,85 6,3 0,05 0,69 4,7

VI 0,17 0,21 1,3 0,06 0,16 0,67 0,17 0,42 1,4 0,11 0,19 0,52
Cd

1. 0,12 0,32 1,8 0,06 0,26 1.3 0,10 0,47 2,6 0,08 0,39 2,0
2. 0,08 0,15 1,3 0,03 0,09 0,85 0,16 0,49 2.9 0,05 0,25 1,7
3. 0,13 0,20 0,89 0,12 0,18 0,62

I* 21 21 23 26 24 23
xxx V* 14 25 24 16 25 25

Vl* 19 23 32 20 24 36
Hg

l. x 26 23 38 27 33 41
2 * xxxx 8 23 20 12 18 17
3. 31 21 23 22 23 21 26

x) 37 of 54 grain samples had too low content for Hg to be determined. Just 2 samples had higher
content than 10 Mg/kg dry matter, xx) Mean 1. and 2. year, xxx) Mean 1— 3 year, xxxx) Mean all series.

cation in Series V and VI, though no increase appears in Series I. Increased
liming hade no effect on the content. The contents of the control pots are
lower in Series V than in Series I and VI, which does not correspond to Exp.
73. At the highest mercury application the content is evidently higher in the
first than in the second and third experimental years.

Table 6 shows the uptake of metals by the harvested crop of Exp. 73, in
percent of the applied amounts for the period 1973—76. Mercury has not
been included in the table, partly because of the severe yield reduction induced
by the highest mercury application, and partly because the mercury uptake
declined considerably already from the second year of the experiment.

The uptake of all heavy metals reflects, to a large extent, the relative
contents in the yields of the respective metals (Table 2) with deviations induced
by varying yields from different treatments.

A much higher proportion of all applied metals has been recovered by the
crops grown in the peat soil than in the mineral soil series. At lowest appli-
cation rate, Series V has recovered 23 percent of nickel, 9 percent of cadmium,
and 6 percent of cobalt at light liming, whereas only a fraction of these metals
has been recovered from the mineral soils. A higher proportion of applied metal
amounts is generally recovered from sandy soil than from the clay soil series.

In most comparisons a higher, even a considerably higher percentage of
applied metal has been recovered at low than at high application rates. This
is to some extent due to yield reduction at high metal application because of
the direct detrimental effect of the metal, and partly to an indirect influence
(manganese deficiency).



325

Table 6. Exp. 73. Uptake of heavy metals in crops for the experimental period 1973 1976,
percent of added.

Grain Straw Grain 4 straw
Soil Light liming Heavy liming Light liming Heavy liming Light liming Heavy liming

Metal series Difference added metal control, mg per potDifference added metal control, mg per pot
50-0 250-0 50-0 250-0 50-0 250-0 50-0 250-0 50-0 250-0 50-0 250-0

I 1.2 0.4 0.8 0.2 1.6 0.8 0.4 0.3 2.8 1.2 1.2 0.5
Cd V 1.6 0,7 1.2 0.3 7.2 3.8 4.2 1.4 8.8 4.5 5.4 1.7

VI 1.0 0.4 0.6 0.2 2.0 1.6 0.6 0.4 3.0 2.0 1.2 0.6

I 4.0 1.4 0.6 0.5 0.6 0.5 0 0 4.6 1.9 0.6 0.5
Ni V 17.6 3.2 6.6 3.6 5.6 2.2 1.6 1.5 23.2 5.4 8.2 5.1

VI 4.6 2.0 1.4 1.2 1.0 1.2 0 0.3 5.6 3.2 1.4 1.5

I 0.02 + 0 0 0.04 0.02 0.08 0.01 0.06 0.02 0.08 0.01
Pb V 0.11 0.12 0.02 0.02 0.94 0.79 0.14 0.21 1.05 0.91 0.16 0.23

VI 0.02 + 0.02 0.02 0.06 0.04 0.02 0.02 0.08 0.04 0.04 0.04

I 0.6 0.2 0 0 1.0 0.6 0.2 0.1 1.6 0.8 0.2 0.1
Co V 1.0 0.8 0.4 0.3 4.8 3.0 2.6 1.5 5.8 3.8 3.0 1.8

VI 0 0.7 0 4-0 1.1 0,4 0.3 0 1.8 0.4 0.3

Soil analyses
After harvesting soil samples were taken from the pots without plants for

chemical analyses with regard to the difefrent metals added. For the first
two years of Exp. 73 and the first year of Exp. 74 these pots were stored in
identical temperatures and were kept in a moist condition during the growing
season like the cropped parallels. During the last two years, however, the
uncropped pots were stored in a room with a moderate temperature also in
winter time. The intention with this procedure was to save time by speeding
those processes in the soil which may exert an influence on the binding or release
of heavy metals.

The method of Egner et al. (1960) with AL-solution has been used for the
soil extraction. The analytical work has been carried out by the National
Swedish Laboratory for Agricultural Chemistry, Uituna, Sweden, during the
first two years, and by the Laboratory at the Department of Soil Science,
Agricultural University of Norway, for the last two years.

The extracted amounts of applied cadmium, nickel, lead and cobalt from
soil in Exp. 73 are presented by Figures 1,2, 3, and 4, respectively; and Table
7 shows the average amounts of extracted cadmium, nickel and cobalt of
added metal.

Cd.
In most comparisons, and as an average for every year, slightly more cad-

mium has been extracted at low than at heavy liming (Figure 1 and Table 7).
Some of the figures for extracted metal amounts can not be explained. Thus,
the extracted amounts of cadmium seem too low for the first year in Series
VI at 50 mg added and in Series I at 250 mg. It does, on the other hand, seem



326

too high for the first year at light liming and 250 mg added cadmium in Series
VI (Figure 1).

A smaller amount of cadmium has generally been extracted from soil
Series I than from Series V and VI. Mean values for rates of cadmium and lime
in percent of added, were:

Soil ser. 1. year 2. year 3. year 4. year
I 30 43 35 34
V 64 50 42 49
VI 53 64 50 49

In Series V the highest amounts of cadmium have been extracted in the
first year, while, surprisingly, the extracted amounts have been highest in
the second year in Series I and Series VI. However, the extracted amounts
throughout the experimental period should be regarded in relation to the
cadmium removed by the crop. According to added rates of cadmium and
lime in Series V, the crop has removed 1.7—8.8 percent of the added cadmium,
that is on the average 5.1 percent. For Series I and Series VI the average
would be 1.4 and 1.7, respectively.

Ni.
In most comparisons considerably more nickel has been extracted after

light than after heavy liming (Figure 2 and Table 7). Evidently less nickel
has also been extracted from Series I than from Series V and VI. As an
average for rates of nickel and lime the nickel extracted in percent of added
has been;

Soil ser. 1. year 2. year 3. year 4. year
I 29 25 21 20
V 63 57 63 51
VI 43 53 43 40

Figure 1. Exp. 73. AL-soluble Cd in soil samples, percent of added



Table 7. Exp. 73. Cd, Ni and Co in soil samples extracted by Absolution at light and heavy
liming, percent of added. Means of the 3 soil series and the 2 rates of metal.

Metal Liming ear Means
1. 2. 3. 4.

Light 53 54 44 46 49
Cd Heavy 46 51 41 42 45

Light minus heavy 7 3 3 4 4

Light 53 54 52 46 51
Ni Heavy 37 36 32 27 33

Light minus heavy 16 18 20 19 18

Light 56 50 45 45 49
Co Heavy 34 26 23 22 26

Light minus heavy 22 24 22 23 23

The lowest amount of nickel has been extracted in Series I and the
highest in Series V. The extracted amount has decreased throughout the experi-
mental period in Series I. Series V and VI show no similar trend.

The percentage of added nickel recovered in crops was on the average
1.9 percent for Series I, 10.0 percent for Series V, and 2.9 percent for Series VI.

Pb.
The extracted amounts of lead are considerably smaller than those of

cadmium and nickel (Fig. 3). Most figures range between 5 and 15 percent of
the applied amount. After application of 50 mg lead the analysis from Series
VI during the first two years shoved either no increase, or, in some cases,
unreasonable high increases in lead content. No figures are given for lead
for those two years.

Figure 2. Exp. 73. AL-soluble
Ni in soil samples, percent of
added.

327



Heavier liming has had no influence on the amount of extracted lead.
Somewhat more lead has been extracted from Series V in the first year than
in the subsequent ones. Figure 3 indicates the reduced amount extracted from
the two mineral soil series also beyond the second year of the experiment.

Co.
The extracted amount shows great variation with soil and lime rates

(Figure 4). Except for the first year, double the amount of cobalt has been
extracted after light liming compared to heavy liming (Table 7) as a mean of
soil and amounts applied. Heavier liming has, however, reduced extracted
cobalt amounts considerably more from Series I and VI than from Series V
(Figure 4 and Table 8) . At light liming, the extracted amount is much smaller
for Series I than for Series V and VI, at high liming it is much smaller also
for Series VI.

Mean values extracted for added rates of cobalt and lime in percent of
added were as follows:

Soil ser. 1. year 2. year 3. year 4. year
I 25 21 15 17
V 73 55 56 54
VI 39 37 30 30

Series I and Series VI show a decreasing trend of extracted cobalt throughout
the experimental period, and in Series V the extracted amount is highest in
the first year.

Table 8. Exp. 73. Co in soil samples extracted by AL-solution, percent of added. Means of
2 rates of metal and 4 experimental years.

Soil series Light liming Heavy liming

I 30 9
V 65 53
VI 52 16

Figure 3. Exp. 73. AL-soluble Pb in soil samples, percent of added

328



The mean value of recovered cobolt in crop in percent of added has for
Series V been 3.6. For Series I and VI the recovering has been less than 1
percent.

Hg.
Only 2—3 percent of the applied mercury was extracted the first year.

The extracted amount for the second year was less than 1 percent in all soil
samples. This metal has therefore not been determined in the last years.

Exp. 74.
The analysis figures for cadmium extracted (not shown in tables or figures)

varied and apperently there are casual fluctuations from year to year. No
more AL-soluble cadmium was recovered after 5 than after 0.5 g, either in the
entire experimental period, or in the third years. The effect of liming has
been slight also in this experiment. The mean extracted amount for all par-
allels and years is 46 percent of the applied cadmium amount, i.e. approximately
the same as in Exp. 73, considering the much higher rates of cadmium in
this experiment. The quantity of extracted cadmium was smaller with regard
to soil from Series I (31 percent) than from Series V (53 percent) and VI (55
percent) in Exp. 74.

Discussion

Lead distinguishes itself among all heavy metals included in this experi-
ment by having no influence on the size of the yield. The lead uptake in the
plants has increased notably, though not strongly, with increased lead appli-
cation. Liming has retarded the lead uptake in the peat soil series, but de-

Figure 4. Exp. 73. AL-soluble
Co in soil samples, pcrceent of
added.

329



330

pending on lead application. Without lead application, liming had no effect
on the lead content. At 50 mg lead per pot, liming has reduced the content
some what, and at the highest application, the reduction was substantial. Cox
and Rains (1972) grew 5 species in pot experiments on two lead contami-
nated soils and with three rates of lime (pH interval approximately 5 —7).
Liming induced decreased lead content in all plants. The reduction increased
in most cases with the increasing content in the plants. Andersson and
Nilsson (1975), however, found only a slight effect on the lead content from
increasing lime rates (pH 4.8, 6.0 and 7.2) on spring wheat grown in a pot
experiment. Varying lime rates were also of insignificant importance for
extracted lead amounts at 1 M NH4Ac from soil samples.

The relatively moderate increase of the lead content in oats in the present
experiment compared to that of the remaining heavy metals, corresponds to
the moderate amount of lead found as AL-soluble in the soil. Since liming
has been shown to have no influence on the amount of AL-soluble lead, the
varying lead content in the plants after different lime rates may be of phys-
iological nature rather than an effect on the Al-solubility of lead in soil.

Cadmium, nickel, mercury, and cobalt have all led to more or less reduced
yields, at least at the heaviest applications. Mercury distinguishes itself here
by reducing the yield severely in the first and, partly, in the second year,
whereas there was no effect as from the third year on.

The mercury content in the yield has declined strongly from the first to the
fourth experimental year (Table 4). This is also so for treatments where
mercury had little or no effect on the yield quantity. In Series I, at the high-
est mercury application, the yield is only reduced by 5—22 percent in the
first year (Table 1). The mercury content is, however, roughly 40—50 times
higher at light liming, and 7 12 times higher at heavy liming than in the
control pots. Series V shows an almost identical picture. In Series VI there
appears a relatively corresponding increase in the content at the lowest amount
of mercury, without simultaneous yield reduction. In the fourth year, however,
all soil series show little or no increase of mercury content in the crop after
mercury application.

Subsequent to the first year’s harvest, the heavy metal content in the soil
was also determined by 2 M HCI extraction. The extracted amounts fluc-
tuate. Partly more, partly less than the amount applied was recovered. With
regard to mercury, the HCI soluble fraction has also been determined after
the fourth year in the pots subject to light liming. The recovered amounts of
the applied metal are presented in Table 9. The figures for recovered mercury
do not indicate any notable decrease in clay and peat soils. The case is totally
different in sandy soil. Even in the first year, some of the mercury has prob-
ably disappeared or at least been insoluble in 2 M HCI at the highest appli-
cation rate (250 mg), and after the fourth experimental year, the extracted
amount is less than one fifth of the applied amount. However, the heavily
reduced amounts in HCI soluble mercury cannot alone explain the normal
yields in the third and the fourth years after the heaviest mercury applica-
tion. Table 4 thus.shows that the mercury content in the plants after the
fourth year is much less at the highest application (250 mg) than for 50 mg in



331

Table 9. Exp. 73. Hg soluble in 2 M HCI, percent of added at low liming.

Added Hg, mg per pot (5 Itr).
Soil series 50 250

1973 1976 1973 1976

I 92 92 69 90
V 81 108 91 76
VI 115 49 36 18

the first year. The availability of the remaining amount seems also to have
been severely reduced during the experimental period.

Cadmium, nickel and cobalt present several common features. All of them
have at highest amounts applied combined with low liming, led to retarded
growth and/or reduced yield. The yield reduction has been pronouncedly
high for nickel. Heavy liming has, nevertheless, practically neutralized the
detrimental effect of this metal. Heavier liming has been less effective in
eliminating the detrimental effect of cobalt, and least effective against cad-
mium. The ability of lime to reduce the metal uptake in oats has been higher
for nickel and cobalt than for cadmium.

In the case of cobalt, reduced content in the yield corresponds relatively
well with the reduced AL-soluble amount in the soil throughout the ecxperi-
mental period. Reduction of the nickel content in the yield does not show the
same good correlation to the extracted amount from the soil, and the reduc-
tion of cadmium in the yield shows only for one of the series some correspon-
dence to the soluble cadmium content in soil.

Andersson and Nilsson (1975) found in pot experiments great reduc-
tion in the cobalt, nickel and cadmium contents at increased liming in spring
wheat and rape (pH 4.8, 6.0, 7.2), although they found no deviation in the
lead content. By soil extraction with 1M NH4Ac, the extracted amounts of
nickel and cobalt declined rapidly with rising pH, while variyng pH values
had little or no effect at all on cadmium and lead. The same authors carried
out another investigation in which extractions of various strengths were used
for cadmium (1974). In their report they claim that highly acid solutions fail
to provide information of the solubility of cadmium at different pH levels.
Coppenetet al. (1972) investigated the cobalt content in Italianrye grass (Lolium
italicum). He found it reduced by a rising pH after lime fertilizer application,
whereas the acid ammonium nitrate increased the cobalt content. Concerning
cobalt, it has for a long time been known that gras grown on soil with a high
pH generally has a lower cobalt content than grass grown on more acid soil.

A comprehensive literature exists on the cadmium content in plants with
regard to different pH. In addition, the solubility of the metal in soil has
often been subject of investigation. John and Van Laerhoven (1972) found
greatly reduced cadmium contents in lettuce and oats grown in pots after
very heavy liming. John (1976) also found in his recent investigations that the
relative cadmium uptake and total content in the plants mentioned above
were notably less at pH 8 than at pH 5.



332

Linnman et al. (1973) found a distinctly reduced cadmium uptake at
increasing pH in the soil within a pH interval of approximately 5—7 when
growing wheat in a pot experiment, whereas Takijima et al. (1973) found a
negative correlation between the cadmium content in rice and the pH of the
soil and the amount of exchangeable Ca.

Williams and David (1976) grew subterranean clover in a pot experiment
with red podzolic soil. With the adding of CaS04.2 H2O, CaC0 3 or MgC0 3
the soil got a pH-interval ranging form 5.1 to 6.8. The yield was not affected
by any treatment. The cadmium content in plants was almost reduced to
one fourth from the lowest to the highest pH. Miller et al. (1976) investigated
in pot experiments with 9 different soils the effect of various soil factors on
the yield and cadmium uptake in soybeans. They found that the soil cation
exchange capacity and the pH was important for the cadmium accumulation
in plants, with a decreasing cadmium uptake at rising values for both factors.

I vai et ai. (1975) obtained somewhat diverging results when growing corn
in a water culture experiment where both cadmium and calcium applications
as well as the pH varied. Calcium retarded the cadmium uptake, whereas
the cadmium content in the plants remained unchanged in the pH interval
4—6. Yield reduction appeared when the cadmium content rose to 20 ppm of
the dry matter.

Jansson (1975) grew spring wheat in pots with and without lime, at pH
5.3 and 7.0, respectively, with or without a cadmium application. A rela-
tively high cadmium application led to severe yield reduction and a very
high cadmium content, particularly without lime. Without cadmium appli-
cation, however, the cadmium content was substantially higher with lime
than without it.

The present experiments indicate that the content of some heavy metals
in plants produced on uncontaminated sphagnum peat soil may be low.
However, this soil type may also prove sensitive in increasing the metal con-
tent should contaminated substances be added.

Acknowledgements. The author wishes to thank the City Council of Oslo for its financial
support by in paying for all the chemical analyses of heavy metals in crop and soil. Thanks
should also be given to the National Agricultural Chemistry Laboratory of Sweden, The Central
Institute for Industrial Research, Oslo, the Chemical Research Laboratory and the Laboratory
at the Department of Soil Science, Agricultural University of Norway, for the heavy metals
determination of a large number of soil and yield samples.

REFERENCES

Andersson, A. & Nilsson, K. O. 1974. Influence of lime and soil pH on Cd availability to
plants. Ambio 3: 198 200.
& Nilsson, K. O. 1975. Effekter pä tungmetallhalterna i mark och växt ved tillforsel
av ratsiani som växtnäringskälla och jordförbättringsmedel. Rapp. 96. Avd. växt-
näringslära, Lantbr.högsk., Uppsala.

Coppenet, M., More, E., Le Corre, L. & Le Mao, M. 1972. Variations de la teneur en cobalt
des ray-grass etude de techniques d’ enrichissement. Ann. Agron. 23(2): 165 196.



333

Cox, W. J. & Rains, D. W. 1972. Effect of lime on lead uptake by five plant species. J, En-
viron. Qual. 1,2; 167 169.

Egner, H., Riem, H. & Domingo, W. R. 1960. Untersuchungen fiber die chemische Boden-
analyse als Grundlage fur die Beurteilung des Nährstoffzustandes der Boden. 11.
Chemische Extractionsmethoden zur Phosphor- und Kaliumbestimmung. Kungl.
Lantbr.hogsk. Ann. 26: 199 215.

Ivai, 1., Hara, T. & Sonoda, Y. 1975. Factors affecting cadmium uptake by the corn plant.
Soil Sci. Plant Nutr. 21(1): 37—46.

Jansson, S. L., 1975. Kadmium i växtnäringsbalansen. Seminar om tungmetaller, sirkulasjon
i jordbruket, 24 31. NJF Seksjon I.

John, M. K., 1976. Interrelationships between plant cadmium and uptake of some other
elements from culture solutions by oats and lettuce. Environ. Pollut. (11) 2; 85 95.
& Van Laerhoven, C. 1972. Lead uptake by, cettuce and oats as affected by lime
nitrogen, and sources of lead. J. Environ. Qual. 1,2; 169 171.

Linnman, L., Andersson, A., Nilsson, K. 0., Lind, B, Kjellström, T.,& Friberg, L. 1973.
Cadmium uptake by wheat from sewage sludge used as a plant nutrient source. Arch.
Environ. Health 27:45—47.

Miller, J. E., Hassett, J. J. & Koeppe, D. E. 1976. Uptake of cadmium by soybeans as
influenced by soil cation exchange capacity, pH and available phosphorus. J. En-
viron. Qual. 5, 2:157 160.

Sorteberg, A., 1974. The effect of some heavy metals on oats in a pot experiment with three
different soil types. J. Scient. Agric. Soc. Finl. 46:277 288.

Takijima, Y., Katsumi, F. & Takezawa, K. 1973. Cadmium contamination of soils and rice
plants caused by zink mining. 11. Soil conditions of contaminated paddy fields which
influence heaby metal contents of rice. Soil Sci. Plant Nutr. 19(3): 173 182.

Williams, C. H. & David, D. J. 1976. The accumulation in soil of cadmium residues from
phosphate fertilizers and their effect on the cadmium content of plants. Soil Sci. 121,
1: 86-93.

Ms received July 13, 1978.

SELOSTUS1)

Raskasmetallien vaikutuksista kauraan
Asbjorn Sorteberg

Norjan Maatalouskorkeakoulu, 1432 Äs-NLH

Norjan Maatalouskorkeakoulullaon vuosina 1973 —76 tehty 4-vuotinen astiakoesarja, jossa
on tutkittu maahan lisätyn kadmiumin, koboltin, lyijyn, elohopean ja nikkelin vaikutuksia
kauran kasvuun ja raskasmetallien ottoon. Savi-, hieta- ja turvemaahan lisätyt raskasmetal-
limäärät olivat 0 mg, 50 mg ja 250 mg 5 maalitraa kohti. Koetekijänä oli lisäksi kalkitus.
Vuosina 1974 76 tehtiin myös toinen koesarja, jossa lisätyt raskasmetallimäärät olivat paljon
pienempiä: 0, 0.5 ja 5 mg/astia. Jälkimmäisessä kokeessa tutkittiin vain kadmiumia ja elo-
hopeaa.

Maahan lisätty suuri raskasmetalliannos, 250 mg/astia, alensi selvästi kaurasatoa. Lyijy
muodosti kuitenkin poikkeuksen, sillä sen lisääminen ei vaikuttanut sadon määrään. Eloho-
pean haitallinen vaikutus kaurasadon määrään loppui kolmantena vuonna. Myös nikkelin
haittavaikutus pieneni vuosi vuodelta, mutta kadmiumin ja koboltin osalta vaikutuksen
pienenemistä ei neljän vuoden kuluessa havaittu. Voimakas kalkitus, jolla maan pH-luku
nostettiin välille 6 7, eliminoi lähes täysin nikkelin haittavaikutuksen ja pienensi huomatta-
vasti koboltin haittavaikutusta.

Kaurasadon kadmium-, nikkeli-, koboltti- ja elohopeapitoisuudet moninkertaistuivat
lisättäessä näitä metalleja maahan 250 mg/5 1. Jo pieni annos kadmiumia, 0.5 mg/5 1, lisäsi
selvästi sekä jyvä- että olkisadon kadmiumpitoisuuksia. 0.5 5 mg elohopeaa s:een maalit-
raan lisättynä ei sen sijaan vielä selvästi kohottanut kaurasadon elohopeapitoisuutta. Ras-



334

kasmetallipitoisuudet pienenivät vuosi vuodelta. Neljäntenä vuonna ei suurimmankaan
elohopea-annoksen vaikutusta kaurasadon elohopeapitoisuuteen voitu enää todeta. Lyijyn
lisääminen maahan aiheutti vain pienehköjä lyijypitoisuuksien kohoamisia kaurasadossa.

Keskimäärin 45 —55 % maahan lisätystä kadmiumista, nikkelistä ja koboltista oli analy-
soitavissa maanäytteistä ammoniumlaktaattiin uuttuvassa muodossa, kun maita oli kalkittu
vain lievästi noin pH s:een. Voimakkaan kalkituksen (pH 6 7) vaikutuksesta maahan lisä-
tystä metallimäärästä oli AL-menetelmällä analysoitavissa huomattavasti pienempiä määriä:
kadmiumia 3—7 %, nikkeliä 16—2O % ja kabolttia 22—24 % AL-liukoiset raskasmetalli-
pitoisuudet olivat korkeimpia turvemaassa ja alhaisimpia savimaassa.

1) Selostuksen laatinut P. Elonen.