Agriculture Reference
In-Depth Information
TABLE 9.4
Changes in Stocks of Soil Organic Carbon during 47 Years in Long-Term
Field Experiments with Crop Rotations and Continuous Monocultures on
Fertilized Plots, 0-20 cm Soil Layer, Field No. 6
Crop Rotation
Continuous
Cereal
Share of Row Crops, %
40
50
60
4 Mg/ha
Manure +
30% Alfalfa
(
Medicago
sativa
)
4 Mg/ha
Manure +
10% Black
Fallow
Winter
Wheat
Maize,
Grain
8 Mg/ha
Manure
Years
Indices
LSD
05
1962
Initial SOC
stocks, 78.7
Mg/ha
2009
SOC stocks
73.4
67.4
64.8
59.5
62.2
2.9
Stock reduction
5.3
11.3
13.9
19.2
16.5
Percentage from
initial stocks
6.7
14.4
17.7
24.4
21.0
Rate of SOC
depletion,
Mg/ha/year
0.11
0.24
0.30
0.41
0.35
approach was initiated in 1995-1996 with a multifactorial experiment including three
main components of each farming system: alternation of crops, fertilization, and soil
tillage in crop rotation. The results from two full rotations are presented below.
9.3.3 s
oil
t
illage
Another long-term experiment conducted by the Department of Sustainable Farming
Systems at Selectia RIFC included eight different systems of soil tillage in a seven-
field crop rotation with 57% of row crops. Mineral fertilizers were applied at the
recommended rates for different crops along with an average of 5.7 Mg/ha at FYM
over the crop rotation. Table 9.5 shows the yield data for winter wheat, sugar beet,
and maize for two variants: annual moldboard plowing for all crops in the rotation
and noninversion tillage for all crops except sugar beet where the moldboard plow
was used only for one rotation. The primary noninversion tillage was performed by
blade working tools at the depth of 25-27 cm for corn for grain and 32-35 cm for
sugar beet. For winter wheat, disks were used for tillage to the depth of 10-12 cm.
Crop yields did not respond to different systems of tillage; however, the stocks of
SOM were higher under annual noninverting soil tillage than under the plow tillage
(Table 9.6). The total losses of SOM during the 14 years for the 0-20 cm layer were
0.8 and 1.3 Mg/ha, respectively. Reduction in soil tillage decreased the total and
annual losses of SOM, but cannot mitigate them completely on arable lands.
