Organic Carbon Sequestration Potential and the Co-Benefits in China’s Cropland - Principles of Sustainable Soil Management in Agroecosystems - page 502

(a)

5

y = 0.04 x + 0.04
R 2 = 0.33

4

3

2

1 50

60 70 80

Overall SOM score

90 100

(b)

6

5

4

y = 0.37 x - 0.38
R 2 = 0.76

3

2

5 15 25

Mean topsoil SOM (g/kg)

35

(c)

7

6

5

4

3

y = 0.09 x + 2.86
R 2 = 0.36

2

10 15 20 25 30 35

Mean topsoil SOM (g/kg)

FIGURE 18.1 Cropland topsoil SOM related to the averaged cereals yield of China's prov-
inces. (a) Overall correlation of provincial mean cereals yield over 1949-1999 with the mean
topsoil SOM content surveyed in the early 1980s. (b) Correlation of the mean cereals yield
over 1994-1999 for North China provinces, with rainfed crops in black triangles and the
white squares representing Jilin and Inner Mongolia. (c) Correlation of the mean cereals yield
over 1994-1999 of South China's provinces, with mainly rice in open triangles. The white
square represents Jiangsu. (Data synthesized from the Yearbook of Agricultural Statistics of
China 2001, China Agricultural Press, Beijing, 2002.)