Systematic analysis of the relation between wheat residual
decomposition and soil
biochemistry factors in the heavy frigid
region of North East China found the following: changes through time in the rate of wheat residual
decomposition showed a distinct seasonal trend with a single peak, in July (12. 14 X 10-3 g. (g .d) -1 ). 14 soil
biochemistry factors were observed and these also changed in a distinct seasonal pattern. A step effect was an obvious feature of the residual decomposition and soil organic matter synthesis. The grey correlative effects of the 14 soil biology chemistry factors on the wheat residual decomposition were arranged as follows: x1 (0. 914) > x4(0. 880) > x3(0. 855) > x12(0. 852) > x14(0. 802) > x2(0. 799) = x11 (0. 799) > x8(0. 788) > x10(0. 775) > x9(0. 760) > x13(0. 709) > x5(0. 700) > x7(0. 694) > x6(0. 657). This allowed the delimitation of the GM(0, 6) predictive model: y(k) = 13. 5x1 (k) + 23. 75x4(k) - 15. 0x3(k) - 16. 5x12(k) - 0. 5x14(k) + 5. 0x2(k)- 1. 6.