期刊
CANADIAN JOURNAL OF SOIL SCIENCE
卷 81, 期 3, 页码 371-382出版社
AGRICULTURAL INST CANADA
DOI: 10.4141/S00-034
关键词
green manure; wheat yields and N uptake; N recoveries; microbial respiration; labile and heavy fractions of OM; C and N contents
类别
A field study was conducted for 5 yr (1993-1997) to evaluate the effects of green manure residues applied to the soil in 1993 and 1995, on wheat (Triticum aestivum L.) yields and N nutrition as subsequent crop in 1994, 1996 and 1997. The effect of green manure application was also evaluated on soil microbial activity (CO2), on C and N contents of whole soil and on labile (LF) and heavy fractions (HF) of organic matter (On. The experiment was initiated on a Le Bras silt loam (Humic Gleysol). The green manures, as a main factor, were clover (Trifolium pratense L.), buckwheat (Fagapyrum esculentum L.), millet (Echinicloa crus galli L.), mustard (Brassica hirta Moench), and colza (Brassica campestris L.), and there was a control without green manure. The sub-factors consisted of four N fertilizer rates for wheat in the subsequent years at 0, 30, 60 and 90 kg N ha(-1). Broadcast application of N-15- labelled NH4NO3, was made in 90 kg N ha(-1) fertilizer treatments. Two green manure applications did not influence the C and N contents of densimetric fractions of OM (LF and HF), but significantly increased those of whole soil, and microbial respiration (CO2). Green manures significantly increased wheat yields and N uptake in 1994 and 1996. Levels of N derived from fertilizer (Ndff) were lower in all green manure treatments as compared to the control, which indicates that the proportion of N derived from soil and green manures (% Ndfs) was higher in these treatments. The contribution of N from green manure varied in the following order: buckwheat < clover < mustard < millet < colza. With the exception of the clover treatment (< 100%), the N recoveries from the other green manure N (NRGM) ranged from 23 to 34% and from 19 to 36 % for 1994 and 1996, respectively. Green manure application provided 15 to 24 kg N ha(-1) in 1994 and from 16 to 36 kg N ha(-1) in 1996 and this contribution accounted for 25 to 31 % of the total wheat N uptake. Significant green manure effects on wheat yield and N nutrition were primarily due to the improvement of soil properties and to high N recoveries from the green manure. In the cold temperate climate of Quebec, green manure incorporation into soil in late summer or early fall of the preceding year allowed N synchronization with wheat N needs in subsequent cropping seasons. Nitrogen fertilizer rates could be reduced after the incorporation of green manures having high yields and N contents in the previous season.
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