Decomposition of cover crop residues in soils and its effects on winter wheat yield
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DOI:10.7606/j.issn.1000-7601.2019.04.10
Key Words: cover crops  decomposition  winter wheat  yield
Author NameAffiliation
LI Zhi-peng College of Urban and Environment science, Northwest University, Xi’an, Shaanxi 710127, ChinaShaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, Northwest University, Xi’an, Shaanxi 710127, China 
WANG Jun College of Urban and Environment science, Northwest University, Xi’an, Shaanxi 710127, ChinaShaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, Northwest University, Xi’an, Shaanxi 710127, China 
SHANG Yu-qing College of Urban and Environment science, Northwest University, Xi’an, Shaanxi 710127, ChinaShaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, Northwest University, Xi’an, Shaanxi 710127, China 
ZHANG Shao-hong College of Urban and Environment science, Northwest University, Xi’an, Shaanxi 710127, ChinaShaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, Northwest University, Xi’an, Shaanxi 710127, China 
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Abstract:
      The nylon mesh bag method was used to study the return of different cover crops (Changwu soyean (S), Ryegrass (R), and 1∶1 Mixture (M)) residue and nitrogen (N) fertilizer level (0, 60, and 120 kg N·hm-2) in Weibei dryland area under the two-factor treatments, the cover crop decomposition, the dynamics of carbon and nitrogen release, and the subsequent yield of winter wheat, and the decomposition rate were analyzed with the Olsen model. The results indicated that the decomposition and release characteristics of carbon (C) and N from each cover crop showed a characteristics of “pre-fast-intermediate slow-late acceleration”, and the decomposition of cover crops was following the Olsen model. On the 276th day, decomposition rates of all treatments were above 70%. In days of 0~35, under the same N treatment, the cumulative decomposition rate and the decomposition rate were in order of S>M>R (P<0.05). On the 35th day, the cumulative decomposition rate of dry matter in S, M, and R treatments reached 61.9%, 55.5%, and 47.5%, respectively. The application of N in 0~35 days enhanced the crop decomposition. The application of N to S and M did not impact the decomposition significantly but the effect on R was significant. After 35 days, the effect of N fertilizer was gradually weakened. The decomposition of the cover crops was accompanied by the rapid release of C and N, especially in the first 21 days, the residual ratio of C and N in S, M, and R reached 40%, 50%, and 60%, respectively. On average, the C-N release rate with treatment S was significantly higher than that with treatment R, but not with that of treatment M. Compared with the fallow control, the tumbling return of cover crops significantly increased the yield of subsequent winter wheat, and the grain yield increased by 10%~35% (P<0.05), among which SN1 and MN1 had the best treatment effect.
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