Huang Ting Miao, Wang Zhao Hui, Hou Yang Yi, Gu Chi Ming, Li Xiao, Zheng Xian Feng
Key Laboratory of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture/College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, Shaanxi, China.
State Key Laboratory of Crop Stress Biology in Arid Area, Northwest A&F University, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2017 Jul 18;28(7):2261-2268. doi: 10.13287/j.1001-9332.201707.010.
With N isotope labeled maize straw in nylon net bags and buried in the wheat field at two N rates of 0 and 200 kg N·hm, the effects of nitrogen application on the decomposition of straw dry matter and the release dynamics of carbon, nitrogen, phosphorus and potassium (C, N, P and K) after maize straw retention were investigated in the winter wheat-summer maize rotation system in Guanzhong Plain, Shaanxi, China. Results showed that N application did not affect the decomposition of the returned straw C and dry matter, but promoted the release of P and inhibited the release of N and K from straw during sowing to wintering periods of winter wheat. From the grain filling to the harvest of winter wheat, the decomposition of the returned straw and the release of N, P and K were not affected, but the release of straw C was significantly enhanced by N application. The release dynamic of straw C was synchronized with the decomposition of the dry matter, and the C/N of straw declined gradually with the extension of wheat growing. Until the harvest of winter wheat, the accumulative decomposition rate of straw dry matter was less than 50%, and the total straw C release rate was around 47.9% to 51.1%. The C/N ratio of the returned straw was decreased from 32.2 to 20.2 and 17.9, respectively at N rates of 0 and 200 kg N·hm. From sowing to harvest of winter wheat, the net release of N, P and K from the straw was observed. The N release was 7.2-9.4 kg·hm and 12.7%-16.6% of the total straw N, and the P release was 1.29-1.44 kg·hm and 29.0%-32.4% of the total straw P, while a great deal of K was released quickly, with approximately 80% of the straw K released before wintering, 51.8-52.5 kg·hm and 90.5%-91.7% of the total straw K released at wheat harvest. It was suggested that the K fertilizer application should be decreased for the winter wheat due to the great amount K release from the returned maize straw, and an extra amount of N and P fertilizer should be applied under the straw retention cropping system.
采用尼龙网袋包裹的氮同位素标记玉米秸秆，以0和200 kg N·hm两种施氮量埋入小麦田，在中国陕西关中平原冬小麦-夏玉米轮作体系中，研究了施氮对玉米秸秆还田后秸秆干物质分解及碳、氮、磷、钾（C、N、P、K）释放动态的影响。结果表明，施氮不影响还田秸秆碳和干物质的分解，但在冬小麦播种至越冬期间促进了磷的释放，抑制了秸秆中氮和钾的释放。从冬小麦灌浆期至收获期，施氮不影响还田秸秆的分解及氮、磷、钾的释放，但显著促进了秸秆碳的释放。秸秆碳的释放动态与干物质分解同步，随着小麦生长进程的推进，秸秆C/N逐渐下降。至冬小麦收获时，秸秆干物质累积分解率小于50%，秸秆碳总释放率在47.9%至51.1%左右。在施氮量为0和200 kg N·hm时，还田秸秆C/N分别从32.2降至20.2和17.9。从冬小麦播种至收获，秸秆中氮、磷、钾均有净释放。氮释放量为7.2 - 9.4 kg·hm，占秸秆总氮的12.7% - 16.6%；磷释放量为1.29 - 1.44 kg·hm，占秸秆总磷的29.0% - 32.4%；而大量钾快速释放，约80%的秸秆钾在越冬前释放，小麦收获时钾释放量为51.8 - 52.5 kg·hm，占秸秆总钾的90.5% - 91.7%。建议冬小麦因玉米秸秆还田钾素大量释放而应减少钾肥施用量，在秸秆还田种植制度下应额外增施氮、磷肥。
