追施不同量尿素下麦后复种油菜对耕层土壤有机碳及微生物量碳氮的影响

目的]研究不同追施尿素量对麦后复种油菜生物产量和耕层土壤有机碳、土壤微生物量碳氮及碳库管理指数的影响,为麦后复种油菜尿素施用量提供依据。方法]在古浪县进行小区试验,设置5个试验水平:追施尿素0,90,120,150,180kg/hm2。结果]追肥可提高麦后复种油菜的生物产量;土壤有机碳、微生物量碳、微生物氮以及碳库管理指数均随追肥量的增加呈抛物线型变化的趋势;碳库指数和碳库管理指数的变化趋势同有机碳的变化趋势;有机碳、微生物量碳与碳库管理指数显著相关,有机碳与碳库管理指数极显著相关,微生物量碳与有机碳含量虽呈现正相关关系,但未达到显著相关性。结论]综合油菜生物产量和土壤微生物量等指标,古浪县麦后复种油菜的施肥量以追施尿素120~150kg/hm2为宜。

Effects of Different Amount of Topdressing Urea on Soil Organic Carbon and Soil Microbial Biomass Carbon and Nitrogen of Multi-cropping Rape After Wheat Planted

Objective] The changes of soil organic carbon(SOC), soil microbial biomass carbon(SMBC), soil microbial biomass nitrogen(SMBN) and carbon pool management index(CPMI) under different amount of topdressing urea in multi-cropping rape after wheat planted were explored to provide scientific basis for urea fertilization.Methods] Plot test was conducted in Gulang County, with five treatment levels of topdressing urea 0, 90, 120, 150, 180 kg/hm².Results] The urea fertilizer was observed that all levels increased biological production of multi-cropping rape after wheat planted. With the increases of urea, SOC, SMBC, SMBN and CPMI all decreased firstly and increased later. CPI and CPMI changed similarly. SOC and SMBC had significant correlations with CPMI; SOC and CPMI correlated extreme significantly; SMBC and SOC correlated positively but insignificantly.Conclusion] If biological yield of rapeseed and soil microbial biomass were both considered, the best fertilizer rate for multi-cropping rape after wheat planted is 120~150 kg/hm² in Gulang County.