冬小麦生长期土壤固定态铵与微生物氮的动态研究

田间试验研究冬小麦生长期土壤固定态铵和微生物N动态变化结果表明 ,施入基肥后土壤固定态铵显著上升 ,春季后固定态铵显著下降 ,至扬花期降至最低点。作物生长后期随吸N量的降低 ,各施肥处理固定态铵含量约升至播前水平。冬小麦全生育期土壤微生物N呈明显季节变化 ,施基肥后短期内有所升高 ,且春季施肥后出现第 2次升高 ,至扬花期土壤微生物N降至最低点 ,至生长后期重新回升。

Dynamics of soil fixed NH4+ and soil microbiomass nitrogen in the growing season of winter wheat

Dynamics of soil fixed NH _4 and microbiomass N in the growing season of winter wheat were studied by field experiment. The results show that the soil fixed NH _4 increases significantly after the application of basal fertilizer, decreases significantly after spring and reaches to the lowest point at flowering stage. It reaches nearly the same level before harvest as that of sowing period because the soil fixed NH_4 pool is complemented by nitrogen mineralization in the late crop growing stage when crop has a low nitrogen uptake. Soil microbiomass N changes with the season. It has a slight increase in short period after the application of basal fertilizer and a second increase after the application of spring fertilizer, reaches to the lowest point at the flowering stage and is recovered in the latest stage because of lower crop N uptake.