不同轮作下油菜季土壤氮素供应和油菜氮素吸收差异研究

comparative field experiment of N fertilizer application with different rates between two different rotations was conducted at Experiment Farm in Huazhong Agricultural University, Wuhan, China, to investigate the effects of crop rotation and N fertilization application on soil N supply and oilseed rape uptake. Two crop rotation were included (i.e., rice-oilseed rape rotation and cotton-oilseed rape rotation) and two given levels of N fertilizer (0 kg/ha and 150 kg/ha) were used in oilseed rape season and two given levels of N fertilizer (0 kg/ha and 150 kg/ha) were used in previous crop of oilseed rape season in each rotation. The results showed that the capacity of soil N supply and the total N uptake by oilseed rape could be considerably enhanced by N fertilizer application. Compared to zero N fertilizer, the net soil N mineralization accumulation was increased to 102 kg/ha in rice - oilseed rape rotation (RR),and 109 kg/ha in cotton - oilseed rape rotation (CR) when the oilseed rape receive 150 N kg/ha fertilizer. Across two crop rotation systems, it was surprising to find that the total N content in soil, soil net N mineralization and N uptake by oilseed rape were all higher in cotton-oilseed rape rotation in the oilseed rape prophase growth, and higher in rice-oilseed rape rotation in the late growth period. It possibly suggested that the cotton-oilseed rape rotation is conducive to oilseed rape prophase growth while the rice-oilseed rape rotation is conducive to oilseed rape late growth. In conclusion, the fertilizer N demand for oilseed rape should be estimated by oilseed rape N requirement and the capacity of soil N supply in the different crop rotations to gain the higher N use efficiency and optimize the economic benefit.