关键词: 水稻油菜轮作, 控释氮肥, 土壤无机氮, 酶活性, 产量, 氮素利用率

Abstract: 【Objective】 In order to study the effects of different nitrogen fertilization treatments on soil nitrogen supply and yield in rice- rape rotation system, the differences of effects in different treatments in the rice and rape rotation system were analyzed. 【Method】In 2014 and 2015, field experiments were carried out to study the effects of different N treatments on the inorganic nitrogen, enzyme activity, yield and nitrogen use efficiency. Four four fertilization patterns were designed, including CK (non- N fertilization), UR (100% urea), 40%CRU (40% controlled- release urea+ 60% urea), CRU (100% controlled- release urea). 【Result】（1）Compared to UR, the soil inorganic nitrogen at the mid-late stage of rice in CRU treatment was increased significantly. With the increasing of N in CRU, the soil inorganic nitrogen in the mid-late stage of rape was all increased. 40%CRU and CRU had a little influence on the soil nitrogen in the mid-late stage of rape. (2) The highest urease activity and protease activity in the early stage of rice and rape were obtained in UR. With the development of growth period, the enzyme activity was higher than UR by controlled- release fertilizers with different patterns. 40%CRU and CRU had a little influence on the soil enzyme at the mid-late stage of rice and rape. The enzyme activity of rice increased at beginning and then decreased afterwards, with the peak at booting stage. With the development of rape growth period, the urease activity reduced gradually. After adding controlled- release fertilizer, the protease activity increased at beginning and then decreased afterwards. (3) The yields of rice and rape were the highest in 40%CRU treatment, compared with UR treatment, the yield of rice increased by 597.04 kg·hm^-2 (2014) and 582.61 kg·hm^-2 (2015), respectively, improved by 7.50%-7.83%; the yield of rape increased by 391.19 kg·hm^-2 (2014) and 378.49 kg·hm^-2 (2015), improved by 15.39%-16.70%, respectively. The regression equation of yield and component factors showed that grain number and seed setting rate were positively correlated with rice yield, compared with UR treatment, 40%CRU treatment increased grain number by 15.17% (2014) and 17.72% (2015), the seed setting rate increased by 4.49% (2014) and 4.44% (2015). The rape yield showed a significant correlation with seed number per pod and total silique number, 40%CRU treatment had the biggest seed number per pod, total silique number increased by 8.98% (2014) and 13.80% (2015) compared with the UR treatment. (4)Nitrogen application significantly increased the overground nitrogen accumulation at the mature stage of rice and rape, and 40%CRU treatment was the highest. Compared with other nitrogen treatments, the nitrogen accumulation in the mature stage of rice in 40%CRU treatment increased by 6.21%-21.83% (2014), 6.51%-20.74% (2015), and the nitrogen accumulation at the mature stage of rape increased by 8.42%-24.74% (2014), and 9.39%-22.77% (2015). Nitrogen application could effectively improve the NAUE, NPP, NAE, and the optimal treatment was 40%CRU, followed by CRU treatment. 【Conclusion】 Controlled-release fertilizer could improve the soil nitrogen and enzyme activity, increase significantly yield of rice and rape, enhance nitrogen use efficiency. And controlled release blend bulk urea will enhance the nitrogen supply of soil at the mid-late growing stage of rice and rape, which can effectively promote the absorption and utilization of nitrogen, thus increase the yield effectively.

Key words: rice-rape rotation, controlled release nitrogen fertilizer, soil inorganic nitrogen, enzyme activity, yield, nitrogen use efficiency