不同栽培模式对冬小麦-夏玉米轮作系统产量、氮素累积和平衡的影响

以河北山前平原区秸秆还田条件下小麦-玉米轮作体系为研究对象,设置农民习惯、高产高效、再高产和再高产高效4个模式,通过定位试验探讨各栽培模式对3个轮作周期作物产量、土壤硝态氮累积量及氮平衡的影响.结果表明: 小麦、玉米产量均以再高产模式最高,高产高效和再高产高效模式次之,均显著高于农民习惯模式;小麦季和玉米季氮肥利用效率(PFP)均以高产高效模式最高,显著高于其他模式;0～400 cm土体硝态氮累积量在 768.4～1133.3 kg·hm^-2之间,其中80%～85%累积在根下90～400 cm土层;4种模式的土壤硝态氮均有明显向下淋移现象,120～150 cm和270～330 cm处均出现了累积峰,以270～330 cm土层硝态氮累积量最大;高产高效模式的土壤硝态氮含量整体水平均低于其他模式,浓度基本维持在30 mg·kg^-1以下,在一定程度上能有效缓解环境压力;冬小麦季0～90 cm土体氮素盈余量均小于夏玉米季,并以高产高效模式的氮素表观损失量最低,显著低于其他模式.综合考虑产量、氮肥利用效率、硝态氮累积和氮平衡,以高产高效模式表现最优,但还有一定的提升空间.

Effects of different cultivation patterns on yield,nitrate accumulation and nitrogen balance in winter wheat and summer maize rotation system.

This study investigated the impacts of four cultivation patterns including farmer practice, high yield and high efficiency practice, super high yield practice, and super high yield and high efficiency practice on yields, soil nitrate and nitrogen (N) balances in 3 winter wheat-summer maize rotations with straw returning in Hebei Province. Results showed that the super high yield practice was identified with greatest winter wheat and summer maize yields, followed by high yield and high efficiency practice, and super high yield and high efficiency practice, which were all greater than that of farmer practice. The N use efficiency of high yield and high efficiency practice was significantly greater than the other cultivation patterns. The total nitrate accumulation in 0-400 cm soil of these cultivation patterns reached 768.4-1133.3 kg·hm^-2, where 80%-85% of the accumulated nitrate were in 90-400 cm soil. Meanwhile, the nitrate leaching was observed in all cultivation patterns and nitrate accumulation peaks at 120-150 cm and 270-330 cm were found. Soil nitrate content of high yield and high efficiency practice was less than 30 mg·kg^-1 and generally lower than other cultivation patterns, which to some extent reduced the environmental risk. In addition, nitrate surplus in 0-90 cm soil during winter wheat season was lower than that during summer maize season, and the high yield and high efficiency practice had the lowest apparent nitrogen loss. Overall, the high yield and high efficiency practice was evaluated to be the best cultivation pattern in consi-deration of yield, nitrogen use efficiency and nitrate accumulation in soil, but there was still certain achievable improvement potential.