陕西关中小麦/玉米轮作区氮肥用量及施氮现状评估

Determination of reasonable nitrogen use and evaluation of application status in wheat/maize rotation system in Guanzhong area of Shaanxi Province

【目的】研究陕西关中冬小麦/夏玉米轮作体系中,2种作物氮肥的合理用量,以此对施肥现状进行评价。【方法】在位于陕西关中地区的杨凌进行氮肥肥效田间试验,利用数学方法得出氮肥合理用量,并将其与实际调查的农户习惯氮肥用量进行比较,以分析二者土壤硝态氮含量与经济效益的差异。【结果】冬小麦、夏玉米推荐氮肥用量分别为140和145kg/hm2,而当前农户习惯氮肥用量分别为(211±139)和(310±131)kg/hm2,明显高于推荐氮肥用量,但二者产量无明显差异。过量施用氮肥导致陕西关中地区冬小麦、夏玉米土壤硝态氮含量(0～100cm土层)较高,分别为117.4和125.3kg/hm2,同时造成经济效益损失达3 014元/hm2。【结论】在陕西关中地区的冬小麦/夏玉米轮作体系下,应减少农户习惯施氮量,提高肥料利用率,减小化肥对环境的污染,降低农民农业投入。

【Objective】 Reasonable nitrogen use amount in winter wheat/summer maize rotation system in Guanzhong area of Shaanxi Province was researched,and it was used as criterium for evaluating the status of farmers＇ N fertilization practices.【Method】 Suggested amount of nitrogen use was calculated from field nitrogen effect experiment in Yangling region,Guanzhong area.It was compared with farmers＇ actual N application rates to analyse the differences from both the amount of soil nitrate nitrogen residue and economic benefit between them.【Result】 Recommended amounts of nitrogen use on winter wheat and summer maize were 140 and 145 kg/hm2,respectively.The current farmers＇ nitrogen use amounts were correspondingly（211±139） and（310±131） kg/hm2,which were significantly higher than recommendation,but there was no obvious difference in yield.Excessive amounts of nitrogen led to higher soil nitrogen accumulation in 0-100 cm soil layer,117.4 and 125.3 kg/hm2 for winter wheat and summer maize,respectively,and meanwhile,the economic benefit was wasted 3 014 yuan/hm2.【Conclusion】 Reducing farmers＇ nitrogen use amounts,increasing nutrient efficiency,decreasing pollution of fertilizers and lowering the farmers＇ input in agricultural should be done in winter wheat/summer maize rotation system in Guanzhong area of Shaanxi Province.