三峡重庆库区柑橘园氮素平衡状况研究

Soil nitrogen balance in citrus orchards of the Three Gorges area in Chongqing

以三峡重庆库区柑橘种植农户调研资料和土壤测试分析数据为基础,从区域角度出发,分析了柑橘园生产体系中的氮肥施用特征和氮素平衡状况。结果表明:果园氮肥投入量为409.7kg/hm2,主要来源于复合肥和尿素;其中通过有机肥投入的氮素水平为76.51kg/hm2,主要来源于畜禽粪尿;柑橘园的总体氮盈余量为363.9kg/hm2,盈余量以奉节、江津和永川区较高;果园氮素投入与氮养分盈余量之间存在极显著的正相关关系。说明过量施用氮肥是氮盈余量高的主要原因。随着氮盈余量增加,果园土壤全氮呈增加趋势,而土壤C/N呈下降趋势,氮素盈余对土壤全氮的影响大于土壤有机质的影响。

Based on data collected from farmer interviews and agricultural statistics database,the characteristics of N fertlizaion and surplus were studied in the Three Gorges area of Chongqing city.The result shows that the average N application rate is about 409.7 kg/ha,with a main source of compound fertilizers and urea.The N input rate through manure application is 76.51 kg/ha,with a main source of animal waste and manures.There is N surplus in the orchards,and the surpluses in Fengjie,Jiangjin and Yongchuan are relatively higher than other regions.The average N surplus is 363.9 kg/ha.There is positive correlation between N surplus and applied N rate in orchards,which indicates excessive N fertilizer input leads to the increase of N surplus.Further,with the increase of nitrogen surplus,total nitrogen of orchard soil tends to increase,while the ratio of soil C/N tends to decrease,indicating that the influence of nitrogen surplus on soil total nitrogen is higher than soil organic matter.