陕西果园主要分布区氮素投入特点及氮负荷风险分析

为了研究果园氮素投入特点及分析氮素负荷特征,加强果园氮素管理、指导果农科学合理施肥。以陕西省果园主要分布区土壤氮素分析、农户投入调查等统计数据为基础,采用盈余法从果树种类和区域角度分析果园生产体系中的氮素输入输出特点及氮素盈余状况。结果表明,陕西果园主要分布区平均化肥氮投入量927.2 kg/hm2,主要来源于尿素和复合肥,其中尿素占调查样本量的40%以上;通过有机肥投入的氮仅为139.4 kg/hm2。94.8%的果园氮素处于盈余,总体平均盈余量为876.3 kg/hm2,其中氮盈余量超过500 kg/hm2的样本占57.5%,盈余量超过1 000 kg/hm2的样本亦占了27.3%。不同果园相比,猕猴桃园氮素投入及盈余量最高,分别为1 432.9、1 186.9 kg/hm2。不同区域果园比较,土壤氮环境负荷以关中灌区果园较高,达1046.1kg/hm2。果园氮素施用与养分盈余量之间存在极显著的正相关。陕西果园氮素的高量投入给土壤环境带来较大的氮素负荷,这对土壤环境和周围水体造成很大威胁。

Analysis of nitrogen inputs and soil nitrogen loading in different kinds of orchards in Shaanxi Province

Accurate information about current soil nutrient concentrations in orchards is necessary for making recommendations about future fertilizer application rates. Additional information is needed about the amount of surplus soil N in the orchards of Shaanxi Province, which is the main apple and kiwi production region in China. Analysis of N inputs and soil N loading is important for N management in orchards. The objective of this study was to quantify both the N application rates and the amount of surplus soil N in orchards in Shaanxi Province. Soil samples were collected from orchards in different parts of Shaanxi Province and then analyzed to determine soil N concentration. Additional information was collected from farmer interviews and an agricultural statistics database. The data was analyzed using the N balance method. The results showed that N fertilizer application rates averaged 927.2 kg N/hm² among the orchards surveyed in this study. More than 40% of the chemical N fertilizer was applied in the form of urea. Manure application accounted for 139.4 kg N/hm². Nearly 95% of the orchards had surplus N, with an average surplus of 876.3 kg N/hm². Nearly, 58% of the orchards had an N surplus of more than 500 kg N/hm². More than 27% of the orchards had an N surplus of more than 1000 kg N/hm². Among the different kinds of orchards, kiwi orchards had the highest N input rate (1432.9 kg N/hm²) and the highest amount of surplus N (1186.9 kg N/hm²). In irrigated areas of central Shaanxi rain-fed region. There was positive correlation between the amount of surplus N and the N application rate. High N inputs to orchards in some regions of Shaanxi Province led to very high soil N loading. This will increase environmental risks in the region.