浦江县土壤碱解氮的空间变异与农户N投入的关联分析

尝试以作物种植前、后土壤N的空间变化为基础与农户调查数据相结合,以GIS技术为手段,辅以地统计分析,探讨县域作物土壤环境空间变化特征及其与农户土地管理行为,特别是N投入行为间关系。其结果对更深入揭示农田碱解氮的演化规律,指导农民合理N投入,减少投入成本,提升生态环境,具有十分重要的作用。通过对Moran’s I指数分析,结果表明:农业N投入普遍偏高,过剩量大;不同区域作物N投入存在较大差异,且农户各自惯性投入依然较强。平原区变异系数大的主要原因在于种植规模化品种少,粮食作物和经济作物N投入差距大;山区和半山区的变异系数小的原因是由于规模化经营尚未形成,种植作物的多样性和N投入的不稳定性综合形成的。此外,研究还表明,GIS空间分析技术与经典试验相结合能有效分析不同农户间的作物种植前后土壤N的变化差异,对建立针对性的、差异化农地利用对策具有十分重要的作用。下一步研究可结合土地利用与覆盖变化、土壤物质循环作更深入探讨。

Correlation analysis of spatial variability of Soil available nitrogen and household nitrogen inputs at Pujiang County

Building and maintaining soil quality is the basis for improving agricultural products quality. The value of available nitrogen (N) largely determines the soil quality and affects the agro- ecosystem quality. A series of classical field experiments have been conducted to analyzed the soil nutrients and examine the effects of soil nutrients on different planting crops. And different kinds of soil dynamics models have been established. There are very few studies on comprehensive analysis through the integration of soil nutrients spatial variability for the fields before and after the crop planting date with household's crop variety and nutrients management level. In this paper, based on the exploration of the spatial variability of soil nitrogen and household land management behavior, GIS combined with Geostatistics was applied to analyze the spatial variation characteristics of soil environment and its correlation with household nitrogen inputs at Pujiang County. The research outcomes will play an important role in revealing evolution rule of agricultural land available nitrogen, guiding reasonable nitrogen inputs, reducing input cost and protecting eco-environment. With the rapid industrial expansion, the economic development indicators and development pressure on farmland in Pujiang country are slightly higher than the national average. A household survey in this region has been conducted for 10 years. Supported by the National Fund and based on the research results of an EU project-IRMLA, this study aims to achieve the further new discoveries regarding the optimal use of farmland resources. Pearson's correlation analysis showed that sampled variables for two times are normally distributed. The strength of a linear relationship for the contents of alkali-hydrolysable nitrogen was found, with close coefficient of variation and degree of variation of only 1.71%. The results showed that soil alkali-hydrolysable nitrogen content was not only determined by the characteristics of soil but also by household-induced nitrogen input. Furthermore, the correlograms of Moran's I further showed the following results: high nitrogen input to agricultural land with high excess volume; different N fertilizer input in different agricultural areas, indicating that current autistic type mode of operation characterized with family household and more self-consciousness restrict the applications of state-of-the-art techniques; the larger Coefficient of Variation (CV) in plain areas due to low planting diversity and big difference between grain and economic crops; smaller CV in mountains and terrace areas due to non-formed scale plantation and nonstablity of planting diversity and nitrogen inputs. The combination of GIS spatial analysis technology and classical test can effectively analyze the changing differences of soil nitrogen before and after the crop planting and set up oriented and differentiated agricultural land use policy. With the basis of measured data, the study revealed the special change rule of agricultural land use type and available N and the interrelationship between land cover and land use.Due to the lack of experimentation support for N cycle, the further study should focus on the integration of land-use cover change and soil material cycle. this study, we only analyzed the measured data for one year and basically reflected the spatial variability of soil available nitrogen. Provided that the test data for many years in the same site be used, the achieved research results should be more precise and objective.