基于农户微观视角下的耕地土壤有机质时空演变规律研究

Study on the Spatial and Temporal Evolution of the Soil Organic Matter of the Cultivated Land Based on the Microscopic Perspective of the Household

对耕地土壤有机质含量变化规律的研究是破解耕地土壤肥力变化规律及其效应的关键。本研究基于野外高密度土样采集,综合运用地统计学和GIS相结合的分析方法,从农户微观视角出发,研究了沈阳市典型区域30 a来在农户土地利用行为影响下土壤有机质含量时空变异特征。研究结果表明:研究区耕地土壤有机质含量受农户土地利用方式、程度和投入强度的变化影响较大。1980~2000年,由于受投资能力、技术水平和管理水平等的限制,加上对耕地的掠夺性经营,导致耕地土壤有机质含量整体呈现下降趋势,有机质含量平均值从30.88 g kg-1下降到22.63 g kg-1,下降了8.25%;随着城镇化进程的加快,在利益的驱使下,农户将劳动力逐渐转移到非农生产中,不愿意从事种植业,耕地培肥被忽视,管理投入大幅度减少,造成耕地土壤肥力供求失衡,地力下降,从2000~2010年整个研究区域土壤有机含量平均值从22.63 g kg-1下降到20.07 g kg-1。空间上,由于受区域社会经济及政策因素压力的影响,农户土地利用行为产生明显的分化,导致离市区越近,土壤有机质下降的幅度越大,离市区越远,下降的幅度越小,甚至远郊区部分区域出现上升趋势。

The study on the soil o rganic matter is a key solution to understand the soil fertility variation and its influences. Soil samples were collected with high-density, and the geo-statistics and geographic information system(GIS) were used. From the microscopic perspectives of farmers, we studied the temporal-spatial variability of soil organic matter contents in the typical areas of cultivation in Shenyang during the past thirty years. The results showed that the changes of the land use patterns, land use intensity and the land input intensity had important impacts on soil organic matter contents. From 1980 to 2000, because of the limitations of the investment capacity, technology and management, as well as the predatory plantation in the cultivated land, the soil organic matter contents gave a generally decreasing trend. In the study area, the average contents of organic matter decreased from 30.88 g kg to 22.63 g kg,with a total decline of 8.25%. With the acceleration of urbanization and impetus for profits, the farmers preferred to engage in the non-agricultural industry rather than in plantation. As a result, farmland fertilization was neglected, and the management investment was greatly decreased, which resulted in an imbalance of supply and demand of soil fertility, and the decline of soil fertility. From 2000 to 2010, the average SOM contents in the study area decreased from 22.63 g kg to 20.07 g kg. Spatially, due to the impacts of regional economy and social and policy pressures, the land-use behavior was clearly differentiated: soil organic matter contents decreased to greater extent being closer to the city, while declined little getting farther away from the city. In some suburbs far away from city, an increasing trend was even observed for soil organic matter contents.