甘肃省泾川县耕层土壤养分时空变异分析

Soil nutrient status is an important indicator of soil fertility to determine the crop yield．The investigation and analysis provides the basic information for future comprehensive evaluation of soil nutrients and fertilizer management resources．In this study, we selected Jingchuan country from southern Gansu province, and collected about 2545 topsoil (0-20 cm) samples in croplands within each county in 2009 and measured the characteristics of OM,N,P and K nutrients, and compared them with the data from the Second National Soil Survey conducted in the early 1980s.For analyzing spatial Variability of Topsoil Nutrient,on the one hand，we used geostatistics software GS+9.0 for spatial variability analysis, the main result was: the block ratio of total nitrogen and available was not less or equal 25%, which showed a strong spatial correlation, with the reasons of soil parent material, climate and other structural factors; the block ratio of organic matter ranged from 25% to 75%, a moderate-intensity correlation, indicating that the impact of random factors and structural factors isroughly equaled; the block ratio of potassium was not greater or equal 75% , which showed weak spatial correlation, of the main infectors of fertilization, tillage practices, cropping systems, and other random factors.On the other hand，we used Geographic Information System for spatial interpolation.The result was : the Kriging figures of organic matter, total nitrogen, available phosphorus showed that the nutrient content of eastern and northern in Jingchuan were relatively higher than other parts; the inverse distance weighted interpolation figure of potassium displayed that AK content was patchy distribution and overall Jingchuan had a high content, an average of more than 150mg/kg.For analyzing Temporal Variability of Topsoil Nutrient, we compared the content of the 4soil nutrients from 1986 to 2009.The result was that the content of the 4 nutrients increased by varying degrees. Such as organic matter increased 31.54%, and the content was basically up to the fourth level from the country fifth level; nitrogen increased 41.19% ,and the content was basically up to third or fourth levels from the country fifth level; available phosphorus increased 70.90%, and the content is basically up to second or third level from the country fourth or fifth level;available potassium increased 26.64%, up to the first or second level from the country third or fourth level.