Research On The Spatial Distribution Of Two Kinds Of Grassland Soil Nutrients In Bin County

This field survey was processed in improved grassland which has been planted alfalfa for4years and the degeneration nature grassland in Gaohui Village, Yongle Town, Xianyang City,Shaanxi Province. Field investigation choose each of the representative locations of eachabove two kinds of grassland was surveyed by placing100quadrats (0.5m×0.5m) along a50m line transect. Through the ring knife method, the surface soil from0-10cm of the100samples and6samples out of the100samples (0.5m×0.5m=0.25m2) selected stratifiedrandomly to obtain10-20cm,20-30cm,30-40cm,40-50cm sample. Take it back to the lab,air drying, sieving, remove impurities. The soil total nitrogen, total phosphorus, totalpotassium, alkali solution nitrogen, ammonium nitrogen, nitrate nitrogen and availablephosphorus content were determined in the laboratory. By using the model of mathematicalstatistics analysis method, the huge dates were analyzed. We could try to find out the spatialdistribution pattern of two kinds of grassland soil nutrients, the relationship of soil nutrientcontent and its spatial heterogeneity, and comparison of alfalfa artificial grassland and naturegrassland contains the differences of soil nutrient content. So as to providing new analyticalmethods of grassland soil nutrition spatial heterogeneity study and provide a theoretical basisfor grassland improvement of the arid and semi-arid areas.The results were as follows:1. The soil nutrient spatial distribution modelThrough the study we found that spatial distribution of soil nutrients of the grassland andbiomass on the ground with the same rule, in line with the gamma distribution model. sevennutrients of improved grassland and natural grassland, by using chi square test, only spatialdistribution of the total potassium do not in line with the gamma distribution model becauseof P<0.05in nature grassland; the spatial distribution of the other six nutrients in naturalgrassland and seven nutrients in improved grassland were fit with gamma distribution model.2. The relationship of between the average soil nutrient content and the spatial heterogeneityof the two types of grasslandThere was a negative correlation between soil nutrient content (including total nitrogen, total phosphorus, total potassium, available phosphorus, alkaline hydrolysis nitrogen,ammonium nitrogen and nitrate nitrogen content) and its spatial heterogeneity index of thedegradation of natural grassland and the sowing alfalfa improved grassland. Therefore,reducing the spatial heterogeneity of soil nutrients can improve the grassland productivity.3. The soil nutrient variability of alfalfa artificial grassland and natural grasslandThe extremely significant difference（P<0.001） were existed between the degradation ofthe natural grassland which reseed alfalfa4years in the total nitrogen, total phosphorus,alkaline hydrolysis nitrogen, ammonium nitrogen, nitrate nitrogen and available phosphorus,while there were no significant difference（P>0.05）in total potassium and nitrate nitrogencontent.