陕西省农田土壤硫含量空间变异特征及亏缺评价

SPATIAL VARIABILITY OF SOIL SULPHUR AND RISK ASSESSMENT OF SOIL SULPHUR DEFICIENCY IN SHAANXI PROVINCE

陕西省 13种耕地土壤 30 5个表层 (0～ 2 0cm)土壤样点分析结果表明 :该省土壤全硫和用0 0 1molL-1Ca(H2 PO4) 2 浸提的有效硫含量分别为 33～ 76 9mgkg-1(均值 36 0mgkg-1)和 4 6～ 15 7 3mgkg-1(均值 2 9 3mgkg-1) ,其中黑垆土 (普通干润均腐土 )、绵砂土 (灌淤湿润砂质新成土 )的有效硫平均含量最低。土壤全硫具有中等空间相关性 ,有效硫空间相关性较差。土壤全硫和有效硫分布具有渐变性 ,其最大相关距离分别为 5 31km和 34km。全硫以较大区域变异为主 ;有效硫以小区域变异为特征。陕西省耕地土壤有效硫含量低于硫亏缺临界值 (18 5mgkg-1)的占总面积的 13 9% ,相当于 5 3 7万hm2 农田缺硫。陕西省中部地区 。

Total sulphur and available sulphur in the 305 samples of top-layer soils collected from thirteen main types of soil in Shaanxi Province were extracted by 0.01 mol L -1 Ca(H 2PO 4) 2 and determined.Results indicated that the contents of total sulphur and available sulphur in these soils ranged from 33 to 769 mg kg -1 (av. 360 mg kg -1) and from 4.6 to 157 mg kg -1 (av.29.3 mg kg -1),respectively.Heilutu soil (Cumulic Haplustolls,ST/1996) and Mianshatu soil (Udipsamment,ST/1996) had the lowest content of available sulphur among these soil types. The ranges of spatial correlation was determined through semivariance analysis of these data and were found to be 531 km for soil total sulphur,and 34 km for soil available sulphur,respectively.Spatial variability for soil total sulphur and available sulphur exhibited a gradual changing tendency, and spatial variation developed in large scale for total sulphur,and in small scale for available sulphur.Soil available sulphur in 13.9% of the total land in Shaanxi Province was lower than the critical value,18.5 mg kg -1,for soil sulphur deficiency,implying approximately 0.537 millions hm 2 of cultivated land could be sulphur-deficient in this province.In central Shaanxi Province,especially the west part of Yan’an city,the risk of soil sulphur deficiency is great.