黄土高原大南沟小流域土壤养分空间分异特征?

本文利用地统计学空间插值分析了陕西安塞县大南沟流域内土壤有机质、全氮、全磷、碱解氮、速效磷、速效钾6种土壤养分的空间分布特征.结果表明:流域内土壤养分含量普遍较低,质量分数平均值分别是:有机质0.964%,全氮0.506g·kg-1,全磷0.609g·kg-1,碱解氮41.295mg·kg-1,速效磷2.009mg·kg-1,速效钾138.506mg·kg-1.各养分空间分布模型:全磷符合指数模型,速效磷和碱解氮符合球状模型,速效钾符合高斯模型,其变程由大到小依次是全磷(870m)、速效磷(724m)、速效钾(207m)、碱解氮(105m).各养分空间分布由高到低总体表现为林地、果园、荒草地、退耕地、农地,坡下部高于坡上部.由于氮素易于淋溶损失,且受人工施肥影响严重,在分布上有连片特征;磷素受母质控制,存在状态稳定,所以空间变异较小;速效钾也易淋溶损失,且与植被类型有较强关系.研究为优化大南沟流域的土地利用模式,从根本上遏制以水土流失为代表的生态环境退化提供科学依据.

Spatial heterogeneity of soil nutrients in Danangou catchment in the Loess Plateau

The amount and distribution of top soil nutrients,SOM,total N (TN),total P (TP),available N (AN),available P (AP)and available K (AK),in Danangou catchment of Ansai County,Shaanxi Province were analyzed by semivariogram of geostatistics, Kriging and IDW method. Soil nutrient in Danangou catchment was found to be generally low,the averages being 0.964% (SOM),0.506 g·kg-1 (TN),0.609 g· kg-1 (TP),41.295 mg·kg-1 (AN),2.009 mg·kg-1 (AP)and 138.506 mg·kg-1 (AK).The model of nutrient spatial distribution was as follows.TP was in accordance with exponential model,AP and AN were in accordance with spherical model. AK was in accordance with gaussian model. The range of spatial heterogeneity in decreasing order was TP (870 m),AP (724 m),AK (207 m)and AN (105 m).Spatial distribution of nutrient overall was:forest land>grassland>orchard land>woodland>farmland/bottom slope>upper slope.N showed continuous distribution because it was easy to leach,and was affected by artificial fertilization.Spatial heterogeneity of P was not strong since P was susceptible to soil parent materials and stable in soil.Available K was also easy to lose;its distribution had strong correlation with vegetation types.This work provides some scientific basis for land use pattern optimization in Danangou catchment and ecological degradation governance,represented by soil and water loss.