土壤及泥沙颗粒组成与养分流失的研究

利用自然降雨影响下的农田为试验样地,分析了降雨前后土壤颗粒组成与养分含量的变化,探讨了流失泥沙颗粒组成与养分的变化特征。结果表明,在降雨后,西瓜地与油菜地表土颗粒组成呈现粘粒与粉粒含量减少,砂粒含量相对增加的趋势;土壤养分含量都有不同程度的下降,其中水解氮与速效磷下降的幅度很大,西瓜地与油菜地水解氮降雨后降幅分别为9.67%和7.99%,速效磷的降幅分别为9.20%和8.76%;全氮养分降幅很小,西瓜地与油菜地分别为2.17%和1.54%;流失泥沙细小颗粒含量与养分含量随时间基本都呈降低的变化趋势,并且细小颗粒含量与携带流失的养分含量有显著甚至极显著的正相关性;流失泥沙具有富集粘粒和富集养分的特性,油菜地与西瓜地粘粒富集率分别为1.23和1.20,两样地全氮与速效磷的富集率都在1.3以上,而全磷和水解氮富集率基本处在1.1-1.3之间。

Study on Soil and Sediment Particle Size Distribution and Nutrient Loss

Croplands under rainfall were used as test fields to analyze changes of soil particle size distribution and nutrient loss before rainfall and after rainfall.Change characteristics of sediment particle size distribution and its nutrient were discussed.The results have shown that after rainfall the clay and silt contents of the surface soil decreased and the sand contents increased in watermelon land and rape land.The nutrient contents of the surface soil declined,and the declined rate were deferent in different forms in watermelon land and rape land,among which the declined ratio of the hydrolysable nitrogen(9.67% and 7.99%) and rapidly available phosphorus(9.50% and 8.76%) was obvious,while total nitrogen(2.17% and 1.54%) lower and total phosphorus lowest.The contents of clay,silt and nutrient of sediment decreased approximately with time change,and the direct correlations were close among the contents of clay and silt and the contents of nutrient.Clay enrichment and nutrient enrichment occurred in sediment,but the enrichment ratio was different: Clay was 1.23 in watermelon land and 1.20 in rape land,total nitrogen and rapidly available phosphorus was higher than 1.3,and total phosphorus and hydrolysable nitrogen was 1.1~1.3.