改良剂降低富磷蔬菜地土壤磷和氮流失的作用

为了解不同改良剂对土壤中磷和氮的稳定作用,进行田间试验研究在施用量为2.5t/hm2时氢氧化铝、石灰石粉、石膏、氯化钙和粉煤灰5种改良剂对蔬菜地地表径流中磷和氮浓度的影响。结果表明,改良剂施用可明显降低土壤有效磷和水溶性磷含量,轻微增加土壤中NH4+-N含量,但对土壤中NO3--N影响不大。施用改良剂可显著降低蔬菜地地表径流中总磷、溶解态磷、颗粒态磷和NH4+-N的浓度,增加水溶性有机氮浓度,但对水溶性总氮和NO3--N浓度影响不明显。与对照比较,施用氢氧化铝、石灰石粉、石膏、氯化钙和粉煤灰5种改良剂的地表径流中总磷浓度下降比例平均分别为13.68%,35.54%,38.72%,43.77%和45.02%,溶解态磷浓度下降比例平均分别为16.05%,32.42%,48.75%,55.38%和38.98%;NH4+-N浓度下降比例平均分别为24.21%,37.84%,11.31%,10.08%和55.56%。总体上,施用氯化钙和粉煤灰降低地表径流中磷浓度的效果好于其他改良剂。

Effects of Amendments to Reduce Runoff Loss of Phosphorus and Nitrogen from a Vegetable Soil with High Test Phosphorus

A field experiment was conducted to evaluate the effectiveness of 5 different amendments in reducing P and N runoff loss from a typical vegetable soil in Zhejiang province.The tested amendments were Al(OH)3,CaCO3,gypsum,CaCl2,and coal combustion residue,and applied at the rate of 2.5 t/hm2.Soil samples from different treatment plots amended with each of five amendments were collected for characterizing water-soluble P,Bray 1-P,and available N.Runoff water samples of 4 runoff events were also collected from each of the different plots for analyzing total P,particulate P,dissolved P,dissolved total N,NH+4-N,NO-3-N dissolved organic N,Ca,Fe,Al.Application of amendments significantly reduced soil available P and water soluble P,and increased soil NH+4-N.However,application of amendments had no significant effect on soil NO-3-N.The reduced effectiveness for water soluble P by using amendments was greater than for available P.Mean concentration of total P in runoff was reduced by 13.68%,35.54%,38.72%,43.77%,and 45.02% for the amendments of Al(OH)3,CaCO3,gypsum,CaCl2,and coal combustion residue,respectively,as compared with control treatment without any of amendments.The corresponding values were 16.05%,32.42%,48.75%,55.38%,and 38.98% for dissolved P,and 24.21%,37.84%,11.31%,10.08%,and 55.56% for NH+4-N.Among the 5 amendments,CaCl2 and coal combustion residue were most effective in reducing P concentration in runoff,followed by gypsum and CaCO3.Application of the amendments had no significant effect on dissolved total N and NO-3-N in runoff water.These results indicate that the use of CaCl2,coal combustion residue,gypsum and CaCO3 could significantly reduce P runoff from vegetable soil,and should be considered in the development of practices for controlling P runoff from vegetable soil.