两种除草剂的土壤生态效应及其对后茬作物生长的影响

采用盆栽试验,研究了分别施用低剂量和高剂量的苄.丁和二氯喹啉酸对水稻田土壤环境以及紫云英生长的影响。结果表明：施用除草剂苄.丁和二氯喹啉酸均不利于后茬冬季绿肥作物紫云英植株干物质的累积,而且施用量越多,干物质累积越少。低剂量的苄.丁显著降低了紫云英植株中N素累积量,而二氯喹啉酸降低紫云英植株中N和K累积量；施用高剂量苄.丁和二氯喹啉酸则降低紫云英植株中N、P和K累积量。无论是施用低剂量还是高剂量的苄.丁和二氯喹啉酸均降低土壤中N、K养分的有效性。低剂量二氯喹啉酸对土壤中有效P含量影响不显著,而施用高剂量二氯喹啉酸显著降低P素养分有效性。施用低剂量苄.丁对土壤中过氧化氢酶、蔗糖酶和尿酶活性的影响均不显著,而低剂量二氯喹啉酸则显著抑制了过氧化氢酶活性。施用高剂量苄.丁和二氯喹啉酸对土壤中蔗糖酶活性影响不显著,但均抑制了过氧化氢酶和尿酶活性。此外,施用低剂量和高剂量苄.丁增加了土壤中细菌数量,而二氯喹啉酸则正好相反。两种剂量的苄.丁和二氯喹啉酸均减少了土壤中放线菌数量,但对真菌数量变化不显著。由此可见,稻田施用二氯喹啉酸对稻田土壤环境以及后茬冬季紫云英作物的药害大于苄.丁。

Effects of two kinds of herbicides on paddy soil ecology and growth of succeeding crops

A pot-cutlture experiment was conducted to study the effects of different doses of bensulfuron-methyl.butachlor and quinclorac on red paddy soil environment and growth of Chinese milk vetch plants, the results showed that applying bensulfuron-methyl.butachlor and quinclorac in paddy soil decreased the dry matter weight of Chinese milk vetch, and the more doses of bensulfuron-methyl.butachlor and quinclorac applied the more dry matter decreased. The lower dose of bensulfuron-methyl.butachlor applied in paddy soil significantly decreased N accumulation, while the quinclorac decreased the N and K accumulation in milk vetch plant. The higher doses of bensulfuron-methyl.butachlor and quinclorac decreased the N, P and K accumulation in milk vetch plant. Applying with either a lower or a higher dose of both bensulfuron-methyl.butachlor and quinclorac decreased the availability of soil N and K. A lower dose of quinclorac did not affect notably the available P content in soil which was decreased remarkably with a higer dose, however. Applying a lower dose of bensulfuron-methyl.butachlor did not had a strikingly influence on the activity of catalase, sucrase and urease in soil, while the activity of catalase was markedly restricted by applying a lower dose of quinclorac. The activity of sucrase was not significantly changed even at a higher dose of bensulfuron-methyl.butachlor and quinclorac which strikingly restricted the activity of catalase and urease. Furthermore, applying a lower or higher dose of bensulfuron-methyl.butachlor increased the amount of bacteria, and an adverse effect of quinclorac was observed. The amount of actinomyce decreased by applying a lower or higher dose of bensulfuron-methyl.butachlor and quinclorac, though the amount of fungi was not changed remarkably. Hence, the quinclorac applied in paddy soil had a worse effect on the soil environment and growth of Chinese milk vetch than bensulfuron-methyl.butachlor.