Sadeghi A M, Isensee A R
USDA, Agricultural Research Service, BARC-West, Environmental Chemistry Lab, Beltsville, MD 20705, USA.
Chemosphere. 2001 Jul;44(2):109-18. doi: 10.1016/s0045-6535(00)00207-1.
This study was conducted to evaluate the effect of hairy vetch cover crop residue on runoff losses of atrazine and metolachlor under both no-till corn field plots and from a laboratory runoff system. A 2-year field study was conducted in which losses of atrazine and metolachlor from vetch and non-vetch field plots were determined from the first runoff event after application (5 and 25 days after application in 1997 and 1998, respectively). A laboratory study was conducted using soil chambers, designed to simulate field soil, water, vegetation, and herbicide treatment conditions, subjected to simulated rain events of 5, 6, 20 and 21 days after application, similar to the rainfall pattern observed in the field study. Atrazine losses ranged from 1.2 to 7.2% and 0.01 to 0.08% and metolachlor losses ranged from 0.7 to 3.1% and 0.01 to 0.1% of the amount applied for the 1997 and 1998 runoff events, respectively. In the laboratory study, atrazine runoff losses ranged from 6.7 to 22.7% and 4.2 to 8.5% and metolachlor losses ranged from 3.6 to 9.8% and 1.1 to 4.7% of the amount applied for the 5-6 and 20-21 day events, respectively. The lower losses from the field study were due to smaller rainfall amounts and a series of small rains prior to the runoff event that likely washed herbicides off crop residue and into soil where adsorption could occur. Runoff losses of both herbicides were slightly higher from non-vetch than vetch field plots. Losses from the laboratory study were related to runoff volume rather than vegetation type.
本研究旨在评估在免耕玉米田块以及实验室径流系统中，毛苕子覆盖作物残茬对莠去津和异丙甲草胺径流损失的影响。开展了一项为期两年的田间研究，测定了莠去津和异丙甲草胺在施用后首次径流事件（1997年和1998年分别在施用后5天和25天）时从种植苕子和未种植苕子的田块中的损失情况。进行了一项实验室研究，使用土壤箱模拟田间土壤、水、植被和除草剂处理条件，在施用后5、6、20和21天进行模拟降雨事件，类似于田间研究中观察到的降雨模式。对于1997年和1998年的径流事件，莠去津损失分别占施用量的1.2%至7.2%和0.01%至0.08%，异丙甲草胺损失分别占施用量的0.7%至3.1%和0.01%至0.1%。在实验室研究中，对于施用后5 - 6天和20 - 21天的事件，莠去津径流损失分别占施用量的6.7%至22.7%和4.2%至8.5%，异丙甲草胺损失分别占施用量的3.6%至9.8%和1.1%至4.7%。田间研究中损失较低是由于降雨量较小以及径流事件之前的一系列小雨，这些小雨可能将除草剂从作物残茬上冲刷到土壤中，在那里可能发生吸附。两种除草剂在未种植苕子的田块中的径流损失略高于种植苕子的田块。实验室研究中的损失与径流量有关，而不是与植被类型有关。
