Field dissipation of acetochlor in two New Zealand soils at two application rates
Field dissipation of acetochlor in two New Zealand soils at two application rates
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DOI：
10.2134/jeq2004.0930
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发表时间：
2004-05-01
影响因子：
2.4
通讯作者：
McNaughton, DE
中科院分区：
文献类型：
--
作者：
Ma, QL;Rahman, A;McNaughton, DE
农药在土壤中的残留具有重要的经济意义和环境意义，常被用作农药风险评价的关键参数。对乙草胺[2‘-ethyl-6’-methyl-N-(ethoxymethyl)-2-chloroacetylanilide]在两个新西兰田间土壤中的持久性进行了两年多的测量，并利用这些数据确定了能够充分描述乙草胺在土壤中持久性的模型。乙草胺按推荐量(2.5kga.i.)喷洒在每个地点的6块休耕地(每块3×9m)上。HA(-1))，并以该速率的两倍。测定了土壤岩心中的乙草胺浓度。在高施肥量下，乙草胺在哈密尔顿粘壤土(腐殖质黑土和伊鲁维亚土)中的持久力符合简单的一级动力学模型(模型1)，但在低施肥量时则高估了乙草胺的持效性。二次模型(模型2)、一阶双指数模型(模型3)、一阶双相模型(模型4)或两室模型(模型5)较好地描述了乙草胺在低施肥量下的持久性。乙草胺初始损失50%(DT50)和90%(DT90)的时间分别约为9和56d，低施用量和高施用量下分别为18和63d。更复杂的模型2到5也比模型1更好地描述了乙草胺在砂壤土中的两相消散，模型1在两种施肥量下都大大低估了乙草胺在施肥日的浓度。在低施用量和高施用量下，DT50和DT90分别为5和29d和7和31d。总体而言，施肥量对哈密尔顿土壤的DT50和DT90值有显著影响，而对霍洛丘土壤的影响不显著。大麦土壤中乙草胺损失较快可能是由于土壤有机碳含量较高，在土壤表层保留了较多的乙草胺，温度和光解作用加剧了乙草胺的流失。
The persistence of pesticides in soils has both economic and environmental significance and is often used as a key parameter in pesticide risk assessment. Persistence of acetochlor [2'-ethyl-6'-methyl-N-(ethoxymethyl)-2-chloroacetylanilide] in two New Zealand field soils was measured over two years and the data were used to identify models that adequately describe acetochlor persistence in the Held. Acetochlor was sprayed onto six fallow plots (3 X 9 m each) at each site at the recommended rate (2.5 kg a.i. ha(-1)) and at twice that rate. Acetochlor concentrations were measured in soil cores. Simple first-order kinetics (Model 1) adequately described acetochlor persistence in Hamilton clay loam soil (Humic Hapludull, Illuvial Spadic) at the high application rate, but overestimated it at the low application rate. A quadratic model (Model 2), a first-order double-exponential model (Model 3), a first-order biphasic model (Model 4), or a two-compartment model (Model 5) better described acetochlor persistence at the low application rate. The time for 50% (DT50) and 90% (DT90) of initial acetochlor loss was approximately 9 and 56 d, and 18 and 63 d at low and high application rates, respectively. The more complex Models 2 through 5 also better described the biphasic dissipation of acetochlor in Horotiu sandy loam soil (Typic Orthic Allophanic) than Model 1, with Model 1 significantly underestimating acetochlor concentrations on the day of application at both application rates. The DT50 and DT90 values were 5 and 29 d and 7 and 31 d at low and high application rates, respectively. Overall, application rate significantly affected the DT50 and DT90 values in the Hamilton soil, but not in the Horotiu soil. Faster acetochlor loss in the Horotiu soil possibly resulted from the higher soil organic carbon content that retained more acetochlor near the soil surface where higher temperature and photolysis accelerated the loss.