Bridges Melissa, Henry W Brien, Shaner Dale L, Khosla R, Westra Phil, Reich Robin
Dep. of Bioagricultural Sciences and Pest Management, Campus Delivery 1179, Colorado State Univ., Fort Collins, CO 80523-1179, USA.
J Environ Qual. 2008 Oct 23;37(6):2212-20. doi: 10.2134/jeq2007.0568. Print 2008 Nov-Dec.
An area of interest in precision farming is variable-rate application of herbicides to optimize herbicide use efficiency and minimize negative off-site and non-target effects. Site-specific weed management based on field scale management zones derived from soil characteristics known to affect soil-applied herbicide efficacy could alleviate challenges posed by post-emergence precision weed management. Two commonly used soil-applied herbicides in dryland corn (Zea mays L.) production are atrazine and metolachlor. Accelerated dissipation of atrazine has been discovered recently in irrigated corn fields in eastern Colorado. The objectives of this study were (i) to compare the rates of dissipation of atrazine and metolachlor across different soil zones from three dryland no-tillage fields under laboratory incubation conditions and (ii) to determine if rapid dissipation of atrazine and/or metolachlor occurred in dryland soils. Herbicide dissipation was evaluated at time points between 0 and 35 d after soil treatment using a toluene extraction procedure with GC/MS analysis. Differential rates of atrazine and metolachlor dissipation occurred between two soil zones on two of three fields evaluated. Accelerated atrazine dissipation occurred in soil from all fields of this study, with half-lives ranging from 1.8 to 3.2 d in the laboratory. The rapid atrazine dissipation rates were likely attributed to the history of atrazine use on all fields investigated in this study. Metolachlor dissipation was not considered accelerated and exhibited half-lives ranging from 9.0 to 10.7 d in the laboratory.
精准农业的一个研究热点是除草剂的变量施用，以优化除草剂使用效率，并将负面的场外和非目标影响降至最低。基于已知会影响土壤施用除草剂效果的土壤特性得出的田间尺度管理分区进行特定地点杂草管理，可缓解苗后精准杂草管理带来的挑战。旱地玉米（Zea mays L.）生产中常用的两种土壤施用除草剂是莠去津和异丙甲草胺。最近在科罗拉多州东部的灌溉玉米田中发现莠去津的降解加速。本研究的目的是：（i）在实验室培养条件下，比较来自三个旱地免耕田不同土壤区域的莠去津和异丙甲草胺的降解速率；（ii）确定旱地土壤中莠去津和/或异丙甲草胺是否会快速降解。在土壤处理后0至35天的时间点，采用甲苯萃取法和气相色谱/质谱分析法评估除草剂的降解情况。在所评估的三块田地中的两块上，两个土壤区域之间莠去津和异丙甲草胺的降解速率存在差异。本研究所有田地的土壤中莠去津降解均加速，在实验室中的半衰期为1.8至3.2天。莠去津的快速降解速率可能归因于本研究所调查的所有田地中莠去津的使用历史。异丙甲草胺的降解未被视为加速，在实验室中的半衰期为9.0至10.7天。
