Laboratory of Soil Microbiology, Division of Crop Production, Central Rice Research Institute, Cuttack 753 006, Orissa, India.
Chemosphere. 2011 Jun;84(1):54-62. doi: 10.1016/j.chemosphere.2011.02.055. Epub 2011 Apr 5.
Combination of divergent active principles to achieve broad-spectrum control is gaining popularity to manage the weed menace in intensive agriculture. However, such application could have non-target impacts on the soil processes affecting soil ecology and environmental interactions. A field experiment was conducted to investigate the impact of separate and combined applications of herbicides bensulfuron methyl and pretilachlor on the emission of N(2)O and CH(4), and related soil and microbial parameters in a flooded alluvial field planted to rice cv Lalat. Single application of the herbicide bensulfuron methyl or pretilachlor resulted in a significant reduction of N(2)O and CH(4) emissions while the combination of these two herbicides distinctly increased N(2)O and CH(4) emissions. Cumulative N(2)O emissions (kg N(2)O-N) followed the order of bensulfuron methyl (0.35 kg ha(-1))<pretilachlor (0.36 kg ha(-1))<control (0.45 kg ha(-1))<bensulfuron methyl 0.6%+pretilachlor 6.0% single dose (0.49 kg ha(-1))<bensulfuron methyl 0.6%+pretilachlor 6.0% double dose (0.54 kg ha(-1)). Cumulative CH(4) emissions (kg CH(4)), on the other hand, followed the order of bensulfuron methyl (47.89 kg ha(-1))<pretilachlor (73.17 kg ha(-1))<bensulfuron methyl 0.6%+pretilachlor 6.0% single dose (93.50 kg ha(-1))<control (106.54 kg ha(-1))<bensulfuron methyl 0.6%+pretilachlor 6.0% double dose (124.67 kg ha(-1)). The inhibitory effect of separate application of herbicides bensulfuron methyl 0.6% and pretilachlor 6.0% on N(2)O emission was linked to lower mineral N, lower denitrifying and nitrifying activity and low denitrifier and nitrifier populations. Inhibitory effect on CH(4) emission, on the contrary, was linked to prevention in the drop of redox potential, lower readily mineralizable carbon (RMC) and microbial biomass carbon (MBC) contents as well as lower methanogenic and higher methanotrophic bacterial population. Admittedly, stimulatory effect of combined application of herbicides bensulfuron methyl 0.6% and pretilachlor 6.0% at double dose on N(2)O and CH(4) emission was related to reversal of the identified indicators of inhibition. Results indicate that while individual application of herbicides bensulfuron methyl 0.6% or pretilachlor 6.0% can reduce N(2)O and CH(4) emission from flooded soil planted to rice, their combined application at normal dose can keep the emission at a comparatively lower level with significantly higher grain yield as compared to the herbicides applied alone.
将不同的活性成分结合起来以实现广谱控制，这种方法在集约化农业中越来越受欢迎，可用于控制杂草威胁。然而，这种应用可能会对土壤过程产生非目标影响，从而影响土壤生态和环境相互作用。本研究进行了田间试验，以调查除草剂苄嘧磺隆和丙草胺单独和联合应用对淹水冲积地种植的水稻 cv Lalat 土壤中排放的 N(2)O 和 CH(4) 以及相关土壤和微生物参数的影响。除草剂苄嘧磺隆或丙草胺的单一应用可显著减少 N(2)O 和 CH(4) 的排放，而这两种除草剂的组合则明显增加了 N(2)O 和 CH(4) 的排放。累积 N(2)O 排放量（kg N(2)O-N）的顺序为：苄嘧磺隆（0.35 kg ha(-1))<丙草胺（0.36 kg ha(-1))<对照（0.45 kg ha(-1))<苄嘧磺隆 0.6%+丙草胺 6.0%单剂量（0.49 kg ha(-1))<苄嘧磺隆 0.6%+丙草胺 6.0%双剂量（0.54 kg ha(-1))。另一方面，累积 CH(4) 排放量（kg CH(4))的顺序为：苄嘧磺隆（47.89 kg ha(-1))<丙草胺（73.17 kg ha(-1))<苄嘧磺隆 0.6%+丙草胺 6.0%单剂量（93.50 kg ha(-1))<对照（106.54 kg ha(-1))<苄嘧磺隆 0.6%+丙草胺 6.0%双剂量（124.67 kg ha(-1))。除草剂苄嘧磺隆 0.6%和丙草胺 6.0%单独应用对 N(2)O 排放的抑制作用与较低的矿化氮、较低的反硝化和硝化活性以及较低的反硝化菌和硝化菌种群有关。相反，对 CH(4) 排放的抑制作用与防止氧化还原电位下降、较低的易矿化碳（RMC）和微生物生物量碳（MBC）含量以及较低的产甲烷菌和较高的甲烷氧化菌种群有关。诚然，除草剂苄嘧磺隆 0.6%和丙草胺 6.0%在双剂量下联合应用的刺激作用与上述确定的抑制指标的逆转有关。结果表明，虽然单独应用除草剂苄嘧磺隆 0.6%或丙草胺 6.0%可以减少淹水土壤中种植的水稻产生的 N(2)O 和 CH(4) 排放，但与单独应用除草剂相比，它们以正常剂量联合应用可以使排放保持在较低水平，同时显著提高粮食产量。
