Studying the effects of herbicides on microbial community and urease activity in the rhizosphere soil of maize is helpful to clarify the mechanisms herbicides used to affect soil microbial environment. In this research, four common preemergence maize specific herbicides, nicosulfuron+atrazine (A1), alachlor+acetochlor+atrazine (A2), propisochlor+atrazine (A3), and acetochlor+atrazine (A4), were selected to use in a pot trial. A preemergence herbicide nonspecific for maize, dinitraniline (A0), was used as the positive control, whereas water instead of herbicide was considered as the negative control (CK). At the maturity stage, the microbial communities and urease activity in the 0-20 cm, 20-40 cm, and 40-60 cm rhizosphere soils of maize were analyzed. Results showed that A0 dramatically suppressed maize growth, with no grain got finally, while A1 displayed the weakest effect. The tested herbicides affected the microbial community in the 0-20 cm layer greater than in the 20-60 cm ones, with A1 displaying the greatest effect. In the 0-20 cm soil, A1 largely reduced the relative abundance of the top three dominant genera, Prevotella, Barnesiella, and Lactobacillus in the CK soil, by 99.0%, 98.7%, and 79.2%, and made Pseudomonas, Gemmatimonas, and Sphingomonas became the new dominant genera, while A2 and A3 displayed similar but slighter effects. All herbicides dramatically reduced the relative abundance of the top one dominant fungal phylum (Ascomycota) and genus (Diatrype) in the CK soil, from 45% to 5.2%-7.9% and 42% to 2.1%-3.2%. A0 dramatically dropped the urease activity in the 0-60 cm soils, by 30.5%-33.1%, whereas A1-A4 displayed an unsignificant effect. In conclusion, A1 is a suitable herbicide for maize. Both the bacterial community and urease activity in the 0-20 cm rhizosphere soil are suitable indices to evaluate the effects of preemergence herbicides on maize growth and soil microbial environment.

中文翻译：

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除草剂对玉米根际土壤微生物群落及脲酶活性的影响

研究除草剂对玉米根际土壤微生物群落和脲酶活性的影响，有助于阐明除草剂影响土壤微生物环境的机制。在这项研究中，选择了四种常见的出苗前玉米专用除草剂烟曲磺隆+阿特拉津（A1），丙草胺+乙草胺+阿特拉津（A2），丙草胺+阿特拉津（A3）和乙草胺+阿特拉津（A4） 。对玉米非特异的芽前除草剂二硝苯胺（A0）用作阳性对照，而以水代替除草剂作为阴性对照（CK）。在成熟阶段，分析了玉米0-20 cm，20-40 cm和40-60 cm根际土壤中的微生物群落和脲酶活性。结果表明，A0显着抑制了玉米的生长，最终没有结实，而A1的效果最弱。测试的除草剂对0-20 cm层微生物的影响大于对20-60 cm层微生物的影响，其中A1的影响最大。在0-20厘米的土壤中，A1大大降低了前三个优势属的相对丰度，普氏菌，Barnesiella和乳杆菌在土壤CK，由99.0％，98.7％和79.2％，并取得了假单胞菌，Gemmatimonas和鞘氨醇成为新的优势属，而A2和A3显示类似，但轻微的影响。所有除草剂均显着降低了最主要的一种真菌门（Ascomycota）和属（Diatrype）的相对丰度。），从CK的45％降至5.2％-7.9％，从42％降至2.1％-3.2％。在0-60厘米土壤中，A0显着降低了脲酶活性，降低了30.5％-33.1％，而A1-A4则没有显着影响。总之，A1是适用于玉米的除草剂。0-20 cm根际土壤中的细菌群落和脲酶活性都是评估芽前除草剂对玉米生长和土壤微生物环境影响的合适指标。