Influence Of Herbicides On Soybean Rhizosphere Soil Microorganism And Enzyme Activity

Soybean is important not only food crop in China, but also super oil crop in Heilongjiangprovince.China Soybean produce make important use of China national economy development andpeople's daily life. The applition and development of Scince chemical herbicide had increasd cropyield and quality, at the same time leaded to a serious problem of environment.So,study on theeffect of soybean rhizosphere by herbicides can appreciate the effect of rhizosphere envioronmentcorrectly and through human method to regulate root growth environment of soybean,acceleratenutritive material translation and its absorbe and usage by soybean, make the better base of siolenvironment. Effect of rhizosphere soil microorganism and soil enzyme activity by five herbicidesChlorimuron-ethyl,Acetochlor, Clomazone,Imazethapyr and 2,4-D butylate which were widely usedin soybean farmland were studied indoor culture. The results of the experiment are as follows:1. This five herbicides all stimulated the amounts of soil actinomycetes mostly, but thestimulative action were disappeared absolutely after treated 28 days.2. Chlorimuron-ethyl restrained the growth of soil bacteria, the action remain long time,butstimulated the growth of soil fungi.Acetochlor restrained the growth of soil bacteria andfungi,too.The effect on bacteria remain longer time. Clomazone stimulated the growth of soilbacteria,the highest amount of application treatment was the most notablely expect 35 day aftertreated, Clomazone stimulated the growth of soil fungi chiefly in 28 days, and all treatmentsslightly restrain the growth of funge after 49 days. Imazethapyr stimulated the growth of soilbacteria atrer treated 7 days,and retrieve to the normally level after treated 21 days. The treatmentof low amount of 2,4-D butylate application slightly "restrain-stimulate-retrieve".The otherstreatments stimulated the growth after treated 7 days, 2,4-D butylate 1000g/hm~2 treatment restrainthe growth of soil fungi in the beginning of the treatment,but others stimulated it.3. Chlorimuron-ethyl,Acetochlor, Clomazone,Imazethapyr and 2,4-D butylate all stimulatedthe soil cellulase activity, the action was the strongest after treated 7 days, and weakenedgradually, retrieve to the normally level after treated 35 to 42 days.Only there were significantlydifference among the Imazethapyr treatments of five herbicides,there weren't significant differenceamong other herbicides' respective treatments.4. Five herbicides all stimulated soil phosphatase activity after treated 7 days,the disciplinarian were differently after treated 7 days.5. Chlorimuron-ethyl,there was a period of time delayed when reach the strongest restrainaction after treated 14 days; Chlorimuron-ethyl 95g/hm~2 stimulated phospatase activity, but thephospatase activity was significant restrained with the amount of application increased. Acetochlorstimulated soil urease activity all the time,the degree strengthen with the amount of application,thestimulate action on phospatase only lasted 14 days,and retrieve to the normally level after treated21 days. The process of effect on soil urease by Clomazone is "inhibit-retrieve-stimulate",theinhibition effect was decreased after 28 days,and retrieved to the normally level. The process ofeffect on soil urease by Imazethapyr is "inhibit-stimulate", the effect on phospatase activity is"stimulate-inhibit", 2,4-D butylate inhibit the urease activity, the effect on phospatase activity is"stimulate-retrieve-inhibit".