A Study Of The Influence Of Quicklime On Rhizosphere Environment Of Soybean

Soybean is a main economic and oil crop.However,soybean disease is popular because of long time continuous cropping,resulting in bad growth,low yield and soil acidification. Soybean grown in acidified soil was improved by application of quicklime,with a better yield. Therefore,to analyze the relationship between rhizosphere microbe and soil enzyme activity is meaningful for soybean fertilization,which may instruct soybean production in practice.The soil in experimental site was a typical acidified soil.Based on present fertilization system,quicklime was applied at different levels.Then,pH values were measured in deferent growth stages of soybean.By using most probable number,Quantitative changes of 5 soil microbe were determined,4 key soil enzymes and 3 microbe including bacteria,fungi and ictinomyces were analyzed.Then after,an optimal way for quicklime application was found out.Te result showed that,soil pH increased slowly with increment of quicklime application. However soil pH decreased to some extent in late stage of soybean growth,which may be caused by soybean root secretion.In growing stage of soybean,soil bacteria such as ammonia-oxidizing bacteria,aerobic nitrogens-fixing bacteria and aerobic cellulose-decomposing bacteria increased greatly, nitrification bacteria increased slightly,and denitrifying bacteria decreased lest.Soil enzymes' influences were as follows:In growing stages of soybean,acid phosphates and invertase,were bated,but urease and catalase were activated.The above result may be determined by enzymes' own characters;further study may be conducted if calcium functioned.After application of quicklime,ictinomyces and fungi increased in the first and decreased later,bacteria increased gradually.Therefore,we could conclude that acidified soil was improved better by applying quicklime based on present fertilization system.Soybean yield took on an increasing trend with adding of quicklime application amount and those of all treatments gained 1.0%-9.5%in comparison with the control after applying quicklime for the strong acid soil.Correlation analysis among all factors and soybean showed that soil enzymes activity enhanced and the quantity of bacterium and actinomyces significantly ascended,which were the most direct reasons for soybean yield increase.The quantity soil functional bacteria changed little and had no obvious role on soybean yield increase.It was concluded that matching a definite amount of quicklime when fertilization had an active accelerating role on enhancing soil fertility and increasing soybean yield for soybean grown in the strong acid soil,but the quantity of quicklime application was determined in the light of practical circumstances in soybean production.