Effect Of Tillage Systems On Soil Microbial Diversity In Black Soil Region

Tillage is an important management measure of agriculture produce process, conservation tillage including notillage and reduced tillage has the advantages of keeping soil and water, improving soil microenvironment and reducing machine work cost. Recently, conservation tillage is taken seriously, but it affects soil microenvironment and crop soil borne disease happened when it puts into practice. In order to discuss the effect of conservation tillage on crop soil borne disease and soil microenvironment in black soil of the north, on the basis of a tillage field trial at Hailun Agro-ecosystem Experimental Station of Chinese Academy of Sciences, the effect of tillage on the population distributing of bacteria, fungi, actinomycete and dominant fungi in soybean soil used dilution plate, Fusarium spp. population structures in corn soil used soil particles plate combined with morphological identification, bacterial genetic diversity in soybean and corn soil by Denaturing Gradient Gel Electrophoresis and microbial population structures diversity by Phospholipid Fatty Acid, soybean and corn growth, root rot and stalk rot in seedling stage were investigated. The tillage systems include reduced tillage, notillage, rotary tillage, combined tillage and moldboard plough.The results showed that, convention tillage was propitious to bacteria, fungi, actinomycete accumulate in soybean soil, and rotary and combined tillage represent dominance. The quantity of dominant fungi including Fusarium spp. and Trichoderma spp. was increased under notillage. F. oxysporum was the dominant population of Fusarium spp. in corn soil under reduced tillage, notillage and rotary tillage, accounting 46.0%～51.2%. The quantity of F. graminearum was the second. The quantity of Fusarium spp. and F. graminearum were increased under notillage. The soil microbial community structure had a high similarity under notillage and reduced tillage. Microbial diversity was decreased under notillage and reduced tillage in soybean soil and was not different in corn soil. The ratio of characteristic fatty acid between fungi and bacteria was the highest under notillage, and the fatty acid (i15:0+a15:0)/16:0 was the lowest under reduced tillage and notillage which reflected bacterial proportion at sampling site, and highest under moldboard plough, indicated that conservation tillage decreased the bacterial proportion; aerobic bacteria was dominate under moldboard plough, and anaerobic bacteria was dominate under reduced tillage and notillage. The soybean height and dry matter accumulate were decreased under notillage, compared with other tillage systems the dry weight decreases 47.8%～64.6% and 53.8%～90.8% respectively, and the soybean growth was increased under rotary tillage, notillage decreased the corn total dry weight 21.8%～39.8%. Corn dry weight was the highest under moldboard plough. Corn height was decreased under reduced tillage, and no difference under notillage. The soybean root rot took most serious under notillage, increased 15.4%～42.9%, and decreased under rotary tillage, but there is no stalk rot occurred in corn field.Reduced tillage and notillage reduce the microbial quantity, decrease the bacterial genetic diversity, increase the quantity of F. graminearum, have negative on crop growth, and increase soybean root rot. But reduced tillage and notillage reduce soil erosion and costs. Therefore, reducing ploughing frequencies and intensities and increasing crop residue coverage on soil are recommended for crop management, which will provide benefits for both the ecotypic well-being and economical efficiency.