| Conservation tillage is a farm management measures to protect environment and improve soil quality, including no-tillage, reduced tillage and straw mulch. Its functions include relieving soil erosion, holding water, increasing the content of organic matter and soil fertility, improving the physical, chemical and biological properties of soil. Conservation tillage could enhance the activity, diversity and biomass of soil microbe, improve the quality and ecological environment of soil, and finally facilitate the growth and development of crop directly or indirectly. The effectiveness of conservation tillage is reflected in the harvest of crop by influencing the growth and development of crop. In order to evaluate the effect of conservation tillage on crop growth and soil microbial diversity, a study was conducted at the long-term tillage experimental field, Hailun Agro-Ecological Experiment Station, Chinese Academy of Sciences, which included no-tillage (NT), reduced tillage (RT) or rotary tillage (ROT) in Mollisols Region. A2-year crop rotation, soybean-corn was established. The effect of tillage on the population distributing of bacteria, fungi, Fusarium and Pythium was studied by dilution plate and Real-time QPCR; soil microbial genetic diversity was studied by denaturing gradient gel electrophoresis (DGGE) and soil microbial function diversity was studied by BIOLOG. Soybean growth and yield was also studied in our research. The objectives of the research were to comprehensively assess the effect of conservation tillage systems on soil microbial ecology and crop growth, and to provide the basis for applications of conservation tillage techniques. The results possess some academic value and significance in the Mollisols ecology research.Experimental results showed that NT and RT inhibited soybean growth at seeding and flowering stages, but the soybean growth and yield was significantly increased under NT and RT compared with ROT at maturing stage. Soybean yield was highest under RT, it reached at2507.3kg-ha-1, which was increased by3.9%compared with ROT. The quantity of soil microbial was increased significantly under conservation tillage, especially fungi, Fusarium and Pythium. The population of soil microbial was highest under RT, and fungi, Fusarium and Pythium was respectively increased by70.1%,45.3%and32.3%compared with ROT in corn field. The quantity of soil microbial changed regularly along the growth of soybean, and was higher under NT at seeding stage, the colony forming units (CFU) of bacteria and fungi were2.71×107·g-1and2.28×105·g-1, respectively, which were increased by8.0%and32%compared with ROT. Real-time QPCR results showed that the genomic DNA quality of soil fungi were significantly increased under NT, and reached at the highest at maturing stage with527ng/g, which was increased by22.2%and17.8%compared with RT and NT. DGGE fingerprint results showed that the gene diversity of bacteria and fungi was increased significantly along the growth of crop, and tillage systems had no significant effect on the bacterial diversity (P>0.05), and the bacterial community structure had a high similarity under RT and ROT. The fungal diversity increased significantly under NT and RT, and it was highest under RT with3.61, which was increased by4.3%compared with ROT. Significant differences were observed on the fungal community structure under NT and ROT. The result of soil microbial functional diversity indicated that NT improved the ability of utilizing carbon source of soil microorganism, and Shannon and Simpson indices were significantly higher under NT than RT and ROT.Conservation tillage would enhance the quantity of soil microorganism, increases the microbial diversity, and improves the soil microbial environment. Although the growth of crop was inhibited at earlier growth stage, conservation tillage would significantly increase the harvest of crop with lower cost. Therefore, conservation tillage could enhance the economic and biological effect of agricultural industry, and play a considerable role in soil rational utilization and sustainable development of agriculture... |
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