| The soil microorganisms living in a controlled environment by the soil particles, has a highly complex spatial distribution and composition. In the field of agriculture and the environment, microbial activity has significant impact on the biochemical processes, such as: N mineralization, denitrification, bio-solid N, C, N cycle, the stability of soil structure and degradation of organic pollutants in soil and so on. The stability of soil aggregates is the most important factor on soil structure. It is essential for researching the distribution of micro-organisms in the soil aggregates to understand and predict the occurrence of these processes as well as the reaction rate.Under different climatic and soil conditions, research has shown that the organic carbon content, microbial population and community are quite different in different sizes of aggregates. The microbial biomass are extremely sensitive to the changes of agriculture farming methods, such as crop rotation measures, organic debris input and fertilizer can cause changes in soil microbial biomass. Therefore, more study in different climatic and soil types is needed.In this paper, The composition characterize of soil aggregates and aggregate porosity and moisture, The distribution patterns of nutrient and bacteria and fungi, The diversities of bacteria and fungi in different water-stable aggregates (WSA), and the effects of tillage methods on the number of nutrient and bacterial and fungal biomass, were investigated in a long-term field experiment. Tillage treatments examined in this study included Conventional Tillage (CT), Flooded Paddy Field (FPF), Combining Ridge and No-tillage (RNT). A wet sieving method was used to separate soil aggregates into six groups based on particle diameter: >4.76 mm, 2.0～4.76 mm, 1.0～2.0 mm, 0.25～1.0 mm, 0.053～0.25 mm and <0.053 mm. The techniques and methods such as the conventional analytical, the chloroform fumigation extraction method, plate culture method, and PCR-DGGE Analysis were used. Main results are as follows:(1) The affection of different cropping systems on composition of soil aggregates and the distribution of soil moisture and porosity: The composition of water-stable aggregates about > 2.0mm, combining ridge and no tillage (RNT)>flooded and paddy field (FPF)>conventional tillage (CT); The porosity of RNT is more bigger than the FPF and CT, The structure and the distribution of pore of RNT is better than the FPF and CT, and soil bulk density of RNT is small and soil structure is loose with a total porosity large, well to keep the soil moisture, can promote the formation of soil aggregates and could be better coordination of water status. In the same soil water potential, the soil moisture content of combining ridge and no tillage (RNT) is greater and more effectiveness than flooded and paddy field (FPF) and conventional tillage (CT).(2) The nutrient content of top soil aggregate size: In the same farming system, different aggregates size, the organic carbon, total phosphorus, total potassium and nitrogen content in the size of 0.053～0.25mm is the lowest distribution (p<0.05); while in the diameter of <0.25 mm, the smaller aggregates size, the higher content of organic carbon, total phosphorus, total potassium and total nitrogen. No regularity of the content of total organic carbon, total phosphorus, total potassium and total nitrogen (p<0.05) in aggregate size of >0.25mm. And combining ridge and no tillage (RNT), can significantly increase the levels of nutrients reserves in aggregates.(3) Microbial biomass carbon, nitrogen distribution: microbial biomass carbon, nitrogen, and dissolved organic carbon in subtropical areas of purple paddy soil aggregate water stability in the distribution of mainly affected by the impact of aggregate structure itself (p<0.05), The effects of tillage was not significant (p> 0.05); microbial biomass carbon in soil aggregates distributed evenly, microbial biomass nitrogen and dissolved organic carbon in the <0.25mm micro-aggregates of the highest concentrations. Combining ridge and no tillage (RNT) will help to improve soil aggregates in the microbial biomass and soluble organic carbon content.(4) Fungal and bacterial biomass was estimated by measuring the amount of ergosterol and muramic acid, respectively, in the samples. Both bacterial and fungal biomass were lowest in the smallest soil particles (<0.053 mm) and highest in the 0.053～0.25 mm fraction. As the size of the soil micro-aggregate increased, the associated bacterial or fungal biomass also rose, however, there were notable response differences between the two taxonomic groups. Of the three tillage methods examined, maximum bacterial and fungal biomass was found in the Combining Ridge and No-tillage (RNT) treatment; minimum biomass occurred under Conventional Tillage (CT). There were significant (p<0.05) differences in fungal and bacterial biomass in the 0.25 mm～1.0 mm and 2.0 mm～4.76 mm particle-size groups among the three tillage methods; there were no significant differences(p>0.05) in the remaining size groups.(5) The diversity of Soil fungi and the advantages of the fungi in different tillage methods: In the diameter of >0.25mm, with the size of soil aggregates increases, No regularity change of fungi; <0.25mm, with the decreasing size of soil aggregates, fungi increase in the number; the size of 0.053～0.25 mm of soil aggregates, the lowest number of fungi (p<0.05). The distribution of fungi is characterized by in the diameter of <0.25 mm. the smaller the aggregate size, the higher the diversity index. The most richness of fungal diversity exist in the combining ridge and no tillage (RNT), there is a large number of fungal hyphae, indicating that the combining ridge and no tillage (RNT) can improve soil fungi in K-response biological, and show a more steady state of no-tillage with soil environment and a more steady state of biological taxa.,(6) Extract the microbial genome of rice soil using kits in different soil aggregate size, and us the genome as a template, using the majority of bacteria and archaea genes V3 area with specific primers, for each soil samples of the microbial genome-specific amplification. The product of about 230bp by denaturing gradient gel electrophoresis (PCR-DGGE) to separate and obtain a better separation effect of different amounts and electrophoretic bands by calculating the Shannon diversity index and found that soil bacteria diversity in the subtropical areas of purple paddy soil aggregate water stability in the distribution patterns of tillage mainly related to the particle size aggregates a certain extent. Bacterial genetic diversity of three kinds of tillage:combining ridge and no tillage (RNT)> flooded and paddy field (FPF) and conventional tillage (CT).Therefore, the porosity numbers of soil and water availability were best in combining ridge and no tillage (RNT). Aggregate size of <0.25mm, soil nutrients with the aggregate reduce the size of the reserves increase. Aggregates of different total microbial biomass C and N, bacterial and fungal biomass and the number of dominant species of the genus, diversity affected by farming methods and the particle size of the aggregates. The combining ridge and no tillage (RNT) increased dominant species of bacteria and fungi,Aggregates of different sizes are in the richness and the evenness of the distribution.In this paper, biomass and diversity of fungal and bacterial in different aggregate size and different tillage on paddy soil of subtropical areas were estimated by bio-labeling and molecular biological methods. This research provided some information for predicting the important role of soil bacteria and fungi in soil nutrient stability,accumulation and transformation processes. Because the occurrence of soil nutrient elements in soil aggregates was related to the location of land,soil type,geographic,tillage practice,the hydrological conditions,land use,fertilizer management, the interrelated research can provided more accurate quantitative prediction for tillage fertilizing, and provided the macro-management theory about the region's soil fertility.
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