| As our knowledge, soil quality could be represented by means of soil microbial characters as well as the soil microbial community refers to the any change in soil ecology. So, it necessary to reveal the soil metabolism and to study the development rules in soil fertility in the evolution process of soil quality.In this thesis, we had studied the effects of different patterns of long-term fertilization and different crop rotation systems on soil microbial biomass, soil enzyme activities and the number of the cultured microorganisms and especially discussed its effect on soil microbial diversity through BIOLOG, high-throughput sequencing. It should be noticed that these researches were based on a long-term fertilization experiment as well as the long-term crop rotation system which were set up at Hengyang red soil experiment station (Chinese Agricultural Academy) since1982. The long-term fertilization experiment were treated as①CK (no fertilizer added),②organic manure (M),③nitrogen, phosphorus and potassium (NPK),④PK plus organic manure (PKM),(⑤)NK plus organic manure (NKM),⑥NP plus organic manure (NPM),⑦NPK plus organic manure (NPKM). The treatments of long-term crop rotation system included①double cropping rice-Chinese milk vetch (RRC),②double cropping rice-oilseed rape (RRO),③double cropping rice-ryegrass (RRR),④double cropping rice-winter fallow (RRW). The results were showed as follows:1, Stable yield of rice had been promoted in southern red rice crop under long-term fertilization and crop rotation trearments, where the NPKM treatment and the RRC treatment showed the most significantly improved production. Compared with CK treatment in2012, the treatments of long-term fertilization had increased by46.1%on average, followed by63.4%increase in NPKM treatment, treatments of NPKM, M and NPK were reduced in turn. In addition, the treatments of long-term crop rotation had annual increased in the rate of15.7%as compared with the RRW treatment, RRC treatment increased20.4%, and treatment of RRO had a higher increase rate than RRR treatment.2, Long-term fertilization and crop rotation can promote the content of SOC, LOC, AN, AP and TN in red soil crop, the NPKM treatment and RRC treatment increased most significantly. As the data from late rice harvest stage in2012showed, the amount of SOC and LOC were increased by84.3%and91.7%, respectively, by comparison with CK. RRC treatment respectively increased by12.9%and99.3%than RRW treatment. Besides, soil pH was indicated lower from long-term application of chemical fertilizer or green plant manure. That might gave us a point that the mechanisms of stable increasing rice in yield and enriching crop should be based on the applying of organic manure and green plant manure, especially, the model of applying balanced combination of organic and inorganic fertilizers as well as winter-planting Chinese milk vetch.3, Long-term fertilization and crop rotation can increase the SMBC, SMBN, SMBP, qMB, SMBN/TN and SMBP/TP, especially increase nitrogen pool and phosphorus pool, the NPKM treatment and RRC treatment increased most significantly in reddish paddy soil. The amount of SMBC, SMBN and SMBP of NPKM treated group were increased by128.1%,77.3%and167.5%, respectively, as compared with the CK in2012late rice harvest, where we still found the same indexes of RRW treatment were increased by28.0%,39.9%and41.8%respectively than RRW. Correlation analysis implied that there was a closely relationship among microbial biomass and SOC, TN and AN content, that suggested soil quality was enhanced by soil microorganism and meaningful for the metabolism of carbon and nitrogen.4, The activity of protease, urease, acid phosphatase, invertase, cellulase and catalase had been enhanced in reddish paddy soil by Long-term fertilization and crop rotation, the NPKM treatment and RRC treatment had the most significantly enhancing effect. The activity of urease, acid phosphatase, invertase and catalase of NPKM treatment had improved19.1%,19.7%,56.4%and105.2%than CK, respectively. Same indexes from RRC observed were respectively increased by64.0%,8.5%,27.2%and27.7%than RRW in2012late rice harvest stage. Moreover, organic manure or combined with chemical fertilize were better than chemical fertilize treated, and same effect were obtained from RRC treatment as compared with RRR or RRO treatment. The result of correlation analysis suggested that soil enzyme activities had highly relationship with the amounts of SOC, TN, AN and AP, what displayed that soil enzyme activity have a strong influence on the metabolism of carbon/nitrogen/phosphorus.5, Long-term fertilization and crop rotation played a significantly effect on improving cultured microbial number in reddish paddy soil, where RRC treatment was significantly higher than RRR or RRO treatment. NPKM treatment most improved the number of bacteria, however, M treatment just most improved the number of fungi and actinomycetes. The bacteria number of NPKM treatment increased by96.9%than CK, and RRC treatment increased by58.9%than RRW in2012late rice harvest stage. As the correlation analysis showed, there was closely relationship between cultured microbial number and SOC or LOC content, that indicate microbial has a significance meaning for increasing soil organic carbon.6, The microbial activity and the ability of using carbon source of RRC treatment was significantly lower than RRR, RRO and RRW treatments in2012late rice harvest stage, RRO treatment was lower than RRC and RRW treatments at stage before green manure turned over in2013. Only RRO treatment at late rice harvest stage had a greater microbial activity as well as greater ability of using carbon source as compared with the stage before green manure turned over. At the same time, if we make a comparison with CK, it was easy to find RRR and RRC treatment reduced significantly in Shannon index, Simpson index and Mclntosh index in late rice harvest stage. Green plant manure treated group decreased significantly in Shannon index and Simpson index in stage before green manure had been turned over. Both Shannon index and Simpson index obtained before green manure turned over were significantly higher than late rice harvest stage ones.Compared with RRW treatment, long-term crop rotation increased the OTU number, Chaol index and Shannon index of bacterial species in2012stage, and also increased Chaol index of bacterial species at the stage before green manure turned over in2013. RRC and RRO treatment had increased the number of OTU and Shannon index of bacterial species at stage before green manure turned over in2013. ALL the OTU number, Chaol index and Shannon index of bacterial species at late rice harvest stage were higher than what we obtained at stage before green manure turned over.The degree and microbe species on utilize carbon source in red soil rice crop under the influence of the green manure and weeds were showed by a significant difference. For example, the diversity of bacteria related to phylum, genus and species were caused lower, meanwhile, the dominant strains among the stage which operated when late rice harvested were assayed as the Proteobacteria, Firmicutes, Chloroflexi and Actinobacteria of bacteria, nevertheless, the other dominant strains among the stage before green manure been turned over were Proteobacteria and Chloroflexi at stage... |
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