| Summary: | 碩士 === 國立臺灣大學 === 農業化學研究所 === 96 === Microbial characteristics of soil have been regarded as important indicators of soil quality. Soil enzyme activities can be used as an index of soil interference, response of crops to organic amendment, soil pollution, soil quality, and fertility. Stable and functional diversity of microbial communities is very important to soil quality. Soil microbial diversity can also be an indicator of soil quality and stabilization of ecology system. The objective of this study was to investigate the effects of different kinds and application rates of organic fertilizers and crop rotation system on soil chemical and biological properties. After long-term application of the different rates and kinds of organic fertilizer, the soils were sampled and the chemical properties, soil enzyme activities related to C, N, P, S cycles, and the microbial communities structure using phospholipid fatty acid (PLFA) analysis were analyzed. Soil samples were taken from three experimental fields: 1. the experiment at KDARES-CBS contains six treatments which were arranged in complete randomized design (CRD): (1) CK (control, without fertilizer), (2) CF (chemical fertilizer treatment), (3) 1X (organic fertilizer with the same amount of N as CF), (4) 2X (organic fertilizer with two fold of N as CF), (5) 3X (organic fertilizer with three fold of N as CF), (6) 4X (organic fertilizer with four fold of N as CF); 2. the experiment at TARI contains seven treatments which were arranged in randomized complete block design (RCBD): (1) CK (control, without fertilizer), (2) Chem (applied chemical fertilizer only), (3) Comp (applied compost only and with the same amount of N as Chem), (4) Comp + 1/3 N (compost combined with one third amount of N as Chem plot), (5) Comp + 2/3 N (compost combined with two third amount of N as Chem plot), (6) GM + 1/3 N (green manure combined with one third amount of N as Chem plot), (7) Peat + 1/3 N (peat combined with one third amount of N as Chem plot); 3. the experiment at TDARES contains seven treatments which were arranged in RCBD: (1) CD (cattle dung manure), (2) HD (hog dung manure), (3) PM (chicken dung manure), (4) SBM (soybean meal), (5) PC (pea seedling residue compost), (6) SA (sequential application of the above five kinds of compost mentioned), (7) Control (without fertilizer). The results indicated that after seven years of different fertilization managements at KDARES-CBS, the 3X treatment was the optimum recommendation application rate of the organic fertilizer. The enzyme activities studied in soil increased with the application rate of organic fertilizer, however, there was no significant difference between 3X and 4X treatments. PLFAs of bacteria, Gram positive bacteria, Gram negative bacteria, actinomycetes and fungi, respectively, also increased with the application rates of organic fertilizer and reached maximum at 3X treatment. There were also no significantly difference effects on soil chemical properties between the 3X and 4X application rates of organic fertilizer. After twelve years of different fertilization managements and rice-corn rotation at TARI, Comp + 2/3 N treatment shared the highest organic matter concentration in the soil. It might be due to the application of compost and the higher crop production resulting in higher amount of crop residues. There were no significant differences among treatments in enzyme activities in the soils of different treatments. The biomass of different microbial communities in GM + 1/3 N treatment was higher than that of other treatments indicating that the effect of fresh residues of green manure applied to soil on microbial lasted till the harvesting of the crop. The results also showed that after 12 years of different fertilization managements have different effect on the diversity and abundance of soil microbes. After seven years of intensive cultivation at TDARES, SBM treatment resulted in the lowest soil pH (4.7), which was due to SBM mineralized rapidly in the soil. The SBM treatment also resulted in the lowest soil enzyme activities and microbial biomass. SBM is not adequate as organic fertilizer applying continuously for crop cultivation. On the other hand, applying PC increased the biomass of different microbial communities, and the highest microbial activities. The study showed that continuously intensive cultivation with applying different organic matter resulted in different effects to soil microbial communities diversity and abundance in the greenhouse.
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