| Summary: | 碩士 === 國立臺灣大學 === 農業化學研究所 === 103 === Owing to the deficiency of the irrigation water and the less anount of rice consumption, alterantive to decrease rice production is to developan an environment-friendly upland cropping systems. The objective of this study was to examine the effects of different upland rotation systems on the chemical and biological properities of soil. There were six types of one-year upland rotation systems, including: 1. Maize followed by sesbania and sesame (denoted as MSS); 2. Maize followed by sesbania and black soybean (MSB); 3. Mung bean followed by sesbania and maize (GSM); 4. Black soybean followed by sesbania and maize (BSM); 5. Sorghum followed by sesbania and Mung bean (SSG); 6. Adlay followed by sesbania and sesame (ASS). The soil samples were taken in the end of the second and the third year of cropping. The chemical and biological properities were analysized. The results showed the soil fertility decreased in all systems after three years of cropping. There was no difference in the soil microbial and chemical properties, including pH, organic carbon and total nitrogen contents of soil, between six systems. After three years of upland cropping, the soil microbial biomass carbon and nitrogen decreased. Enzyme activities of soils increased in response to soil nutrient deficiency, including acid/alkaline phosphomonoesterase, urease and arylsulphatase. However, the activity of dehydrogenase decreased. The bacteria and fungi populations were different between upland and paddy soil, which indicated that the soil microbial properties significantly affected by the soil water management. Furthermore, the microbial interaction led to the population growth and declined as the result of competition and synergism. In summary, the results indicate that short-term upland rotation resulted in the reduction of the soil nutrients and the growth of soil microbial community.
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