| Summary: | 碩士 === 國立臺灣大學 === 農業化學研究所 === 88 === There is close relationship between fertilization management and sustainable use of soil. Improper fertilization not only decreases crop growth but destroys physical and chemical properties of the soil. To maintain the crop production and ecological balance, it''s important to practise the sustainable farming. A field experiment was set at Chishan, Kao-Hsiung to study the feasibility of organic farming in the southern part of Taiwan. The trial included six treatments with the combinations of three cultivation methods and two rotation systems. The three cultivation methods were organic farming (OF), conventional farming (CF), and intermediate farming (IF). Two rotation systems were designed to contain a conventional rotation crops and a suggested better rotation crops. This study was to investigate the effect of different fertilizers on the growth, nutrient uptake and nitrogen composition of crops in various growing stages in the two rotation systems in the soil that has been cultivated with the same practice for ten years. Sesbania as green manure, asparagus lettuce, and corn were cultivated in rotation system I and sesbania, sweet corn, and paddy rice in rotation system II. The relationship among fertilization management, rotation system and sustainable use of soil was also studied. The plant samples were separated according to the different organs, dried to constant weight, and grounded, the concentrations of total nitrogen, nitrate nitrogen (NO3-N), ammonium nitrogen (NH4-N), total soluble reduced nitrogen, soluble organic nitrogen, insoluble nitrogen, phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), manganese (Mn), copper (Cu), and zinc (Zn) were analyzed. The results indicate that autumn cropped asparagus lettuce and spring cropped corn had higher yields with IF in rotation system I. In rotation system II, autumn cropped sweet corn and spring cropped paddy rice with CF had higher yields. The yields of edible part of OF and IF were higher than those of CF, except the paddy rice. The amount of N uptake of paddy rice of CF was significantly higher in different growth stages, however, those of the other crops of OF and IF were not different with the CF. Different cultivation methods has no significant effects on the concentrations of NH4-N, NO3-N, insoluble nitrogen, total soluble reduced nitrogen and soluble organic nitrogen of the plants. Most N in plants was in forms of insoluble nitrogen and the soluble organic nitrogen, and plants contained little NH4-N and NO3-N. The exchangeable P, K, Ca and Mg of soil increased due to long-term application of organic fertilizer, as compared with the CF. However, there was no significant different in the concentration and uptake of P, K, Ca and Mg of plants between treatments, except those of paddy rice of which the P, K, Ca, and Mg uptake of CF were higher than those of IF and OF. The concentrations of Fe, Mn, Cu and Zn of the plants were higher in CF, but the concentration of Fe in the sweet corn of OF were higher than that of IF and CF. In conclusion, there was no significant difference in the plant nutrient concentrations among treatments. The concentration of Mn in edible parts of asparagus lettuce, sweet corn and paddy rice and that of Zn in sweet corn of CF were higher that those of the OF and IF treatments. The application of organic fertilizers associated with high amounts of Cu and Zn could increase the uptake of these elements and the presence of high amount of organic matter in soil also increased the uptake of Fe and Mn. In consideration of the sustainable cultivation, crop yields and proper use of organic waste, a combination application of organic and chemical fertilizers is a better practice.
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