不同施肥管理對土壤有機質含量及組成之影響

Abstract

土壤長期施用不同有機肥料會影響土壤有機質含量與品質，土壤有機質具有影響土壤物理與化學特性、增加通氣程度、養分循環、提供微生物碳源與外源化合物分解等功效。使用有機資材為肥料施入土壤中可增加養分循環與再利用，為永續農業 (sustainable agriculture) 的重要單元，有機資材被分解後將會釋放養分，增加土壤生產力。本研究目的在探討長期施入不同種類之肥料與不同之耕作方式，對於土壤有機質之含量與土壤有機質之易變動庫與難分解庫的濃度分佈的影響。試驗材料分別取自台中霧峰農試所第35號永續農法試驗、高雄改良場旗南分場有機農法試驗與桃園農業改良場溫網室蔬菜試驗等三處試驗田。各別測定土壤基本性質、可溶性有機碳及以酸水解測定土壤有機質中易變動庫含量：包含鹽酸一階段水解，同時測定土壤中有機氮之含量；硫酸二階段水解，第一階段測定土壤醣類含量與總聚酚I，第二階段測定土壤纖維素含量與總聚酚II。研究顯示，在長期施入不同氮肥量與氮肥種類之試驗 (農試所35號試驗田) 土壤，施有機肥料者比單施化學肥料者多2-217%的總碳、硫酸水解之易變動庫多4.4-30.7%的可水解碳，易變動庫則以同時施有機肥料與化學肥料者較高。在不同農耕法的試驗 (旗南分場) 土壤，可知所有輪作均以施入有機肥料者，土壤總碳含量較高。在水旱田輪作下，以有機肥料與化學肥料同時施用者比單施有機肥料或單施化學肥料更提高鹽酸可水解之易變動氮庫含量，而醣與纖維素之濃度均以有施入有機肥料之處理較多。在施用單一種不同有機肥料 (桃園改良場) 的試驗中，可知在相同施氮量下，雞糞堆肥處理與豌豆苗殘體堆肥處理總碳累積較多。施大豆粕使土壤中的氮大部分成為鹽酸可水解氮。在硫酸可水解部分中易被生物利用之碳量大小為：大豆粕處理＞豌豆苗殘體堆肥處理＞未施肥之對照組＞輪施=牛糞堆肥處理=豬糞堆肥處理＞雞糞堆肥處理。綜上所述，施用有機資材至土壤中可增加土壤易變動庫與碳與氮之含量。

Different fertilizers applied to the soil affect the soil organic matter content and quality, especially after a long-term application. Soil organic matter affects the soil physical and chemical properties, aeration extent, nutrient cycling, energy supply to soil microorganisms, and detoxification of the anthropogenic chemicals. Application of the organic material as a kind of fertilizer is an important practice of the sustainable agriculture. After the decomposition of the organic material, it supplies the nutrients and increases the productivity of the soil. The aim of this study was to investigate the effects of different fertilization management and different kinds of fertilizers on the soil organic matter concentration and its compisition. Soil samples were taken from a 13-year field experiment (TARI) with seven treatments, a 20-year experiment (KDARES-CBS) with two rotation systems under three fertilization managements, and a 7-year green house experiment (TDARES) with seven treatments, respectively. Some selected soil chemical properties, dissolved organic carbon (C) concentration, C fractions hydrolyzed by HCl solution, C fractions two-step hydrolyzed by H2SO4 solution were to be analyzed. The organic nitrogen (N) in soil also analyzed after hydrolyzing by HCl solution. The polysaccharides (saccharide C), polyphenol (polyphenol I), the cellulose (cellulose C), and polyphenol (polyphenol II) concentrations were to be analyzed after H2SO4 solution two-step hydrolysis respestiviely. The result of the study of different kinds of N fertilizers and different amounts of N input (TARI) indicated that application of organic fertilizer increased 2-217% of the total C and 4.4-30.7% of labile pool of C concentrations as compared with that of applying only chemical fertilizer. The application of both organic fertilizer and chemical N fertilizer also increased the labile pool C concentration. In the study of different kind of rotation systems (KDARES-CBS), application of organic fertilizer increased total C, saccharide C and cellulose C concentration of the soil. Conbined application of the organic fertilizer and chemical fertilizer increased the labile C and N pool of the soil. In the study of application of different kinds of organic fertilizers for seven years (TDARES), the application of chicken dung compost (PM) and pea seeding residue (PC) accumulated more C in the soil on the basis of application of the same amount of N. The application of soybean meal (SBM) resulted in the most of soil N as labile N. The biologically available C as charactilized by H2SO4 hydrolysis are in the following order: SBM > PC > Contral > sequential application of compost (SA) = cattle dung compost (CD) = hog dung compost (HD) > chicken dung compost (PM). In conclusion, application of the organic fertilizers increase the labile C and N pools of the soil and the extent of their effects depends on the properties of the organic fertilizers applied.