本研究目的在探討施入不同種類之肥料在水 (水稻) 旱 (玉米) 田輪作下，經十三年對土壤有機碳濃度與土 壤有機碳與氮之易變動庫與難分解庫濃度的影響。試驗材料取自農業試驗所永續農法試驗田。共有七種施肥 處理，分別為：(一) 未施肥之對照組 (CK)；(二) 化學氮肥區 (Chem-N)：(三) 堆肥區 (Comp)；(四) 堆肥配合化 學氮肥區化學氮肥量之三分之一區 (Comp + 1/3 N)；(五) 堆肥配合化學氮肥區化學氮肥量之三分之二區 (Comp + 2/3 N)；(六) 綠肥配合化學氮肥區化學氮肥量之三分之一區 (GM + 1/3 N)；(七) 泥炭配合化學氮肥區化學氮肥量 之三分之一區 (Peat + 1/3 N)。採取之土壤分別測定土壤一般性質、水溶性有機碳及以酸水解劃分不同組成之土 壤有機氮與碳含量。結果顯示未施肥、僅施化學氮肥及施綠肥配合少量化學氮肥施用之土壤有機碳之增加緩 慢，堆肥與泥炭配合化學氮肥施用，使土壤有機碳增加較多。各種施肥處理土壤之水溶性有機碳之濃度低且 不因施肥管理之不同而有大的影響。鹽酸溶液把土壤中大部分 (> 90%) 的氮都水解，但是長時期施用泥炭與堆 肥，可以慢慢累積土壤中的難分解氮含量；施用化學氮肥與綠肥之促發反應，使土壤中難分解氮與碳庫較小 (與只施堆肥之處理比)，泥炭與堆肥施用，增加難分解庫之氮與碳，也增加易變動庫氮與碳，即提高土壤品 質。以硫酸二階段劃分土壤中碳庫及氮庫之結果與以鹽酸水解之結果相似；硫酸所劃分之難分解氮庫約佔總 氮的10%，硫酸水解所得之五個碳劃分中，以難分解碳庫與總聚酚I碳庫佔總碳之比例最高 (各約30%)，其次 為最易利用之醣碳庫 (約佔總碳之20%)，再次為總聚酚II碳庫 (約佔總碳之10%)，最少者為纖維素碳庫 (約佔總 碳之5%)，不同的施肥處理會影響其濃度，佔總碳之比例應是受肥料性質的影響較大。

The aim of this study was to investigate the effects of different fertilization managements and application of different kinds of fertilizers on the concentration and composition of soil organic carbon (SOC) and nitrogen (N) under upland-lowland rotation for 13 years. There were seven treatments, namely (1) CK (without fertilization); (2) Chem-N (applying chemical N fertilizer only); (3) Comp (applying compost with the same rate as N of Chem-N treatment); (4) Comp + l/3 N (applying compost complemented with 33% of chemical N fertilizer as Chem-N treatment); (5) Comp + 2/3 N (applying compost complemented with 66% of chemical N fertilizer as Chem-N treatment); (6) GM + 1/3 N (applying green manure complemented with 33% of chemical N fertilizer as Chem-N treatment); (7) Peat + 1/3 N (applying peat complemented with 33% of chemical N fertilizer as Chem-N treatment). Soil samples were taken for the analyses of soil chemical properties and water soluble organic carbon (WSOC) concentration. In addition, soil carbons fractionated by hydrochloric acid solution and sulfuric acid solution were analyzed. The results showed that CK, Chem-N and GM+ 1/3 N resulted in slightly increase in SOC compared with the SOC at the time when the experiment was established. However, the application of compost and peat complemented with chemical N fertilizer resulted in higher concentration of SOC. Water soluble organic C concentrations were low in all treatments and fertilization management had no effect on WSOC concentration. Most N (< 90%) in soil was hydrolyzable by hydrochloric acid solution. Long-term application of compost and peat resulted in slight increase in recalcitrant and labile soil N and C, and thus increases soil quality. Chemical N fertililzer and green manure application resulted in priming effect and decreased recalcitrant soil N and C compard with applying compost plot. The results of two-step sulfuric acid solution fractionation were similar to that of hydrolization by hydrochloric acid solution. About 10% of soil N was recalcitrant N according to sulfuric acid solution hydrolization. Sulfuric acid solution fractionated the SOC into five fractions and the proportion of carbons in different fractions to total SOC were in the following order: recalcitrant pool C (30%) ≒ polyphenol I C (30%) > sacchride C (20%) > polyphenol II C (10%) > cellulose C (5%). The concentration of each fraction differs among treatments, probably due to the properties of the fertilizers.