農業長期生態系之水旱田輪作對土壤肥力的影響: 以雲林分場水旱田輪作試驗區為例

Abstract

臺南區農業改良場雲林分場農業長期生態系試驗區已歷經 12 年，當中包含水旱輪作區及水田連作區。本次研究將以兩種施肥量對於水旱輪作土壤肥力之影響進行討論，並試圖以灌溉水質探討土壤肥力之影響。2007 年至 2018 年之土壤電導度監測結果顯示各期作土壤EC 值皆低於 0.6 dS m-1 ；高投入制度 (CA) 及低投入 (SA) 制度所推薦之施肥量，在 2007 ～2018 年的監測期間，土壤導電度未高於 0.6 dS m-1 。土壤有機質隨著土壤深度增加而降低：0 ～ 15 公分土壤有機質範圍 0.7 ～ 2.4%；15 ～ 30 公分土壤有機質平均約 1%；30 ～ 50 公分土壤有機質約 0.4 ～ 0.7%。土壤有效性磷及鉀以表土 0 ～ 15 公分最高，並且隨著土壤深度增加而下降。主要原因是施肥位置大多為表面撒施，故以表土磷累積量最高。土壤酸鹼值及有效性鈣鎂在 2009 及 2014 年有明顯提高的現象，進一步比對灌溉水酸鹼值及鈣鎂離子監測資料。結果顯示溝水酸鹼值於 2009 年及 2014 年並未出現明顯的變化，然而溝水之鈣鎂僅於 2009 年出現較高測值，尚無法充分解釋土壤有效性鈣鎂提高的原因。 Agricultural long term ecosystem has been set up to the 12th years at the Yunlin branch, TNDARES. The long term effect of fertilizer on soil quality under lowland- upland rotation system would be revealed by monitoring the soil data. The results showed that soil EC was always below 0.6 dS m-1. Soil O.M. was maintained at the range between 0.7 and 2.4% in 0~15 cm soil depth, and soil organic matter was decreased by soil depth. Soil available P and K showed the highest content at the 0~15 cm in soil depth. In 2009 and 2014 soil pH, and available Ca and Mg raised, but pH of irrigation water did not significantly increased and Ca, and Mg of irrigation water increased. Irrigation water may not be the major reason for the increase of the soil pH, Ca and Mg.