有機農田土壤肥力即時偵測技術研發與應用

Abstract

長期的施用有機質肥料可能導致土壤中累積多量的有機質及營養鹽，致使礦化的養分量超過作物生長所需的量，降低作物產量及品質且污染環境。因此，建立有機農田土壤肥力快速診斷施肥推薦技術，供調節施肥之依據，甚為重要。傳統之土壤速測法在田間採取土壤樣本後，需經過風乾處理及一連串的分析步驟，耗費甚多人力與藥品等資源，且無法在有機農田現場診斷、立即推薦施肥。土壤測速箱（soil test kit）雖可在田間進行速測，惟仍需消耗化學藥品，且精確度較低，使用上並不普遍。電磁感應偵測技術在土壤性質的測定上是一種低成本、快速且是非破壞性之方法: EM38（Electromagnetic induction detector）之測值與傳統土壤與肥力測值間具顯著正相關，惟EM 38 測值受土壤水分及金屬資材之顯著影響。應用電導度計於有機農田施肥前進行現場測定，測值與土壤有機質及有效養分含量間均呈顯著正相關，可作為推荐施肥之依據。惟應用上仍需考慮下列因子：pH、元素間平衡、土壤排水性、有機質含量、設施有無、有機液肥有無、栽培季節等。塩度計測值與EC 值間亦呈顯著正相關，可於田間即時測定，惟其測值受水分含量之影響。 The negative impacts of the overuse of chemical and organic fertilizers have raised concerns in agricultural fields, so application of soil testing for fertilization recommendation is acting more and more important. In Taiwan, there are applying voluminous organic material in agricultural fields, especially in organic cultural farms. So it is important to development and utilization of "on-site" diagnosis of soil fertility in organic cultural fields, in order to recommend rational fertilizer application. Soil fertility is the ability of a soil to deliver to roots the nutrients needed for the optimum growth of a specified crop. Traditional soil testing not only used a lot of times, labors, and chemical reagents, but also produced lots of toxicant. It can not diagnosis soil fertility in organic cultural fields. Although "soil test kit" method can diagnosis some soil properties in the fields, it could not be a useful tool, owe to its’ low sensitivity. Used electromagnetic induction detector to detect soil EC is a nondestroy, rapid, and low cost method, its’ value had significantly positive relationship with traditional EC meter value, but its’ values are significantly affected by soil moisture content and metal materials. Testing soil EC value before planting server as a good guide for fertilization recommendation. Application of liquid organic fertilizer had a positive response to increase yield. The responses of plants grown in different season to soil EC are different. Salt meter value had significantly positive relation with soil EC value, can server as a guide of diagnosis of soil fertility for fertilization recommendation. In practices, use the "on-site" and quick soil diagnosis to regulate and recommend rational fertilization in organic cultivated vegetable fields, need to consider some parameters; soil pH, balance between nutrients, organic matter content, with or without protection structure, application of liquid organic fertilizer or not, cultivation season etc.