連續十七年有機農耕法之土壤理化性質的評估

Evaluation of Soil Physical and Chemical Properties after Receiving Continuous Organic Farming Practice for Seventeen Years

10.6730/JAAT.200806_9(3).0006

趙維良(Wei-Liang Chao)；趙震慶(Chen-Ching Chao)

有機農耕法 ； 慣行農耕法 ； 土壤 ； 理化性質 ； Organic farming ； Conventional farming ； Soil ； Physical and chemical properties

台灣農學會報

9卷3期（2008 / 06 / 01）

270 - 291

繁體中文

有機農耕法為台灣重要農耕法之一。本研究探討自民國七十七年開始，連續十七年觀測有機農耕法對土壤理化性質之衝擊。田間試區位於台灣南部高雄縣旗山鎮高雄區農業改良場旗山分場。共設六種處理，即三種農耕法（有機農耕法：生物防治與施用牛或豬糞堆肥，假設堆肥所含有機氮礦化率為50%；慣行農耕法：施用化學肥料與化學農藥；折衷農耕法：畜糞堆肥與化學肥料各佔50%及最低量低毒性化學農藥。三種農耕法田間作物殘體均犁入土中），二種輪作系統（每二年一輪，每輪六種作物，包括一作綠肥）。各處理無重複，小區面積為0.1公頃。均於作物收穫期採表土(0∼15 cm)為樣品，各小區依田字形分為四部份採樣，供土壤理化性質之分析。 有機、折衷農耕法與慣行農耕法相比，耕種一年後土壤 pH 明顯上升一個單位，兩年後土壤有機質與全氮含量顯著上升，四至六年時土壤之陽離子交換容量、總孔隙率及粒團安定度均顯著高於慣行農耕法，而總體密度亦顯著下降。土壤溶液導電度為0.27至2.98 dS m^(-1)，輕質有機質含量為0.93至11.78 g kg^(-1)土，其含氮量為8.5至29.3 g kg^(-1)，三者測值高低依序為有機農耕法〉折衷農耕法〉慣行農耕法，部份期作三耕作法之間差異顯著。經十七年耕作後，土壤有機質、全氮、陽離子交換容量及輕質有機質在有機農耕法土壤中含量高於慣行農耕法二至三倍。本結果顯示有機農耕法正面影響土壤有機質含量，進而改善土壤理化性質。

Organic farming is one of the frequently used farming systems in Taiwan. This study reports the impact of continuous organic farming practices on soil physical and chemical properties, which started in 1988. Field trials were set up at the Kaohsiung District Agricultural Improvement Station in Chishan, Kaohsiung county, located in the southern part of Taiwan. The trial involved six treatments with the combinations of three farming practices: organic, using biological control and cow or swine dung compost, with the assumption that the rate of organic nitrogen mineralization was 50%; conventional, using chemical fertilizer and pesticides; intermediate, using 50% cow or swine dung compost and chemical fertilizers with minimum low toxic pesticides. Two rotation systems were used, six crops per cycle, and it took two years to complete a cycle. All crop residues were plowed back into the soil after harvest regardless of farming practices. Each treatment had no replication with a plot size of 0.1 ha. Each plot was divided into four parts, and soil samples were collected from the surface layer (0-15 cm) at harvest, The physical and chemical properties of these soil samples were studied. Organic and intermediate farming practices resulted in a significant increase in soil pH after one-year tillage. soil organic matter, total nitrogen content showed an increase after two-year tillage, cation exchange capacity, total porosity and aggregate stability, and decrease bulk density showed an increase after four-to six-year tillage compared with those under conventional farming practices. The electrical conductivity of soil solution was 0.27 to 2.98 dS m^(-1), the light froction organic matter content was 0.93 to 11.78 g kg^(-1) soil, and the nitrogen content was 8.5 to 29.3 g kg^(-1). In some cropping systems, the farming practice produced a significant impact on the soil physical and chemical properties, in the following order according to degree: organic＞intermediate＞conventional. After seventeen-year tillage, the organic matter content, total nitrogen content, cation exchange capacity and light fraction organic matter content in soil receiving organic farming practice were 2 to 3 times higher than those receiving conventional farming practice. These results indicated that by positively affecting soil organic matter content, organic farming practice can effectively improve soil physical and chemical properties.

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