土壤有機質與蔬菜栽培

Abstract

蔬菜在生產中，將土壤的營養吸走，尤其在密集耕作制度下，土壤需有良好的保養，才能維持長期地力。為了維持長期的地力，土壤有機質扮演重要的角色。因為土壤有機質對土壤物理性、化學性及生物性影響甚鉅，功效甚多，因此，土壤有機質存在的質與量，將影響蔬菜的生產量及品質，其原因是土壤有機質具有下列之功效：(l)有機質可改善土壤物理特性，改善土壤團粒構造，良好的土壤通氣及排水；(2)增加土壤保水能力；(3)增加土壤之保肥力，以吸附及交換植物營養元素，提高肥料緩效性；(4)分解後釋放植物所需之營養元素；(5)鉗合微量營養元素及協助植物營養元素之溶解度及有效性；(6)增加土壤之緩衝能力，使土壤之酸鹼反應緩和；(7)提供土壤有益微生物之活動，使土壤微生物進行對抗病菌大量發展；(8)分解人為或天然之毒性質及作用；(9)色黑有助吸熱及早春種植等；(10)部份組成分有助植物代謝及生長之功效。蔬菜所需要的土壤有機質是來自甚多來源，主要可以從有機肥料、植體殘質、種植綠肥等，包括易分析及較不易分解有機質，其中易分解之有機質可迅速供應較大量營養，而不易分解之有機質則主要供土壤改良劑，其效果可維持較長。建立正確的施用有機質肥料，才能確保土壤有機質含量及蔬菜生產量及品質。 Vegetable production involves large utilization of soil nutrients, particularly in the intensive cropping system. Management of soil fertility is an important factor for vegetable production, since soil organic matter play a significant role in soil ferility. Organic matter contributes to crop production through its func- tion on the physical, chemical and biological properties the soil. Some of the important and benefical properties of soil organic matter are listed here (1) improves soil physical properties, (2) increases soil water-holding capacity,(3) has high adsorptive of exchange capacity for nutrients,(4) slow release plant nutrients by the decomposition of organic matter,(5) aids in micronutrients and other nutrients through chelation and solubilization, (6) increases soil buffer capacity, (7) supports a greater and more varied microbial population which favors biological control for soil diseases, (8) reduces toxicity of toxic substances both natural and man made, (9) dark color favors heat absorption and eariler spring planting, and (10) certain components may exert plant growth promoting effects. Organic sources of the soil include a large and diverse group of substances that supply from farm manures and organic commercial fertilizers. Nutrient supply rate and proportion of organic matter were depend on type and source of materials. Peat, humic acid and woody composts with slow decomposition rate can be used to improve soil fertility for long periods. Establishment of correct methods for application of organic materials is essential for high vegetable quality production.