有機肥料之施用與土壤重金屬之聚積、作物吸收之關係

Abstract

目前施用於農地之有機肥料，依其來源大略可區分為畜牧廢棄物如豬糞尿水，畜殖堆肥，都市廢棄物如下水道之污泥，垃圾堆肥，農業廢棄物如蔗渣或作物殘留，工業廢棄物如酒精廢醪。重金屬在各種有機肥料內之含量依材料之不同而不同，施用有機肥料除了可供給植物所需之微量元素，過量之重金屬負荷和不良之土壤管理，可直接造成重金屬在土壤之累積及作物之毒害。畜牧堆肥，都市垃圾污泥和農業廢棄堆肥中之Zn，Cu和Ni已發現可導致作物之毒害。重金屬在土壤之累積程度依Input-output及土壤之性質而異。作物吸收重金屬除了受土壤性質，土壤重金屬濃度，有機堆肥之種類影響外，不同品種之同一種作物在同一環境下，重金屬之吸收量亦不同“為保護土地資源，欲施放於土壤之有機資材，其成份需要分析管制，隨有機肥料進入土壤之重金屬量，均需作年施用量及總量監測。 According to the sources, the organic fertilizers applied to agricultural land in Taiwan recently, are grouped into livestock wastes-feces and urine excreted by swine; animal manures; municipal wastes-sewage sludges and urban waste composts; agricultrual wastes-bagasse and crop residues; and industrial organics-alcoholic siop. The heavy-metal concentrations in organic fertilizers depend on the organic meterials used. Application of organic fertilizers to agricultural land could supply the micronutrients to crops, but the problems induced by heavy-metal overloading and inproper soil-management of land, which could lead to the heavy-metal accumulation in soils and cause phytotoxicity on crops, need to be considered. Zinc, copper, and nickel in livestock manures, municipal refuses, sewage sludges, and agricultural composts causing phytotoxicity have been identified. The extent of heavy-metal accumulated in soils depends on both input-output balance of heavy metals and soil characteristics applied. Soil characteristics, heavy metal concentrations in soil solutions and kinds of organic fertilizers used all affect the uptake of heavy metals by plants. Different varieties of crops have different metal-uptake, even in the same environment. In order to protect the land resources, chemical analysis of applying organic fertilizers needs to be carried out, annual loading rate and maximum cumulative amount of heavy-metal need to be controlled.