長期進行有機農耕法對土壤微生物族群與活性之衝擊

The Impact of Long-Term Organic Farming on the Soil Microbial Populations and Activitie

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

《中華農學會報》 8卷6期 (2007/12) Pp. 517-536

https://doi.org/10.6730/JAAC.200712_8(6).0003

摘要

農耕管理制度之不同，尤其是施用合成農藥與否及施用有機質量相異時，勢必影響土壤微生物族群之大小與活性之高低。試區自1988年7月起設置於高雄縣旗山鎖高雄區農業改良場旗南分場，連續耕作到2005年6月止共計十七年，每年種植三期作物，均於收穫時採土分析，比較有機農耕法與慣行農耕法土壤微生物活性與族群數之差別，期瞭解歷經長期進行有機農耕法對土壤微生物性質之衝擊。
歷年結果顯示平面測數土壤總菌數與真菌數，兩種耕作法測值互有高低差異不顯著。生質碳與生質量－寧海因反應氮在長期進行有機農耕法之土壤顯著高於慣行農耕法之土壤。MPN法測定銨化菌、硝化菌及脫氮菌等菌類族群數，有機農耕法土壤高於慣行農耕法，差異顯著與否視期作與微生物種類而異。土壤微生物活性，包括土壤呼吸作用、固氮作用、短期硝化活性、脫氮作用、N2O釋放、脫氣酵素活性、脫氮潛勢及大豆根瘤乙快還原活性，皆以有機農耕法顯著高於慣行農耕法之土壤。總之，在高溫多雨的台灣熱帶地區長期進行有機農耕法有助於增進土壤微生物生質量與活性。

關鍵字

有機農耕法 ； 土壤 ； 微生物 ； 生質量 ； 活性

並列摘要

The different farm management systems could have a variety of effects on soil microorganisms and microbial activities, especially in fields with various amounts of organic matters and with of without chemical pesticides. This study was conducted to compare the microbial properties of soils collected from fields managed under organic and conventional farming systems for the past seventeen years (Jul. 1988 to Jun. 2005). The field was located at Chishan, Kao-Hsiung County. Surface soil samples were collected after the planted crops were harvested and used to measure the number of specific microbial populations and the activity of selected metabolic functions.
The results shown that, the change of total bacteria and filamentous fungi between organic and conventional farming treatments and crop variety were not significant when a viable plate count technique was used. However, the biomass carbon and biomass ninhydrin-reactive nitrogen increased significantly in the organic farming plot. The number of ammonifiers, nitrifying bacteria and denitrifiers was determined by MPN assay. The results indicated that the numbers of these bacteria in the organic farming soil were slightly higher than those in the conventional farming soil. When microbial activities, including soil respiration, nitrogen fixation, short-term nitrifying activity, denitrification, N2O emission, denitrifying enzyme activity, denitrification potential in soils and acetylene reduction of soybean nodule were assayed, soil form the organic farming system showed significantly higher activities than those from the conventional farming system. This study suggests that, the long-term organic farming practice would increase soil microbial biomass and microbial activity in the tropical region of Taiwan.

並列關鍵字

Organic Farming ； Soil ； Microorganisms ； Activity ； Biomass