Evaluation of Soil Microbial Population of Paddy Fields in Gyeongnam Province Area

경남지역의 논토양에서 미생물의 다양성 평가

To use as a fundamental data for the sustainable agriculture, which is nowadays a major trend to keep the productivity and conserve the environment, 487 paddy soil samples were collected from 21 regions of the Gyeongnam Province and analyzed the chemical characteristics and microbial population of the soil. The microbial population densities were bacteria $298{\times}10^5$($4{\sim}3000{\times}10^5$ range), fungi $63{\times}10^3$($2{\sim}441{\times}10^3$ range), actinomycetes $19{\times}10^5$($0.2{\sim}1250{\times}10^5$ range), Bacillus sp. $53{\times}10^4$($4{\sim}890{\times}10^4$ range) and Pseudomonas sp. $198{\times}10^4CFU\;g^{-1}$($4{\sim}1724{\times}10^4CFU\;g^{-1}$ range), respectively. The microbial populations of the soil were in general higher in southern area than in the northern area of the Gyeongnam Province. The average ratio of bacteria/fungi population was 473. As soil clay content increased, the populations of aerobic bacteria, actinomycetes and Pseudomonas sp. were remarkably decreased. The ratio of aerobic bacteria and fungi was 1554 in sandy loam and clay loam 1144, while Bacillus sp./fungi ratio was 11 in clay loam and 10 in loam. On the topographical differences, aerobic bacteria and Bacillus sp./fungi ratio were the higher in coastal plains than any other areas. The microbial population densities from different soil types were generally lower in ill-drained paddy field than those of other paddy field. The content of $P_2O_5$, K, Ca, $NO_3-N$ and EC in soil were positively correlated to the population densities of aerobic bacteria, actinomycetes, fungi, Bacillus sp. and Pseudomonas sp.. The soil organic matter and Mg content were also positively correlated to the population densities of aerobic bacteria, actinomycetes, fungi and Bacillus sp.

벼 생산력과 환경보전을 상호 보완할 수 있는 지속농업 체계를 구축하는데 필요한 기초자료를 제공함과 아울러 관리기술을 개발하고자 경남지역에 산재된 논토양 487개소의 화학성과 미생물상을 연구한 결과는 다음과 같다. 논토양의 평균 개체수는 호기성 세균 $298{\times}10^5$($4{\sim}3000{\times}10^5$), 사상균 $63{\times}10^3$($2{\sim}441{\times}10^3$), 방선균 $19{\times}10^5$($0.2{\sim}1250{\times}10^5$), Bacillus sp. $53{\times}10^4$($4{\sim}890{\times}10^4$), Pseudomonas sp. $198{\times}10^4$($4{\sim}1724{\times}10^4$)$CFU\;g^{-1}$였다. 토양 미생물 균수는 남부지방이 북부지방보다 많았으며 평균 B/F비는 473 이었다. 토양의 점토함량이 증가할수록 호기성 세균, 방선균, Pseudomonas sp.의 균수는 감소하였다. B/F비는 사양토와 식양토에서 각각 1554, 1144로 높았고 Bacillus sp./fungi 비율은 식양토, 양토에서 각각 11, 10 으로 높았다. 지형별 미생물 균수 변이는 하해혼성평탄지에서 호기성 세균과 Bacillus sp./fungi 비율이 높았으며 토양유형별로는 습답에서 미생물의 균수가 낮았다. 토양 무기성분중 EC, $P_2O_5$, K, Ca, $NO_3-N$ 함량은 호기성 세균, 방선균, 사상균, Bacillus sp., Pseudomonas sp. 균수와 정의상관이 있었고 토양 유기물과 Mg 함량은 호기성 세균, 방선균, 사상균, Bacillus sp.와 정의상관이 있었다.