Abstract
BACKGROUND:Cultivation of alternative crops in paddy fields is necessary because of the decrease in rice consumption and the increase in excess stock of rice. The study was conducted to investigate the effects of alternative crops cultivation in paddy fields on soil physico-chemical characteristics and crop yield. METHODS AND RESULTS: Soybean (Glycine max), red-clover (Trifolium pratense), and water convolvulus (Ipomoea aquatica) were selected for alternative crops in the first and/or second year and rice was planted in the third year. When alternative crops were cultivated in the previous year, soil bulk density, soil hardness, and water content were lower than those for rice cultivation. Water-depth decreasing rate and aggregate content were greater for the upland-upland-paddy cropping system than upland-paddy-paddy cropping system. Cultivation of red-clover and water convolvulus for two years resulted in the high soil organic matter content. In the third year, available phosphate, exchangeable potassium, and soil cation exchange capacity were relatively high when soybean was cultivated in the previous year. In the first year, water convolvulus cultivation showed greater productivity than red-clover cultivation while the opposite pattern was found in the second year. Rice yield in the third year was greater for soybean or red-clover as a previous crop than for water convolvulus as a previous crop. CONCLUSION: The results suggest that cultivation of alternative crops in paddy fields can improve soil physical properties including bulk density, hardness, water content, and aggregate content as well as rice productivity.
논에서 대체작물의 재배에 따른 토양 물리화학성과 작물 수량의 변화를 살펴보기 위하여 하성충적지에 분포된 규암 미사질 양토의 배수 약간양호인 토양에서 콩, 레드클로버, 공심채를 대체작물로 재배하여 3년간 경작시험을 수행하였다. 경작처리는 콩-벼-벼, 콩-콩-벼, 레드클로버-레드클로버-벼, 레드클로버-벼-벼, 공심채, 공심채-벼, 공심채-벼-벼 작부체계로, 3년차에는 모든 처리에서 논으로 복원한 다음 벼를 재배하여 토양 물리화학성과 작물 수량을 조사하였다. 앞그루가 밭일 때 토양의 용적밀도와 경도 수분함량이 감소하였고 공극률은 증가하였다. 대체작물을 2년 재배하였을 때에 1년 재배하였을 때보다 토양 입단량과 감수심이 높았다. 토양 유기물 함량은 레드클로버와 공심채를 2년 동안 재배하였을 때 높았다. 3년차에 유효인산과 치환성 칼리 함량 토양 CEC는 앞그루가 콩이었을 때 높았다. 대체작물의 1년차 생산성은 공심채가 레드클로버보다 높았으나, 2년차에는 반대였다. 3년차의 벼 수량은 앞그루가 콩과 레드클로버일 때가 공심채일 때보다 높았다.