수수×수단그라스 재배시 녹비작물 혼입에 따른 새만금간척지 토양환경 개선 효과

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본 연구는 새만금간척지에서 동계 녹비작물 헤어리베치를 재배하여 토양에 환원 후 관행시비 (NPK), 녹비혼입구는 질소 추비기준량 (<TEX>$100kg\;ha^{-1}$</TEX>) 대비 30 50 70 100% 감비, 질소무시비로 처리하여 사료용 수수<TEX>$\times$</TEX>수단그라스 (G7) 재배시 토양이화학성, 토양염농도, 생육 및 수량성을 검토한 결과는 다음과 같다. 공시토양은 유기물, 유효인산 함량이 매우 적고 치환성마그네슘 나트륨 함량이 많은 강알칼리성 염류토양 이었다. 헤어리베치 혼입시 생체중 <TEX>$18,345kg\;ha^{-1}$</TEX>, T-N 3.09% 및 탄질률 12.8를 나타냈다. 동계 하계작물 재배기간 동안 토양염농도는 0.1%이하로 염피해는 없었다. 수수<TEX>${\times}$</TEX>수단그라스 생초수량 및 건물수량은 N30%감비 > 관행시비 > N50%감비 > N70%감비 > N100%감비 > N무시비 순으로 높았다. 생초 및 건물수량성은 관행시비 (<TEX>$55,050kg\;ha^{-1}$</TEX>, <TEX>$16,250kg\;ha^{-1}$</TEX>) 대비 N30% 감비에서 7%, 9% 증수되었다. 시험 후 용적밀도가 낮아지고 공극률이 증대되었다. 또한 pH가 낮아졌고, 유기물, 유효인산 및 치환성칼슘 함량은 증가하였으며 치환성칼륨 나트륨 함량은 감소하였다. 따라서 새만금 간척지에서 수수<TEX>${\times}$</TEX>수단그라스 재배시 녹비직물헤어리베치 토양환원으로 질소비료 질감 및 토양환경 개선효과를 기대할 수 있었다. This study was carried out to investigate the incorporation effect of green manure crops (GMC) such as the hairy vetch on improvement of soil environment in reclaimed land during sorghum<TEX>${\times}$</TEX>sudangrass hybrid (SSH) cultivation over the past three years from 2009 to 2011. Plots consisted of conventional fertilization (CF) and incorporation of GMC were divided by rates of additional nitrogen fertilizer (<TEX>$100kg\;ha^{-1}$</TEX>) and decreased percentage of 30 50 70 100 fertilization in addition to non nitrogen fertilization (NNF). Soil physico-chemical properties, growth and yield potential were examined. The results were as follows. The testing soil was showed strong alkaline saline soil with low organic matter contents and less available phosphate while exchangeable sodium and magnesium were higher. Soil salinity was increased during cultivation of summer crop. However, SSH was not affected by salt content. The fresh weight of GMC at incorporation time was <TEX>$18,345kg\;ha^{-1}$</TEX>. Content of total nitrogen at incorporation time was 3.09% and the C/N ratio was 12.8. Fresh and dry matter yield of SSH were higher in the order of 30%, CF, N50%, N70%d, N100%, and NNF. Fresh and dry matter yield of SSH increased in the order of CF (<TEX>$55,050kg\;ha^{-1}$</TEX>, <TEX>$16,250kg\;ha^{-1}$</TEX>), N contents from 30% to 9%. Soil physical properties, such as bulk density were decrease with incoporation of GMC, while porosity was increased. Soil chemical properties, such as pH was decreased while content of exchangeable calcium, available phosphate, and organic matter were increased. Also contents of exchangeable sodium and potassium were decreased with incorporation of GMC than those before experiment. Thus, we assumed that incorporation of hairy vetch was more effective that can lead to reduce chemical nitrogen fertilizer and to improve soil environment in cultivating SSH on Saemangeum reclaimed land.