시설재배(施設栽培) 토양(土壤)에 축적(蓄積)된 질산태질소(窒酸態窒素)의 유효도(有效度)

Use Efficiency of Nitrate Nitrogen Accumulated in Plastic Film House Soils under Continuous Vegetable Cultivation

질소(窒素)가 다량 축전된 시설재배지(施設栽培地)에서 작물 재배기간중 $NO_3{^-}-N$의 동태를 조사하여 토양검정에 의한 질소시비추천(窒素施肥推薦)의 기초자료로 활용코자 1작기(作期) 봄배추, 2작기(作期) 상추, 3작기(作期)에 가을배추를 공시(供試)하여 재배시험(栽培試驗)한 결과를 요약(要約)하면 다음과 같다. 1. 시험전 토양중 질산태질소함량이 370mg/kg인 조건에서 질소무시용구의 1작기(作期) 봄배추 수량은 175MT/ha이었고, 2작기(作期) 상추의 경우 질소시비구(窒素施肥區)와 무시비구(無施肥區)간에 수량차이는 인정되지 않았다. 3작(作) 가을배추의 경우에는 질소시비효과(窒素施肥效果)가 현저하여 무질소구 수량에 비하여 토양검정조절구의 수량은 62%증가되었다. 2. 토양질산태질소의 감소량(減少量)은 시험전 370mg/kg에서 2작(作) 재배전 85mg/kg, 3작(作) 재비전 43mg/kg으로 작기별(作期別) 감소율(減少率)은 각각 77.89%이었다. 3. 작기별(作期別) 토양질소(土壤窒素)의 수지(收支)는 1작(作) 재배후 식물체가 흡수한 비율이 14.5%, 토양내 잔존율(殘存率)이 25.4%, 손실량(損失量)이 60.1%이었고, 2작(作) 재배후에는 식물체의 이용율(利用率)함이 25.3%, 토양내 잔존율(殘存率)이 51.8%, 손실량(損失量)이 22.9%이었다. 3작(作) 재배후에는 식물체의 흡수율(吸收率)이 62.8%, 토양내 잔존율(殘存率)이 19.4%, 손실량(損失量)이 16.8%이었다. 4. 작물별(作物別) 식물체중 양분흡수량(養分吸收量)은 2작(作)까지는 처리간 차이가 없으나, 3작(作) 가을배추는 무질소구에 비하여 토양검정조절구에서 질산태질소 및 질소흡수량이 많았다.

These experiments were conducted to monitor the change in $NO_3{^-}-N$ in a plastic film house where $NO_3{^-}-N$ have been accumulated in the soil of high level (about 370 mg/kg) The objective of this study was to obtain the information needed to establish the N Fertilizer recommendation based on the available N content in the soil for vegetable cultivation. The cultivated crops were chinese cabbage in the spring, lettuce in the summer, and chinese cabbage in the autumn. The crops were cultivated with and without N application. The concentration of $NO_3{^-}-N$ in the soil was analysed before and after the cultivation of each crop. When $NO_3{^-}-N$ in the soil is as high as 370 mg/kg. even without N application, the yield of the first season crop, cabbage in the spring was 175 ton/ha and that of second season crop, lettuce in the summer was 53 ton/ha. These yields were comparable with those obtained under the application of N fertilizer: meaning that no N application would be needed for those crops when $NO_3{^-}-N$ in the soil is as high as 370 mg/kg. The yield of third crop, cabbage in the autumn was higher under N application than that under no N application by 62%. The fate of $NO_3{^-}-N$ in the soil differed along with the crop sequence. In the first crop, 14.5% was absorbed by crop, 25.4% remained in the soil and 60.1% was unaccounted for. In the second season, 25.3% was absorbed by crop, 51.8% remained in the soil and 22.9% was unaccounted for. In the third crop, 62.8% was absorbed by crop, 19.4% remained in the soil and 16.8% was unaccounted for.