논토양(土壤)의 탈질작용(脫窒作用)에 관(關)한 연구(硏究) -제(第) 3 보(報) : 볏짚 및 규산질비료(珪酸質肥料)의 시용시기(施用時期)가 탈질(脫窒)에 미치는 영향(影響)

Studies on the Denitrification in the Submerged Paddy soil -III. Pretreatment of rice straw and silica fertilizer in submerged and upland soil Condition

담수상태(湛水狀態)와 밭상태(狀態)의 토양조건(土壤條件)에 볏짚과 규산질비료(珪酸質肥料)를 시용시기별(施用時期別)로 처리(處理)한 후(後) 토양(土壤)에 이몰(理沒)하였다가 질내(窒內)에 채취(採取)하여 담수항온(湛水恒溫)하면서 탈질량(脫窒量)을 조사(調査)한 결과(結果)는 다음과 같다. 1. 볏짚과 규산질비료(珪酸質肥料)의 병용시 탈질량(脫窒量)은 항시담수구(恒時湛水區)보다 밭상태(狀態)로 유지(維持)하다 담수처리(湛水處理)한 구(區)에서 현저(顯著)히 증가(增加)되었다. 2. 볏짚 및 규산질비료(珪酸質肥料)의 시용시기별(施用時期別) 탈질량(脫窒量)은 이앙(移秧) 2주전(週前) 시용구(施用區)가 조춘(早春) 및 가을 시용구(施用區)보다 현저(顯著)한 증가량(增加量)을 보였다. 3. 질소(窒素) 1 mole 탈질(脫窒)시키는데 소요(消要)되는 탄소량(炭素量)은 항시담수구(恒時湛水區)가 밭상태(狀態)의 토양(土壤)보다 많았으며 볏짚과 규산질비료시용(珪酸質肥料施用)은 탄소(炭素)의 소모량(消耗量)은 감소(減少)시켰다. 4. 항온기간중(恒溫期間中) 무기태질소생성량(無機態窒素生成量) 및 초산화성율(硝酸化成率)은 항시담수구(恒時湛水區)보다 밭상태(狀態)의 토양(土壤)에서 현저(顯著)한 증가(增加)를 보였다.

A pot and laboratory experiments were conducted to find out the effects of pretreatments of rice straw and silica fertilizer in submerged and upland soil condition on the evolution of nitrous oxide with different application time. The results obtained were summarized as follows; 1. Evolution of nitrous oxide was remarkably increased with pretreatment of rice straw and silica in upland condition than that of submerged condition. 2. Effects of application time of rice straw and silica fertilizer on the evolution of nitrous oxide were high in order of two weeks before transplant > early spring (February) > late autumn (November) application. 3. The consumption ratio of carbon for the evolution of one mole nitrogen was pronounced more in submerged condition than that of pretreated in upland condition. Application of rice straw with silica fertilizer was remarkably reduced the consumpotion of carbon on the denitrification path way. 4. Amount of mineral nitrogen as $NH_4^+-N$, $NO_2^--N$, and $NO_3^--N$, and nitrification rate were remarkably high in pretreatment of rice straw and silica in upland condition than that of contineusly submerged soil condition.