Effects of rice straw application on the biological nitrogen fixation of paddy field -2. Effects of rice straw annual application on the biological activities and nitrogen fixing microbial flora

논토양의 생물적(生物的) 질소고정(窒素固定)에 미치는 볏짚시용효과(施用效果) -II. 질소고정미생물(窒素固定微生物) flora와 그 활성(活性)에 미치는 볏짚연용효과(連用效果)

The effects of rice-straw annual application on nitrogen fixing microbial flora in the soil of paddy fields and their biological activities were investigated. Experiments were performed in both NPK fertilizer applied soil and rice-straw applied soil of Agricultural Station in Aomori-ken, Japan. The following results were obtained. 1. The ARA by phototrophs was significantly increased in both soil plots. From the soil plot in which 300ppm-nitrogen was applied, the increase of ARA began to be seen from three weeks later. On the other hand, 33ppm-nitrogen applied soil plot and non-nitrogen applied soil plot showed the ARA increase from the beginning. The amount of ARA by non-phototrophs was only one-tenth of that by phototrophs. 2. For the first three weeks, the phototrophic bacteria (mainly Rhodopseudomonas) were predominant in both soil plots. Since then, as the ARA rapidly increased, the proliferation of blue-green algae forming heterocysts was remarkably promoted. Such effects were more distinct in the rice-straw annually applied soil plot than in the NPK fertilizer annually applied soil plot. 3. The degree of proliferation of blue-green algae depended on the amount of applied nitrogen. While Anabaena, Nostoc and Cylindrospermum were largely proliferated in the non-nitrogen applied soil plot, Cylindrospermum and Calothrix were in the 33ppm-nitrogen applied soil plot, but Calothrix tended to predominated in the 100ppm-nitrogen applied soil plot.

논토양의 질소고정미생물(窒素固定微生物) flora와 그 활성(活性)에 미치는 볏짚 연용효과(連用效果)를 밝히기 위하여 일본 청삼현(靑森縣) 농업시험장내 화학비료연용구(化學肥料連用區) 및 볏짚연용구(連用區) 작토층(作土層)을 공시토양으로 하고 질소시비량(窒素施肥量)을 달리하여 질소고정미생물 flora의 변천(變遷)과 대응하는 질소고정활성의 변화정도를 조사하였다. 1. 시용(施用)볏짚의 광합성미생물(光合成微生物)에 의한 ARA는 양토양(兩土壤) 모두 질소 300ppm 첨가구에서는 3주후(週後)부터, 질소 33ppm 및 무첨가구에서는 시용초기(施用初期)부터 ARA가 현저히 증가하였다. 비광합성미생물(非光合成微生物)에 의한 ARA는 광합성미생물(光合性微生物)에 의한 ARA의 1/10에 지나지 않았다. 2. 시용(施用)볏짚에 서식(棲殖)하고 있는 질소고정미생물 flora를 조사한 결과 초기 3주간에는 양토양(兩土壤) 모두 광합성세균(光合成細菌)(Rhodopseudomonas)이 주로 증식(增殖)하였으며 균량(菌量)과 ARA는 상관관계가 인정되었다. 그후 ARA의 급격(急激)한 증가에 대응(對應)하여 heterocyst형성 염조(鹽藻)의 증식이 현저히 증가하였는데 이상과 같은 효과(效果)는 화학비료연용구(化學肥料連用區) 토양보다 볏짚연용구(連用區) 토양에서 더욱 뚜렷하였다. 3. 염조류(鹽藻類)의 증식(增殖)은 질소시비량에 따라 약간씩 달라 질소 무시용구에서는 Anabaena, Nostoc, Cylindrospermum이 주로 증식(增殖)되었으나 질소 33ppm 시용구에서는 Cylindrospermum, Calothrix, 질소 100ppm 시용구에서는 Calothrix가 왕성히 증식(增殖)되는 경향이었다.