Behavior of selected microbial populations and their activity in rice [Oryza sativa] and wheat [Triticum aestivum] rhizosphere and non-rhizoshere soils in longterm experimental paddy fields with and without organic matter application in southwest Jap
1995
Hayano, K. (Kyushu National Agricultural Experiment Station, Chikugo, Fukuoka (Japan)) | Watanabe, K. | Asakawa, S.
A comparative study of the dynamics of microbial populations and their activity was made from 1987 to 1989 on rice and wheat rhizosphere and non-rhizosphere soils of two well controlled paddy field experimental plots at Chikugo in southwest Japan. Both experimental plots were in the same field (Gray Lowland Soils) where rice was cropped yearly from June to October for more than the past 20 years and, since 1985 rice was cropped in summer and wheat cropped from November to May. One plot received an application of inorganic fertilizer at 140 kg N ha(-1)yr(-1), and the other received an application of inorganic fertilizer at 120 kg N ha(-1)yr(-1) and rice straw compost at 20 ton ha(-1)yr(-1). Mid-summer drainage during the rice growing seasons increased the bacterial population in rhizosphere soil that received an application of rice straw compost. With the exception of this case, populations of bacteria, actinomycetes, fungi and anaerobes, were usually constant overtime regardless of growth stage and soil management. The rhizosphere effect of rice on microorganisms examined here, was generally low irrespective of the rice growing stage, microbes examined, and soil management, while the rhizosphere effect of wheat was clear. In plots receiving rice straw compost, enzyme activity, amino acid content, and release of amino acid-N after incubation of soil at 30 degrees C for 24 hr in presence of toluene were higher than control plots. These estimates for rhizosphere soil in the rice growing stage were higher than in non-rhizosphere soil. According to the results obtained here, the interaction between microbial populations and their activity in rhizosphere and non-rhizosphere soils and application of organic manure, and growth of crop plants, were discussed
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