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Volume 26
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[in Japanese]Article type: Article
1984 Volume 26 Pages 1-
Published: December 20, 1984
Released on J-STAGE: May 31, 2017
JOURNAL FREE ACCESSDownload PDF (128K) -
Michinori NISHIOArticle type: Article
1984 Volume 26 Pages 3-11
Published: December 20, 1984
Released on J-STAGE: May 31, 2017
JOURNAL FREE ACCESSSome of the problems encountered in microbiological analysis of the effects of organic manure application to upland crops are discussed. 1) In the analysis of the microbiological effects of organic manure application on plant growth, it is important to differentiate vegetables from cereal crops, since the levels of fungal and bacterial biomass and their ratio may be different between the two plant groups, mainly due to difference in the duration of cultivation which covers less than 3 months for vegetables and about 6 months for cereal crops. 2) The role of biomass, which has a very high turn-over rate, may be important in relation to the sink and source of nitrogen in soils with organic manure application, where the multiplication and death of microorganisms are greatly accelarated. It is thus essential to develop new and more accurate methods for the determination of biomass and its turn-over rate in soil, immediately after organic mannure application. 3) It was found that organic manure applicated first promoted fungal and bacterial growth in the non-rhizosphere region of soil in proportion to the amount of organic manure applied. Thereafter organic manure application increased microorganisms growth in the rhizosphere in proportion to the increase of biomass in the non-rhizosphere region of soil. Based on these findings, it was concluded that it was necessary to conduct systematic studies on the effects of soil management in the nonrhizosphere zone of soil on the microflora present in the rhizosphere. 4) In studies on the stimulation of plant growth by physiologically active substances produced by microorganisms in soil with organic manure application, it is important to recognize that the response to a given substance varies with the plant species.View full abstractDownload PDF (1037K) -
Hajimu KOMODAArticle type: Article
1984 Volume 26 Pages 13-20
Published: December 20, 1984
Released on J-STAGE: May 31, 2017
JOURNAL FREE ACCESSSignificance of organic soil amendments for the biological control of soilborne diseases is discussed. Organic matter added to the soil supplies soil microorganisms along with organic and inorganic nutrients, and thus affects the activity and survival of the soilborne pathogens. This phenomenon occurs since the microorganisms are able to utilize organic matter in accordance with their saprophytic ability, and in turn, are affected directly or indirectly by the activity of the antagonistic microorganisms which is enhanced by addition of organic matter. These relationships can be applied to the biological control of soilborne diseases. During the last two decades in Japan, organic soil amendments have experienced an abnormal development, and large amounts as well as various kinds of 'organic matter', including byproducts or wasts from other industries and urban wasts which usually are not composted enough, have been applied to agricultural lands. During this period, various kinds of 'organic matters' have been analysed to evaluate their effect on various soilborne pathogens. Based on these experiments, the effect of organic soil amendments on the incidence of soilborne diseases was found to vary (1) with the kind of organic matter and its degree of decomposition, presumably due to differences in the constituents, (2) with the soil type and the soil management, presumably due to differences in the soil microflora, (3) with the kind of pathogen, presumably due to differences in the saprophytic ability of the pathogen, and (4) with the kind of crop, due to unknown reasons. In addition, some of these amendments were ineffective as well as promoted the incidence of diseases. Effect of organic soil amendments on the incidence of soilborne diseases must be investigated from the following two viewpoints : effect of the activity of microorganisms on the activity and survival of the pathogen, and effect of nutrients released from organic matter on the resistance of the host plant to the pathogen.View full abstractDownload PDF (878K) -
Koji YOSHIDA, Yoshihisa OHNISHIArticle type: Article
1984 Volume 26 Pages 21-29
Published: December 20, 1984
Released on J-STAGE: May 31, 2017
JOURNAL FREE ACCESSTomatoes were cultivated in a vinyl greenhouse using Red-Yellow soil with low fertility. Thereafter, the effects of succesive applications of large amounts (50t/10a, 50t plot) of farmyard manure (FYM) on the yield of tomato and population of soil microorganisms were analyzed compared with practical applications (5t/10a, 5t plot) of FYM. Several crops were grown twice without fertilizer application between the third and fourth croppings of tomato. Yields and soil microorganism population were also evaluated. (1) The yields of tomato in the 50t plot and 5t plot were not significantly different until the third cropping. On the fourth cropping, the yield of the 50t plot was lower than that of the 5t plot due to salt accumulation. But the yields during the fifth to sixth croppings at which FYM was not applied were higher in the 50t plot than in the 5t plot. (2) Changes in the soil microbial population were remarkable and there was little difference between the amounts of FYM applied. However, the B/F (Bacterial/Fungal numbers determined by the dilution plate method) ratio and the numbers of ammonium-oxidizing bacteria tended to be higher in the 50t plot than in the 5t plot. (3) In the 50t plot, the successive changes in the population of ammonium-oxidizing bacteria were similar to the changes of the nitrate nitrogen contents. (4) During three croppings, nitrogen fertility in the 5t plot did not increase, whereas that in the 50t plot increased remarkably and remained at high levels after two croppings of tomato grown without FYM. (5) The yields of several crops in the first cultivation period between the third and fourth croppings of tomato were higher in the 50t plot. (6) In the soils where several crops were grown, the numbers of fungi and bacteria were higher in the 5t plot and 50t plot, respectively. B/F ratio was higher in the 50t plot and in the soil where sorghum and corn were grown.View full abstractDownload PDF (795K) -
Kazuyuki INUBUSHIArticle type: Article
1984 Volume 26 Pages 31-39
Published: December 20, 1984
Released on J-STAGE: May 31, 2017
JOURNAL FREE ACCESSThe process of ammonification in submerged soil was investigated both under laboratory and field conditions. This process which operates in submerged soil was found to be composed of two first-order reactions with different rate constants. Four parameters involved in the reaction formula were subject to change in the incubation temperature, pretreatment of the soil (air drying) and soil composition. Mineralizable N (the amount of NH_4^+-N formed during the anaerobic incubation of air dried soil for 4 weeks at 30℃) was found to be a reliable index for the evaluation of the amount of easily decomposable organic N (EDON) which was accumulated in the soil by addition of organic debris. It was found that the long term accumulation of EDON was common to all the soil examined. Short term accumulation of EDON which was caused by the addition of algal debris occurred in the upper layer (0-1 cm) during the period of submergence. On the other hand, the amount of EDON remained more or less constant in the lower layer (1-10 cm), in spite of the fact that the rice plant absorbed N actively from the soil organic N. Then, the new organic N pool ("available N") which was more active than mineralizable N and was a direct source of N for rice plant was studied. The "available N" was estimated by anaerobic incubation of chloroform-fumigated soil for 4 weeks at 30℃ and was considered to be derived from biomass N and unstable non-biomass N. In the paddy fields amended with ^<15>NH_4^+, the amount of "available N" increased in the upper layers but decreased gradually in the lower layers. In the middle and later stages of rice growth, "available N" and N taken up by rice plant were quantitatively highly correlated and their ^<15>N specific activities were similar. These facts suggest that "available N" is the main N source for rice plant in these stages.View full abstractDownload PDF (843K)
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