Soil Microorganisms

Man made disease

[in Japanese]

Article type: Article
1987 Volume 29 Pages 1-
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_1

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Effect of Chemical Fertilizers and Rice Straw Compost on Microorganisms in Paddy Soils

Yukari SHIOTA, Tetsu HASEGAWA, Itsuo OKIMURA

Article type: Article
1987 Volume 29 Pages 3-8
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_3

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Soil samples from paddy field plots under long-term soil amendments were examined using standard plate counts and CO_2 evolution procedures. The field was established in 1925 to investigate the effect of different soil treatments on rice crops. Nine plots iucluded absence of nitrogen, phosphorus, potassium, calcium and any of these elements, application of Ca alone, fertilizers and 75, 225kg/a of rice straw compost added annually. Aerobic, anaerobic, gram-negative bacterial populations and CO_2 evolution were low for the soils to which fertilizers, P and Ca were not applied, and high for the soils that received annual applications of compost. Fungal populations were low for the soils to which fertilizers and P were not applied and high for the soils amended with compost. These results indicated that soil pH affected the growth of the bacterial populations whereas a low content of P in soils affected the growth of the fungal populations.

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Distribution of Pseudomonas strains producing fluorescent pigment and Bacillus strains on the roots of cucumber and in soils

Kunihiko KATOH, Tadashi ISHIGAMI, Mitsuo INAYAMA, Akira FUJITA, Toshit ...

Article type: Article
1987 Volume 29 Pages 9-15
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_9

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Spring and autumn cucumber was grown annually on 4 plots with and without green manure application. The distribution of Pseudomonas strains producing fluorescent pigment and Bacillus strains on the roots of cucumber and in soils was studied using 4 selective media. Most of the counts on P-1 medium (Pesudomonas strains producing fluorescent pigment) ranged from 10^5 to 10-6/g dry soil, while in most cases the number of P. putida was larger than that of P. fluorescens both in the soils and on the roots of cucumber. The counts of B. megaterium increased in the soil in June and July. Continuous planting of cucumber did not affect the number of Pseudomosas strains producing fluorescent pigment.

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Evaluation of Selected Rhizobium Strains for Symbiotic Effectiveness on Cowpeas under Tropical African Conditions

S. ASANUMA, A. AYANABA

Article type: Article
1987 Volume 29 Pages 17-22
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_17

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To evaluate the symbiotic effectiveness of selected Rhizobium strains, inoculation trials were conducted in the wet season in 1982 at three locations in West Africa: Samaru in northern Nigeria, Maradi in the Niger Republic and Kamboinse in Burkina Faso. Cowpea cultivar VITA 7, one of IITA's improved cultivars, was grown at each location along with a local check. Five Rhizobium strains collected from locations with diverse geographical conditions in the tropics were used either as four single strain inoculants or a mixture strains of 5 inoculant. Competitiveness of two of the strains, IRc252 and IRc430A, in terms of nodulation on either cultivar was largely dependent on the soil moisture conditions and was very high under adequate moisture conditions. Inoculated plants did not always produce the same nodule mass as uninoculated plants; in some cases they produced considerably less. However, there were no significant differences in the grain yield of each treatment, suggesting that some strains, IRc252 with VITA 7 at Samaru, NUM716 and T242 with the local cultivar at Maradi, and IRc252 and NUM716 with the local cultivar at Kamboinse, are symbiotically more effective than indigenous strains. Indigenous rhizobial strains present in West African soils appeared to be effective enough to induce nodulation in cowpeas and enable to achieve satisfactory grain yield.

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Life Cycle and Control of Plasmodiophora brassicae, Causing Clubroot Disease of Cruciferous Plants

Takashi NAIKI

Article type: Article
1987 Volume 29 Pages 23-37
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_23

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The history of the occurrence of clubroot disease of cruciferous plants, caused by Plasmodiophora brassicae WORONICHIN, and its geographic distribution in the world were described briefly. The current status of the control of the disease in relation to the life cycle of the pathogen and enviromental factors, such as soil temperature, moisture, pH, soil type and spore concentration in soil, which affect the disease incidence, was also discussed. It was pointed out that detailed information on the life cycle of the pathogen is essential to develop more effective integrated control methods of this disease.

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Soil Biomass and Turnover Rate of Its Nitrogen in Grassland

Seigo OKANO, Michinori NISHIO, Yasuo SAWADA

Article type: Article
1987 Volume 29 Pages 39-47
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_39

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Distribution and seasonal changes of microbial biomass and the turnover rate of soil biomass N were investigated to assess the role of soil biomass as the source of available N in grassland ecosystems. 1) Microbial biomass ranged from 72 to 135g dry wt. m^<-2> 20cm^<-1> throughout a year. One third of the microbial biomass was present in the root mat layer(0-3cm in depth). 2) The fumigation-incubation method was suitable for measuring the amount of soil biomass N in the root mat layer(0-2.5cm in depth), but not in the deeper layers. The relationship between the soil biomass C and N and flush N (Fn) in the root mat layer, the amount of mineralized N generated by fumigation-incubation, was expressed by the equations Bc=8.8 Fn and Bn=1.8 Fn, where Bc and Bn are soil biomass C and N estimated from the biovolume determined under the microscope assuming that the C and N contents are 50 and 10% of dry wt., respectively. 3) The amount of ^<15>N in the soil biomass, which was labelled by applying (^<15>NH_4)_2SO_4 and glucose, decreased slowly in a pasture during a period covering 63 to 828 days. Its half-life was found to be 1.25 years, and its turnover rate was estimated to be 0.55 year^<-1>. The total soil biomass N in the standing crop averaged throughout the whole period was 40kg N ha^<-1>. Thus, 22kg N ha^<-1> yr^<-1> was considered to have been released through soil biomass in the root mat layer. This amount was equivalent to 20% of N, which was mineralized from soil and absorbed by herbage.

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[title in Japanese]

[in Japanese]

Article type: Article
1987 Volume 29 Pages 49-
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_49_1

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[title in Japanese]

[in Japanese]

Article type: Article
1987 Volume 29 Pages 49-50
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_49_2

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[title in Japanese]

[in Japanese]

Article type: Article
1987 Volume 29 Pages 50-
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_50_1

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[title in Japanese]

[in Japanese]

Article type: Article
1987 Volume 29 Pages 50-51
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_50_2

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[title in Japanese]

[in Japanese]

Article type: Article
1987 Volume 29 Pages 51-52
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_51

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[title in Japanese]

[in Japanese]

Article type: Article
1987 Volume 29 Pages 52-53
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_52

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[title in Japanese]

[in Japanese]

Article type: Article
1987 Volume 29 Pages 53-54
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_53

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[title in Japanese]

[in Japanese]

Article type: Article
1987 Volume 29 Pages 54-55
Published: February 01, 1987
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.29.0_54

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