The symptom of blighted leaves was observed for the melon plants grown on an isolated soil bed after steam sterilization (SS) in a greenhouse in Kochi Prefecture, Japan. To clarify the causes of this symptom, soil and plant analyses were conducted in the first experiment. Manganese concentrations in the leaves with the symptom were higher than 1000mg kg^<-1> and exchangeable Mn in the soil was higher than 30mg kg^<-1>, which indicated the observed symptom was due to Mn excess. In the second experiment, formation of Mn oxide-dissolving substances after SS was examined for several organic amendments, because large amounts of palm chips had been supplied to the soil before SS in the first experiment. As a treatment similar to SS, palm chips, bark compost, and cattle feces manure were autoclaved. The water extracts were collected before and after the autoclave treatment and the Mn oxide-dissolving capacities of the extracts were evaluated. The Mn oxide-dissolving capacity of the water extracts after SS was remarkably higher than before SS, and the value was highest in palm chips, and followed by bark compost, and cattle feces manure. Fractionation and HPLC analysis of the water extracts after SS revealed that the main substance behind Mn oxide reduction in palm tips was arabinose and that in bark manure was malic acid. Further, Mn oxidedissolving capacities of the water extracts were almost completely explained by the amounts of arabinose or malic acid found in these materials. From these results, it was considered that reducing substances such as arabinose were released by SS from the palm chips which had been applied in large quantity before SS and these reducing substances dissolved the soil Mn oxides and increased the amounts of available Mn, which led to the occurrence of Mn toxicity to the plants.

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We isolated fungi colonizing oat (Avena sativa L.) and eucalyptus (Eucalyptus camaldulensis Dehnh) roots to select the strains that promote the seed germination and seedling growth of cabbage. Twenty-nine strains were inoculated into the soil which grows cabbage seedlings. This inoculation test was repeated three times. From the results of the test, we found that MT0011 and EU0013 strains promoted seed germination. In the first inoculation test, seven strains increased the dry weight of cabbage seedling significantly compared with the control. In the second test with the strains that promoted cabbage growth, MT0008 and EU0013 strains significantly increased the dry weight of seedlings. In the third test, only EU0013 significantly increased seedling growth. The ITS region for DNA (ITS 1-5.8SrDNA-ITS2) of 28 isolated strains were sequenced to examine the molecular phylogeny. Isolates were classified into two divisions, Zygomycota and Ascomycota. Nine strains showed the highest similarities with same accession number AF504832 (Uncultured fungus clone D50). MT0011 was clustered with fungi belonging to Drechela sp. from the sequence data on the rDNA ITS region. EU0013 was identified as Penicillium sp. from the morphological feature conidiophore and the sequence of the ITS region.

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"Kitanokaori" is a new variety of winter wheat (Triticum aestivum L.) for bread use bred at the National Agricultural Research Center for Hokkaido Region. The grain protein content of wheat for bread use should be higher than 120g kg^<-1>. Much nitrogen application is necessary to obtain high grain protein content. Therefore, it is necessary to determine the optimum amount of nitrogen to obtain the required protein content and to prevent nitrogen from remaining in the soil. Field experiments were conducted for four years from sowing in 2000 to study the effect of the amount of nitrogen and the time of top-dressing. In the experiment in which sowing was carried out in 2003, nitrogen treatments were 40, 40-60, 40-60-0-60, 40-60-0-60-30, 40-60-0-60-60, 40-60-60-60, 40-60-60-60-30, 40-60-60-60-60, 40-60-30-30, 40-60-30-30-30 and 40-60-30-30-60 (each value showing the amount of applied nitrogen at sowing-re-growing stage-panicle formation stage-flag leaf stage-full heading stage, kg ha^<-1>). The experiments were conducted in Andosol, which has moderate nitrogen fertility, and in Histosol, which is fertile soil. Kitanokaori did not lodge with high-applied nitrogen, and both yield and protein content increased with an increase in applied nitrogen. In a moderate climate, Kitanokaori reached a protein content of 120g kg^<-1> when the amount of absorbed nitrogen was about 190kg ha^<-1>, and the yield was about 7.8Mg ha^<-1> at that time. The top-dressing at the panicle formation stage was effective to raise the yield and the top-dressing at the full heading stage was effective to raise the grain protein content. It is recommended that the amount of applied nitrogen should be 160kg ha^<-1> until the flag leaf stage, and additional nitrogen should be applied at the full heading stage to obtain a grain protein content of more than 120g kg^<-1>. Nutritional diagnosis at the full heading stage will be necessary to determine whether more nitrogen is needed to achieve the required protein content. When the amount of total applied nitrogen did not exceed 220kg ha^<-1>, the amount of absorbed nitrogen was over 90% of applied nitrogen, and there was little inorganic nitrogen in the soil after harvest. Therefore, it was considered that the residue of nitrogen in the soil was small within 220kg ha^<-1> of nitrogen application, while favorable growth and high yield were obtained.

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Nutrient amounts in livestock manure management, including manure treatment and use, were estimated using published statistical data and other information. The eight categories for manure treatment were defined in this study as : composting at facility, composting at stockyard, raw feces, dried feces, urine, slurry, purification and other. The three categories for use of manure were defined as : application to farmland, sale and exchange and other. The regional daily excretion units per head of dairy and beef cattle, including the amount of excreta, nitrogen (N), phosphorus (P) and potassium (K), were calculated based on the quantities and qualities of feed in each region. There was found to be a difference in the values for Hokkaido and other regions. Concerning manure treatment methods in the dairy sector, the sum of the proportion of raw feces and compost at stockyard was high in Hokkaido. On the other hand, the sum of the proportion of composting at facility and dried feces was high in Hokuriku, Tokai, Kinki and Shikoku. In Kyushu, the proportion of slurry production was higher than in any other region. The amounts of N, P, and K in compost estimated in this study were compared with those calculated from published statistics. The results were as follows : The amounts of N, P, and K in dairy cattle compost, N and K in beef cattle compost, and N in poultry compost in this study were similar to the amounts cited in reported statistics. The amounts of P in beef cattle, swine, and poultry compost in this study were lower than those cited in reported statistics. As for the use of manure, application to farmland is the most common use of manure in the dairy and beef cattle sector. The proportions of purification, and sale and exchange were high for the swine and poultry sectors, respectively. Large amounts of liquid manure, such as urine and slurry, are applied to farmland. To clarify the nutrient load resulting from liquid manure, the usable amount of dairy slurry was calculated based on both the standard application rate of fertilizer and the area of grassland and forage crops. As a result, the amount of usable N was lower than the amount of liquid manure N in the Kanto-Tosan, Tokai and Kinki regions.

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"Kitanokaori" is a new variety of wheat for bread use bred at the National Agricultural Research Center for Hokkaido Region. The grain protein content of wheat for bread use should be higher than 120g kg^<-1>. Much nitrogen application is necessary to obtain high grain protein content. Therefore, it is necessary to determine the optimum amount of nitrogen to obtain the required protein content and to prevent nitrogen from remaining in the soil. The nutrition diagnosis using leaf color was investigated to predict the need and the amount of top-dressing. Field experiments were conducted for four years with nitrogen treatments in Andosol, which has moderate nitrogen fertility, and in Histosol, which is a fertile soil. The leaf color was measured using a chlorophyll meter SPAD502 (CM value) at the middle part of the leaf, avoiding the center rib. The colors of the 10-15 uppermost second leaves were measured in one plot and averaged. A close relation was found between leaf color at the full heading stage and grain protein content at harvest. Leaf color at the full heading stage is therefore a good index to control the protein content. Considering the effect of top-dressing at the full heading stage in each CM value, the diagnosis criterion was decided. When the CM value is over 52 at the full heading stage, more nitrogen application is not needed. When the CM value is 50-52, 30kg N ha^<-1> of top-dressing at the full heading stage is needed, and when the CM value is 45-50, 60kg N ha^<-1> of top-dressing is needed to obtain a grain protein content of more than 120g kg^<-1>.

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The effects of Collembola (Folsomia candida Willem) on nutrient cycling, microbial biomass, and soil respiration were studied using intact soil microcosms. Intact soil microcosms (dia. 10.6cm and depth 15cm) were taken from pine forest soil, and were divided into four treatments : the unmanipulated control and three Collembolan manipulations in which microcosms were defaunated by deep-freezing, and then F. candida were introduced at three densities (0, 50, 100 per microcosm). The microcosms were incubated on forest floor with a roof. At 3- to 4-week intervals the microcosms were irrigated with deionized water for analyses of nutrients (Na^+, K^+, NH_4^+, Ca^<2+>, Mg^<2+>, Cl^-, NO_3^-, SO_4^<2->) in the leachate. Soil respiration was measured using an infrared gas analyser. After 13 and 34 weeks of exposure, microcosms were destructively sampled. Collembola did not significantly affect microbial biomass C, N, and P nor soil respiration. Because the experiment was started in winter, nutrient leaching increased from spring to summer with increasing microbial activity. At the end of the experiment, leached nitrate from microcosms was significantly different between the 0 and 50 Collembolan treatments. Total established Collembolan biomass was under 4% of the soil microbial biomass in the microcosms, while manipulation of Collembola affected soil nitrogen dynamics at high microbial and collembolan activity.

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[in Japanese]

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