In this study, the agricultural utilization of coffee grounds was examined. The results were as follows. 1. The application of coffee grounds in soils inhibited the seedling growth of Chinese mustard. From experiments on nitrogen and toxic substance alleviation, it was suggested that this inhibition is rcsultant of nitrogen starvation and the existence of toxic substances. However, in the summer, when 2.5kg m^<-2> of coffee grounds was applied together with nitrogen fertilizer at 15 to 20g m<-2>, the coffee grounds didn't inhibit the seedling growth of Chinese mustaard with a maturing period of more than one month. 2. When more than 10 kg m<-20> of coffee grounds was applied into soil, the aggregated structure of soil was developed.

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The composting conditions of coffee grounds were examined. The results were as follows 1. Only coffee grounds piled in an outdoors environment for six months inhibited the root growth of Chinese mustard. 2. In the case of composting mixed with bark, it was necessary for the capacity ratio of coffee grounds to be below 30%, the content of chicken droppings and urea were 25g kg<-1> and 5g kg<-1>, respectively, and the composting period was more than three months.

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At the Bibai peatlands in Hokkaido, Japan, the decomposition of peat is enhanced due to the drying tendency of the Peatland. Accordingly, the Sasa senanensis community invades the Sphagnum colmmunity, whose area is diminishing rapidly. Peat samples were collected from this area on a transect line which passed through the original Sphagnum community as well as that of the jnvading Sasa community. This paper aimed to clarify the effect of the change in vegetation as well as the decomposition of peat on the composition of fatty acids and sterols in peat. The total yield of fatty acid in the more decomposed (<2 mm) fraction was larger than that in the less decomposed (>2 mm) fraction. It was also remarkably larger at sites where the decomposition of peat was enhanced. The distribution of fatty acids in peat was bimodal, peaking at palmitic acid and at cerotic acid. Results of regression analysis and principal component analysis also suggests that fatty acids with chain lengths shorter than 18 and longer than 20 behave differentry. Among individual fatty acids, the yields of palmitic acid and arachidic acid were larger at sites covered densely with Sasa senanensis. Yield of stearic acid and cerotic acid, on the other hand, tended to be larger at sites where the vegetation of Sphanum was preserved. Yields of fatty acids with a chain Iength longer than 24 were remarkably higher at sites where the decomposition of peat was enhanced due to the lowering of the water table. As for sterols, β-sitosterol, campesterol, stigma-sterol and cholesterol were detected in peat samples. Sterols except cholesterol were considered to originate from plants, and more abundant in the >2 mm fraction than in the <2 mm fraction as well as at sites with denser Sasa senanensis vegetation than Sphagnum vegetation. Cholesterol, on the other hand, was considered to originate from the soil biota which decompose plant residues, and was contained in larger amounts in the <2 mm fraction than in the >2 mm fraction.

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Allophane and imogolite are frequently found as main clay components in soils developed on pyroclastic materials such as volcanic ash and pumice. The relative contents of both components are different between soils, but genetic factors affecting the relative contents are not clear. Thes Study was conducted in an attempt to analyze the factors by means of a model experiment and the molecular orbital method. A mixture of aluminum chloride and orthosilicic acid solution (Si/Al=1:2) was titrated with sodium hydroxide solution for preparing a solution having an OH/Al ratio of 2:1 Various amounts of metal ions (Na, K, Ca, Mg) were added to the solution as chloride, and heated at 90 ℃ for 110 h. The main reaction product in the solution without adding the metal ions was imogolite. The amount of imogolite in the reaction products decreased as the concentration of metal ions was increased. However, allophane was found as a product when metal ions were added, and its amount increased as the concentration of metal ions was increased. The effects of metal ions on inhibiting imogolite formation and on facilitating allophane formation were great in the following order : Na, K < Ca, Mg. These metal ions affect dissociation of the silanol group of orthosilicic acid. The higher the concentration of metal ions, the greater the dissociation. The degree of dissociation is higher by alkaline earth-metal ions than by alkali metal ions under the same ion charge concentration. This indicates that the dissociation or non-dissociation of orthosilicic acid causes differential formations of imogolite and allophane. Molecular orbital calculation (ab initio) proved that non-dissociated orthosilicic acid induces the formation of imogolite with tubular morphology because this form of acid is asymmetrical in molecular configuration. The calculation, on the other hand, showed that dissociated orthosilicic acid gives rise to the formation of allophane with hollow spherical morphology because of the symmetrical configuration of the acid.

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Three varieties of paddy rice, "Musashikogane", "Asanohikari" and "Yumeminori", transplanted late in May, were cultivated an under no-nitrogen condition. The relation between quantily of soil niLrogen absorption and accumulated value of mean air temperature (accumulated temperature) was applied to a logistics curve and the process of soil rlitrogen absorption by paddy rice was quantitatively analyzed. 1) For all three varielies of paddy rice, Musashikogane, Asanohikari and Yumcminori, the actually measured values agreed well with the equation of Soil nitrogen absorption quantity estimated by accumulated temperature, which was applied to the three-dimensional λ-type logistic curve. Hence. it was concluded that this equation accurately expressed the actual soil nitrogen absorbing process. 2) The quantity of Soil nitrogen absorption by paddy rice increased exponentially till the accumulated temperature reached 920℃ for Musashikogane and 1020℃ for Asanohikari and Yumeminori, and then gradually increased. 3) The quantity of soil nitrogen absorption by paddy rice from the time of transplanting to maturing stage estimated by the accumulated temperature of the normal value was 74 kg ha^<-1> for Musashikogane, 79 kg ha^<-1> for Asanohikari and 72 kg ha^<-1> for Yumeminori. 4) The ratio of soil nitrogen absorption by paddy rice among maximum tillering stage, panicle formation stage and heading time estimated by the accumulated temporature of the normal value was 33% till the maximum tillering stage, 61% till the panicle formation stage and 77% till the heading time for Musashikogane. In the same way, for Asanohikari the ratios were 30%, 61% and 82%, respectively, and for Yumeminori 31%, 64% and 80%, respectively. 5) The quantity of soil nitrogen absorption by paddy rice per day estimated by the accumulated temperature of the normal value peaked at the time of maximum tillering stage. It was on the 39th d before heading time for Musashikogane, 35th d for Asanohikari and 41st d for Yumeminori. After the maximum tillering stage, it decreased gradually till the heading time, but the rate of decrease was smaller after the heading time.

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In order to analyze the microbial biomass and community structure in soil, we investigated the amounts and Composition of phospholipid fatty acids which had been annually applied with rice straw compost (0, 20, 40, 80 Mg ha^<-1>) and extracted from the upland light colored andosol of experimental plots. The phospholipid content increased with increasing compost application levels. The major fatty acids were 16 : 0, 18 : 0, 18 : 1 ω 7, 18 :1 ω 9, 18 : 1 ω 5, 16 : 1 ω 7, 16 : 1 ω 5, 16 : 1 ω 9, i17 : 1 ω 8, p11-19 : 1, 20 : 1, 18 : 2 ω 6, 20 : 4, 17 : 0cyc, 19 : 0cyc, p10 17 : 0, i15 : 0, a15 : 0, i16 : 0, i17 : 0, a17 : 0, p10-19 : 0 and24 : 0 2OH. The phospholipid fatty acid composition indicated that the main origin of the soil phospholipids was bacterial membrane iipids. The proportion of the branched chain fatty acids heightened as amount of applied compost was increased. Their proportions in solis in March and April were lower than in October and December, however, the proportions of cyclopropane fatty acids, 16 : 1 ω 7 and 18 : 1 ω 7, in soils in March and April were higher than in October and December. These results suggest that the ratio of Gram-positive bacteria to Gram-negative bacteria increased under cultivation of wheat. The phospholipid fatty acid content was closely correlated with thc available N ; the amount of N mineralized during four weeks of incubation at 25 ℃. Correlation coefficients between available N and soil content of fatty acids were 0.94 for i15 : 0, 0.93 for p10-17 : 0, 0.90 for p10-19 : 0, 0.76 for 16 : 0, 0.70 for 18 : 2 ω 6 and 0.64 for 18 : 1 ω 7. There were also significant correlations belween the counts of bacteria by microscopical method and phospholipid fatty acid content. Thc proportion derived from soil microbial biomass seemed to be high in soil phospholipid because 23-41% of the Soil phospholipid content declined after chloroform fumigation. The size of biomass based on phosptolipid fatty acid analyses was higher than the size based on microscopical counts and lower or higher than the size based on fumigation-incubation, depending on the conversion factors.

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In order to analyze soil microbial biomass and community structure, we investigated the amounts and composition of phospholipid fatty acids extracted from four different types of upland soils. The contents of phospholipid fatty acid of aoil were higher in the order of Humic Andosol ≒ Light Colored Andosol > Gray Lowland soil > Red soil. In light colored Andosol and Gray Lowland soil, phospholipid fatty acid content in soil of the 20-30 cm depth layer was lower than in the 0-10 and 10-20 cm depth soil layers. The major fatty acids in four types of soil were 16 : 0, 18 : 0, 18 : 1 ω 7, 18 : 1 ω 9, 18 : 1 ω 5, 16 : 1 ω 7, 16 : 1 ω 5, 16 : 1 ω 9, i17 : 1 ω 8, p11-19 : 1, 20 : 1, 18 : 2 ω 6, 20 : 4, 17 : 0cyc, 19 : 0cyc, p10 17 : 0, i15 : 0, a15 : 0,i16 : 0, i17 : 0, a17 : 0, p10-19 : 0 and 2OH-24 : 0. The phospholipid fatty acid composition indicated that the origin of the soil phospholipids was bacterial membrane lipids. The proportion of the branched chain fatty acids in the 20-30 cm depth soil layer was lower than that in 0-10 and 10-20 cm depth soil layers, indicating that the ratio of Gram-positive bacteria to Gramnegative bactcria would be higher in the 20-30 cm layer than in the 0-10 cm and 10-20 cm layers. An anaiysis of variance tests showed a significant change in the proportion of 18 : 1 ω 7, 16 : 0, i15 : 0, p11-19 : 1, p10-19 : 0, 18 : 2 ω 6 (seasonal change) and p10-17 : 0, a15 : 0, 16 : 1 ω 7, 18 : 1 ω 9, 17 : 0cyc, 19 : 0cyc (soil types). In the principal components using a principal component analysis of the compositions of phospholipid fatty acid, the total cumulative variance was retained as 67.0%. The data to distinguish seasonal changes werer present in the first principal component and the data to distinguish each soil type existed in the second principal component. A cluster analysis classified the composition of phospholipid fatty acid as to groups of soils sampled in February 1997 and other soils.

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The growth and photosynthetic responses of 2-year-old seedlings of red pine (Pinus densiflora SIEB. et ZUCC. ) grown in brown forest soil originating from granite acidified by adding H_2SO_4 solution were investigated. The seedlings were grown in a greenhouse for 120 d from May 10 to September 7, 1996. The pH level was reduced, and the concentration of Al in the soil solution increased as the amount of H^+ added as H_2SO_4 solution was increased in the soil. The dry weight growth of the seedlings reduced as the amount of H^+ added to the soil was increased. There was a highly positive correlation between the dry weight growth of the seedlings grown in the acidified soil and the molar (Ca+Mg+K) / Al ratio in the soil solution. The net photosynthetic rate of the seedlings grown in the acidified soil declined as the amount of H^+ in the soil increased. In the seedlings grown in acidified soil, the quailtum yield and carboxylation efficiency of photosynthesis decreased, which suggests that soil acidification induced an inhibition of photochemical reactions of photosynthesis and a reduction in the activity and / or amount of Rubisco.

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The responses of soybean (cv. T202) to Vesicular-Arbuscular Mycorrhizal Fungus (VAMF ; Glomus elunicatum) under 3 different phosphorus application levels (P_1, 100 mg P ; P_5, 500 mg P ; P_<30>, 3000 mg P/2×10^<-4> a pot, 2.3 kg air dry Soil) in an Andosoil (Bray II-P < 0.1 μg g^<-1>ds. ) weere examined in regards to growth, VAM formation, acetylene reduction activity (ARA), N accumulation and P absorption at the growth stages of initial flowering, milk-ripening and maturing. Positive effects of VAMF infection on growth, P and N accumulation, and ARA were obtained, especially in the earlier growth stage, corresponding to the level of VAMF infection rates and infected root lengths which were higher in lower P applications (P_1, & P_5). In the initial flowering stage, significant stimulations of ARA and P accumulation in nodules were observed due to VAMF infection at lower P application levels (P_1, P_5), resulting in earlier N accumulation in pod-grain at the milk-ripening stage, however, accompanying steep decreases in ARA and nodule P concentrations at this stage as compared to non-VAMF treatment. Even under the 50% cut-off of light by shading from just before milk-ripening to the maturing stage, positive effects of VAMF on growth and N and P accumulations were found. Under the high-P application level (P_<30>), VAMF infection affected soybean growth negatively in the milk-ripening stage, whereas in the final maturing stage, it brought about stimulative effects on drymatter production and N and P accumulations in pod-grain through maintaining ARA activity, maybe due to unknown factors except the improvement of P nutrition.

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