We applied anaerobically digested cattle slurry obtained from a biogas plant to a cabbage field as a nitrogen fertilizer and compared the growth of the cabbage plant and the chemical properties of the soil in the field applied with the digested slurry with those in the field applied with chemical fertilizer. Ammonia in the digested slurry volatilized easily when the digested slurry was applied to the surface of the cabbage field. On the other hand, covering the surface of the field with soils reduced remarkably ammonia volatilization as soon as the digested slurry was applied to the field. We applied two third of the digested slurry for basal fertilizer to the ditches (about 15cm in depth) in the field and covered with soils. One third of the digested slurry was applied to the surface of the field. We did not notice the differences in the growth of the cabbage plant and some chemical properties of the soil such as inorganic nitrogen content, soil pH and available nitrogen content between the digested slurry and chemical fertilizer. We concluded that the digested slurry was available for nitrogen fertilizer instead of chemical fertilizer in the cabbage cultivation.

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In order to gain a basic understanding about the relationships between the vertical distribution of organic carbon content of low specific gravity fraction (mainly consists of charred plants) and the soil age or organic C storage in the soil profile of a cumulative Andisol, Miyakonojo, Miyazaki, Japan, forty four soil samples were successively collected from surface and buried horizons (Ap, A, AC and A/C) of the profile. The oldest horizon studied contains the tephra erupted in 12.8cal ka. (1) Microscopic observation of the fraction less than specific gravity 1.6g cm^<-3>, which was isolated after HCl-HF treatment of the soil samples, indicated that the charred plant fragments, which are black or blackish brown, were the main components in this fraction (<1.6 fraction). (2) The total organic C content of the bulk soil (SOC) and organic C content of the <1.6 fraction (POC), ranging from 19.4 to 117 and from <0.5 to 15.8g kg^<-1> dried bulk soil, respectively, were much higher in the 2A (contains the tephra erupted in A. D. 1235) and 4A (contains the tephras erupted in 6.4 and 4.6cal ka) horizons than in the other horizons. No constant relationships were found between the elapse of soil age and the change of POC or SOC. (3) The POC was highly correlated (r=0.875, significant at 0.1% level) with the SOC. Similar relationship was found between the proportion of the POC to the SOC and the SOC (r=0.802, significant at 0.1% level). The POC/SOC value was 5% or more in 17 samples from a total of 44 soils, with a maximum value of 15.2%. (4) From the findings in the present and previous studies, it was assumed that in Japanese Andisol, charred plants contribute to C storage as one of the constituents of soil organic matter.

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New maximum levels for Cadmium in food crops set by the Codex committee make it all the more important to develop the technologies for reducing cadmium risks in farm land in Japan. The purpose of this study was to investigate the potential of A. halleri ssp. gemmifera for phytoremediation of cadmium in farm land. Two experiments were undertaken. 1) The relation between root volume and cadmium concentration of soil was examined by using cylindrical containers which were filled with soil containing cadmium (2.3mg Cd kg^<-1>) and planted. Half of planted containers were harvested and analyzed to get samples of soil and plants' root after one month cultivation and the other half after two months. After two months cultivation the plants' root volume was seven times greater than after one month. Cadmium amount accumulated in the shoots after two months increased by five-fold above one month. When soil in containers was divided into three parts for detailed analysis, there was a clear negative correlation between root volume and soil cadmium concentrations. 2) Two farmland soils containing cadmium (4.3mg Cd kg^<-1>, 5.0mg Cd kg^<-1>) were placed in pots and plants cultivated five times in each. After the fifth cultivation the cadmium concentration of the soil was reduced by 60-80%. The reduction in cadmium was mostly in the exchangeable fraction extracted by the 1mol L^<-1> MgCl_2. But cadmium levels in the other fractions were also reduced by about 60%. It suggested that this plant might be able to uptake cadmium from the other fractions in soil. The material balance of cadmium in these experiments was equated. This study suggested that A. halleri ssp. gemmifera is a promising plant for phytoremediation of cadmium in farm land.

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This experiment aimed to establish a method for diagnosing nitrogen nutrition using petiole juice in 'Delaware' grapes with heating started from December or January in Japan. The method of sample preparation and the optimum leaf position for the diagnosis of nitrogen nutrition in 'Delaware' grapes were discussed. Pure water was added to petioles sliced into 2 to 5mm lengths, and kept for 24h. The nitrate concentration in supernatant was then measured using a simple reflection photometer system. The optimum leaf positions for measuring nitrate concentration in petiole juice were considered to be the 4th to 6th. The optimum nitrate concentration in the petiole juice at the flowering stage in 'Delaware' grapes cultivated with heating started from December or January in Japan was 200-800mg L^<-1>.

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[in Japanese]

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