Organic amendments are the necessities of sustainable usage of crop land. However, it is not established yet how to evaluate their quality. In this report, the authors evaluated the quality of 11 organic amendments which were sold at local markets around Kyoto City based on their CO_2 evolution rates, chemical analyses, and seedling tests using Komatsuna (Brassica campestris L.). The amendments included composts made of yard trimmings, animal wastes, and food-industry sludge, together with dried chicken manure and rapeseed cake. Chemical analysis (pH, EC and total nitrogen content) indicated that all the composts accorded with the recommended quality standard. Evolution rate of CO_2 for all the materials were recorded up to 20 d. The rates were lower for the compost (0.13 to 1.7mg C evolved per g dry matter per day), and the rates were kept constant up to 20 d. which indicates that those materials were well fermented. In the plant test, an aliquot of the amendment equivalent to 200 mg total nitrogen was applied to 1kg sandy soil in a pot. Under the current dressing rate, none of the amendments inhibited germination, but the plant growth differed from material to material, maybe because of the different amounts of available nitrogen in them. It is concluded that a compost is stable if the CO_2 evolution rate is below 2mg C evolved per g dry matter per day, and that this criterion is applicable to all composts irrespective of the starting materials.

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The barnyard manure produced on a dairy farm (0.78-0.82kg kg^<-1> water content) was stored on a grassland for a period of 82-127d. In order to consider the influence of the difference in the method of manure management on the behavior of fertilizer nutrients from the barnyard manure, two methods of treatment were prepared. One of them was the CM, which involves covering the barnyard manure with a sheet, and the other was the NCM, in which the barnyard manure was not covered with a sheet. The barnyard manure was measured prior to and after storage. Concentrations of N, P, and K were also determined prior to and after storage. In 1999, the amount of the effluent and the concentrations of fertilizer nutrients in the effluent from the barnyard manure were investigated. The following results were obtained : 1) The concentrations of N, P, and K in the barnyard manure were 3.8-6.6g kg^<-1>, 1.5-1.9g kg^<-1>, and 4.0-10.4g kg^<-1> at the end of storage, respectively. As compared with the NCM, the concentrations of N and K in the barnyard manure were observed to be higher in the CM at the end of storage. Furthermore, the difference between the two treatments with respect to the concentration of P in the barnyard manure at the end of storage was negligible. 2) More than half of the nitrogen in the barnyard manure was lost during storage. It was considered that the main cause was not the outflows accompanied by the movement of water, but discharge to the atmosphere by ammonia volatilization and denitrification of the barnyard manure. 3) The rates of disappearance of P and K from the barnyard manure at the end of storage were 7-10%, and 23-47%, respectively. With respect to both the nutrients, the rate of disappearance in the CM was observed to be lower than that in the NCM. Covering the barnyard manure with the sheet considerably reduced the amount of effluent, and was thus very effective in reducing the loss of P and K in the effluent. 4) Based on these results, it was concluded that covering the barnyard manure with a sheet was an effective method with respect to keeping the losses of fertilizer nutrients from the barnyard manure to a minimum, maintaining the fertilizer efficiency of the barnyard manure at a high level, and preventing water pollution caused by the outflow of fertilizer nutrients.

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Denitrification rates in 4 different kinds of soils applied with organic materials were determined together with CO_2 emission rates by the combination of an acetylene inhibition method and an intact core method. The soil types examined were Cumulic Andosols, Low-humic Andosols, Yellow soils, and Gray Lowland soils. The applied organic materials were cattle feces compost and dried hog feces. The application rates of the organic materials were adjusted so that the practical amounts of N supply for the crops were equivalent to chemical fertilizer. The significant results obtained in this study are described below. 1) The denitrification rates were remarkably enhanced by the application of dried hog feces. The rates after 3 days from the application ranged from 0.2-0.5mg N kg^<-1> d^<-1>, and were especially high in Yellow soils and Gray Lowland soils. The results indicated that the significant period for calculating the total amount of denitrification was within 1 month after the application of organic materials. 2) Effect of irrigation on denitrification was experimentally investigated by adding water to the soil cores after 3 days from the application of organic materials. Although the irrigation positively affected both CO_2 emission and denitrification, only denitrification was enhanced by two or three orders of magnitude in the soils amended with dried hog feces. 3) The square roots of denitrification rates were highly correlated with CO_2 emission rates. This suggested that denitrification rates were probably dependent on the amount of denitrifying enzyme in the soil and the development of anoxic conditions, both of which were affected by the decomposition of applied organic materials.

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In order to elucidate the influence of the differences in chemical constituents of cow manure on dry matter production of timothy (Phleum pratense L.) in a field experiment, 17 different types of manure collected from dairy farms in Konsen district, Hokkaido, were applied to grassland surface. The range of water and total nitrogen (N) contents in the cow manure was 0.53 to 0.83 kg kg^<-1>, and 2.88 to 5.38g kg^<-1>, respectively, on a fresh weight basis. The application rate of the cow manure was 40 Mg ha^<-1>. 1. Grass yield in the cow manure treatments was higher than that in the non-manure treatment. Although the application rate of the cow manure was the same, great differences were found in the grass yield among the manure treatments. 2. Great differences were found in the recovery rate of N from the timothy grassland when cow manure was applied. It was thought that the fertilizer efficiency of cow manure applied to timothy grassland fluctuated depending on the difference in the chemical constituent of cow manure. 3. It was possible to evaluate the potentially mineralizable N in the cow manure from the water content of cow manure. 4. From these results, the N efficiency of cow manure applied to timothy grassland can be evaluated by multiplying the total N content of the cow manure by the N mineralization rate.

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A technique for reducing fertilizer application while maintaining harvest by top-dressing based on nitrate diagnosis of petiole sap in the semi-forced cultivation of tomatoes was demonstrated at farmers' greenhouses where soil conditions and fertilizer application practices were different. Petiole sap from leaves beneath fruit which was 2-4 cm was measured for nitrate concentration and top-dressing based on nitrate diagnosis was applied when the nitrate concentration fell below 2000 mg L^<-1>. Top-dressing based on nitrate diagnosis could be maintained at 1000-2000 mg L^<-1> during the harvest time when the nitrate concentration of tomato petiole sap decreased to the minimum under these conditions and harvests equivalent to those obtained by top dressing conventionally applied by the farmers were secured. The amounts of top-dressed nitrogen ranged from 0-50% of those conventionally applied by the farmers. In addition, soil nitrate after cultivation with top-dressing based on nitrate diagnoses decreased considerably from that with top dressing conventionally applied by the farmers. Soil nitrogen was thought to be utilized effectively. Both a simple reflection photometer and nitrate test strips were used for the measurement of the nitrate concentration of tomato petiole sap. The nitrate test strips were considered practical because they were easy to handle in the field and low in price.

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[in Japanese]

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