Development of crop management techniques for higher yield by optimun control of root zone environment

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1. Guidance of management technique for upland crops through direct diagnosis of root-zoneIn Canada, direct testing of the nutrient situation of each farm are made administratively by having recognized the importance of knowing fertilizer requirements of the crop physically and chemically. For example, the province of Saskatchewan established Soil Testing Laboratory with many professional staffs and modern experimental equipments in the campus of the Saskatchewan University. They lead farmers the most optimun design of fertilizing method to each field through the direct testing. They recommend sampling procedures as follows.Recommendations for nitrogen and sulphur fertilization are based on the measured levels of nitrate-nitrogen and sulpate-sulpur in the soil samples submitted from each field. Testing samples from the 0-6, 6-12, and 12-24 inch depths results in a more accurate assesment of the N and S status of the soil than testing of the surface, soil only.The Lovoratory has a netwo … More rk of soil sampling agents. About thermal situation of field, however, they have no services, becauseof land using type farming and vast area of fields.2. Assesment of thermal enviroment of root-zone and diagnosis of frozen layer and snow depth of fieldsIn the northern region of the Great Praily in the United States, crop season depend on the period of accumulation of snow and ups and downs of frozen layer. The climatologists of the department of soil science of the University study on these problems and developed a special but a simple measuring scale for frozen layer and snow depth using chemical substances. They measure climatic and micro meteorological conditions, and analyzed them with the heat-balance method to assesment of thermal environment of root-zone in fields.3. As a first experiment, the optimum physicoenvirommental conditions of a root zone are a for the photosynthesis, growth and quality of fruits in cultivation of strawberry were analyzed by physical control of the soil moisture, soil temperature and other factors at the root zone area during the period of growth, while utilizing the physioecological properties intrinsic to the plant, in an experimental greenhouse strawberry field. The results of experimental cultivation of strawberry over four years from 1986 may be summarized in terms of the relation between the environmental elements at the root zone area and the growth of strawberry as (1) the number of fruits increases by controlling the soil moisture to a dry condition and the weight increases by controlling it to a moist condition, (2) the optimum soil moisture for increasing the total crop weight corresponds to a water content of approximately 30.0% and (3) the sugar content in fruits can be best obtained by maintaining the soil temperature at a high level (until about 28ﾟC) and by cotrolling the soil moisture at a water content of approximately 35.0%, when cultivated using standard fertilization as a nutrient in the soil. Less