著者

辻 藤吾

出版者

日本土壌肥料學會

雑誌

日本土壌肥料學雜誌 = Journal of the science of soil and manure, Japan (ISSN:00290610)

巻号頁・発行日

vol.71, no.4, pp.464-471, 2000-08-05

参考文献数

7

被引用文献数

1

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Sulfur absorption and critical contents of sulfur in disordered rice plants during their initial growth were investigated. The results obtained were as follows; 1) The total sulfur content of rice shoots which were inhibited at the time of late planting by the application of a paste-like fertilizer showed 0.12% in dry matter. When this growth was recovered by using the same fertilizer as that used by a farmer, sulfur content was raised to as high as 0.28% in dry matter, together with a remarkable increase in dry matter. 2) A similar response was observed for the early planting of rice in a farmer's paddy with enhanced increments of total sulfur, from 0.09 to 0.40% in dry matter, by the application of magnesium sulfate, the major component of the commercial fertilizer. Also, dry matter increments were twice as high as those recovered by the surface drainage. 3) Surprisingly, the yellow stunting of the initial growth disorders were found by the incorporation of a chloride fertilizer into the plow layer as a basal. Such nutritional disorders were restricted during the tillering stages and the total sulfur content of the shoots decreased to as low as 0.13% in dry matter. However, the higher absorption of inorganic sulfate between the maximum tillering stage and young panicle formation period contributed greatly to the recovery of sulfur deficiency in the rice. 4) Total sulfur contents as well as N/S ratios were significantly correlated to the relative yields. These critical levels were 0.12 to 0.13% of total sulfur and 25 to 21 of N/S ratios when the relative yields were 50 to 55%. The levels were considered practical indicies as far as the present growth disorders are concerned.

著者

辻 藤吾

出版者

日本土壌肥料學會

雑誌

日本土壌肥料學雜誌 = Journal of the science of soil and manure, Japan (ISSN:00290610)

巻号頁・発行日

vol.71, no.4, pp.472-479, 2000-08-05

参考文献数

13

被引用文献数

3

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Sulfate transformation under submurged conditions was investigated by the incubation of Submurged soils applied with granular and paste-like high analysis fertilizers. Secondly, soil samples collected from the fixed paddies for the soil fertility survey, both of farmers and experimental stations, were analysed for humus and sulfur. The results obtained were as follows; 1) Paste-like and granular fertilizers were applied in a layer and mixed in the whole layer respectively, followed by the extraction of soluble and available sulfur with appropriate extractants. As a result, both soluble and available sulfur decreased as the Eh of soils decreased, indicating appreciable amounts of sulfate were transformed to sulfide. 2) Five soils of fixed paddies in which the humus contents differed appreciably were selected to check the changes in available sulfur within 15 y. As a result, humus contents showed relative increases within 15 y, however, the content of available sulfur tended to decrease. The ratios of available to total sulfur significantly decreased within 15 y, indicating the influences of soil pH and/or farmers' practices of fertilizer selection upon the ratios. 3) Soil samples, especially of well-drained paddy in an experiment station, decreased the available sulfur within 20 y. It can be concluded that the greater Eh is reduced in the soils, the higher level of sulfide formed, thus the rice plants will become deficient in sulfate due to the formation of unavailable iron sulfides. This will be much enhanced considering the recent trends of lower levels of available sulfur, which coincidentally inhibited the initial growth of rice in early planting cultivation in our district.

著者

辻 藤吾

出版者

日本土壌肥料學會

雑誌

日本土壌肥料學雜誌 = Journal of the science of soil and manure, Japan (ISSN:00290610)

巻号頁・発行日

vol.71, no.4, pp.454-463, 2000-08-05

参考文献数

7

被引用文献数

4

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The author investigated the regional growth disorders of early-planted rice, of which initial growth is severely and peculiarly inhibited, causing yellow stunting of lower leaves and no increase in stem number after approximately 30 to 40 d of transplanting, to paddies supplemented with a basal paste-like fertilizer at the row sides. No specific responses were found among rice varieties. The field experiments and soil analysis of paddies were carried out; firstly to reproduce the disorders in the late planting of rice, and secondly, to diagnose the components of a commercial fertilizer which has been effectively used by a farmer to recover the disorders. The results obtained were as follows; 1) Disordered paddies contained appreciable amounts of ammonium nitrogen in the soil, indicating no effects of nitrogen deficiencies to rice plants. 2) The specific growth disorders of yellow stunting were also found in the late-planted rice cultivation. Furthermore, the application of a granular fertilizer at the row sides showed less growth disorders as compared to the paste-like fertilizer when they were treated in the same experimental paddy. 3) An experiment to separate the farmers practical fertilizer into a few nutrients for diagnosis showed that any nutrient other than sulfate contributed less to recover the disorders. Consequently, in the following early rice planting experiment, in which the growth disorders by paste-like fertilizer were also induced, the application of magnesium sulfate responded well for recovery within several days under a submurged condition, whereas the recovery by surface drainage took more than 10 d. As a conclusion, the author suggests the disorders will be induced primarily by developed soil reduction, hence causing nutritional disorders in rice plants related to temporary sulfate starvation in the soil.