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Article type: Cover
2004 Volume 75 Issue 2 Pages
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Article type: Appendix
2004 Volume 75 Issue 2 Pages
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Article type: Appendix
2004 Volume 75 Issue 2 Pages
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Article type: Index
2004 Volume 75 Issue 2 Pages
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Article type: Index
2004 Volume 75 Issue 2 Pages
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Takuhito Nozoe, Reynaldo Rodriguez, Ruth Agbisit
Article type: Article
2004 Volume 75 Issue 2 Pages
161-167
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In an experiment in rice cultivation at the International Rice Research Institute (IRRI), waterlogging in the field during the fallow season suppressed the growth of paddy rice especially in the early stage of subsequent cultivation. This symptom became more prominent when the field was waterlogged during the previous fallow season, no rice straw was applied, and the amount of applied fertilizer was small. This growth suppression, which was observed both in wet and dry seasons, was reduced by the application of the mixture of nitrogen, phosphorus and potassium fertilizer. The amount of phosphorous in the suppressed rice was smaller than that in rice without suppression. Those findings suggest that one of the factors that suppress the rice growth might be the deficiency of pho.sphorus in rice. The growth suppression was associated with high soil pH. The small Fe(II) content of soil was attributed to the high soil pH because there was negative correlation between soil pH and Fe(II) content. Namely, the waterlogging during the fallow season decreased the amount of Fe(II) in the soil because Fe(II) was oxidized to Fe(III) under an oxidative condition. During the subsequent cultivation season, this low Fe(II) content in soil kept the soil pH high. The application of rice straw improved the rice growth because of the decrease in soil pH. The production of CO_2, which was generated as the terminal product of straw decomposition, presumably decreased the pH.
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Takashi Wakamatsu, Akira Takahashi, Kazuo Sato, Takashi Kuboi, Hideaki ...
Article type: Article
2004 Volume 75 Issue 2 Pages
169-178
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The stable isotope ^<15>N was applied as ^<15>NH_4Cl to the forest floor of a 50-year-old Japanese red pine (Pinus densiflora) forest in Gunma Prefecture, to investigate the behavior of atmospheric ammonium in the soil. The ^<15>N pulse was monitored for 70 d by measuring δ^<15>N values of understory vegetation, organic soil, mineral soil and soil solution within a rooting zone (40 cm depth). The gross rates of nitrogen mineralization, immobilization, and nitrification in the soils were also measured using the ^<15>N dilution technique, to determine the relationship between the ^<15>N behavior and nitrogen turnover through microbial biomass. After 30 d, understory vegetation assimilated only 5% of the ^<15>N added. The remaining ^<15>N was retained in the organic horizon (56%) and mineral soil (44%). Even after 70 d, the organic horizon retained 37% of the ^<15>N added. The majority (95%) of the total nitrogen that leached from the organic horizon to the mineral soil was nitrate. During 30 d after ^<15>NH_4^+ addition, δ^<15>N values of nitrate increased markedly in the surface mineral soil (10 cm depth). After that, the peak of δ^<15>N values was observed in the deeper soil (40 cm depth). These results indicate that atmospheric ammonium leaches to the mineral soil after being nitrified in the organic horizon. The ammonium production and immobilization rates (145 mg N kg^<-1> d^<-1>) in the organic soil were 7-fold higher than the gross nitrification rate (20 mg N kg^<-1> d^<-1>). This suggests that microbial immobilization plays an important role in the retention of ^<15>N in the organic horizon. The rates of nitrogen transformations observed in this study were approximately 10-fold higher than those in Dutch forests, where atmospheric inputs of nitrogen have been almost equal to those in the site of this study. The rapid nitrogen turnover at this site may be attributed to higher air temperature and precipitation, and to lower soil acidity.
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Akiyoshi Saeki, Hisashi Shimogaki
Article type: Article
2004 Volume 75 Issue 2 Pages
179-184
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Molybdenum (Mo) is one of the monitored substances and recognized nutrient elements considered to be essential for the growth of plants and causes molybdenum (Mo)-induced copper (Cu) deficiency in ruminant animals. Furthermore, it is suggested that various kinds of coal fly ash from coal-fired electric power plants contain small amounts of Mo as trace elements, most solutions in contact with coal fly ash exhibit high pH, and the pH of the eluent is gradually lowering with permeation into soil layers. However, the effects of lowering pH in alkaline water-on adsorption characteristics of Mo have not been sufficiently investigated. The purpose of this study is to clarify the adsorption characteristics of Mo on typical soils in Japan and the effects of soil organic matter on the elimination of Mo from solution. The adsorption experiments were carried out under aerobic conditions and room temperatures of 22±3℃. The adsorption characteristics of Mo on various soils were investigated as a function of solution pH, Mo concentration and soil organic matter using batch experiments. The obtained results are summarized as follows: 1) Adsorption characteristics: The range of solution pH in which Mo was capable of being adsorbed on various soils exhibited about pH 4 to 7; it did not sufficiently exhibit at high pH of 8 to 12, because the magnitude of Mo adsorbed on various soils was dependent on the soil solution pH, the existence of Mo species in solution and the electric charge of the soil particle surface. 2) Incorporation of Mo into soil organic matter: The organic matter was dissolved from soil matrix when allowed to stand in contact with an alkaline solution. Dissolved organic matter precipitated as a dark brown crystalline solid with acidification of dilution and most of the dissolved Mo was ultimately incorporated into the organic precipitation.
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Yoshihiro Kaneta, Takashi Sato, Noritoshi Furuta, Midori Ikuno, Hitomi ...
Article type: Article
2004 Volume 75 Issue 2 Pages
185-190
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We investigated the effect of soil moisture in heavy soils of upland fields (UF) and upland fields converted from paddy fields (UCPF) on soybean rhizosphere activities. The soybean rhizosphere activities were based on the nitrogen fixation activity and nitrogen absorption activity by analysis of ureides, nitrate and amino acids in the xylem sap. The oxidized soil layer in the UCPF was thicker than that in the UF. At a 40 cm depth in the UCPF, soil structure developed a little. The soil-moisture below a depth of 20 cm after rainfall in the UCPF was greater than that in the UF. The dryness was progressing to the subsoil in the UF compared with that in the UCPF. The daily range of soil moisture tension at a 10 cm depth in the UCPF was low compared with that in the UF. The soil moisture in the UF increased in nighttime and decreased in daytime. Soil monoliths, 30 cm in width, 5 cm in thickness and 30 cm in depth, were sampled for root length density. Soybean in the UCPF had a smaller root length density of 0-20 cm in the depth layer than that in the UF. The nitrogen fixation activity and nitrogen absorption activity at the flowering time in the UCPF were remarkably lower in the UF. Seed yield in the UCPF was 1-2% smaller than that in the UF. The higher yield in the UF was mainly due to the increase in the 100-seed weight.
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Eiji Goto, Yasuo Miyamori, Susumu Hasegawa, Osamu Inatsu
Article type: Article
2004 Volume 75 Issue 2 Pages
191-201
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We investigated influences of timing in applying rice straw, application of different kinds of decompositional accelerators with nitrogen fertilizers, and intermittent irrigation on methane emission from paddy soil in Hokkaido Kamikawa Agric. Exp. Stn. (Brown Lowland soil). .Further, we aimed at reduction, by combining them. Results are as follows. 1) Decomposition of rice straw progressed in incubation at a low temperature (5℃), and accelerated with application of decompositional accelerators with nitrogen fertilizers. 2) Decomposition rates of rice straw mixed in soil at 0-8 cm were higher than that left on the soil surface from fall to the beginning of the next rice cultivation. Furthermore, the combination of application of decompositional accelerators and nitrogen fertilizers accelerated the rates. 3) Methane emission rates were decreased by intermittent irrigation either before the panicle formation stage or after the heading period. Intermittent irrigation that decreased soil moisture above pF 1.8 before the panicle formation stage, in particular, substantially decreased methane emission, which was as effective as midsummer drainage. 4) The combination of intermittent irrigation during the rice cultivation period and application of a decompositional accelerator with nitrogen fertilizer after the harvest of rice decreased methane emission, as compared with the case of leaving rice straw on the soil surface during the winter and continuous irrigation during the rice cultivation period. These results suggested that the above cultivation management (combining rice straw mixed in soil and application of decompositional accelerator in fall, and intermittent irrigation), was effective for mitigating methane emission from paddy fields in a cold district.
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Masanao Uchitsu, Tadashi Yokoyama, Toshihumi Murakami
Article type: Article
2004 Volume 75 Issue 2 Pages
203-210
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Clubroot caused by Plasmodiophora brassicae is one of the most severe diseases of Chinese cabbage in Nagano, Japan. The fungi are classified into several races based on host-parasite relationships. However, determination of the race of P. brassicae isolated from an individual clubroot requires several time-consuming steps such as a cross-inoculation test using several host plants. Genetic diversity among races in P. brassicae is not understood well. In this study, to understand whether phylogenetic relatedness of Japanese isolates of P. brassicae is directly reflected in differences of host specificity among those isolates, we compared the nucleotide sequence of 18S, 5.8S and the ITS region of the rRNA of ingenous isolates of P. brassicae obtained from Nagano Prefecture with those of several strains obtained from the United States and England. Most of the nucleotide sequence of the ITS region of 7 fungal isolates and the partial nucleotide sequence of the 18S rDNA region of 5 fungal isolates were sequenced. The nucleotide sequence of 18S rDNA did not show clear differences among 5 fungal isolates. However, 18S rRNA sequences of P. brassicae (U18981) of the United States were remote from those of Nagano isolates. The nucleotide sequences of the ITS region of 7 Nagano isolates were similar to those of P. brassicae isolated from Australia, England and Korea. Therefore, we found no relationship between phylogenetic relatedness of the ITS region and host specificity of Nagano isolates. However concerning the 5.8S rDNA region, phylogenetic differences based on sequences of 5.8S could distinguish race 9 and 4 isolates from race 8 and 16 isolates classified by the Williams methods.
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Akitoshi Yokoyama, Yuichi Saeki, Keiko Oguchi, Yoshitaka Nagatomo, Hir ...
Article type: Article
2004 Volume 75 Issue 2 Pages
211-216
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Auxin is known to promote rooting of crops. However, it is not known whether the function of auxin could be enhanced by the addition of zinc. In this study, we examined the effect of zinc on the auxin-induced rooting of rice. The results were summarized as follows: 1. There was no significant effect of zinc on the shoot and root weight of rice without application of auxin. 2. When auxin was applied at 0.1 mg L^<-1>, the rooting of rice was increased with the addition of zinc until 36 mg L^<-1>. 3. Application of 0.3 mg L^<-1> auxin induced callus formation rather than rooting of rice. 4. These results indicate that the increased rooting of rice could be attributed to the interaction effect of auxin and zinc and not due to other indole compounds and counter ions of zinc.
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Michio Komada, Makoto Takeuchi
Article type: Article
2004 Volume 75 Issue 2 Pages
217-221
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Masayuki Hara, Yukio Furuichi, Hitoshi Obata
Article type: Article
2004 Volume 75 Issue 2 Pages
223-227
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Naoya Chishaki, Shunji Inanaga
Article type: Article
2004 Volume 75 Issue 2 Pages
229-231
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Keiichi Murakami, Itsuo Goto
Article type: Article
2004 Volume 75 Issue 2 Pages
233-235
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Akifumi Murase, Toshiro Fujiwara, Takafumi Ogushi, Koyo Yonebayashi
Article type: Article
2004 Volume 75 Issue 2 Pages
237-240
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Takayuki Fujiwara, Masayuki Hara, Keiichi Murakami
Article type: Article
2004 Volume 75 Issue 2 Pages
241-245
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Shigekazu Nakamura, Yasuhide Mochizuki
Article type: Article
2004 Volume 75 Issue 2 Pages
247-249
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Kazunori Shirai, Tsunehisa Inoue, Masahiro Imagawa, Ryozo Yamada
Article type: Article
2004 Volume 75 Issue 2 Pages
251-256
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Toshihiko Tanahashi, Hideji Yano
Article type: Article
2004 Volume 75 Issue 2 Pages
257-260
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Emiko Okubo, Tadashi Ono
Article type: Article
2004 Volume 75 Issue 2 Pages
261-264
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Satoshi Nakatsu, Syuji Higashida, Akihiro Sawazaki
Article type: Article
2004 Volume 75 Issue 2 Pages
265-268
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Masaru Kobayashi, Toru Fujiwara
Article type: Article
2004 Volume 75 Issue 2 Pages
269-274
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Shin-ichiro Mishima, Makoto Matsumori, Tsunehisa Inoue
Article type: Article
2004 Volume 75 Issue 2 Pages
275-281
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Ryusuke Hatano, Kazuyuki Inubushi
Article type: Article
2004 Volume 75 Issue 2 Pages
283-284
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Takuji Sawamoto
Article type: Article
2004 Volume 75 Issue 2 Pages
284-285
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Yasuto Shirato
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2004 Volume 75 Issue 2 Pages
285-286
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Osamu Nakahara
Article type: Article
2004 Volume 75 Issue 2 Pages
286-287
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Kenji Matsumori
Article type: Article
2004 Volume 75 Issue 2 Pages
287-289
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Katsutoshi Taki
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2004 Volume 75 Issue 2 Pages
291-292
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Keiichi Mogaki
Article type: Article
2004 Volume 75 Issue 2 Pages
293-294
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Tsutomu Hattori
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2004 Volume 75 Issue 2 Pages
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Article type: Article
2004 Volume 75 Issue 2 Pages
297-302
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[in Japanese]
Article type: Article
2004 Volume 75 Issue 2 Pages
302-
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Article type: Appendix
2004 Volume 75 Issue 2 Pages
303-304
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2004 Volume 75 Issue 2 Pages
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[in Japanese]
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2004 Volume 75 Issue 2 Pages
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Article type: Appendix
2004 Volume 75 Issue 2 Pages
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2004 Volume 75 Issue 2 Pages
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2004 Volume 75 Issue 2 Pages
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2004 Volume 75 Issue 2 Pages
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Article type: Appendix
2004 Volume 75 Issue 2 Pages
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2004 Volume 75 Issue 2 Pages
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Article type: Cover
2004 Volume 75 Issue 2 Pages
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2004 Volume 75 Issue 2 Pages
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