Effect of Rice Hull Application on Vegetable Soybean Growth, Yield and Quality in Upland Field Converted from a Paddy Field
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- スイデン テンカンバタ ニ オケル モミガラシヨウ ガ エダマメ ノ セイイク シュウリョウ オヨビ ヒンシツ ニ アタエル コウカ
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We tried to improve the soil physical conditions of a clayey upland field converted from a drained paddy field by the application of rice hulls. Nitrogen starvation occurred with rice hull application due to the high C/N ratio. Vegetable soybean is able to grow under N starvation conditions because of N_2 fixing activity. Rice hulls (2kg m^<-2> or 4 kg m^<-2>) were applied in 1997, and vegetable soybean was cultivated in 1997 and 1998. 1) As a result of a soil incubation examination, in the first year, 20 mg N kg^<-1> and 48 mg N kg^<-1> were immobilized with rice hull treatments of 2 kg m^<-2> and 4 kg m^<-2>, respectively. In the second year, 8 mg N kg^<-1> and 22 mg N kg^<-1> were immobilized. 2) With the immobilization of N in the rice hull treatment of 2 kg m^<-2>, it was possible to correspond by increasing the amount of fertilizer-N (3 g m^<-2>). However, in the 4 kg m^<-2> rice hull application treatment, fertilizer-N must be increased more. 3) Analysis of the field soil and bleeding xylem sap indicated that the soil NH_<4->N/NO_<3->N ratio was high, while the NO_<3->N amount was low in the xylem sap from the rice hull plot. A large quantity of ureide-N in xylem sap was detected in the plants of the rice hull plot, which suggests the promotion of N_2 fixation in rice hull treatment. 4) The rice hull treatment increased the yield more than conventional treatment. Especially, when basal fertilizer-N was increased, the degree of yield increase became high. The yield increase was due to an increase in the number of pods per node. The factor was related to N_2 fixation activity during the flowering stage. 5) The sugar and free amino acid concentrations in the seed, which are related to taste, didn't have a consistent relationship between the rice hull and fertilizer-N treatments. But it was clear that when vegetative growth was suppressed and yield decreased, the taste became bad. In conclusion, rice hull application affected the growth and yield of vegetable soybean. The problem of nitrogen starvation after the rice hull application could be alleviated by increasing fertilizer-N. Moreover, the rice hull treatment increased the N_2 fixation activity of root nodules and increased the yield.
- Japanese Journal of Soil Science and Plant Nutrition
Japanese Journal of Soil Science and Plant Nutrition 71 (6), 801-808, 2000
Japanese Society of Soil Science and Plant Nutrition