EASILY DECOMPOSABLE ORGANIC MATTER IN PADDY SOILS : VII. Effect Of Various Pretreatments on N-Mineralization in Submerged Soils
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概要
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Three soils were subjected to 8 pretreatments including air-drying, oven-drying, freeze-drying, and extraction with organic solvents. These pretreated soils and untreated moist soils were incubated at 30℃ under submerged conditions. Time course of N-mineralization was markedly affected by the pretreatments. However, N-mineralization of all the soils could be expressed by a mathematical equation reported previously : N=N_<oq>[1-exp(-K_q・t)]+N_<os>[1-exp(-K_s・t)] where N is the amount of mineralized N during t weeks of incubation, N_o is the maximum amount of mineralizable N and K is the rate constant, although these parameters varied widely among the soils examined. This fact suggests that the effect of the pretreatments can be expressed by the changes of the parameters. It was found that N_<oq> =M-s・N_<oq>, where M was the constant for each soil and s amounted to about 0.79-0.86. In the various soil pretreatments, N_<oq> was closely related to the amount of water-soluble carbohydrates which were extracted from the soils before the incubation. Eleven kinds of soils, both moist and air-dried, were incubated at 20, 30, and 40 under submerged conditions for 12 weeks. Effect of air-drying pretreatment on N_<oq> and N_<os> was found to depend on the incubation temperature ; a high incubation temperature was associated with a linear relationship. A conceptional model was proposed to explain the effects of pretreatments and incubation temperature on N_<oq> and N_<os>.
- 社団法人日本土壌肥料学会の論文
著者
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Wada Hidenori
Faculty Of Agriculture The University Of Tokyo
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Ishibashi Kazuyuki
Faculty Of Agriculture The University Of Tokyo
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