沖積水田土壌の地力窒素の無機化モデルについて

概要

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Study on N mineralization in 4 paddy soils comprising three paddy soils which originated from alluvial soils and one from volcanic ash soil were undertaken using anaerobic incubation in vinyl bags buried 5 cm below the ground surface. The results obtained are summarized as follows: 1) Two equations representing a single exponential model: N_<Nt>=A{1-exp(-k_a×t_a)}+C and a double exponential model consisting of two components: N_<t_a>, t_b=A{1-exp(-k_a×t_a)}+B{1-exp(-k_b×t_b)}+C were used to compare the mineralization potential, where N_<t_a> and N_<t_a>, t_b are the amounts of ammonium N in soil in the time (t_a, t_b), A is potentially all mineralizable N, B is the potential denitrification or immobilization of labile mineralized N, and k_a and k_b are the mineralization rates. Variance (V) of the double exponential model was smaller than the V of the single exponential model in all soils. 2) The B and k_a of the paddy soils which originated from volcanic ash soil were smaller than those of the alluvial soils. 3) The organic material was hardly altered by dry treatment in one of the alluvial soils in which the E_<a_a> and E_<a_b> were extremely low.
1989-02-05