Effect of Soil Characteristics and Potassium Application Rate on the Plant-Absorbable Potassium Forms and Transport Mechanisms in Soil

作者：Mori Yuki^*; Yoshida Minako; Wada Shin Ichiro

来源：Journal of the Faculty of Agriculture, Kyushu University, 2012, 57(2): 485-488.

DOI：10.5109/25210

• diffusion
• exchangeable K
• mass flow
• nonexchangeable K
• potassium

Although the demand for saving potassium (K) fertilizer application is increasing, the evaluation of available K by exchangeable K that is operationally defined as 1 M ammonium acetate-extractable K has limitations. In order to investigate the contribution of soil K forms and transport mechanisms for K uptake, pot experiment was performed using two soils with varying K application rate. The spinach grown in vermiculite-rich soil absorbed considerable amount of K from nonexchangeable fraction and the transport mechanism was mainly by diffusion, whereas the plant cultivated in volcanic ash soil, which contain less vermiculite, mostly absorbed exchangeable K and the contribution of mass flow was substantially high. Exchangeable K and soil solution K in vermiculite-rich soil did not much increased at the high rate of K application. A part of applied K might become readily absorbable-nonexchangeable K. To evaluate K supplying capacity of soil, it is necessary to quantify not only exchangeable K but also the K fixation and the amount of K released from nonexchangeable sites. In soil whose K fixation capacity is low, the transport of K from soil might be modeled by solute transport and cation exchange.

• 出版日期2012-9