Nutrient supplying capacity of a paddy rice soil

Abstract

Abstract The availability of a nutrient is related to the soil solution concentration of the nutrient, soil buffer power and the effective diffusion coefficient. A field experiment was conducted at the Rice Research and Extension Center, near Stuttgart, Arkansas to determine these parameters for ammonium (NH4), phosphorus (P), and potassium (K) under the flooded conditions of paddy rice (Oryza sativa L.) and to use these parameters to calculate the relative importance of mass flow and diffusion to nutrient movement to rice roots. Three rice cultivars were grown on a Crowley silt loam. Saturated soil samples were taken from the 0‐ to 40‐cm depth at active tillering [36 days after emergence (DAE)], maximum tillering (41 DAE), 1.25 cm internode elongation (55 DAE), booting (77 DAE) and heading (88 DAE). Labile and solution concentrations, buffer power and effective diffusion coefficients of NH4, P, and K were determined on 5 cm depth increments. In general, labile and solution concentrations of NH4, P, and K...