Influence of alternate submergence and drying of rice soils prior to resubmergence on available phosphorus

Summary Four acid rice-soils (0–20 cm, air-dry, and <2 mm) were subjected to 3 cycles, each consisting of 30-day submergence followed by air-drying at room temperature or oven-drying at 105°C for 3 days. The available phosphorus was determined colorimetrically by Bray's P-2 extractant (0.03N NH₄F+0.1N HCl) using 1:20 soil extractant ratio. The beneficial effect of 30-day submergence followed by drying of soil prior to resubmergence on native phosphorus was apparent in all soils studied except Shirgaon clay soil, which was probably due to presence of relatively more active Fe in that soil.