Hydrus-1D for Simulating Potassium Transport in Flooded Paddy Soils

Abstract

ABSTRACT Understanding the transport of potassium (K) in flooded rice fields is important for the efficient management of K fertilizers. In this study, the data from lysimeter experiments were used for simulating the water flow and K transport using Hydrus-1D and the influence of split doses of recommended K fertilizer on its availability to paddy crop was investigated. Paddy crop was grown in non-weighing-type lysimeters. The depth of ponding water, soil matric potential heads, K concentration of ponding water and soil solution were measured during three paddy growing seasons. The Hydrus-1D model was calibrated and validated using the lysimeter data and simulated the water flow and K concentrations well. The deep percolation was 51–56% of the applied water and the K load in deep percolation was 0.3–0.7% of the total available K. About 56–62% of K is utilized by rice crop. The applied K was observed to be remained mostly within the top 20 cm soil depth and did not transport to deeper layers. The recommended dose of K fertilizer with four equal splits applied at four crop growth stages could increase the K availability to paddy throughout its growing period, and it may be the best K management practice for paddy.