Modeling the water and nitrogen transports in a soil�paddy�atmosphere system using HYDRUS-1D and lysimeter experiment

Abstract

Efficient water and fertilizer use is of paramount importance both in rain-fed and irrigated rice cultivation systems to tread off between the crop water demand during the dry spell and the fertilizer leaching. This lysimeter study on paddy in a lateritic sandy loam soil of the eastern India, to simulate the water and solute transports using the HYDRUS-1D model, reveals that this model could very well simulate the soil depth-specific variations of water pressure heads and nitrogen (N) concentrations with the efficiency of >86 and 89%, respectively. The change in the level of water ponding depth did not have a significant effect on the time to peak and the temporal variability of N concentration in the bottom soil layer. The lysimeter-scale water balance analysis indicated that the average deep percolation loss and crop water use were 35.01���2.03 and 39.74���1.49% of the total water applied during the crop growth period, respectively. Similarly, the amount of N stored in the plant and lost through soil storage, deep percolation, and other losses (mineralization, denitrification, and gaseous N loss to the atmosphere through plant leaves) were 1.60���0.16, 0.17���0.04, 12.00���0.48, and 86.23���0.41% of the total applied nitrogen, respectively. The simulation results reveal that a constant ponding depth of 3�cm could be maintained in paddy fields to reduce the N leaching loss to 7.5�kgN/ha. � 2017, The International Society of Paddy and Water Environment Engineering and Springer Japan.