Assessment and simulation of water and nitrogen transfer under furrow irrigation

The objective of this study is to simulate water and nitrogen transfers under two furrow irrigation technologies (every furrow irrigation (EFI) and alternative furrow irrigation (AFI)) on Chromic Luvisol in Sofia region, Bulgaria. A bi-dimensional water and solutes transport modeling approach, HYDRUS-2D model [Simunek, J., Sejna, M., Van Genuchten, M.T., 1999. The HYDRUS-1D and HYDRUS-2D codes for estimating unsaturated soil hydraulic and solutes transport parameters. Agron Abstr. 357] is adopted in order to consider the technology of irrigation and fertilization. The model is calibrated in six steps using detailed data observed in two cropped lysimeters. The data consist of water and nitrogen (N) profiles below ridge and furrow bed, precipitation, drainage and water/N uptake by plant. Hydrological components of the soil are derived from laboratory: water retention data (step (i)) and adjusted to field conditions when EFI is approximated by one-dimensional (step (ii)). Then a two-dimensional water flow is adopted in model simulations for parameter calibration and verification, under EFI (step (iii)) and under AFI technology (step (iv)). This model calibration and validation is then used to calibrate the solute transport parameters, that is the aim of step (v) and step (vi). EFI and particularly AFI technologies points out the necessary 2D model using for the N transfer simulation under specific fertilizer applications. Thus, this calibrated model allows predicting the impact of furrow irrigation practices and distribution uniformity on drainage and nitrogen leaching under the studied conditions.