Distribution of soil water and nitrate in furrow irrigation under different plastic mulch placement conditions for a maize crop: Field and modelling study

*Corresponding author e-mail: ebrahimian@ut.ac.ir A b s t r a c t. The use of plastic mulch in furrow irrigation increases irrigation efficiency and improves crop yield. In this study, the effect of the placement of plastic mulch on the furrows and/or on the ridges on reducing water loss and nitrate leaching for furrow-fertigated maize was investigated. Field experiments were carried out including four different treatments which differed according to the placement of plastic mulch on a clay loam soil: plastic mulch on the ridge, plastic mulch on the furrow bed, plastic mulch on the ridge and the furrow bed and control treatment without the mulch. The HYDRUS-2D model was used to simulate water movement and nitrate transfer within the soil. The HYDRUS-2D model was well calibrated and validated using field data. Three irrigation scenarios were also compared including 125, 100 and 75% of the crop water requirement. In the case of using mulch and full irrigation (i.e. 100% crop water requirement), nitrate losses compared to the control treatment with 25% over-irrigation decreased by 52, 44, and 30%, in the the treatments of mulch on the furrow bed, mulch on the ridge and mulch on the ridge and the furrow bed, respectively. Deep percolation of irrigation water also decreased by 53, 48, and 41%, respectively. The use of plastic mulch on the furrow bed with less irrigation depth could be used to prevent water and nitrate losses in furrow irrigation.