EVALUATION OF FERTIGATION IN DIFFERENT SOILS AND FURROW IRRIGATION REGIMES

The application of plant nutrients with irrigation water (fertigation) is a cost-effective and efficient method for fertilizer application to enhance crop production and reduce potential environmental problems in comparison to conventional methods. In this study, the distribution uniformity of fertigation and fertilizer losses through runoff and deep percolation were evaluated at field scale in different furrow irrigation regimes and soils. A numerical fertigation model was calibrated and validated. Experiments were carried out in three soil textures and potassium nitrate was injected during the first half of the irrigation (FH), in the second half (SH) and during the entire irrigation event (T). These options were conducted under free-draining and blocked-end conditions with a cutback method. The distribution uniformities of low half (DULH) and low quarter (DULQ) of water and fertilizer were calculated to evaluate different fertigation scenarios. There were no significant differences among distribution uniformities in the three fertilizer application treatments (FH, SH, T). However, injection in the first half and during the entire irrigation event was better in terms of distribution uniformity and infiltrated fertilizer. The best case in blocked-end conditions was injection in the second half of the irrigation event, preferably starting before completion of the advanced phase. In this case, fertilizer losses due to runoff from the outlet were zero and distribution uniformity was somewhat higher, whereas in free-drainage conditions, fertilizer application during the first half of the irrigation provided acceptable fertilizer uniformity and lower fertilizer losses due to runoff. No significant difference was observed between the distribution uniformity of free-drainage and blocked-end experiments. A fertigation model was applied to the experimental data and the results showed good agreement with the field data. Measurements also showed that water and fertilizer losses due to deep percolation in fertigation was not a concern when proper irrigation parameters were selected, such as inflow rate. Copyright (C) 2012 John Wiley & Sons, Ltd.