Optimum Design of Alternate and Conventional Furrow Fertigation to Minimize Nitrate Loss

Abstract

Alternate furrow fertigation has shown potential to improve water and fertilizer application efficiency in irrigated areas. The combination of simulation and optimization approaches permits to identify optimum design and management practices in furrow fertigation, resulting in optimum cost, irrigation performance or environmental impact. The objective of this paper is to apply 1D surface and 2D subsurface simulation-optimization models to the minimization of nitrate losses in two types of alternate furrow fertigation: a) variable alternate furrow irrigation; and b) fixed alternate furrow irrigation. For comparison purposes, optimizations are also reported for conventional furrow irrigation. The model uses numerical surface fertigation and soil water models to simulate water flow and nitrate transport in the soil surface and subsurface, respectively. A genetic algorithm is used to solve the optimization problem. Four decision variables (inflow discharge, cutoff time, start time and duration of fertilizer solution injection) were optimized to minimize the selected objective function (nitrate loss) for two fertigation events performed during a maize growing season. The simulation-optimization model succeeded in substantially reducing the value of the objective function, as compared to the field conditions for all irrigation treatments. In the experimental conditions, optimization led to decreased inflow discharge and fertilizer injection during the first half of the irrigation event. This was due to the high potential of the field experiment to lose water and nitrate via runoff. In the optimum conditions, alternate furrow fertigation strongly reduced water and nitrate losses compared to conventional furrow irrigation. The simulation-optimization model stands as a valuable tool for the alleviation of the environmental impact of furrow irrigation.

Surface fertigation: a review, gaps and needs

“…For this reason, Xu et al (2013) proposed a two-dimensional coupled model for simulating surface water and solute transfer in basin fertigation. Ebrahimian et al (2013b) presented a 1D surface and 2D subsurface simulation-optimization model to minimize nitrate losses in two types of alternate furrow fertigation (variable and fixed alternate furrow irrigation) and in conventional furrow irrigation. The model used numerical surface fertigation (Abbasi et al, 2003c) and soil water (SWMS-2D) models to simulate water flow and nitrate transport in the soil surface and subsurface, respectively.…”

“…For instance, if an irrigation event shows high percolation losses, fertilizer injection early in the irrigation time will lead to relevant fertilizer leaching (Jaynes et al, 1992 sely, if the irrigation event shows large runoff losses, injecting fertilizer late in the irrigation time will lead to large runoff losses (Ebrahimian et al, 2013b). Key questions in recommending fertigation practices include when, how much and what kind of fertilizer to apply in surface irrigation water.…”

“…This set can be readily applied to other fertilizers and to different irrigation systems. The fertilizer Distribution Uniformity of the low quarter (or half) and the fertilizer Application Efficiency have been used in most literature references (Boldt et al, 1994;Playán & Faci, 1997;García-Navarro et al, 2000;Abbasi et al, 2003b;Zerihun et al, 2003;Sabillón & Merkley, 2004;Adamsen et al, 2005;Perea-Estrada, 2005;Strelkoff et al, 2006;Ebrahimian et al, 2013b;Ebrahimian & Playán, 2014). All these references analyzed fertilizer distribution uniformity.…”

The effect of different fertigation strategies and furrow surface treatments on plant water and nitrogen use

“…There are many studies that evaluated fertigation timing in furrow irrigation (e.g., Bouwer et al 1990;Playán and Faci 1997;Sabillón and Merkley 2004;Adamsen et al 2005;Burguete et al 2009;Ebrahimian et al 2013b). For example, Bouwer et al (1990) and Soroush et al (2012) recommended that in order to avoid leaching of fertilizers to groundwater, fertigation should be applied toward the end of an irrigation event.…”

“…Burguete et al (2009) developed a simulation model, which considered overland water flow, solute transport and infiltration, and used it to evaluate the effects of irrigation discharge, fertilizer application timing and furrow geometry on fertilizer uniformity. Ebrahimian et al (2013b) used genetic algorithms and the one-dimensional surface and two-dimensional subsurface models to optimize timing of fertigation in alternate furrow irrigation. They concluded that by optimizing the start time and the duration of fertilizer injection, they could reduce nitrate losses due to deep percolation and surface runoff by up to 50 %.…”