Is Irrigating Soybean Profitable In Uruguay? A Modeling Approach. (1st March 2019)

• Record Type: Journal Article
• Authors: Montoya, F.; Otero, Á.
• Is Part Of: Agronomy Journal. Volume 111:Number 2(2019)
• Page Start: 749
• Page End: 763
• Publication Date: 2019-03-01
• Subjects: Agronomy -- Periodicals; 630
• DOI: 10.2134/agronj2018.05.0300
• Languages: English
• ISSNs: 0002-1962

Abstract

Abstract : Core Ideas: AquaCrop model was suitable for simulating the soybean biomass and yield at harvest. Goodness of fit obtained for all variables of soybean is considered satisfactory. Supplemental irrigation increase the soybean yield under different El Niño/Southern Oscillation cycle. Profit margins were around 6 to 36% higher under irrigation than rainfed conditions. Rainfed crop may be suitable when the sale price was lower than 350 US$ t –1 . Use of climatic models to predict the El Niño/Southern Oscillation (ENSO) cycle coupled with decision support system tools can optimize management of the major crops grown in South America. AquaCrop model was applied in this paper based on field data from a soybean deficit irrigation trial in the northwestern region of Uruguay. The AquaCrop model was suitable for simulating the biomass and yield at harvest, as well as the soil water content of the soybean crop root zone, with an acceptable goodness of fit (Willmott aggregation index [IoA] > 0.80) and low estimation errors (NRMSE < 20%). After calibration and validation, AquaCrop was used to simulate 35 characteristic years for this area to analyze soybean production under irrigation and rainfed conditions, as well as to study the effect of different sowing dates and the ENSO cycle on soybean yield. This research concluded that irrigation would significantly increase the crop yield, providing stable yields for farm systems regardless of the sowing date and the ENSO cycle considered. Additionally, irrigation reducing the dependence on favorable weather for planting, allowing more flexibility in sowing date for growers. The calculated profit margins were between 6 to 36% higher using irrigation than under rainfed conditions when soybean sale price was higher than 275 US$ t −1 . With lower soybean sale price, the rainfed crop may be the most desirable option for growers regardless of ENSO cycle.