Validation and application of AquaCrop for irrigated cotton in the Southern Great Plains of US

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ORIGINAL PAPER

Validation and application of AquaCrop for irrigated cotton in the Southern Great Plains of US Blessing Masasi1   · Saleh Taghvaeian1   · Prasanna H. Gowda2 · Gary Marek3 · Randy Boman4 Received: 19 June 2019 / Accepted: 16 December 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract Dwindling water resources and weather variability present two of the major limiting factors for irrigated cotton production in the Southern Great Plains (SGP) of the United States. Under these conditions, there is a dire need to understand the trends and fluctuations in cotton yields to help producers make better irrigation and crop management decisions. Crop models coupled with long-term weather data provide an opportunity for evaluating yield variabilities by simulating numerous potential scenarios. In this study, the AquaCrop model was calibrated and validated for cotton at two sites in the SGP. The validated model was then applied to investigate the effect of variable irrigation capacity (IC) on cotton yield during a 33-year period (1981–2013). The AquaCrop model performed with acceptable accuracy for simulating canopy cover, soil water content, evapotranspiration and yield indicating that it is a potential tool for evaluating variable cotton irrigation scenarios in the SGP. The response of cotton yield to IC was highly dependent on heat unit availability. Yields increased significantly with increase in water availability in years when total growing season heat units were above 1100 °C day. The yield response to irrigation diminished considerably as the magnitude of growing season heat units decreased. No significant increase in mean cotton yield was found at IC higher than 0.3 L s−1 ha−1.

Introduction The Southern Great Plains (SGP) is one of the major cotton producing regions in the United States (Parton et al. 2007). Texas and Oklahoma, which form part of the SGP, rank among the leading cotton-producing states in the country (Nair et al. 2013; Steiner et al. 2015). Cotton production in these two states contributes significantly to the economy of the region and country at large (Krueger et al. 2017). According to Steiner et al. (2018), Oklahoma and Texas generated a combined revenue of approximately $1.67 billion from cotton in the year 2012 alone. However, water Communicated by Allan Andales. * Blessing Masasi [email protected] 1



Department of Biosystems and Agricultural Engineering, Oklahoma State University, Stillwater, OK, USA

2



USDA-ARS Southeast Area, Stoneville, MS, USA

3

USDA-ARS Conservation and Production Research Laboratory, Bushland, TX, USA

4

Formerly Southwest Research and Extension Center, Oklahoma State University, Altus, OK 73521, USA



availability and quality for irrigation have persistently been one of the major limiting factors for cotton production in the SGP (Tolk and Howell 2010; Steiner et al. 2018). The Ogallala aquifer, which is the major source of irrigation in the western part of the region, has been plagued by significant declines in i