Abstract
Over semi-arid agricultural regions such as the U.S. Southern High Plains (SHP) producers of dryland crops need to know which management practices increase yields and decrease production risk. Here, a modelling approach is used to explore management options (MO) that increase dryland cotton yields and estimate those practice’s yield risk effects under current SHP climate conditions. To simulate current dryland yield variability, dense distributions of lint yield outcomes were generated using the CROPGRO-Cotton crop model driven by weather inputs from 21 SHP weather stations during 2005-2016. Management effects were explored by repeating simulations over 32 MOs defined by 4 planting dates, 4 planting densities, and applying or not applying nitrogen. Both earlier planting date and decreased plant density increased median simulated yields, with earlier planting having the greatest positive yield effects. The MO that produced the highest median lint yields planted on the earliest planting date (May 15), at the lowest density (3 plants m-1), and applied no nitrogen. Recent SHP field studies generally confirm the earlier planting date effect, but suggest insignificant yield effects for different seeding rates. Even so, negligible yield effects and lower input costs favor lower seeding densities from a profit standpoint. These crop simulations demonstrate a modelling-based method for climate-related agricultural risk management, and suggest mid-May planting dates and low plant densities as part of management practices that increase yields and profits in dryland SHP cotton production.
Highlights
The Southern High Plains (SHP) of west Texas are home to some of the United States most concentrated upland cotton (Gossypium hirsutum L.) production, the region’s environment is not ideally suited to growing cotton
Crop photosynthesis can be optionally calculated on an hourly basis, the model runs over daily time steps and requires daily weather data
There is a somewhat weaker plant density effect, with 3 of the 4 highest median yields generated by simulations with the lowest planting density
Summary
The Southern High Plains (SHP) of west Texas are home to some of the United States most concentrated upland cotton (Gossypium hirsutum L.) production, the region’s environment is not ideally suited to growing cotton. SHP cotton lint yields are positively correlated with the cumulative exposure to daily average temperatures exceeding a base temperature during the summer growing season (Peng et al, 1989; Wanjura et al, 2002). This threshold is typically 15.6◦C (60.0 ◦F), and the resulting seasonal accumulations are referred to as growing degree days (GDD). The SHP accumulates fewer summer GDD, has generally later spring planting dates due to cooler soil temperatures, and has shorter summer growing seasons (Mauget et al, 2017; hereafter M17)
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