Annual rainfall and dryland cotton lint yield - Southern High Plains of Texas

Authors: Lascano, Robert; Payton, Paxton; Mahan, James; Goebel, Tim; Gitz, Dennis

Submitted to: Agricultural Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2021
Publication Date: 2/14/2022
Citation: Lascano, R.J., Payton, P.R., Mahan, J.R., Goebel, T.S., Gitz, D.C. 2022. Annual rainfall and dryland cotton lint yield - Southern High Plains of Texas. Agricultural Sciences. 13:177-200. https://doi.org/10.4236/as.2022.132014.
DOI: https://doi.org/10.4236/as.2022.132014

Interpretive Summary: In the Texas High Plains (THP), the depth to the water-table of the Ogallala aquifer continues to increase and as a result more of the cropping systems in this region use less irrigation-water from the aquifer and depend upon adequate rainfall to produce crops. The production of crops from rainfall alone in a semiarid environment is referred to as dryland agriculture. This shift, of producing crops with a diminishing supply of irrigation-water from the Ogallala aquifer to dryland cropping systems represent the future of the THP. Therefore our purpose was to quantify dryland cotton lint yields as determined by the annual amount of rainfall at the county level. For this purpose we identified and selected sixteen counties in the southern THP as our study-area. Cotton lint yield (Lbs/Acre) divided by the annual rainfall (inches) is called crop water productivity (CWP). In our analysis we used a 47-year record (1972 – 2018) of dryland cotton lint yield provided by the National Agricultural Statistics – USDA and of rainfall provided by the National Oceanic and Atmospheric Administration. Our analysis indicated that three datasets used in our study (county level annual rainfall and dryland cotton lint yield, and their ratio CWP) were normally distributed. During this 47-year time period, only one year (2011) — a record low rainfall of 7 inches — failed to produce a cotton crop. The average dryland cotton lint yield ranged from a high of 357 Lbs/Acre in Lubbock County to a low of 225 Lbs/Acre in Andrews County. However, the counties with the highest CWP, i.e., more cotton lint per unit of rainfall, were Glasscock, Midland and Martin. The significance of this result is that these three counties are located in the southern region of the THP and are subject to extreme environmental conditions of high ambient temperatures, and low rainfall and yet producers manage to produce a cotton crop year-after-year. We conclude that the management production methods used by these dryland cotton producers represent the future schemes that will need to be adopted in other counties to sustain the emerging dryland cropping systems across the THP.

Technical Abstract: The Texas High Plains (THP) is in a transition phase of producing crops with a diminishing supply of irrigation-water from the Ogallala aquifer to dryland production schemes. This shift is driven by the fact that the depth to the water table of the Ogallala aquifer continues to increase. Dryland cotton production systems are prevalent in the southern counties of the THP and our purpose was to use the long-term dryland cotton lint yields of theses counties as precursors of the future cotton production patterns that will emerge in this region. For this purpose, from 1972 to 2018, we calculated the ratio of dryland cotton lint yield per unit of rainfall at the county level. This ratio is called crop water productivity (CWP) and has units of mass per unit volume (g/m3). In our analysis we used cotton lint yield data provided by the National Agricultural Statistics and rainfall data provided by the National Oceanic and Atmospheric Administration. Our results indicated that the three datasets used in our analysis, i.e., cotton lint yield, rainfall and CWP were all normally distributed. In this time period, 1972 to 2018, only one year 2011 – a year with a record drought of 179 mm of rain failed to produce a cotton crop in all the counties used in our analysis. The mean cotton lint yield +/- standard deviation ranged from 400 +/- 175 kg/ha in Lubbock County to 252 +/- 144 kg/ha in Andrews County. However, the counties with the highest CWP > 90 g/m3 were Glasscock, Midland and Martin County. The importance of this result is that these counties are in the southern region of the THP and are subject to extreme environmental conditions and yet cotton producers manage to produce a cotton crop year-after-year. We conclude that management production methods used by these dryland producers represent the future schemes that will need to be adopted in other counties to sustain emerging dryland cropping systems across the THP.