Simulated dryland cotton yield response to selected scenario factors associated with soil health

Authors: ALE, SRINIVASULU - Texas A&M University; HIMANSHU, SUSHIL - Texas A&M University; Mauget, Steven; HUDSON, DARREN - Texas Tech University; Goebel, Tim; LIU, BING - Texas Tech University; Baumhardt, Roland - Louis; BORDOVSKY, JAMES - Texas A&M University; Brauer, David; Lascano, Robert; Gitz, Dennis

Submitted to: Frontiers in Sustainable Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2020
Publication Date: 2/9/2021
Citation: Ale, S., Himanshu, S., Mauget, S.A., Hudson, D., Goebel, T.S., Liu, B., Baumhardt, R.L., Bordovsky, J., Brauer, D.K., Lascano, R.J., Gitz, D.C. 2021. Simulated dryland cotton yield response to selected scenario factors associated with soil health. Frontiers in Sustainable Food Systems. https://doi.org/10.3389/fsufs.2020.617509.
DOI: https://doi.org/10.3389/fsufs.2020.617509

Interpretive Summary: Agriculture in the west Texas panhandle is dependent on irrigation water drawn from the Ogallala aquifer. Because there is negligible recharge,the aquifer is becoming depleted after nearly nearly a century of pumping irrigation water. Well capacities are dropping. The region is moving away from irrigated agriculture and moving back towards dryland production systems. Recently it has been suggested that soil health management is key to sustaining agriculture. One oft repeated claim of the soil health movement is that increasing soil organic material by 1% will lead to an inch of precipitation storage within the soil. That is, one inch of soil organic carbon equals on inch of water. We questioned whether this hypothetical one inch of soil moisture capacity or a one percent increase in organic matter would affect cotton yields, especially in west Texas and similar regions. A large multi-disciplinary team of scientists was brought together to test this hypothesis. The research team consisted of soil scientists, crop physiologists, agronomists, crop modelers, economists, and a research climatologist from the USDA-ARS in Lubbock and Bushland, TX; Texas Tech University; and West Texas A&M. The work was funded through the USDA-ARS Ogallala Aquifer Program project and the USDA-ARS Water Availability & Watershed Management National Program. The researchers found that a hypothetical increase of 1 inch of soil moisture capacity would increase crop yields by more than 25% but that increasing soil organic carbon had little effect. How to increase soil moisture holding capacity by the hypothetical one inch remains in question. Other characteristics associated with soil health such reducing rainwater runoff and increasing infiltration and drainage could increase yields; as has been done with furrow diking and terracing. How much soil health management would cost to implement and how they would affect profitability and yield stability also remains in question.

Technical Abstract: Diminishing irrigation well capacities, increasing energy costs, and additional equipment costs associated with irrigation groundwater extraction and application are driving a transition to dryland agriculture on the Texas High Plains (THP). The primary goal of this modeling exercise was to investigate whether and to what extent hypothetical changes in soil properties putatively associated with soil health would affect dryland cotton yields (Gossypium hirsutum L.). The CROPGRO-Cotton module within the Decision Support System for Agrotechnology Transfer (DSSAT) cropping system model was used to simulate the effects of reduced surface runoff, increased soil water holding capacity, soil organic carbon (SOC), soil albedo (e.g., through stubble mulching), and soil drainage (e.g., enhancing infiltration with no-tillage/cover crops) on seed cotton yield by altering related soil properties. Mean seed cotton yields simulated with baseline soil properties of a Pullman clay loam soil at Halfway on the THP were compared to those obtained with altered soil properties using weather data from 2005 to 2019. Simulated mean seed cotton yield increased by: a) 26.7% when the soil water holding capacity was increased by 25 mm (1 in), b) 6.9% when the runoff curve number was decreased from 73 to 60, c) 15.9% when soil albedo was increased from 0.2 to 0.4, and d) 57.6% when the soil drainage factor (fraction/day) was doubled from 0.2. No significant change in mean seed cotton yield was simulated when SOC was increased by 1%. The effect of 51 mm (2 in) of pre-plant irrigation on dryland cotton production was also assessed, simulating as a scenario in the transition to dryland agriculture, and it resulted in an insignificant 12.3% increase in seed cotton yield. Finally, a combination scenario with simultaneous implementation of four statistically significant scenarios resulted in the highest increase (92.5%) in mean seed cotton yield. An economic and risk analysis of simulated yields under different scenarios also indicated that a combined suite of soil health improvements reduces revenue risk for producers from dryland cotton production with most of that impact coming from soil drainage improvements. These results provide useful insights into potential ways of increasing dryland seed cotton yields through management of soil physical and chemical properties associated with soil health.