Modeling basin-scale impacts of cultivation practices on cotton yield and water conservation under various hydroclimatic regimes

Authors: TAN, LILI - China Agricultural University; ZHANG, YINGQI - China Agricultural University; Marek, Gary; ALE, SRINIVASULU - Texas A&M Agrilife; Brauer, David; CHEN, YONG - China Agricultural University

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2021
Publication Date: 12/24/2021
Citation: Tan, L., Zhang, Y., Marek, G.W., Ale, S., Brauer, D.K., Chen, Y. 2021. Modeling basin-scale impacts of cultivation practices on cotton yield and water conservation under various hydroclimatic regimes. Agriculture. 12(1). Article 17. https://doi.org/10.3390/agriculture12010017.
DOI: https://doi.org/10.3390/agriculture12010017

Interpretive Summary: Declining well capacities associated with depletion of the Ogallala Aquifer have led to concerns about the future of irrigated crop production on the Texas High Plains (THP). Cotton, having seasonal water requirements approximately two thirds that of corn and high yield potential, is becoming more prevalent in the THP. However, large data gaps exist for cotton irrigation strategies, planting date, and cultivar selection. Using limited, but appropriate climate and field research data, simulation modeling can be an effective tool for evaluating cotton growth under different management regimes. Scientists from ARS (Bushland, Texas), China Agricultural University and Texas A&M AgriLife Research used a Soil Water Assessment Tool (SWAT) equipped with an improved management allowed depletion function to simulate cotton yield and seasonal water balance components for dryland and irrigated conditions. In general, simulations indicated that less frequent irrigations of greater depth resulted in decreased seasonal irrigation totals with slightly increased yields. Later planting depths resulted in decreased yields due to limited heat unit accumulation for all cultivars for both dryland and irrigated scenarios. Overall, these results characterize potential management strategies for maximizing cotton yields while reducing groundwater withdrawals on the THP.

Technical Abstract: The Soil and Water Assessment Tool (SWAT) model equipped with a physically based management allowed depletion (MAD) auto-irrigation function was used to assess the impacts of cultivation practices on water conservation and crop yields of irrigated and dryland cotton (Gossypium hirsutum L.) for the Double Mountain Fork Brazos watershed in the Texas High Plains (THP). Cultivation practices were modeled using different irrigation application depths, alternative planting dates, and various maturity cultivars for cotton. Results showed the largest irrigation depth (38.1 mm) led to reductions in seasonal irrigation amounts and cotton crop evapotranspiration (ETc) with slightly increased cotton yields compared to the baseline periods under different hydroclimatic regimes. However, soil water content, surface runoff, and water yield values were increased using the large irrigation depth. The opposite results were observed for the small irrigation depth of 12.7 mm. Early planting of cotton resulted in decreased irrigation and ETc and the increase of cotton yields for both irrigated and dryland conditions, particularly for the normal and wet years. By contrast, the late planting scenarios indicated the opposite for those variables generally. Simulated hydrologic variables were relatively stable using various maturity cultivars. Nevertheless, more than 10 percent reductions in irrigated cotton yields under diverse hydroclimatic years and dryland yields under normal and wet years were identified with the short-season cotton cultivar. The opposite was determined for the long-season cotton cultivar with similar absolute change percentages. These outcomes suggest the larger irrigation application depth, early planting date, and short-season cultivar are promising cultivation practices for enhancing cotton yields and benefiting water conservation in the THP.