**1. Introduction**

Upland cotton (*Gossypium hirsutum* L.) is an economically significant fiber crop in Texas, United States (U.S.). According to the National Agricultural Statistics Service [1], the total value of cotton lint and seed production is approximately 2.1 billion USD per year in Texas. The semi-arid Texas Panhandle is one of the most essential cotton production regions in the U.S. This region holds enormous potential for growing both irrigated and dryland cotton, where cotton was grown on ~1,755,000 ha in 2019, which accounted for approximately 32% of the U.S. total cotton acreage [1]. However, cotton growth and yield in this region are often negatively affected by many abiotic factors such as drought, extreme weather events, and irrigation water availability.

Climate and cultivation practices are treated as two major drivers affecting water conservation and crop production in the Texas Panhandle. Cultivation practices that maintain or improve the resilience of the agroecosystem, typically at a basin or regional scale, are promising in this challenging semi-arid environment [2,3]. Pursuing high cotton yield has driven the extensive use of the southern Ogallala Aquifer, which has resulted in a significant decline in the groundwater level with minimal recharge [4,5]. Decreased groundwater levels have led to changes in cultivation practices that reduce water pumping

**Citation:** Tan, L.; Zhang, Y.; Marek, G.W.; Ale, S.; Brauer, D.K.; Chen, Y. Modeling Basin-Scale Impacts of Cultivation Practices on Cotton Yield and Water Conservation under Various Hydroclimatic Regimes. *Agriculture* **2022**, *12*, 17. https:// doi.org/10.3390/agriculture12010017

Academic Editors: Alban Kuriqi and Luis Garrote

Received: 30 November 2021 Accepted: 23 December 2021 Published: 24 December 2021

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from the southern Ogallala Aquifer while maintaining cotton profitability. Therefore, recommendations on alternative cultivation practices for cotton production, including using different maturity cultivars [6,7], irrigation application depths (per application) [8], and planting dates [9,10], are necessary to explore, which are also relatively easy ways for growers to incorporate into an agricultural production system.

Genetic advances in cultivar maturity have the potential to preserve profitable yields under water and temperature stresses. The rationale for short- and long-season cultivars aims to take advantage of increased growing season precipitation and decreased temperature stress (heat or cold stress) during major growth stages depending on regional hydroclimatic conditions [11]. Similar to the short- and long-season cultivars, alternative planting dates may provide an opportunity to reduce the period of crop stress according to the local environment [9,12,13]. In the semi-arid Texas Panhandle, cotton is an important cash crop managed under both irrigation and dryland conditions [1]. Cotton is generally seeded in mid-May and harvested around the end of October. Early or late planting dates offer a window to make full use of in-season precipitation and optimum temperature according to hydroclimatic variability between years. Regarding irrigation management, changes in irrigation application depth have shown positive effects on water conservation in semi-arid agriculture [8,14].

The Soil and Water Assessment Tool (SWAT) model has been used to conduct effects studies for agricultural cultivation practices [15,16]. However, little comprehensive information is available for the effects of cultivation practices concerning water conservation and crop production in an intensively irrigated region. The objectives of this study were therefore to: (1) assess the impacts of irrigation application depths on water conservation for irrigated cotton in the Double Mountain Fork Brazos (DMFB) basin; and (2) evaluate the effects of alternative planting dates and maturity cultivars on water balances and cotton yield under both irrigation and dryland conditions. The widely used agro-hydrologic model, the SWAT [17], was chosen in this research [18–20]. The SWAT model, equipped with the more physically-based management allowed depletion (MAD) auto-irrigation function [21], was selected to assess the cultivation practices on water conservation and cotton yield in the DMFB basin in the Texas Panhandle.

#### **2. Materials and Methods**

#### *2.1. Study Region*

The DMFB basin in the Texas Panhandle has a delineated area of approximately 6000 km2 (The values of elevation range from 495 to 1152 m, and the average value is approximately 809 m.) (Figure 1). The long-term average annual precipitation across the study basin ranges from 457 to 559 mm, and the long-term mean annual maximum and minimum temperatures are approximately 24 ◦C and 9 ◦C, respectively. The topography of the DMFB basin is relatively flat. There is a long history of cotton cultivation in the study basin and cotton is grown in approximately 30% of the basin (Figure 1). The dominant types of soil in the DMFB basin are Amarillo sandy loam and Acuff sandy clay loam [22].

Daily precipitation, minimum air temperature, and maximum air temperature data from 1990 to 2009 were obtained from seven National Oceanic and Atmospheric Administration-National Centers for Environmental Information (NOAA-NCEI) weather stations within and adjacent to the DMFB basin (Figure 1). Two U.S. Geological Survey (USGS) gages within the DMFB basin (08079600 and 08080500; Gage I and Gage II) containing streamflow data from 1994 to 2009 were accessed in this study.

**Figure 1.** Location, land uses, weather stations, and stream gaging stations of the Double Mountain Fork Brazos basin.
