Assessing Water Use Efficiency, Soil Health, and Pollinators within a Transition from Irrigation to Dryland Management in the Texas High Plains

This Research and Education Grant project was awarded a 2021 James Harrison Hill, Sr. Young Scholar Enhancement Grant award in the amount of $2,009. The award provides high school and undergraduate college students the opportunity to conduct sustainable agriculture research, as part of an existing Research and Education Grant project.

View the project final report

Commodities

Practices

• Crop Production: irrigation, pollination, water management
• Production Systems: agroecosystems, dryland farming, integrated crop and livestock systems
• Soil Management: soil quality/health

The rapid decline in water supply for irrigation in the Texas High Plains is encouraging some growers to convert their irrigated cropland to production of dryland crops and low water requiring forages. Reduced irrigation will directly depress crop yields and financial security. Research on the impacts of transitioning toward reduced water input can reveal soil and crop management practices that build up the soil’s health. Switching to more diverse cropping systems can enhance numbers and activities of introduced and native bees, which are potential pollinators. We studied changes in soil health indicators, ground-nesting bees (as an indicator of pollinator habitat), and water use by annual crops and perennial forages in the context of transition from high irrigation to low irrigation to dryland management. Studies were conducted on four commercial farms in the South Plains of the Texas High Plains, and the Texas Tech University pasture research facility near New Deal, TX. Three of the growers were already part of long-term studies by a cooperating agency (USDA-ARS) for soil health; hence three additional years of data (through 2023) extended the analysis. In addition, pollinators (i.e., native bee communities) were sampled in 2021-2022 to determine if communities were related to irrigation transition scenarios and soil conditions. Differences in soil conditions were documented across fields including reductions in soil water content, potassium, sodium, and soil organic carbon with transition to subsurface irrigation and dryland systems (from center pivot irrigation). Furthermore, severe drought in the final year of the project reduced total fungi and multi-enzyme activities. However, differences detected in soil conditions were not revealed in the bee communities across irrigation-transition scenarios or in relation to soil conditions. A total of 4427 bee individuals and 71 morphospecies were collected across the four farms, which is a relatively high number when considering the region is intensively managed for crop production. The CRP site (DgC), the house site (H_site) and the tree-lined field border (Ma T1) produced the greatest number of morphospecies and total abundances of native bees; these on-farm habitats should be further investigated to better understand use by native bees in foraging and soil-nesting, and how they might benefit sustainable crop production.  

1) Estimate the water use and water-use efficiency of annual crops and perennial forages transitioning to limited irrigation and dryland production.

2) Evaluate soil health indicators under different transitions to dryland including changing annual crops from irrigated to dryland production, and interseeding alfalfa into established perennial grassland.

3) Compare irrigated and recently transitioned dryland croplands, alfalfa, grass-alfalfa, and grass pastures on ground-nesting bee communities as indicators of insect pollinator health and abundance.