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ARS Home » Plains Area » Lubbock, Texas » Cropping Systems Research Laboratory » Wind Erosion and Water Conservation Research » Research » Research Project #439641

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

Location: Wind Erosion and Water Conservation Research

Project Number: 3096-13000-010-002-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Oct 1, 2020
End Date: Sep 30, 2023

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. The purpose of this project is to assess crop water use efficiency, soil health, and pollinators in recently transitioned limited-irrigation and dryland crops relative to irrigated crops. Specific objectives are: 1) Estimate the water use and water-use efficiency within transitioning to limited irrigation and dryland production of annual crops and perennial forages, 2) Evaluate soil health under different transitions to dryland including changing annual crops from irrigated to dryland production, and interseeding alfalfa into established perennial grass, and 3) Compare the pollinators between irrigated and recently transitioned dryland croplands, and among alfalfa, grass-alfalfa, and grass pastures.

Our research will evaluate two types of transitions to dryland in the Texas High Plains: 1) Forages under limited irrigation and dryland, and 2) Irrigated crop transitioning to dryland. The research will be conducted in growers’ land showing different transitions to dryland crop production near Littlefield, TX and at the Texas Tech University (TTU) forage research plots at New Deal, TX. The study will have a soil water efficiency evaluation component, and will include evaluation of pollinator communities. For the soil health assessment led by Dr. Acosta-Martinez, we will conduct soil samplings (0-15 cm depth) in summer and fall of 2020, 2021, and 2022. Different soil health indicators will be evaluated to determine changes in the microbial community size, composition and activities that affect essential soil functions. Soil microbial biomass carbon (C) and nitrogen (MBN) will be determined by the chloroform-fumigation extraction (15 g of field-moist sample ) procedure according to Brookes et al. (1985) and Vance et al. (1987) using a CN analyzer (Shimadzu Model TOCV/CPH-TN, Shimadzu Corp., Kyoto, Japan). Soil microbial community size and structure will be characterized according to the ester-linked FAMEs (EL-FAMEs) method (Schutter and Dick, 2000) to define the relative abundance of broad taxonomic microbial groups. Four different enzyme activities will be determined for C (ß-glucosidase), C and N (ß-glucosaminidase), P (acid phosphomonoesterase) and S (arylsulfatase) cycling . The activities of these four different enzymes will be determined simultaneously using a combined assay (Acosta-Martínez et al. 2019) from common methods (Tabatabai, 1994; Parham and Deng, 2000). Additionally , selected chemical and physical parameters will be evaluated (e.g., soil pH, water infiltration ,and different soil organic matter pools).