Cholula et al. (2026) Effects of deficit irrigation on yield and nutritive value of alfalfa varieties in Northern Nevada’s semi-arid environment

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Date: 2026-01-12
• Authors: Uriel Cholula, Manuel A. Andrade, Juan K. Q. Solomon
• DOI: 10.1016/j.agwat.2026.110140

Research Groups

• Department of Agriculture, Veterinary and Rangeland Sciences, University of Nevada, Reno, NV, USA

Short Summary

This study assessed the effects of deficit irrigation (DI) on alfalfa yield, nutritive value, and crop water productivity (CWP) for two varieties in Northern Nevada's semi-arid environment over three growing seasons. It found that while moderate DI reduced yield, mild DI offered a balance of reduced yield, enhanced CWP, and improved nutritive value, making it a viable water-saving strategy.

Objective

• To assess the effects of deficit irrigation (DI) on dry yield, crop water productivity (CWP), and forage nutritive value of two alfalfa varieties (drought-tolerant Ladak II and highly productive Stratica) in Northern Nevada's semi-arid environment.
• Principal hypothesis: A drought-tolerant alfalfa variety would be less sensitive to the negative effects of DI compared to a highly productive alfalfa variety.

Study Configuration

• Spatial Scale: Field experiment at the Valley Road Field Laboratory in Reno, Nevada, USA (39°32'29.42" N, 119°48'18.09" W, 1370 m above sea level), characterized by a cold semi-arid climate.
• Temporal Scale: Three summer growing seasons (2021, 2022, and 2023).

Methodology and Data

• Models used:
  • Soil water balance equation (Eq. 3) for evapotranspiration (ET) estimation.
  • Linear mixed-effects model (LMM) for statistical analysis of dry yield, CWP, and nutritive value parameters (NDF, ADF, RFV).
  • Tukey’s Honest Significance Difference (HSD) test for mean comparisons.
  • Equations for moisture content, dry matter percentage, crop water productivity (CWP), and relative feed value (RFV).
• Data sources:
  • Surface drip irrigation system for applying three irrigation treatments: 100 % (full irrigation, FI), 80 % (mild DI), and 60 % (moderate DI) of soil water depletion replenishment.
  • Time domain reflectometer (TDR) soil moisture sensors (TDR-315H, Acclima) at 0.2 m, 0.6 m, and 0.9 m depths for volumetric water content (VWC).
  • Solar-powered nodes and a gateway with a Long Range (LoRa) radio system for wireless data transmission.
  • PyHOLA software for VWC data download.
  • Weather station at the Valley Road Field Laboratory (WRCC, 2023) for daily meteorological variables (air temperature, solar radiation, precipitation).
  • Research plot harvester (36 A, RCI Engineering) for biomass collection.
  • EZ 400, Topcon Agriculture for fresh biomass weighing.
  • Convection oven for drying biomass subsamples.
  • Wiley mill for grinding dry biomass.
  • Automated fiber analyzer (ANKOM2000, ANKOM Technology) for neutral detergent fiber (NDF) and acid detergent fiber (ADF) determination.
  • Soil analysis for field capacity (FC), permanent wilting point (PWP), and bulk density.

Main Results

• Yield: Across the three growing seasons, moderate DI decreased seasonal dry yield by 13.9 % and mild DI by 4.6 % compared to full irrigation (FI). The drought-tolerant variety (Ladak II) produced similar yields to the highly productive variety (Stratica) under the same irrigation treatment.
• Crop Water Productivity (CWP): Seasonal mean CWP significantly improved under DI. Mean CWP increased from 11.5 kg ha−1 mm−1 in 2021 to 19.2 kg ha−1 mm−1 in 2022 and 18.5 kg ha−1 mm−1 in 2023. Moderate and mild DI treatments resulted in higher CWP compared to FI.
• Nutritive Value: Mean acid detergent fiber (ADF) content was not affected by irrigation treatment. However, neutral detergent fiber (NDF) (p < 0.001) and relative feed value (RFV) (p < 0.01) were significantly influenced by irrigation treatment, with mild and moderate DI decreasing NDF content and improving RFV compared to FI. Forage nutritive value was not affected by alfalfa variety.
• Soil Water Depletion (SWD): The highly productive variety (Stratica) consistently depleted soil water faster than the drought-tolerant variety (Ladak II).

Contributions

• Provides localized data on the effects of deficit irrigation on both alfalfa yield and forage nutritive value in the unique semi-desertic climatic conditions of Northern Nevada, addressing a gap in existing literature.
• Demonstrates that a mild deficit irrigation strategy can offer a viable balance between alfalfa yield, nutritive value, and water conservation for producers in water-limited regions.
• Shows that a drought-tolerant alfalfa variety did not significantly outperform a highly productive variety in terms of yield or nutritive value when subjected to the same irrigation amounts.
• Highlights the importance of multi-year analyses due to environmental variability (e.g., snowfall, temperature) affecting treatment responses.

Funding

• University of Nevada, Reno (UNR) Office of Research and Innovation
• Nevada Agricultural Experiment Station (NAES) of UNR
• Truckee Meadows Water Authority
• U.S. Department of Agriculture’s National Institute of Food and Agriculture (USDA-NIFA) - Data Science for Food and Agricultural Systems program (project award No. 2023–67022–40041)
• U.S. Department of Agriculture’s National Institute of Food and Agriculture (USDA-NIFA) - Engineering for Precision Water and Crop Management program (project award No. 2023–67022–40558)

Citation

@article{Cholula2026Effects,
  author = {Cholula, Uriel and Andrade, Manuel A. and Solomon, Juan K. Q.},
  title = {Effects of deficit irrigation on yield and nutritive value of alfalfa varieties in Northern Nevada’s semi-arid environment},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2026.110140},
  url = {https://doi.org/10.1016/j.agwat.2026.110140}
}