Zhang et al. (2026) Evaluating mobile drip irrigation as a water-saving alternative to center pivot irrigation for large-scale alfalfa production

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Date: 2026-09-26
• Authors: Haohui Zhang, Wentao WANG, Yongmin Yang, Xin Hui, Feng Ma, Feng Ding, Yan HaiJun
• DOI: 10.1016/j.agwat.2026.110817

Research Groups

• College of Urban and Rural Construction, Zhongkai University of Agriculture and Engineering, Guangzhou, China
• College of Water Resources and Intelligence Engineering, China Agricultural University, Beijing, China
• College of Water Resources and Architecture Engineering, Northwest A&F University, Shaanxi, China
• Institute of Agricultural Resources and Environment, Xinjiang Academy of Agricultural Sciences, Urumqi, China
• State Key Laboratory of Efficient Utilization of Agricultural Water Resources, Beijing, China

Short Summary

This two-year field study compared mobile drip irrigation (MDI) and center pivot irrigation (CPI) for large-scale alfalfa production in water-limited conditions. MDI demonstrated potential as a water-saving alternative by reducing non-productive water losses, maintaining higher root-zone soil water content, and numerically increasing alfalfa yield and irrigation water productivity compared to CPI.

Objective

• To evaluate whether mobile drip irrigation (MDI) can serve as a water-saving alternative to center pivot irrigation (CPI) for large-scale alfalfa production, and to clarify the process-level basis associated with its performance, considering root-zone soil water dynamics, inter-row soil evaporation, short-term sap flow responses, hay yield, forage quality, and water productivity.

Study Configuration

• Spatial Scale: Large-scale field experiment in Zhuozhou, Hebei Province, China (39°27′ N, 115°51′ E). The experimental field featured a 140 m long center pivot irrigation system, with one span modified to MDI and another serving as the CPI control. Comparison areas included three 5 m × 5 m sampling plots within each irrigation system.
• Temporal Scale: Two-year field study (2022–2023). Alfalfa growing seasons lasted 199 days in 2022 and 181 days in 2023.

Methodology and Data

• Models used:
  • Soil-water-balance approach for actual crop evapotranspiration (ETc act).
  • Empirical equations for inter-row soil evaporation, crop water productivity (WPc), irrigation water productivity (WPI), and relative feed value (RFV).
• Data sources:
  • Meteorological data: Continuous collection using an automatic weather station (U30, HOBO, USA) at 0.5 h intervals (solar radiation, air temperature, wind speed, relative humidity, precipitation). Periodic measurements with a handheld weather meter (4500DT, Kestrel, USA) during irrigation events (near-surface wind speed, air temperature, atmospheric pressure, relative humidity).
  • Soil water content: Twice-weekly measurements using a TDR Trime-tube system (Trime-T3 TDR, IMKO Ltd., Germany) at 0–20 cm, 20–40 cm, 40–60 cm, and 60–80 cm depths. Independent reference measurements from oven-dried soil samples.
  • Inter-row soil evaporation: Daily quantification using custom-designed micro-lysimeters (110 mm inner diameter, 200 mm length) weighed at 08:30.
  • Alfalfa sap flow rate: Continuous monitoring using stem sap flow sensors based on the heat-balance method (SGA-3, Dynamax, USA), recorded every 10 min with a data logger (CR-1000, Campbell, USA).
  • Alfalfa hay yield: Determined at the early flowering stage by harvesting plants from 1 m × 1 m quadrats (9 per irrigation system area per cutting). Fresh biomass was weighed, and subsamples were oven-dried (105°C for 0.5 h, then 75°C for 48 h) to calculate dry-to-fresh ratio.
  • Water productivity indicators: Calculated from measured hay yield, actual crop evapotranspiration, and applied irrigation amount.
  • Forage quality: Oven-dried alfalfa samples analyzed using near-infrared reflectance spectroscopy (NIR-TR-3750, Foss NIR Systems, Inc., Sweden) for crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF).
  • Deep percolation: Measured using three deep drainage lysimeters (25 cm diameter) distributed across the experimental field.

Main Results

• Mobile drip irrigation (MDI) consistently maintained higher root-zone soil water content in the 0–40 cm layer compared to center pivot irrigation (CPI) during irrigation-dominated periods. Mean soil water content under MDI was 29.73% and 30.87% higher in the first and second cuttings of 2022, and 15.89% and 4.51% higher in the corresponding cuttings of 2023.
• Inter-row soil evaporation tended to be higher under CPI than under MDI, particularly at moderate evaporation rates (1.0–2.5 mm d⁻¹), indicating reduced non-productive water losses with MDI.
• During irrigation events, MDI showed no obvious short-term suppression of alfalfa sap flow rate, whereas CPI induced a pronounced transient reduction, with sap flow rate remaining approximately 1.7 g h⁻¹ lower than MDI for about 24 hours after irrigation.
• Annual hay yield under MDI was numerically 11.48% higher in 2022 (17,502.69 kg ha⁻¹ vs. 15,700.02 kg ha⁻¹) and 4.22% higher in 2023 (9341.28 kg ha⁻¹ vs. 8963.14 kg ha⁻¹) than under CPI. A statistically significant difference was observed in the second cutting of 2022 (p = 0.005).
• Irrigation water productivity (WPI) was numerically higher under MDI in all irrigated cuttings, with a significant difference in the second cutting of 2022 (3.81 kg m⁻³ for MDI vs. 3.10 kg m⁻³ for CPI). Crop water productivity (WPc) varied without consistent system differences.
• Forage quality responses were modest; MDI increased crude protein (CP) in some cuttings (e.g., 23.16% for MDI vs. 19.41% for CPI in the first cutting of 2023, p < 0.05), but relative feed value (RFV) did not consistently improve and occasionally declined.

Contributions

• Provided novel process-level evidence, including inter-row soil evaporation and short-term sap flow responses, to explain how MDI influences root-zone soil water status and irrigation water productivity in large-scale alfalfa production.
• Demonstrated that MDI can reduce non-productive water losses (soil evaporation and transient sap flow suppression) while sustaining or numerically improving alfalfa yield and overall forage quality under water-limited conditions.
• Quantified the interannual and within-season variability of MDI's benefits, highlighting its particular advantage during irrigation-dominated growth periods in arid and semi-arid regions.

Funding

• China Agriculture Research System of MOF and MARA (Grant No. CARS-33)
• Regional Collaborative Project of Xinjiang Uygur Autonomous Region (S&T Assisting Xinjiang Project) (Grant No. 2024E02004)
• National Key Research and Development Program of China (Grant No. 2022YFD1300804)

Citation

@article{Zhang2026Evaluating,
  author = {Zhang, Haohui and WANG, Wentao and Yang, Yongmin and Hui, Xin and Ma, Feng and Ding, Feng and HaiJun, Yan},
  title = {Evaluating mobile drip irrigation as a water-saving alternative to center pivot irrigation for large-scale alfalfa production},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2026.110817},
  url = {https://doi.org/10.1016/j.agwat.2026.110817}
}