Guo et al. (2025) Incorporation alfalfa with annual forage enhances even water use and maintains forage yield resilience in a semiarid region

Identification

• Journal: Agricultural Water Management
• Year: 2025
• Date: 2025-09-27
• Authors: Hongyan Guo, Shuai Hou, Yanyan Zhang, Yangyang Liu, Yafang Wang, Chugang Mei, Kai Gao, Zhou Lin, Zhixin Zhang
• DOI: 10.1016/j.agwat.2025.109838

Research Groups

• College of Grassland Agriculture, Northwest A & F University, Yangling, Shanxi, China
• People’s Government of Touzha Town, Pingluo County, Shizuishan, Ningxia, China
• College of Grassland Science, Inner Mongolia Minzu University, Tongliao, China
• College of Forestry and Grassland Science, Jilin Agricultural University, Changchun, China

Short Summary

This study investigated whether intercropping alfalfa with annual forage crops could improve soil water distribution and maintain forage yield resilience in a semiarid region. Findings show that intercropping significantly enhanced soil water content, water productivity, and overall yield advantage, particularly with alfalfa-maize combinations, offering a feasible solution for efficient water management.

Objective

• To investigate the effects of spatial and temporal variations in the soil water distribution of topsoil (0–30 cm) and subsoil (30–160 cm) layers under intercropping with shallow- and deep-rooted forage species.
• To analyze the relationship between water utilization and competition when annual forage crops are incorporated with perennial alfalfa.
• To comprehensively evaluate the productivity, land use, and economic benefits of adding annual forage crops into monoculture perennial forage production.

Study Configuration

• Spatial Scale: Field trial in Shiyaogou (36°51’ N, 109°19’ E), Ansai District, Yanan city, Shanxi Province, China, a typical rainfed semiarid region of the Loess Plateau (altitude 1100 m). Experimental plots were 4 m × 5 m. Soil layers analyzed were 0–30 cm (topsoil) and 30–160 cm (subsoil).
• Temporal Scale: Two growing seasons, from April to October in 2021 and 2022. Measurements were taken at the seedling, flowering, and maturity stages of annual forage crops.

Methodology and Data

• Models used: Not applicable in the sense of complex simulation models (e.g., ISBA, mHM). The study utilized established formulas and statistical methods for calculating:
  • Expected Yield (Ex_Y)
  • Land Equivalent Ratio (LER)
  • Competitive Ratio (CR)
  • Compensatory Effect (CE)
  • Selection Effect (SE)
  • Monetary Advantage Index (MAI)
  • Soil Water Storage (SWS)
  • Water Competition (ΔSWS)
  • Water Compensation (ΔSWR)
  • Water Use (WU)
  • Water Productivity (WP)
  • Water Equivalent Ratio (WER)
  • Statistical analysis: Analysis of Variance (ANOVA) and Least Significant Difference (LSD) method (P < 0.05) using SPSS 27.0.
• Data sources:
  • Field trial: Monoculture systems of alfalfa (Golden Empress), forage maize (Zhongyuandan No.32), sweet sorghum (Wulate No. 1), Sudan grass (Hercules), and Japanese millet (Haizi No. 1), as well as four alternate intercropping systems combining alfalfa with each annual forage crop.
  • Forage yield: Aboveground biomass harvested from 100 cm sections of two rows per plot, oven-dried at 105 °C for 30 minutes then 80 °C to constant weight.
  • Soil water content: Soil samples collected with a 3.8 cm diameter auger from 9 layers within 0–160 cm depth, determined by the gravimetric drying method.
  • Meteorological data: Measured monthly precipitation and temperature at the experimental site.
  • Economic data: Market values of forage crops obtained from ymt.com for MAI calculation.

Main Results

• Alfalfa intercropping systems with annual forage crops improved the water content of the topsoil (0–30 cm) by 6.5 %-81.4 % and subsoil (30–160 cm) by 10.7 %-23.2 % compared to alfalfa monoculture.
• The alfalfa-maize system significantly reduced interspecific water competition in the subsoil by 16.4 %-27.6 % and increased topsoil water compensation by 0.3 %-13.1 %. This led to an average increase of 29.5 % in topsoil water storage and 12.0 % in subsoil water storage at the maturity stage.
• Alfalfa-maize, alfalfa-sorghum, alfalfa-Sudan grass, and alfalfa-Japanese millet intercropping systems presented 151 %, 44 %, 54 %, and 32 % greater water productivity (WP) than alfalfa monoculture, respectively.
• The improvement in soil water conditions within the intercropping system resulted in greater interspecific compensatory effects than selection effects, conferring a yield advantage of 64.6 %-80.6 %.
• The alfalfa-maize combination resulted in 0.5–7.6 % LER improvement, 13.8–28.8 % MAI enhancement, and 12.3–43.1 % CR reduction, coupled with water compensation benefits and favorable water productivity (WER > 1).
• Overall, the yield loss of alfalfa intercropped with annual forage crops was effectively compensated for, offering a feasible solution for efficient water management.

Contributions

• Demonstrated that intercropping annual forage crops with perennial alfalfa effectively mitigates subsoil desiccation and promotes more uniform soil water use across soil profiles in semiarid regions.
• Provided evidence that this intercropping strategy enhances water compensation in the topsoil during alfalfa regrowth, leading to balanced and efficient water use.
• Showed that efficient water use in intercropping systems drives compensatory effects, resulting in increased forage yield and land use efficiency (LER > 1).
• Identified the alfalfa-maize combination as the most effective intercropping system for achieving the best yield and monetary advantage indices, addressing uneven water use in perennial legume alfalfa.
• Offered a cost-effective and sustainable solution for soil desiccation, extending the productive years of perennial forage systems and maintaining stable, high-yield agricultural systems in arid and semiarid environments.

Funding

• National Key Research and Development Program of China (2023YFD1900402–01, 2023YFD1900402–02)
• National Natural Science Foundation of China (32101441)

Citation

@article{Guo2025Incorporation,
  author = {Guo, Hongyan and Hou, Shuai and Zhang, Yanyan and Liu, Yangyang and Wang, Yafang and Mei, Chugang and Gao, Kai and Lin, Zhou and Zhang, Zhixin},
  title = {Incorporation alfalfa with annual forage enhances even water use and maintains forage yield resilience in a semiarid region},
  journal = {Agricultural Water Management},
  year = {2025},
  doi = {10.1016/j.agwat.2025.109838},
  url = {https://doi.org/10.1016/j.agwat.2025.109838}
}