Arbuscular mycorrhizal fungi inoculation to boost nitrogen use efficiency in irrigated cropping systems

Overview

This research program investigates the use of arbuscular mycorrhizal fungi (AMF) inoculation as a soil amendment to increase nitrogen (N) use efficiency in corn-cotton cropping systems. Excessive nitrogen fertilizer application is common in production agriculture, but its effectiveness depends on adequate soil moisture, and continued inputs often lead to nitrate leaching below the root zone where it becomes unavailable to crops and a potential environmental concern. By introducing beneficial AMF into the root zone, the soil's capacity to retain applied nitrogen for plant uptake can be enhanced, supporting higher crop productivity while reducing nutrient losses.

The work is particularly relevant for semi-arid regions such as the Texas Wintergarden in southwest Texas, where irrigation management and nitrogen losses are critical concerns for both farmers and the broader watershed. The project aims to generate site-specific, field-validated data that can encourage broader adoption of AMF-based soil amendments among corn and cotton growers.

Technical specifications

Research hypotheses being tested:

• AMF inoculation increases nitrogen uptake and utilization efficiency under both full and deficit irrigation regimes
• Under full irrigation, gains in nitrogen efficiency come primarily from reduced nitrate leaching into deep soil profiles due to AMF-related nitrogen capture
• Under deficit irrigation, gains come mainly from improved nitrogen uptake under drying soil conditions, facilitated by the AMF hyphal network

Experimental approach:

• Field experiment conducted in one quarter of a 50-acre center-pivot field in Uvalde, Texas
• Two-factor design testing irrigation level (full versus deficit) and AMF status (inoculated versus non-inoculated)
• Pre-experiment survey of background AMF populations in the soil
• Comprehensive monitoring of water, nitrogen, and agronomic performance parameters
• AMF status measured from field-collected soil and root samples
• Hydrus 1-D computer modeling used to simulate water and nitrogen flow dynamics through the soil profile

Technology readiness level

The project is at the field validation stage. Scientific literature broadly supports the underlying hypothesis, but adoption by farmers has been limited due to a lack of site-specific data under varying soil and weather conditions. This program is designed to close that gap by generating regionally relevant field data in the Texas Wintergarden and pairing it with computer modeling to predict outcomes under different irrigation and nitrogen management scenarios. Outputs will include agronomic recommendations and quantitative evidence to support broader on-farm adoption of AMF inoculation as a nitrogen management practice.