Amendments and seeding did not augment erosion control structure effectiveness in dry rangelands

Abstract

Rangelands in the Western United States are crucial for providing ecosystem services and supporting rural food systems, but they face increased degradation from erosion. Existing erosion management activities leverage physical interventions such as rock structures, but little is known as to whether biological interventions such as seeding or organic amendments may enhance soil health and augment the effects of such rock structures. This study investigates the effectiveness of combining rock structures with organic amendments (wood mulch or compost) and native perennial grass seed addition to address erosion on rangelands. The study was conducted across five cattle ranches in New Mexico with 9–18 active head cuts studied at each ranch. Rock rundown structures were built at each headcut and a plot above each structure received an organic amendment treatment (compost, mulch, or control) and seed addition treatment (seeded or control). Across sites, we found none of the seed additions resulted in plant establishment; therefore, we aggregated all seed addition treatments and focused only on organic amendments and measured soil and vegetation characteristics after one year. Consistently, the rock structures themselves led to channel accretion, but organic amendments had no significant effect on infiltration rate, aggregate stability, channel erosion/accretion, aboveground biomass, vegetation cover, plant richness, or soil organic carbon. Our results indicate that rock structures are an effective solution for addressing small headcuts on arid rangelands but organic amendments and native seed addition were not effective on this time scale, potentially due to severe drought during much of the year in the region. Ranchers and field technicians noted trends of enhanced soil moisture in the amendments compared with controls and were thus interested in pursuing further investigation in amendments in the future, despite the lack of effect in this study.