The LTAR Grazing Land Common Experiment at the Jornada Experimental Range: Old genetics, new precision technologies, and adaptive value chains

Long‐term research is essential for guiding the development of agroecosystems to meet escalating production demands in a manner that is environmentally sound and socially acceptable. Research must integrate biophysical and socioeconomic factors to provide geographically scalable knowledge that involves stakeholders across the research‐education‐extension‐policy spectrum. In response to this need, the Long‐Term Agroecosystem Research (LTAR) network developed a “Common Experiment,” which seeks to develop and disseminate multi‐region, science‐based information to enable implementation of visionary agricultural innovations while simultaneously promoting food security, well‐being, environmental quality, and climate adaptation and mitigation. The core design of the Common Experiment contrasts prevailing and alternative/aspirational production systems, with the latter including novel innovations hypothesized to advance sustainable intensification in locally appropriate ways. Treatments in the Common Experiment represent a diversity of production systems under cropland, grazing land, and integrated crop/grazing land management. Where possible, treatments are evaluated at multiple spatial scales (e.g., from plot to enterprise) and are designed to evolve over the course of the experiment with stakeholder input. A common assessment framework guides data collection for the experiment and is complemented by metric‐specific protocols and an emerging data management infrastructure. Currently, there are large differences among sites in the application of the experimental framework and degree of stakeholder engagement; differences largely grounded in pragmatic issues related to land access, site expertise, and resource availability. The full potential of the LTAR Common Experiment may be realized with strategic investments in network capacity.

The LTAR Common Experiment: Facilitating improved agricultural sustainability through coordinated cross‐site research

Liebig,

Abendroth,

Robertson

et al. 2024

The LTAR Grazing Land Common Experiment at Walnut Gulch Experimental Watershed

Heilman,

Archer,

Williams

et al. 2024

The Walnut Gulch Experimental Watershed (WGEW) Long‐Term Agroecosystem Research (LTAR) network common experiment addresses the aspirational practice of brush management (BM) to reverse the prevailing condition of woody plant encroachment (WPE) and increase perennial native grass production. Across the western United States, the decision to implement BM includes consideration of management objectives, cost, and the expected impact on a diverse suite of ecosystem services. Maintaining or restoring grass cover will help meet the LTAR sustainable production, economic, and social goals, and averting degradation will meet environmental goals. This common experiment, focused on hydrologic and erosion impacts of BM, aims to inform land management decisions on three major plant communities in the Southwestern United States: creosote bush (Larrea tridentata), mesquite (Prosopis velutina), and pinyon–juniper (PJ, Pinus and Juniperus spp.). On the WGEW, applying tebuthiuron pellets to creosote bush increased grass cover and reduced runoff and erosion. The 2016 BM experiment on the Santa Rita Experimental Range applied a commonly used liquid herbicide cocktail but achieved only 7% mortality on mesquite, probably because of the timing of the aerial application. Experiments manipulating rainfall amount and intensity on plots receiving fire, chemical, or mechanical BM treatments on PJ communities aim to improve process representation in simulation models. The deliverables of these BM experiments will be to (i) improve the performance of runoff and erosion models, (ii) enhance our ability to identify areas most at risk from reduced hydrologic function and soil erosion after shrub proliferation, and (iii) better predict how landscapes will respond to BM interventions. Ranchers, land management agencies, and watershed conservation organizations will benefit from training and availability of improved tools to focus treatments on areas where greatest net benefits might be realized.

The Long‐Term Agroecosystem Research (LTAR) network: Cross‐site transdisciplinary science to support a sustainable and resilient agriculture

Tsegaye,

Eve,

Hapeman

et al. 2024

The Long‐Term Agroecosystem Research (LTAR) network is a collaborative initiative funded by the U.S. Department of Agriculture, Agricultural Research Service, aimed at advancing sustainable, resilient agriculture through coordinated research conducted on croplands, grazing lands, and integrated crop/livestock systems. Here we provide an overview of the LTAR network, highlighting its vision, mission, initiatives, recent network activities, and future directions. Network‐level research is critical for developing contextually relevant solutions to the challenges faced by agricultural producers. Long‐term data collection, stakeholder engagement, and the integration of scientific knowledge are needed to enhance agricultural productivity and its resiliency, environmental quality, profitability, and social well‐being into the future.