Statement of Issues:

Soil health is fundamental to sustainable intensification of agricultural and forest productivity that is necessary to meet demands of a growing human population without degrading ecosystem functionality (Struik and Kuyper, 2017).  Soil health can be defined as the ability of soil to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and well-being (Karlen et al., 1997), and is typically quantified with respect to soil physical, chemical, and biological attributes. Thus, healthy soils support optimal productivity, maintain biodiversity, support climate-resilient agricultural enterprises, sequester atmospheric carbon to mitigate global warming, ultimately providing the foundation for sustainable intensification (Paustian et al., 2016).

In order to help maintain sustainable agroecosystems, over the last decade (~ 2010 to 2020), a USDA-sponsored initiative successfully generated a great deal of excitement around soil health. But zeal to implement soil health management practices outpaced identification of sound soil health assessment methods and sometimes led to claims that overreached what could be accomplished in terms of organic matter accumulation, optimal biogeochemical cycling to maintain productivity, or other soil attributes, especially for soils of the arid and semiarid western US. More recently, the NRCS Soil Health Division, the Soil Health Institute (SHI), and university and federal researchers have begun to scientifically develop effective, environment-specific, chemical, physical, and biological assessment methods, or to identify and refine those developed over the last 40 to 50 years (e.g., Norris et al., 2020; Cornell University, 2020; Soil Health Institute, 2020a; USDA-NRCS, 2011; Stott, 2019).

As such, soil health assessment is becoming an effective indicator of management system sustainability (e.g., Ippolito et al., 2017; Karlen et al., 2014; Stott et al., 2012) and federal and state agencies are developing inventory and incentive strategies. But the many combinations of soil type, regional climate, management history, economic drivers, time, and variable climate change trajectories do not follow state or other jurisdictional boundaries, meaning that the most effective soil health assessment tools vary from place to place, over time, and cross US state boundaries. Water-constrained systems of the western states, with inherently low organic matter and at times high salinity, require different approaches toward assessment than more humid regions. The multi-state research project proposed here would implement a coordinated strategy to identify best soil health management and assessment approaches for western US production systems. This effort is intended to complement and extend current NRCS and SHI efforts by more broadly including expert land grant university and USDA scientists from across widely varying western and Pacific Island agroecosystems.

The W2196 workgroup currently includes scientists and educators from across the western US within and outside the State Agricultural Experiment Station System, many of whom have decades of experience assessing soil health and quality in many western forest, crop production, and livestock production systems. Representation consists of the following land grant institutions:  the University of Arizona, University of Hawaii, the University of California – Davis, the University of California – Riverside, Utah State University, Montana State University, the University of Wyoming, New Mexico State University, the University of Nebraska, and Kansas State University.  We plan to continue partnerships with the USDA-NRCS and USDA Forest Service for western US representation, so our workgroup efforts complement and expand on those of the NRCS and USFS. Members of this multi-state research group propose to continue investigating the soil physical, chemical, and biological attributes necessary to maintain sustainable agricultural intensification and forest productivity in the western US over time.  Collaborative investigations and data sharing will generate needed knowledge, and identify knowledge gaps, to develop and promote healthy western US soils while minimizing the potential for unintended negative consequences (e.g., off-site nutrient, erosional, and yield losses, etc.). 

Justification:

Acknowledging the principles and practices that promote improvements in soil physical, chemical, and biological attributes to create sustainable, resilient agroecosystems is the epicenter of soil health.  More importantly, fully understanding the interplay and intricacies among these three soil components within the context of managed agroecosystems, over time, is paramount for feeding, clothing, and fueling an ever-expanding human population, while reducing environmental degradation and the human footprint.

Members of the original W1196 group successfully completed the first phase the project. Many have and continue to work collaboratively on research related to soil health issues in the Western US. All members of the committee currently have projects that focus on various aspects of soil health in many western production, rangeland, and agroforestry systems.  Numerous research examples listed below all have a direct soil health focus:

• Debankur Sanyal (Assistant Professor and Extension Soil Health Specialist, University of Arizona): 1) Specializes in soil biogeochemistry, while primarily focused on the roles of soil biota, climate, and agronomic management practices in the cycling of nutrients and carbon in the agroecosystems aimed at sustainable crop production systems through climate-smart approaches; 2) Developing a soil health assessment framework for desert soils in the arid and semi-arid regions and developing novel protocols to measure soil biogeochemical properties, especially carbon and nitrogen fractions.


• Rebecca Lybrand (Associate Professor, Pedologist, University of California, Davis): 1) integrating soil health assessments across scales by connecting microscale soil analyses to field- and landscape-level analysis outcomes 2) Evaluating soil health parameters across contrasting bioclimate gradients and landscapes within the western US (Sonoran Desert, AZ; Coastal Redwoods, CA; Perhumid Coastal Temperate Rainforest, AK);


• Jonathan Deenik (University of Hawaii): 1) works across soil mineralogical classes in south Pacific islands; 2) soil organic C alterations in south Pacific islands; 3) soil health assessments on on-farm soil health demonstration trials; linkages of soil health to soil fertility and yields, 4) soil health monitoring in row crop and agroforest systems


• Tai Maaz (University of Hawaii): 1) soil health assessments and scoring approaches in tropical soils and for Pacific islands, 2) development of rapid, low-cost assessments of soil health and farmer-facing tools, 3) linkages of soil health to soil fertility and yields, 4) soil health monitoring in row crop and agroforest systems.


• Matt Yost (Utah State University): 1) 10-16 approaches to water management, optimization; 2) previous experience with the Soil Health Partnership, their indicator database, and soil health tests for data correlation analyses; 3) cover crops and/or interseeding; 4) member of the State of Utah Soil Health Partnership;


• Clain Jones (Montana State University): 1) long-term cropping system by inorganic N fertilizer rate studies; 2) western US soil acidification issues;


• John Idowu (New Mexico State University): 1) numerous cropping systems, management, and land resources areas research, in conjunction with streamlining soil health indicators; 2) tillage management and short-term soil alterations; 3) soil amendments (e.g., pecan waste) and irrigation; 3) cover crop research; 4) weed control; 5) soil health and greenhouse gas emissions in dryland or irrigated systems; 5) halophytes;


• Bijesh Maharjan (University of Nebraska): 1) soil health benchmarking using the concept of Soil Health Gap (Maharjan et al. 2022); 2) a comprehensive soil health assessment using the understanding of Soil Health Cycle (Maharjan et al., 2024)


• Augustine Obour (Kansas State University): 1) grazing cover crops and annual forages impacts on crops and soil health in dryland agroecosystems; 2) tillage or strategic tillage and crop rotations effect on soil properties in dryland crop rotations; 3) On-farm regenerative agriculture research across Kansas


• Pedro Martinez (Assistant Professor of Pedology, University of California, Riverside): 1) landscape scale analysis of soil organic matter dynamics to support soil health assessments; 2) biotic and abiotic controls on soil aggregation relevant to soil health indicators.

Utilizing the strength of the above members and dozens of soil health projects, our multi-state research group has and will continue to facilitate a coordinated regional effort to develop and evaluate soil health indicators using a sound, co-designed scientific approach that has resulted in a minimum data set of indicators for several soil-environment-management system scenarios. Meetings of representatives from western Land-Grant universities, state and federal agencies, and others will continue to foster exchange of ideas and approaches, as well as participate in working groups to collaborative sub-regional projects. This proposal renewal builds upon the first phase of our multi-state project and emphasizes the need to expand the soil health outreach and education activities resulting from many of the existing projects of members.