On-farm research explores the linkages between pasture management, soil health and ecosystem services

Story by Abby Augarten

There is increasing interest among farmers to manage for soil health because of its ability to impact productivity, nutrient cycling, carbon sequestration, and water quality. However, when it comes to measuring soil health there are challenges determining which soil health tests are most beneficial and accessible to farmers, what the impacts of management are, and what constitutes a good benchmark for a healthy soil?

Research focused on identifying valuable and reliable soil health measurements that are responsive to management can provide farmers with tools to manage their systems to improve and track soil health.

Grassland 2.0 folks at UW-Madison, the UW-Madison Center for Integrated Agricultural Systems (CIAS) and Wisconsin graziers are collaborating this season to address these soil health measurement challenges and equip graziers with the tools to monitor and address soil health in real time.

First, a little background.

When it comes to soil health measurements, there are indicators to measure the three different properties of soil health – chemical, physical, and biological. Chemical properties, including soil pH and nutrient levels, are well-studied and commonly used to inform management decisions. Only recently have the biological and physical components of soil health been explored as valuable measurements. Biological soil health indicators have become popular tools as indicators of nutrient cycling and agronomic performance and often measure the active pool of organic matter in the soil. By measuring potentially mineralizable nitrogen (PMN), mineralizable carbon (C-min), permanganate oxidizable carbon (POXC), and soil protein (ACE) we can better understand microbial activity and the food sources available to sustain the microbial community. Physical soil health indicators, including wet aggregate stability, provide insight into the soil’s ability to resist runoff and erosion, drain or store water, and support plant root growth. Soil health assessments that quantify specific biological, chemical, and physical indicators of soil function can help to evaluate these relationships.

^{While results vary based on soil type and management, overall, the results are clear. Well-managed pastures rank highest in soil health assessments.}

In several soil health research studies conducted at the Wisconsin Integrated Cropping Systems Trial which measure soil over a thirty year time period, the well-managed pasture had higher biological and physical soil health indicators compared to annual cropping systems(1,2,3). Despite these findings, most of the soil health research in the Midwest has focused on annual cropping systems. To address this gap, colleagues at UW-Madison and UW-Madison CIAS are working with graziers to conduct soil health research on pastures in the Driftless and Central regions. .

By their nature, well-managed pastures include many soil health practices – continuous cover, grazing livestock, species diversity, and absence of tillage. These contribute to the high performance of pastures in soil health assessments. However, there is also a lot of variability in how pastures are managed. The relationship between pasture management and soil health metrics has yet to be explored.

Each pasture is unique in soil type, landscape, and management. In Wisconsin, there are a diversity of management approaches regarding rotation, stocking density, pasture species composition, soil fertility management, and winter grazing practices (4,5). How do these management approaches impact soil health?

This season, folks on the Grassland 2.0 team are working to measure and analyze biological and physical soil health indicators across Wisconsin pastures with different management approaches to create pasture-specific soil health benchmarks. Having these benchmarks will allow Wisconsin graziers’ to make better decisions about their soil in real time and answer key questions about their soils – Is there room to improve my soil health? What management practices offer the most potential to build my soil health? What ecosystem benefits can I expect from my current management approach?

Soil sampling and in-field assessments will begin this June in collaboration with thirty graziers located in the Driftless and Central regions of Wisconsin.

Abby Augarten, Research Assistant in the Ruark Nutrient Cycling and Agroecosystems Lab