Since 2015, the Soil Health Institute has been working to develop a national strategy aimed at improving soil health on farms across the U.S.
Stakeholders involved with the organization — which includes farmers, ranchers, government agencies, scientists, and consumers — have been identifying gaps in key research areas, measurements, economics, communication and education, and policy, and specifying actionable steps to address these gaps.
In poring over numerous studies during this time on a range of soil health topics, they’ve reaffirmed that a chief benefit of soil health is the relationship between soil organic carbon and the soil’s capacity to hold plant-available water.
SHI’s review of research, conducted across a range of soil textures, found a 1-gram increase in soil organic carbon increases available water by 1-4.9 grams for every 100 grams of soil, say Steven R. Shafer and C. Wayne Honeycutt of SHI.
Increasing soil organic carbon can enhance resilience of soils and cropping and grazing systems, SHI says. Soil organic carbon can be increased in both rangeland and cropland, as the organization notes a 21-year study that found light, prescribed grazing can increase SOC even more than levels maintained with no grazing.
SHI has also reviewed studies that indicate across a wide range of soils and climates, cover crops can reduce nitrate leaching losses by over 60%. A meta-analysis of 69 separate studies from across the U.S. also showed that cover crops reduced nitrate leaching losses by an average of 70%.
Honeycutt and Shafer say crop rotation and nutrient management also play key roles for protecting and enhancing water quality through soil health. In fact, reduction in nitrate loss to groundwater is generally due to plant uptake of that nitrate by a cover crop, they say.
The SHI says that to ensure benefits to water quality, fertilizer recommendations for the following crop must account for nitrogen that will become available from the decomposing cover crop, or perhaps any manure applications, they say.
Since many practices used to enhance soil health also influence nutrient availability, Honeycutt and Shafer believe nutrient management is inherently a key soil health practice, and an entire “systems perspective” is required to optimize benefits and minimize nutrient losses.
Those of you who’ve been seeding cover crops on your farm are already eons ahead many of your neighbors. But to take full advantage of your investment, it’s important to identify a way to quantify the nutrient benefits of covers on your farm through proper soil testing procedures, rather than just being happy with establishment.
Are your cover crops paying off for you? It’s been said before … you can’t manage or improve what you don’t measure.