Past the learning curve: does soil health lower N requirements?

There’s a need to clarify whether reducing N fertilizer is possible for farmers whose long-term soil health practice shave improved soil function. Farmers refer to a steep learning curve for reduced tillage and cover crop systems, but describe eventually reducing N rates for corn due to increased biological delivery of N. It is complicated to attribute changes in N delivery to any single factor, but this question is pertinent to many farmers both at early and
advanced stages of adopting soil health management practices. We propose to test corn response to N at short-term and long-term soil health locations and compare these to conventional fields on similar soil types.

Specifically, we would perform N rate trials, determining economic optimum N rate (EONR) on three sets of tripletfarmer fields per year representing two stages of soil health adoption. Treatments would include: “Long term soilhealth” (~10 years’ of consistent cover crops and minimal tillage), “short-term soil health” (1-3 years of cover cropsand no-, or strip- till practices, after conversion from “conventional” practices), and “conventional” fields (at least 10years’ of full-width tillage, no cover crop, small grain, or perennial forage crops). Soil sampling would include organicmatter pools which have been linked to yield and N response, indicators of enhanced N delivery to corn.

This novel exploration of N use in different systems responds to farmers’ concerns about fertility needs during the transition to reduced tillage and cover crops. Partial budget assessments from each farm will clarify risk and profits associated with soil health corn production systems both in the short- and long-term. Partnering with a diverse research team and technical and outreach staff in Soil and Water Conservation Districts in three counties, we anticipate reaching growers across a broad spectrum of practices and Minnesota geographies.