RALEIGH, N.C. — In response to rising fertilizer costs and increasing grower interest in soil health practices, the N.C. Department of Agriculture & Consumer Services’ Agronomic Services Division has released a new step-by-step guide to help farmers measure the nutrient value of their cover crops and reduce fertilizer inputs.
The guide provides instructions on how to collect cover crop biomass samples, submit them for analysis, and calculate nutrient value on a per acre basis. The resource was created to give growers clear, practical steps they can apply immediately in the field. Prior to terminating their cover crops each spring, growers can follow the sampling guidelines to determine nutrient content and adjust fertilizer plans accordingly.
“There has been a growing interest in the nutrient value of cover crops in recent years,” said Dr. Kristin Hicks, lab director of the Plant/Waste/Solutions/Media Lab. “With recent spikes in fertilizer prices, we expect that interest to increase significantly. We created this quick guide with the goal of making it as easy as possible for growers to determine how much a cover crop could offset the need for fertilizer inputs.”
A key recommendation in the guide is for growers to submit samples through the Waste and Compost Analysis service instead of the Plant Tissue Analysis service — a directive that can be surprising to some.
“In the case of cover crops, you aren’t growing it for harvest but as a fertilizer for eventual land application or incorporation, similar to manure or compost,” Hicks said. “The Waste Analysis is designed to report nutrient concentrations on a per acre basis for this purpose.”
Hicks emphasized that enabling growers to quantify the nutrient value of cover crops enhances their ability to make informed fertilizer decisions.
“Growers want to get the most out of the cover crops they invest in,” Hicks said. “By giving them straightforward sampling methods and quick nutrient calculations, we hope to empower them to reduce input costs while improving their soil’s long-term productivity.”
Cover crops provide a range of agronomic benefits. For example, legume species such as crimson clover, hairy vetch and Austrian winter peas fix atmospheric nitrogen, reducing the need for synthetic nitrogen fertilizers. Cereal species like barley, oats and rye scavenge leftover nutrients from previous crops, keeping them in the rooting zone for the next planting. Cover crops also help increase soil organic matter, suppress weeds, reduce erosion and improve water holding capacity.
Step-by-step guidelines and a printable field guide are available on the Agronomic Services website at www.ncagr.gov/Agronomic-Services by clicking on the “Determining the Nutrient Value of Cover Crops” link.
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