Manure is one of the largest nutrient resources available on many farms, yet its fertilizer value is often underestimated in nutrient management plans. When properly credited, manure can supply substantial nitrogen to crops while reducing reliance on commercial fertilizer.
Recent on-farm research conducted through the Cornell Nutrient Management Spear Program highlights the value of manure in corn production systems. Through the Value of Manure Project, scientists have been evaluating how manure contributes to crop nutrition under real farm conditions. Results from these trials show that dairy manure can significantly reduce fertilizer nitrogen requirements while maintaining or improving corn yields.
To evaluate manure performance under realistic conditions, researchers partnered with dairy farms across New York. Rather than using small research plots, the team established replicated strip trials within commercial corn fields.
These strips allowed researchers to compare areas receiving dairy manure with areas managed primarily with commercial fertilizer. In several fields, additional sidedress nitrogen fertilizer was applied to determine whether extra nitrogen improved crop performance following manure application.
This approach allowed the research team to evaluate manure performance across a wide range of soil types, weather patterns, and management practices typical of dairy farms.
Less nitrogen from fertilizer
Across multiple sites and growing seasons, manure consistently supplied nitrogen that supported crop growth. On average, corn fields receiving manure required approximately 20 to 25 pounds less fertilizer nitrogen per acre to achieve yields comparable to fields without manure. In several trials, applying additional fertilizer nitrogen after manure application did not significantly raise yields.
Continue reading this article published in Journal of Nutrient Management.
