Manure is making a comeback, not just as a nutrient source but as a long-term investment in soil health, crop yields and fertilizer savings.
New data from Cornell University’s Nutrient Management Spear Program (NMSP) and PRO-DAIRY confirm what many farmers have long suspected: manure’s magic doesn’t stop after one season.
In a report titled “The Power of Manure: Boosting Yields for Multiple Years,” researchers Aidan Villanueva, Juan Carlos Ramos Tanchez, Kirsten Workman and Quirine M. Ketterings show that the right kind of manure management boosts bushels, strengthens soils and trims the nitrogen tab for more than one growing season.
“Manure contains all 17 essential nutrients,” the paper begins, and when managed right, it supports a circular economy – reducing dependence on chemical fertilizers while reinforcing soil resiliency.
The trickiest nutrient to tame is nitrogen (N). Unlike other nutrients, N in manure comes in several forms, some available immediately, others slowly released as organic matter breaks down. That slow-release feature turns manure into a two-season powerhouse.
To test its long-term value, the researchers launched the “Value of Manure” project, backed by the New York Farm Viability Institute, Northern New York Agricultural Development Program, USDA-NIFA and NYS DEC. The project now includes data from 19 trials across three years, but two standout trials, at “Farm A” in Central New York and “Farm B” in Northern New York, offered two full years of side-by-side analysis.
At both farms, researchers applied manure to three crop strips in 2023 and left three untreated. Each strip was divided into six subplots receiving different amounts of sidedress N, from 0 up to 200 lbs./acre. No manure was applied in 2024, allowing for an analysis of second-year benefits.
They then calculated the most economical rate of nitrogen (MERN), the fertilizer “sweet spot” where returns from added yield no longer outweigh the cost of added N.
At Farm A, with its Lima silt loam soil, manure made an immediate and enduring difference in corn grain yield.
In 2023, with no sidedress N, manured plots yielded 101 bushels/acre, compared to just 69 bushels/acre on non-manured ground – a 32 bushel/acre bonus from the barn. Even in 2024, a year later, the manure-treated strips still produced 64 bushels/acre vs. 57 bushels/acre, showing a seven-bushel second-year advantage.
When fertilizer was applied at the MERN, manure still mattered. In 2023, manured plots yielded 176 bushels/acre compared to 155 bushels/acre for untreated ones. In 2024, yields were 200 vs. 187 bushels/acre – meaning manure gave a 13 bushel/acre second-year bump even with fertilizer applied.
Manure also influenced fertilizer needs. In 2023, manured plots needed 13 lbs./acre more N to reach MERN, but in 2024, they needed 36 lbs./acre less, confirming carryover contributions. Across both years, manure reduced fertilizer needs by 23 lbs. N/acre, boosted yields by 34 bushels/acre and increased profitability by $159/acre, not counting application costs.
At Farm B, on Grenville loam soil, manure worked similar wonders on corn silage.
Without sidedress N, 2023 yields reached 24.8 tons/acre on manured plots, beating non-manured plots by 4.2 tons. In 2024, manured plots still led by 1.7 tons/acre.
At the MERN, manure added 1.4 tons/acre in 2023 and 0.8 tons/acre in 2024. More dramatically, in 2023, non-manured strips needed 109 lbs. N/acre more to reach MERN, a major fertilizer offset. However, in 2024, sidedress needs were the same in both treatments, suggesting the residual benefit faded more quickly in this silage system.
Even so, manure delivered a two-year gain of 5.9 tons/acre without sidedress N and 2.2 tons/acre at the MERN. The bottom line? An added $206/acre in value from manure over two seasons.
Across both farms, the data painted a clear picture: manure offers both immediate and residual benefits that add up to serious savings and yield bumps.
Over two years:
- Farm A saw cumulative grain yield increases of 39 bushels/acre (no sidedress) and 34 bushels/acre (at MERN), with 23 lbs. N/acre fertilizer saved and $159/acre gained.
- Farm B enjoyed 5.9 tons/acre extra silage (no sidedress), 2.2 tons/acre at MERN and 109 lbs. N/acre saved in 2023, with a $206/acre windfall.
With trials continuing into 2025, the researchers will soon see whether manure’s third-year impact still holds strong. For now, the message is clear: this waste has lasting worth.
