Value of Hay as Fertilizer
Capture and utilize nutrients in feed fed this winter by delivering it to livestock where it can benefit the soil and enhance future forage production.
January 6, 2026
If hay is being fed, is there an opportunity to feed cattle on ground where the nutrients can be utilized for growing tame perennial or annual forages that would respond to the fertilizer? [Photo by Troy Walz.]
by Aaron Berger, University of Nebraska Extension
Have you ever stopped to think about what the dollar value of the nutrients in hay is worth as fertilizer once they have been processed by the cow?
Mature cows at maintenance should excrete 100% of the nutrients they consume in terms of nitrogen (N), phosphorus (P) and potassium (K). For example, let’s assume 100 cows are being fed 30 pounds (lb.) per head per day on a dry-matter (DM) basis of 17% protein alfalfa hay that is 0.3% phosphorus and 2.4% potassium. What is the value of the nutrients available to the pasture or field where the manure is being deposited?
- 3,000 lb. of DM alfalfa hay X 0.17 crude protein (CP) = 510 lb. of protein.
- Nitrogen X 6.25 = crude protein.
- 510 lb. crude protein divided by 6.25 = 81.6 lb. of nitrogen in the fed hay.
Only about 25%-35% of the nitrogen in manure and urine is typically available to be used by the soil for plant growth on perennial pasture or hay land the first year. The balance is lost to volatilization as ammonia or is tied up with organic matter. If planning to apply additional fertilizer, soil test prior to doing so.
- 81.6 lb. nitrogen X 0.25 = 20.4 lb. of nitrogen into the ground from the fed alfalfa hay.
The availability of phosphorus and potassium in manure and urine from feed consumed is 100%. To find the value of phosphorus and potassium in the fed alfalfa follow these steps:
- 3,000 lb. X 0.003 = 9 lb. of phosphorus.
- 3,000 lb. x 0.024 = 72 lb. of potassium.
There is approximately $60 worth of nitrogen, phosphorus, potassium and sulfur in the hay that is being fed to and excreted by those 100 cows every day.
There is approximately $60 worth of nitrogen, phosphorus, potassium and sulfur in the hay that is being fed to and excreted by those 100 cows every day.
Here is the math that calculates the value per ton of these nutrients.
- In one ton of alfalfa hay, there are approximately 16 lb. of nitrogen (N), 6 lb. of phosphorus (P), 48 lb. of potassium (K) and 6 lb. of sulfur (S) available to and absorbed by the soil in excreted manure and urine where the hay is fed.
- The fertilizer nutrient value of these minerals at current market prices is $0.70 per pound of nitrogen ($11.20), $1.00 per pound of phosphorus ($6.00), $0.40 per pound of potassium ($19.20) and $0.75 per pound of sulphur ($4.50), which would in total equal $40.90 per ton.
- This value doesn’t include other micronutrients or the benefit of organic matter in manure and hay that isn’t consumed and remains on the ground that benefits the soil.
It is common to see weed problems develop on rangeland where cattle are fed during the winter months. The nutrients from the hay are often concentrated in feed areas and the availability of nitrogen in rangeland situations often encourages weed growth. When hay is being fed, is there an opportunity to feed cattle on ground where the nutrients can be directly absorbed into the soil and utilized for growing planted perennials or annual forages that would respond to the fertilizer?
Fertilizer prices are up, and hay and other commodity feed prices are lower than they have been in recent years. Plan now to capture and effectively utilize the nutrients in feed that is fed this winter by delivering it to livestock in places where it can benefit the soil and enhance future forage production.
Editor’s note: Aaron Berger is an extension livestock educator for the University of Nebraska.
Angus Beef Bulletin EXTRA, Vol. 18, No. 1-A
Topics: Management , Pasture and Forage , Sustainability
Publication: Angus Beef Bulletin
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