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Fertilizing Winter Pastures - Does it Pay?

Posted Aug. 2, 2007

Since fertilizer prices remain at all-time highs, many producers ponder the question, "Is it worth it to fertilize winter pasture?" I'll try to answer that in the space below. The assumptions that I will use are that the pasture is already established, will be used to run stockers for growth, is composed of wheat, rye, ryegrass, triticale, or a mixture of two or all of these grasses, and will be completely grazed out.

Research data show that if you do not fertilize winter pastures, you will produce about 2,000 pounds per acre of dry matter forage in a season. With good grazing management, cattle can consume all the forage except about 500 pounds per acre. Simple subtraction shows that the cattle will consume about 1,500 pounds of dry matter forage per acre from unfertilized winter pastures (2,000-500).

The average response from fertilization across many research trials is about 20 pounds of dry matter winter pasture forage per one pound of actual nitrogen applied, if soil pH, P and K are adequate (soil-test to see if you need lime, P or K). If we apply 100 pounds of actual nitrogen per acre, we should produce an average of 2,000 pounds of winter pasture forage per acre above that made by no fertilization. This adds up to 4,000 pounds of winter pasture forage per acre produced (2,000 pounds per acre made with no fertilization plus 2,000 pounds per acre made by fertilizer). If we subtract the 500 pounds per acre the cattle cannot consume, we have 3,500 pounds of usable forage per acre for the stockers.

If urea costs $450 per ton, the price of actual nitrogen is $0.49 per pound. This means the cost of the fertilizer for 100 pounds of actual nitrogen per acre is $49 plus application. If we assume the application charge is $5 per acre, the total cost of nitrogen plus application is $54 an acre.

On the average, stocker cattle will gain about 1 pound per 8 pounds of dry matter winter pasture forage consumed. Paragraph two showed that we have 1,500 pounds of usable forage per acre with no fertilization. A simple calculation shows that you can produce about 188 pounds of beef per acre with no fertilization on winter pasture (1,500/8).

The fertilized winter pasture produced about 3,500 pounds of usable forage per acre for a fertilizer cost of about $54 an acre. The gain produced on the fertilized pasture is about 438 pounds of beef per acre (3,500/8). This is an increase of about 250 pounds of beef per acre for a cost of $54 an acre, making the cost of gain $0.216 per pound. Check with an economist, but I'm pretty sure that will pay.

Keep in mind that this article is not intended as a decision-making aid to determine whether you should plant winter pasture for stockers or not. There are many other costs associated with winter pasture besides fertilizer. But, if you have winter pasture, I think it shows that you should fertilize it to capture the full advantage of the pasture.

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