Manure has changed over the years, more so in value than composition.

More and more, people recognize manure's true value. The nitrogen content in finishing manure is down 10-15%. Phosphorus content is as much as 50% lower than it was just a few years ago.

Bill Crawford would know. He analyzes manure from southern Minnesota farms as a service he likes to call “post-nutritional engineering.”

Crawford is the environmental manager for Preferred Capital Management, a swine management company in Fairmont, MN.

As a resource, manure is becoming increasingly valuable as the cost of commercial fertilizer keeps increasing. Feeding strategies like split-sex feeding, phase feeding and wean-to-finish programs have all affected what ends up in the pit. By targeting the nutritional needs of the pig, extra nutrients are minimized, so less ends up in the manure, says Crawford.

That doesn't mean the manure has fewer nutrients. “It's become more concentrated because we also don't waste as much water in these buildings. So the nutrient density of the manure is higher — there are more pounds of nitrogen (N), phosphorus (P) and potassium (K) per tanker load today, and it will cover more acres,” he notes.

If a farm is feeding phytase, there is a 30-50% reduction in the amount of phosphorus in the manure.

Using synthetic amino acids will reduce nitrogen in the pit, but not as dramatically as phytase, he says.

New feeding strategies that use DDGS from ethanol production have some effect on the nutrient content of manure, but have more implications for the nutritionists and feedmill operations putting the swine rations together.

Cost Benefits

Compared to commercial fertilizer, the nitrogen and phosphorus in swine manure is typically 80% available and potassium is 90% available when incorporated into the soil for the next crop. Cost differences, however, are great.

“Swine finishing manure applied to a field supplying the correct amounts of N-P-K to raise 200-bu./acre corn may cost $40-$60 an acre. The same amount of N-P-K from a fertilizer plant might cost $100 or more per acre,” says Crawford. “That's huge money when looking at the cost of producing corn on those acres.”

The attached spreadsheet (Table 1) shows price trends for fertilizer over the last four years. Table 2 shows manure analysis results for sows and finishers, with and without phytase.

Crawford says sow manure is much less nutrient dense due to feeding programs and increased water usage. Manure application rates of 10,000 to 11,000 gal./acre to get the correct nutrient level from sow operations are common. Finishing facilities, on the other hand, may have application rates of 3,500-4,000 gal./acre to supply the same amount of N-P-K per acre.

Skyrocketing Fertilizer Prices

The trend is apparent: N, P and K costs keep going up. “There is a reduced value of P component in manure, but typically we're still putting enough P out there for the next corn crop, even when phytase is used in the feeding program. We simply don't have the excess we used to have,” Crawford explains. “The number of swine units lowering the amount of excess nutrients being land-applied through manure, particularly phosphorus, is a positive step toward protecting the environment.”

Both crop farmers and pork producers are benefiting from the high cost of commercial fertilizer. Grain farmers are putting up hog buildings in return for the manure. Pork producers who don't have the land base can expand, and crop farmers can get fertilizer for their corn crops for less cost per acre.

Table 1. Fertilizer Prices Over Time in South Central Minnesota
Fall 2003 Fall 2004 Fall 2005 August Price Estimate 2006
Nitrogen cents/lb. of N
0.195 0.244 0.256 0.26
Phosphate cents/lb. of P
0.255 0.283 0.33 0.30
Potash cents/lb of K
0.138 0.158 0.217 0.21
Table 2. Average Nutrient Content of Manure for Sow Farms
Total Pounds of Nutrients per 1,000 gallons of Manure
Nitrogen, 21 lb. Phosphorus, 17.5 lb. Potassium, 11 lb.
Sow Farms using Phytase
Nitrogen, 20 lb. Phosphorus, 12.1 lb. Potassium, 10.6 lb.
226 Phytase units per ton of feed
Average Nutrient Content of Manure for Finishing Farms
Total Pounds of Nutrients per 1,000 gallons of Manure
Nitrogen, 59 lb. Phosphorus, 39 lb. Potassium, 34 lb.
Finishing Farms using Phytase
Nitrogen, 49 lb. Phosphorus, 19 lb. Potassium, 35 lb.
226 phytase units per ton of feed