The Texas AgriLife Extension Service of Texas A&M University reports that although no significant differences in corn yield were found between organic and chemical sources of nutrients, a Texas AgriLife Research economist found manure generates higher economic returns than anhydrous ammonia.

Seong Park, AgriLife Research economist, recently had his research published in the Agronomy Journal. The work was based on studies conducted in the Oklahoma Panhandle while at Oklahoma State University and finalized while in his new position in Vernon, TX.

The long-term experiment involved the use of pig and beef manure on irrigated corn fiel. The testing was conducted because both the Oklahoma Panhandle and northern Texas Panhandle regions have been experiencing rapid growth of animal population and density. Park reports when swine manure is stored in open-air lagoons and properly applied, and the economics calculated, the effluent offers minimal environmental and nuisance concerns.

Based on previous research, Parks explains that animal manure helps reduce both waste management costs and the need for chemical fertilizers, because it contains multiple essential crop nutrients. He says the key between animal manure transitioning from a cost to a benefit is determined by agronomic and economic factors, such as chemical fertilizer costs and equipment and labor needed to apply each.

Anhydrous ammonia was the most costly nitrogen source across all three equivalent nitrogen rates of 50, 150 and 450 lb. of nitrogen per acre, with costs of $30.86, $54.88 and $126.95 per acre, respectively. He says the higher costs of anhydrous were due to the purchase price, which is not required normally with the use of beef and swine manure. Swine effluent had the lowest costs at $12.06, $17.98 and $34.51 per acre for the three application rates.

The lower costs for the swine effluent are associated with the ability to apply it through existing irrigation equipment, requiring only minimal cost to pump from the lagoon to the center pivot, Park explains. Both the anhydrous and beef manure require the purchase of application machinery, he states, which adds a fixed cost. Because of that cost, beef manure application costs were higher than swine, at $30.52, $35.47 and $47.19 per acre, respectively, at the same rate. Beef manure becomes a more economical choice if the crops are located away from the manure’s farm of origin, Park says. While swine effluent has a lower breakeven price, it is too bulky to transport off-farm to other producers.

"The breakeven is figured by using the actual price of corn plus the cost of fertilizer," he says. "During this study, there was a widening margin in the breakeven between the animal manure-treated corn crops and anhydrous ammonia-treated corn crops, which generated an increased profitability for producers and increased the economic viability of marketing beef manure as a commercial fertilizer."

Park says if beef manure averages $2.20 per ton with a shipping cost of 50 cents per mile, it can be profitably transported up to 29 miles from its point of origin in the Oklahoma and Texas panhandles and can be competitive with high anhydrous ammonia prices, as experienced from 2005-2007.

Improved soil properties, such as micronutrient levels and soil pH, are additional benefits gained by using animal manures, Park says. Throughout his experiment the beef-manure and swine-effluent plots maintained higher soil pH levels than the corresponding anhydrous plots. Additionally, continued application of anhydrous can lead to acidification and, thus, losses in productivity, he adds. Appropriate nutrient-management practices should be implemented to prevent environmental damages.

Park says that site-specific conditions, such as weather, animal waste management practices and soil properties would need to be taken into consideration when adapting this information to locations outside of the Oklahoma Panhandle. "This is a unique economic study on various nitrogen fertilizers using rare and valuable data from a long-term field experiment from 1995 to 2007," Park says. "The next step is to determine best nutrient practices based on this experimental data."
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