Manure as a Fertilizer Makes Cents

Chris Augustin, NDSU Extension Service Nutrient Management Specialist

Before the 1940's manure was the predominant fertilizer. Since that time, advances in technology allowed humans to mine and create fertilizer that was affordable and easy to manage. Through the years the value of manure was forgotten. However, with the current high prices of conventional fertilizers, manure is again looked at as a high valued fertilizer.

I early May, the Carrington Research Extension Center applied the winter accumulated manure. Prior to the application the soil and manure were sampled for nutrient analysis. The manure analysis showed that in each ton of manure there were 10 pounds of nitrogen (N), 8 pounds of phosphorous (P), and 10 pounds of potassium (K), all plant available (10-18-10). Accounting for the cost of custom hauling and applying the manure, the cost of the nutrients from the manure was $0.10/lb N, $0.08/lb P, and $0.10/lb K. This is roughly one-sixth the cost of anhydrous ($0.64/lb N), one-thirteenth the cost of 11-52-0 ($1.09/lb P), and one-fourth the cost of potash ($0.41/lb K). Figure 1. illustrates the cost of one pound of plant available nutrient from various fertilizers.

Not only do you gain fertilizer benefits, but manure is also a soil enhancer. Manure is rich in organic matter, which increases water holding capacity, reduces erosion, prolongs fertility, and adds important soil microbes. Consequently, conventional fertilizers only add nutrients.

The cost to haul manure may seem high, but when you calculate the crop nutrient value, it is quite affordable. In this scenario, the manure was hauled over three miles and the loads were less than full to ensure that no manure was spilled onto the highway. If the manure is hauled a shorter distance and the travel route allows for maximum load weights, the cost is even less.

Manure must be sampled and applied properly. Conventional fertilizers and spreaders are calibrated and so should manure spreaders. Spreader calibration ensures that desirable amounts are applied, which reduces the potential to pollute. Most crops require approximately 4 parts of N for every part of P and manures typically have near equal amounts of N and P. Because of these inconsistent ratios, it is very important to soil test and track soil P levels when applying manure to meet crop N requirements. Other costs fo occur with manure, including cleaning of pens and storage. However, scraping and cleaning of pens is important for good pen management and there are application costs for spplying conventional fertilizers as well.

A few crop producers have started to purchase manure or help pay for the hauling and application costs of manure to their land. These producers realize the benefits for the soil and their crops; while at the same time save money on fertilizer inputs.