Manure Makes a Comeback

Since the development of the Haber-Bosch process (the basis for all synthetic nitrogen fertilizers) in the early 20th century, farmers have turned away from manure as a fertilizer.

Today, with synthetic fertilizer costing nearly $1,000 per ton, manure is again becoming a cost-effective way of putting nitrogen and other nutrients back into the soil.

According to livestock environment associate specialist Tommy Bass, a ton of manure contains between $30 to $40 dollars’ worth of nutrients, although not all will be available to the soil in the first year.

In addition to nitrogen, manure provides a wide range of nutrients, including phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, copper and zinc.

Manure was replaced by synthetic fertilizer in part because it is difficult to transport and can be costly to spread. Moreover, not all manure has the same nutrient content. According to professors at the University of Michigan and Purdue University, “Efficient use of manure as a fertilizer is complicated by the imbalance of nutrients in manure, variability in many sources of manure, difficulties in estimating nutrient availability, and the relatively low nutrient concentration limiting the distances manure can profitably be transported.”

Despite these disadvantages, farmers, environmentalists, academics and government officials are working together to find new ways of effectively reusing this natural waste. For example, in 2005, agricultural, environmental and political leaders in the Shenandoah Valley were working together to encourage new technologies to store and process poultry and other farm animal manure as well as efforts to effectively transport manure to areas where it was needed.