Farm Horizons, February 2003
A scientific look at issues involving livestock
By Jim Salfer
Some folks see livestock as an environmental problem and large livestock operations as a threat to the social structure of rural America.
Others cite livestock as rural areas' best value-added industry and an important source of local, well-paying jobs.
Often, these arguments become heated and emotional. To add some light to this debate, I researched the scientific literature. Here's what I discovered through that effort:
Livestock manure and water pollution
Many people believe that livestock around our lakes and rivers increase the risk of pollution.
But research shows the opposite to be true. University of Nebraska scientists summarized all of the research across the country 16 studies examining the effects of manure application on nutrient runoff and soil loss.
These trials showed that nutrient runoff was reduced by 2 to 62 percent, and soil loss was reduced by 15 to 65 percent from the application of manure. The research also showed that runoff and soil loss declined as manure application rates increased.
The research data indicate that if manure is handled properly, it reduces the risk of water pollution. The scientists believe this is because the manure improves the organic matter content and physical property of the soil.
Livestock numbers and land area for manure
The amount of land needed for manure application is sometimes cited as a concern. In 1997, here in Stearns County, we did a comprehensive evaluation of the mix of crops, animal numbers and the nutrient requirements of crops. Stearns County has by far the most livestock of any Minnesota county.
However, the evaluation showed all the manure in Stearns County only provides about 28 pounds of nitrogen per acre of land in crops that use nitrogen (corn, potatoes, oats, and so on).
Typically, crops need 100 to 150 pounds of nitrogen per acre for good yields. Thus, all of the manure can potentially provide only about 20 percent of the nitrogen needed by the crops.
Diversified land use and erosion protection
Livestock, especially those that graze or use forages, tend to increase crop diversity.
When cows end up leaving a farm, the farm generally becomes a cash crop farm producing mostly corn and soybeans, regardless of the slope of the land. The land mix is no longer likely to include small grains, alfalfa and pasture.
Without these soil covers, heavy rains can cause large gullies and extensive soil erosion that reduces water quality in lakes and streams.
There is odor associated with livestock. However, with the newer manure-hauling equipment and incorporation of manure into the soil, the strong odor is usually limited to periods of pumping and hauling. Some people believe it is their right to live in a rural agricultural area without the smell of livestock next door.
Although this may be true, a case can also be made that livestock producers have the right to make decisions that allow them to reach their personal and business goals. This may mean expanding their businesses. And producers who can't stay in the livestock business may opt to sell to land or housing developers.
Livestock increase local economic activity. University of Minnesota research has shown that dairy producers tend to buy more of their inputs and personal items closer to home than do nonlivestock producers.
Every 1,000 dairy cows generate about $2.83 million in cash flow. Farm business management. Records also show that the typical central Minnesota farm family spends over $327,000 annually, with most of that spent in the local community.
Coexistence of a large human population with livestock
Lancaster County, Pa., has about 470,000 people and a population density of 496 people per square mile. Stearns County, Minn., has about 133,000 people and a population density of 106 people per square mile.
Both counties have high livestock numbers. Data from these two counties show that livestock and people can live and thrive together.