USDA PHOTO
Manure Happens: Usage & Benefits Composting manure.
BY CHRISTOPHER CUMO Before the advent of industrial agriculture, manure was a go-to fertilizer and soil amendment. Farmers who kept livestock had their own natural fertilizer factories. Today growers know that many organic materials — grass clippings, pine needles, leaves and other plant materials — can be beneficial, but manure is sometimes viewed as too unpleasant, at least when fresh, to keep pace with the fertility needs of large-scale farming. This juxtaposition of old practices and a 21st century mentality requires a renewed appreciation of manure’s benefits. For eco-farmers striving to use the best inputs available, the quality of manure used to boost crop and soil health is a growing concern. One question is whether manure produced from pastured livestock is superior to manure from confined animals. Retired University of Nebraska soil scientist and crop nutritionist Charles Shapiro cautions that “‘better’ is a vague term with no scientific information,” making notions of improvement or betterment difficult to evaluate because personal preferences come to the fore. The progressive farmer knows that some people gravitate toward unsupported generalities and that any manure assessment depends on mea56 Acres U.S.A.
surable parameters. That is, farmers are as ready as scientists to embrace empiricism in judging manures.
HAPPY MEDIUM Kentucky organic farmer and stockman Lisa Munniksma frames her position in terms of manure management options. Her four-stage process stands at the junction between old and new — a recurrent theme, because she advocates that modern farming return to a time when livestock roamed the pasture dropping dung at intervals to deliver optimal nutrients to the soil, neither depriving nor supersaturating it with organic compounds. In Munniksma’s vision, simplicity defines the best approach to improving and maintaining soil health. Too little organic matter degrades croplands, dismaying farmers and policymakers alike. Soil without organic materials is little more than pulverized rock. Geologists and paleobotanists have demonstrated that no land plants grew during Earth’s early epochs due to a lack of organic matter. Eons passed before enough bacteria, yeasts and other microbes had decayed to provide the organic compounds necessary to nourish plants. Scientists call these microbial aggregates stromatolites; their decay yielded the organics suitable for absorption by plant roots,
although the first terrestrial plants might have lacked roots. Aspen Grove Gardens owner Robert Pavlis warns that too much organic matter is a problem as well. It can skew soil pH and imbalance nutrients. Pavlis pinpoints manure as the most potent and easily overused organic soil amendment, calculating that annual additions can endanger soils by distorting the nitrogen and phosphorus ratio, altering soil pH for crops that tolerate only modest variations. Changes in soil pH especially hurt legumes, whose roots house nitrifying bacteria that perish when too many or too few acids impair microbial metabolism. These problems plague an entire species, Phaseolus vulgaris. Vulgaris is the root of the English word “vulgar,” which just means “common.” But nothing is ordinary about this species because it contains most New World beans — the lima bean being a notable exception. Without P. vulgaris, global nutrition would arguably collapse. Even in food surplus nations like the United States, Walmart shelves would look barren without cans and jars of kidney (both red and white), great northern, pinto, black, navy, flageolet, cranberry and wax beans. Many texts preach what might be termed force-feeding, recommending the addition of as much manure as can be hauled in during a day’s exertions. This difficulty reinforces Munniksma’s position that soils need only moderate doses of manure to be healthy, an aim achieved by allowing livestock to roam while they eat and excrete. Wherever livestock are confined, manure is produced. This requires stockmen to discard it, notes food and agriculture writer Tove Danovich, leading to excessive algae and bacteria in water, which in turn can cause human illnesses via infections such as E. coli. University of Nebraska biological systems engineer Richard Koelsch adopts the chemical and nutritional perspective that manure’s ability to promote soil health and fertility depends on what livestock eat and on how well they derive nutrients from it.
