Manure | Archives | Aggie Horticulture
Manure

1. Q. I have been using manure for years. I am glad that you have finally recognized the benefits of manure and will hopefully use your influence on local agricultural producers to use manure rather than commercial fertilizer. They are poisoning our environment.

A. Wrong, manure shoveler! Unfortunately, I will not be able to recommend the use of manure by large scale farming operations. The wide scale use of manure to fertilize large acreage of cropland is a logistical impossibility. If all the cattle feedlot manure collected in Texas were assembled and uniformly distributed at an annual application rate of 10 tons per acre, it would only cover 400,000 acres of farmland. That is all the farmland within a 50 mile radius of San Antonio. A little arithmetic shows that all the manure from a 25,000 head feedlot could be used up within a 1.6 mile radius of the feedlot if every neighboring farmer applied it at the 10 ton per acre application rate. It would only take a 2.3 mile radius around the feedlot for all the farmland to be fertilized annually with 5 tons per acre. The problem is nutrient concentration. Horse manure has a plant food content of about 0.75 percent each of nitrogen and potassium, and about 0.25 percent phosphate. Commercial fertilizer such as urea has 46 percent nitrogen. To produce the crops which are presently grown in the U.S., 57 million metric tons of urea will be used annually. Since manure is 61 times weaker, it would take 3,420 billion metric tons (7 trillion 48 billion pounds) and that is a lot of shoveling for even the most dedicated of the manure advocators. Besides, just think of the strain it would put on the digestive systems of U.S. animals -- the animal rights people would never stand for it!


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