The uses for compost as a soil amendment can be evaluated on the basis of characteristics: (1) fertilizer value, (2) value as a soil conditioner, (3) value for land reclamation, (4) value as livestock bedding, and (5) value as nursery container media.
The fertilizer value of compost is low. The nitrogen, phosphorus, and potassium (NPK) contents are approximately 11/2% N, 2% P and 1% K. (11/2% N, 4.6% P205, 1.8% K2O)
Compost has advantages over standard, inorganic fertilizers. The fertilizer elements will not leach unless compost is excessively applied. Compost possesses a full complement of trace elements while inorganic fertilizers on the market generally are lacking in these elements. It is important to know the amount of each nutrient released per year from the composts.
A superior value of compost is its potential as a soil conditioner. Compost eventually becomes humus and improves soil tilth. Compost provides soil aggregation or a tendency to "crumb" which in turn enhances the air-water relationships of the soil. Soil water-holding capacity and water infiltration are increased, erosion and soluble nitrogen leaching are reduced, cation exchange capacity is increased. The landscaping and nursery industries utilize most of the composts produced today.
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| The Paygro Company, Inc., in South Charleston, Ohio, composts beef cattle manure with sawdust, bark, and other wastes. Some sawdust is added for bulking in addition to that already mixed with the manure before delivery to the plant. Fifty dry tons are handled daily and are packaged for retail sale in 8-, 25- and 40-pound polybags. The plant consists of two 10' x 20' x 400' reactor bins under a 100' x 500' roof with partiality enclosed sides. |
The value of compost for land reclamation is clear. The main concern is environmental effects of phosphorous, trace elements, or certain heavy metals if compost is applied excessively. However, loadings up to 40 to 50 tons per acre have been found acceptable, particularly when applied early in the spring.
An important value for properly cured compost in livestock operations is its use as bedding. It is dry enough to be moisture absorbent. However, its main advantage over other types of bedding is its tendency to resist propagation of flies.
Another successful application for compost has been its use as an amendment in container media for nurseries and florists. Incorporation of disease suppressive composts in media with appropriate chemical and physical properties has successfully solved soilborne disease problems in nursery and greenhouse crops. Some of the container media not only suppress the diseases, but they eradicate pathogens as well. Again, proper use requires experience. For example, incorporation of excessively high levels of compost into container media increases fungus gnat problems.