The adage about one person's trash being another person's treasure applies to animal manures used appropriately to supply nutrients to crops as well as to hay and pasture fields.

Animal manures are a good source of nutrients for forage crops and can be put on fields almost anytime during the growing season. In addition to nitrogen, manures contain potassium and phosphate that many pasture and hay fields need, according to Monroe Rasnake, Extension soils specialist with the University of Kentucky College of Agriculture.

"Following some basic guidelines will help you to reap the most nutritional benefit from animal waste and reduce the risk of any environmental problems," he said.

To be sure the crop is receiving the nutrients it needs, Rasnake recommended that farmers take soil test samples every three or four years and keep records of soil nutrient levels. Also maintain accurate records of application rates and times. These practices will help farmers plan future manure applications.

"When sampling animal manure to measure its nutrient content, take samples as close as possible to the time you plan to apply it," he said. "This will give you more accurate information on the amounts of nutrients being applied and will help you decide whether to apply additional fertilizer. Calculate the application rate needed to provide the crop's nutrient requirements. Never apply manure at rates higher than needed solely to supply nitrogen.

"To reduce the risk of environmental problems, don't apply manure to frozen or wet soils because heavy rains could wash the manure directly into streams. Another consequence is soil compaction from using application equipment on wet soils. To prevent water contamination, never spread manure near or in streams, sinkholes or water wells."

Rasnake gave more guidelines to gain benefit from nutrients in animal manures.

* Apply manure close to the time a crop needs the nutrients. For example, the best application times for cool-season forages would be in late summer to early fall and from late winter to early spring.

* Apply manure soon after a field has been cut for hay or grazed. Manure might damage forage plants if applied before harvest, or animals might refuse to eat the forage.

County Extension offices have materials to help farmers make wise decisions on using animal manure on crops, including information on taking soil test samples, calculating the nutrient value of the manure, and other management considerations.