Persistence of the substance on or in the soil

How long will it remain in place before being converted to another form or being lost through volatilization or leaching?

Animal waste can be deposited on pasture or rangeland, in streams where the animals congregate on hot days, or in confinement facilities where the waste must be removed and eventually returned to the land. In general, the more manure deposited by animals on pasture or feedlots or spread on the land, the greater the concentration of contaminants in runoff or percolating water.

The following examples illustrate how animal waste or the particular constituents within the waste (nutrients, bacteria) can be limited in a watershed or at land spreading sites, assuming a water quality problem has been identified and the source is a livestock operation. Measures to be used are:

• Remove all animals from the watershed.

• Reduce the number of animals.

• Use cropping systems that require more nutrients throughout the year.

• Apply wastes in split applications throughout the growing season, thereby making smaller amounts of manure available each time.

• Apply wastes over more acres at recommended rates. (Nutrient application rates far exceeding agronomic recommendations can result if, for convenience sake, wastes are applied to only the fields nearest the confinement facility.)

• Incorporate the manure, thus limiting the availability of particular constituents. P and NH4 will become bound within the soil profile and be less available for detachment.

• Collect and transport wastes to fields in other watersheds or bag the material for sale elsewhere.

• Compost the waste to reduce the availability of N.

• Treat the waste in a lagoon and land apply the waste only from the upper liquid zones of the lagoon to reduce the amount of N. Some of the N will volatilize, and some will settle.

The FOTG, Conservation Practice Physical Effects, lists the most common soil and water control practices used to prevent detachment and interrupt transport of contaminants to surface water.

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