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Animal waste must be applied to the soil so that the nutrients in the waste are not greater than the soils capacity to adsorb and store them. The rate and timing of animal waste applications are important to the protection of our natural resources (soil, water, air, plants, and animals).

Applied waste should be incorporated into the soil as soon as possible to preserve nutrient value and reduce the opportunity for runoff or odor complaints.

Incorporating manure into the soil conserves more of the ammonia (NH3)during periods of warm, dry weather and prevents NH3 toxicity to the growth of plants.

Animal waste should be applied based on a limiting nutrient, either nitrogen (N) or phosphorus (P). The rate is usually governed by the amount of N that is mineralization and the crop N requirement. However, it is important to know that using manure as a N source can result in an over-application of P).

The goal is to match the timing of the crop’s nutrient requirement with the release of nutrients from the manure. Less than ¸ the N and P are available the first year after application.

N that is mineralized from manure applied in previous years should be considered, i.e., subsequent manure rates should be reduced.

A good animal waste management program should include: achieving high irrigation efficiencies and tillage practices that maintain or improve soil tilth and reduce soil compaction and/or crusting (i.e., to maintain infiltration, permeability, aeration, and enhance the biological decomposition process).

Building a soil P residual can be beneficial in soils that readily fix P into an insoluble, unavailable form for plant uptake (e.g., clayey soils and those high in lime).

The concentration of soluble and labile P can increase significantly at high application rates of manure. Therefore, knowing the amount of clay (i.e., mineralogy), oxides, organic matter, and lime in a particular soil gives the upper limit at which P applications can occur in the soil before soluble P concentration increases, thus causing potential problems.

The soluble salt content of manure can be high and the amount must be considered when applying to farmland, where crops to be grown have a low salt tolerance. The % salt in waste may be estimated by multiplying the combined % of K+, Ca2+, Na+, & Mg2+ as determined by lab analysis by a factor of two.

The salt concentration in manure are directly related to salt levels in the cattle rations, as most of the dietary sodium and chloride is excreted. Consequently, since manure contain variable salt levels, precaution must be taken when they are used to avoid excessive salt accumulation, especially on poorly drained soils (e.g., clayey soils or soils with shallow water tables).

Manure applications can actually increase P movement into the soil because organic phosphorus is more mobile through the soil profile than inorganic phosphorus.