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Swine Manure for Spring Planting

Updated April 20, 2023
Ryan Samuel

Ryan Samuel

Assistant Professor & SDSU Extension Swine Specialist

Additional Authors: Anthony Bly
Tractor loading a liquid manure applicator in a bare field.
Swine manure is a valuable fertilizer that offers many benefits to farmers and the environment. Courtesy: Canva

The application of swine manure in the fall means nutrients for spring-planted crops and soil nutrient building for nutrients applied beyond crop needs. Therefore, it is important to understand and account for the available nutrients in your fertilizer plans. The nitrogen content tends to be the focus nutrient to consider from liquid swine manure, but the phosphorus and potassium contributions to crop production should be accounted for spring planting. Additionally, swine manure can also provide other micronutrients, such as calcium, magnesium, sulfur, sodium, iron, manganese, zinc, and copper.

Nitrogen, with contributions from organic and inorganic forms, provides nutrients for plant growth. The nitrogen levels in swine manure are difficult to generalize, because the phase of production (sows versus nursery, grow-finish or wean-to-finish) and the use of feed formulation strategies and/or feed additive technologies will alter the levels of nitrogen coming from swine operations. There is no good standard book value for manures, and it is important to get an accurate determination of the swine manure nutrient profile by submitting samples to a commercial lab. For calculation of the available nitrogen from the manure sample analysis report, consider that 35% of the organic nitrogen is available for the first year and 50% of the organic nitrogen is available in year two. The relatively slow release of nitrogen from organic matter decomposition reduces potential leaching and runoff. However, swine manure application is applied at rates that limit potential environmental impacts and excessive nutrient buildup in the soil, but, at the same time, provides nutrients for optimal crop production.

Phosphorus levels of swine manure can be influenced by the inclusion of exogenous feed enzymes, such as phytase, into the diets and the corresponding reductions in dietary phosphorus inclusions. Therefore, as with nitrogen, it is important to determine the phosphorus content of the swine manure. Crop photosynthetic energy process are highly dependent on phosphorus. Potassium provided by swine manure controls crop plant nutrient and water transport and improves overall health and disease suppression. As with nitrogen, phosphorus and potassium contents are reported as P2O5 and K2O and are directly equivalent to the commercial fertilizer rate. All forms of phosphorus (abbreviated as P) and potassium (abbreviated as K) in the manure sample at the laboratory are measured and reported in total P and K found in the manure.

Injection of swine manure is the most-common practice to reduce any odor and loss of nutrients. When injected, 98% of the inorganic manure nitrogen (abbreviated as N) can be credited to the crop needs, since most of the inorganic N is in the ammonia/ammonium forms. The ammonia N form is a gas and can escape into the atmosphere.

Swine manure is a valuable fertilizer that offers many benefits to farmers and the environment. High nutrient content, slow release of nutrients, and rich micronutrient profile make swine manure an excellent choice for promoting healthy plant growth and improving soil fertility. Producers can promote sustainability and achieve high yields, reducing the need for synthetic fertilizers without over-applying swine manure and stretch this important on-farm commodity across more acres. Manure and soil testing are key information components to making this manure/crop system highly efficient.

Related Topics

Swine, Soil Fertility, Soil Health