Manure's Effect on Plant Growth

Nitrogen

• Nitrogen is a key component of synthetic fertilizers because of its ability to promote rapid plant growth. The building block of life, nitrogen helps plants build protein needed for their cells to grow. Nitrogen also forms a key component of chlorophyll, the pigment that lets plants derive energy from sunlight, and plays a role in metabolic processes involving the use and transfer of energy.

  Livestock manures contain nitrogen and help encourage rapid, healthy growth in plants, particularly of the foliage, seeds and fruit. The amount of nitrogen found in manure depends on the animal from which it came. Rabbits and chickens vastly outperform other livestock in terms of nitrogen. Their manures contain 2.4 and 1.1 percent nitrogen, respectively. Other livestock manures contain between 0.4 and 0.6 percent nitrogen.

Phosphorus

• Phosphorus also plays an essential role in how plants grow and use energy. Similar to nitrogen, phosphorus causes plants to grow rapidly. Plants fed phosphorus experience rapid growth of the roots, as well as abundant blossoms. Phosphorus also helps plants to survive stressful conditions, such as drought or poor soil.

  Manure acts as an organic source of phosphorus and can provide these benefits to plants. Phosphorus levels of manure also depend on the animal species. Duck and rabbit manures contain about 1.4 percent phosphorus, while chicken manure contains about 0.8 percent. Other manures contain only about 0.3 percent.

Potassium

• The third primary macronutrient used by plants, potassium also helps with protein synthesis and energy processes. Plants that receive adequate potassium produce healthy fruits and better withstand the diseases that can threaten yields. Most livestock manures contain only about 0.5 percent potassium, with the exception of sheep; their manure contains nearly 1 percent potassium.

Organic Matter

• Most commercially available fertilizers supply the three primary macronutrients -- nitrogen, phosphorus and potassium -- often in more abundant quantities than supplied by manures. As an organic fertilizer, manure differs from synthetic fertilizers in its contribution of organic matter to the soil in addition to nutrients. Organic matter improves soil structure, making the soil easier to work. Organic matter also improves the soil's ability to retain water and nutrients, resist pH changes, avoid toxic levels of trace minerals and remain disease-free. All of these attributes promote plants that grow quickly and produce abundant yields.