Soil fertility is the ability of soil to sustain plant growth and optimize crop yield. This can be enhanced through organic and inorganic fertilizers to the soil
Soils rarely have sufficient nutrient for crops to reach their potential yield. Applying organic fertilizers without prior knowledge of their properties may cause yield decline under low application or pollute the environment with excessive application. Understanding the nutrient variability and release pattern of organic fertilizers is crucial to supply plants with sufficient nutrients to achieve optimum productivity, while also rebuilding soil fertility and ensuring protection of environmental and natural resources.
An integrated soil fertility management aims at maximizing the efficiency of the agronomic use of nutrients and improving crop productivity. This can be achieved through the use of grain legumes, which enhance soil fertility through biological nitrogen fixation, and the application of chemical fertilizers.
Animal manures supply different amounts of nutrients depending on the animal species, feed, bedding and manure storage practices. The amounts of nutrients that become available to the plants depend on the time of year the manure is applied and how quickly it is worked into the soil.
Compost contains only plant material, then it is considered plant waste and carries no timing restrictions. For a product to technically qualify as compost under the NOP, it must start with a carbon to nitrogen ratio between 25:1 and 40:1 and be maintained at a temperature of between 131°F and 170°F for 15 days, during which time the materials must be turned a minimum of five times.
Blood meal is dried slaughterhouse waste and allowed under the NOP, even from non-organic animals. Blood meal contains about 12 to 13 percent nitrogen and unless used carefully, it can burn plants with ammonia, lose much of its nitrogen through volatilization and encourage fungal growth. It is also very expensive.
Fish meal and fish emulsion are, like most animal by-products, rich in nitrogen. Fishmeal contains about 10 percent nitrogen along with about 6 percent phosphate