Optimize crop growth with manure

By Scout Nelson

Manure is not only a significant source of nutrients for crops but also a complex element to manage, especially when it comes to phosphorus. This nutrient is essential for plant growth but poses environmental risks if mismanaged. Unlike nitrogen, phosphorus binds to the soil, which can be beneficial for reducing loss through leaching but problematic due to its potential buildup and runoff.

Phosphorus in manure occurs in two forms: inorganic, which is immediately available to plants, and organic, which requires mineralization by soil microbes to become available. This process varies significantly depending on environmental conditions.

Efficient management of these forms is key to utilizing the full potential of manure while safeguarding against over-application that leads to environmental degradation.

In the soil, phosphorus exists in three pools: solution, active, and fixed. Solution phosphorus is readily available for plant uptake, active phosphorus attaches to soil particles and is released slowly, and fixed phosphorus breaks down very gradually, providing a long-term supply but at an almost negligible rate annually. Understanding these pools helps in strategizing for sustainable phosphorus use in agricultural settings.

Testing manure for its phosphorus content is a critical step in managing its application. Nutrient levels in manure can vary widely depending on factors such as animal diet, housing, and manure storage methods.

Testing ensures that the application rates meet crop needs without leading to excess phosphorus in the soil. In regions like Minnesota, phosphorus availability from manure is estimated at 80% when calculating application rates, although this figure can vary by state or region.

Farmers are encouraged to test their manure and apply it based on the specific phosphorus requirements of their crops. This practice not only promotes optimal crop growth but also mitigates the risk of phosphorus runoff into nearby water bodies, which can lead to algal blooms and other ecological problems.

By adopting smart testing and application practices, farmers can make the most of the nutrients in manure while protecting natural resources. Understanding and managing the dual nature of phosphorus in manure is essential for modern, environmentally responsible farming.

Photo Credits:gettyimages-eugenesergeev