Phosphorus is an essential macronutrient for most crops, so it’s needed in the soil. But you know what they say about too much of a good thing. Soils with high phosphorus levels can lead to runoff, putting the environment (especially waterways) at risk. Many areas have regulations requiring a plan to reduce high soil-phosphorus levels over time. From a general nutrient management standpoint, we recommend refraining from applying phosphorus to the soil until the high levels have drawn down to a more moderate level.
With commercial fertilizer, this is easy: simply don’t apply a phosphorus fertilizer. If manure is your most common nutrient source, this is trickier. The nutrient ratio of manure is fixed, so we can adjust the application rate up and down, but the overall ratio of nitrogen to phosphorus (and all other nutrients) will remain the same. As if that weren’t challenge enough, manure also tends to overapply phosphorus for most crops when applied at a nitrogen-based rate.
Here are five ways to manage high phosphorus soils while using manure:
1. Refrain from manure application on high phosphorus areas
The best way to lower phosphorus levels is to avoid applying that nutrient for a few years. This may not be possible for those with large amounts of manure and few spreadable acres.
2. Acquire more land
Increasing manure-spreadable land base (while maintaining the same amount of manure) will allow more flexibility with application so high phosphorus fields can be skipped. Though this might not be financially feasible for many, it’s worth considering as a long-term goal for farms that have many high-phosphorus fields.
Source: umn.edu
Photo Credit: GettyImages-CasarsaGuru
Categories: Minnesota, Crops