High phosphorous levels in your soil are usually the culprit of over-fertilizing or adding too much manure. Not only does excessive phosphorous harm plants, it can also stay in your soil for years. While there's nothing you can do to lower phosphorous levels immediately, options do exist to continue feeding your plants the nutrients they need without introducing more phosphorous.
Avoid adding manure as fertilizer. Manure is typically high in phosphorous and can quickly lead to a spike in phosphorous levels. This is especially true if manure is being added to increase nitrogen levels in the soil. Plants can usually remove slightly excessive amounts of phosphorous, but there's a limit to how much phosphorous each plant can remove each year. Plants reach that cap significantly faster when manure is added strictly to increase nitrogen.
Plant nitrogen-fixing vegetables to increase nitrogen without increasing phosphorous. Examples of such vegetables include beans and peas. If nitrogen levels are extremely low, planting nitrogen-fixing vegetables alone will not fix your problem.
Add phosphorous-free fertilizer. All fertilizers contain a string of numbers that follow this format: "X-X-X." The first number is nitrogen, the second phosphorous and the third potassium. Phosphorous-free fertilizers will always have a "0" in the second column.
Spray foliar zinc and iron on plants in high phosphorous soils. High phosphorous levels require additional zinc and iron treatments for plants to maintain their health. Texas A&M University suggests mixing a spray that contains water with 1 percent foliar zinc and iron, then applying that spray to plants every week if phosphorous levels are excessively high. You may apply it every four weeks if phosphorous levels are slightly high. Soils with 300 parts per million phosphorous will take up to five years to go back to acceptable levels.
Things You Will Need
- Foliar zinc and iron
- Phosphorous-free fertilizer
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