Things You\’ll Need
Soil test kit
Nitrogen-binding grasses or legumes
Animal manure can cause soil nitrogen levels to rise.Jupiterimages/Photos.com/Getty Images
Nitrogen is an important plant nutrient, responsible for promoting leafy green foliage in plants. Phosphorus and potassium are the two other important plant nutrients. However, the amount of nitrogen in your soil can sometimes become excessive, especially if you use large quantities of animal manure, which is very high in nitrogen. Soil nitrogen levels change over time, so testing your soil will reveal how acidic or alkaline it is. Soil with a pH of 6.0 or lower is very acidic and might contain excess nitrogen.
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Test your soil to determine whether it is acidic or alkaline. If it measures 6.0 or lower, it is acidic and may contain excess nitrogen.
Limit nitrogen-based fertilizer if your soil test reveals a pH under 6.0. Instead, use organic compost and mulch, both of which have a lower nitrogen content.
Plant nitrogen-fixing cover crops in the areas of your soil that have excess nitrogen. Grasses and legumes, such as fava beans, are good choices to plant in such areas because when you harvest them, excess nitrogen will cling to their roots and be removed from the soil.
Dig hydrated lime into your soil. If it is sandy, use 4 ounces of lime for every square yard of soil; if it is clay, use 12 ounces for every square yard.
Dig organic materials into your soil to raise the pH level and help to neutralize excess nitrogen. Good choices include hardwood ash, crushed marble, bone meal and oyster shell.
If your climate allows you to grow cover crops over winter, plant them in fall. If not, plant them in early spring, as soon as you can work the soil.
Be patient when you attempt to raise the pH of your soil. After you add nitrogen-neutralizing materials, the pH takes time to rise.