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.