High nitrogen in soil can be reduced by continuing to grow plants at the site. Grass or leafy vegetables use a lot of nitrogen and can be used to reduce the N levels in soil. Corn, lettuce, spinach, kale or cabbage are a few plant types that could be grown to use the excessive nitrogen. Avoid trying to leach the nitrogen from the soil, since it could possibly leach into ground water. The existing soil can also be diluted by adding a low nutrient soil at a rate of about 50:50 in the top 6-8 inches. If you have raised beds, you can remove some of the existing soil and add the low nutrient soil. If you have in-ground beds, then the addition of the soil may raise the soil level somewhat.