The most noticeable sign visible to the naked eye that you have a overabundance of nitrogen in your soil is beautiful, lush, green plants with very few or unreasonably small fruits or flowers. You may also find some leaves wilting, then turning yellow to brown, and looking burnt.
To be sure, though, you should test the soil. There are home testing kits you can use or you can send soil samples to a lab. Once you have the results, then you'll know how you need to proceed to amend your soil to proper levels. If you find you have too much nitrogen, follow these guidelines to help your garden become a welcoming haven to flower and vegetable growth. It is not recommended to make any of these modifications without a proper soil test, though, to ensure you are doing the correct thing for the health of your soil.
Choose Nitrogen Absorbing Plants
The easiest solution for any gardener is to plant more things that bind nitrogen. Corn, cabbage, squash, and broccoli are a few examples. These nitrogen absorbing plants will most likely not have very many or very strong fruit or flowers, as they are acting as sponges for the soil, rather than as plants for growing food. You can plant these crops in succession and monitor how the plant growth changes, or if you soil is particularly off, you can plant them all at once.
Add More Mulch
Mulch is also an excellent, and easy, way to deplete the nitrogen excess in your soil. Mulch, in general, absorbs nitrogen and when you have a garden with healthy soil, you have to be careful not to add too much or it will be detrimental to your plants. However, when you have too much nitrogen, the mulch works in your favor and draws the excess out. Sawdust as a mulch works great for this as well.
Add More Water
Soaking your garden with lots of water will cause the nitrogen to leach further down into the soil, sending it much deeper than the roots of your plants. This method moves the nitrogen away while not getting rid of it entirely.
Do Not Fertilize
In short, it is possible to over-fertilize and unintentionally add more nitrogen to your soil than is needed. While it might seem second nature to want to add growth supporters to your soil, the nitrogen found in all fertilizers with only make your problem worse. By skipping the fertilizer, you force the plants to soak up the nitrogen already in the soil, thereby reducing the overall nitrogen levels in your garden.
This may sound counter-intuitive, however there is always the option of just letting your garden grow. Let the plants that are already there soak up as much nitrogen as possible and begin anew the following year after a soil test. This means you will not have a great crop for the current season but often self-remediation is all a garden needs to get on the right path again.
Whichever method you choose, be sure to watch how the plant foliage changes and test your soil again before planting a crop which you plan to harvest.