Whether your organic gardening efforts are restricted to your back yard or if you are converting from conventional farming to organic, your results are directly dependent on fertile, biologically active soil. This means that your soil has acceptable pH and has a good balance of organic matter offering nutrients to support healthy plants. In order to maintain this healthy environment you need to add organic material to the soil on a regular basis.
Organic matter can be compost, manure and cover crops. Some organic fertilizers like fish emulsions are acceptable amendments to the soil. Here is a short list of the most readily available organic materials and minerals that you can use to amend your soil content.
- Alfalfa pellets (good for nitrogen and potassium)
- Dried blood (very high in nitrogen)
- Bone meal (raw – very high in phosphorus; good for nitrogen)
- Bone meal (steamed – extremely high in phosphorus; low for nitrogen)
- Compost (non-fortified- good for nitrogen and potassium)
- Fish emulsion (non-fortified- good for nitrogen, phosphorus and potassium)
- Manure (fresh dairy and horse- low for nitrogen, phosphorus and potassium)
- Manure (fresh poultry – good for nitrogen, phosphorus)
- Soybean meal (extremely high for nitrogen, good for phosphorus and potassium)
- Wood ashes (good for phosphorus and extremely high in potassium)
- Minerals like rock and colloidal phosphate are very high in phosphorus content
- Minerals like Epsom salts, granite dust, greensand, potassium magnesium sulfate and dolomitic lime are good for potassium content.
Some natural minerals are frowned upon for organic production. For example, potassium chloride should be avoided as it can build up the chloride in your soil. Green manure must be handled in a manner to minimize the risk of crop contamination. Usually this means that you can’t use fresh manure unless you are mixing it in with a cover crop like soybeans or if the harvest of edible crops will not take place within 4-6 months-after biological activity has broken down the manure.
When planning for soil amendment be sure to review the national and state standards for certification. They will list approved, restricted and prohibited materials. Just because a fertilizer is labeled as ‘organic’ or ‘natural’ doesn’t mean it’s approved for certification.
There are tables that you can reference as to how much supplement to add to your soil. Over-application can lead to problem in crop production as well as polluting your environment – which presumably that’s what you are trying to avoid. When there is too much nitrogen or phosphorus there is potential for surface and groundwater contamination. Heavy applications of manure can cause similar contamination. Learn how to test your soil and monitor changes each year. Talk with your local agricultural agent to get guidance on proper application and testing procedures.