For urban farmers, who generally have a small growing space, itâ€™s very much possible to give your crops a balanced nutritional boost with a homemade complete organic fertilizer.
The major concern when designing a complete organic fertilizer is achieving as much balance as possible without creating excess nutrients. Deficiencies are easy to remedy; excesses â€¦ well, as Hugh Lovel once joked, “Itâ€™s easy enough to resolve soil nutrient excesses, no more difficult than getting too much salt out of the soup.â€ť
My complete organic fertilizer is designed to, above all, avoid creating excess; therefore, it cannot completely ensure there are no minor nutrient or trace element deficiencies. Thereâ€™s no way out of this problem except to custom-design a new complete organic fertilizer every year or two based on soil test results.
Making a complete organic fertilizer yourself requires that you first obtain up to 10 ingredients. (Sourcing them might take some clever shopping because garden centers donâ€™t expect home gardeners to request some of these substances. I hope that will change.) Making complete organic fertilizer will involve nearly the same effort and expense as getting a soil test and formulating something perfectly suited to your land. And no complete organic fertilizer can possibly grow food to the degree of nutrient-density that can be achieved from remineralization according to a soil test result.
Making complete organic fertilizer requires measuring ingredients by volume using ordinary kitchen equipment and then thoroughly blending and uniformly distributing the fertilizer in your garden. I measure out fertilizers with a worn-out quart-sized, Teflon-coated saucepan and a cheap, plastic liquid measuring cup. For trace elements, I measure accurately using a kitchen measuring-spoon set. Perfect accuracy is not required; plus or minus 10 percent is good enough.
This complete organic fertilizer recipes makes enough to generously cover 100 square feet.
- 3 quarts oilseed meal (such as soybean meal, cottonseed meal or canolaseed meal); or 1Â˝ quarts feather meal or fish meal; or a combination of 2 quarts oilseed meal, 1 pint feather meal and 1 pint fish meal
- 1 quart soft or colloidal rock phosphate or bonemeal
- 1 quart kelp meal and/or 1 pint Azomite (for trace minerals)
If you garden where the land originally grew a forest, add 1 pint agricultural limestone, 100# (fine grind) and 1 pint agricultural gypsum;i
if you garden where the land originally grew prairie grass or is a desert, add 1 quart agricultural gypsum;
if you do not live in Cascadia, add 1/3 cup potassium sulfate.
- 1 tsp. laundry borax (1/2 gram actual boron)
- 1Â˝ tsp. zinc sulfate
- 2 tsp. manganese sulfate
- 1 tsp. copper sulfate
Mix ingredients thoroughly in a 5-gallon bucket use one of these mixing methods:
- Slowly pour the materials from one bucket to the next and then back. Repeat this about six times.
- Stir materials with your hands.
The first method works the best, but it can raise a bit of dust and is best done outdoors.
Applying Your Complete Organic Fertilizer
The amount of complete organic fertilizer to spread may be adjusted to suit the soilâ€™s capacity to hold plant nutrients. Generally, sandy soils are light; clay soils usually are heavyâ€”unless you live in the southeastern United States, where the clays are old, tired and very light. Here are tips for customizing the application to your gardening situation:
For Fertile Garden Beds
When preparing an already fertile bed for planting, first spread compost 1/4-inch thick. Thatâ€™s a thin scattering, but if done once a year, itâ€™s enough to maintain an existing high level of organic matter. You can also use well-rotted manure or incompletely ripened compost spread twice as thick.
Over the organic matter, uniformly spread the complete organic fertilizer at the rate of 4 quarts per 100 square feet, and dig it into the garden. If you practice no-till gardening, then simply spread your soil amendments and then mix them in shallowly with a rake or hoe, if and where you can.
For Traditional Garden Rows
If the garden is arranged in traditional long rows, then spread the complete organic fertilizer (and compost) in a broad band about 2 feet wide, with the seeds or seedlings placed down the center of this fertile strip.
For this arrangement, I suggest spreading 4 quarts of complete organic fertilizer over each 50-foot row. After digging, itâ€™s best (but not absolutely necessary) to delay sowing for a few weeks, allowing the nutrients to blend into the soil and its ecology, as well as letting the soil settle. This will restore capillarity, a natural movement of moisture toward the surface, helping to keep germinating seeds moist when you do plant them.
For Light Soils
Light soils respond powerfully to complete organic fertilizer at 4 quarts per 100 square feet.
For Heavy Soils
Heavy soils may need closer to 6 quarts complete organic fertilizer per 100 square feet the first few times you use it. After a heavy soil has been fertilized for a few years, you can reduce the amount to 4 quarts.
For Slow Plant Growth
If plant growth slows during the crop cycle or if growth did not seem rapid enough from the beginning, then side-dress with additional COF at half the starting rateâ€”2 quarts per 100 square feet. (Side-dressing means sprinkling the fertilizer over the ground that the plants will be growing into in the next three weeks and then shallowly hoeing it in, if possible.) If a side-dressing produces no growth response, it was not needed and should not be repeated.
For a Second Cropping
If youâ€™re refertilizing for a second crop in the same year, spread and work in a half-dose of complete organic fertilizer; no more compost should be required. Two quarts per 100 square feet should do. Low-demand crops following ones previously given complete organic fertilizer probably donâ€™t need another application.
What Iâ€™ve just given you is a complete, workable, soil-fertility maintenance system that will produce nutrient-dense food. Youâ€™ll gradually develop plenty of soil organic matter; youâ€™ll have plenty of minerals in the sort of balance that makes plants grow big, fast, healthy and with more nutrition.
After you have distributed complete organic fertilizer a few times, youâ€™ll learn to gauge by eye how thick it needs to be spread in order to make the plants grow fast. Most gardeners using complete organic fertilizer for the first time are surprised that their plants grow so rapidly.
Excerpted with permission from The Intelligent Gardener: Growing nutrient-densefood (New Society Publishers, 2013) by Steve Solomon with Erica Reinheimer. For more information or to order the book, call 800-567-6772 or visit www.newsociety.com.