By Kirsten Conrad,
Agriculture Natural Resource Extension Agent, Virginia Cooperative Extension
Organic Sources of Nitrogen Fertilizers
Most of the soil test results we receive at the VCE Horticultural Help Desk for vegetable gardens are high in phosphorus and potassium leaving nitrogen as the nutrient needed most. However, many of our organic fertilizers contain similar amounts of all three nutrients.
So, what can we use that provides more nitrogen than phosphorus and potassium? Following is a short list of such fertilizers. (Note: this is lbs per 100 sq ft NOT per 1000 sq ft. )
Product |
Analysis |
Pounds
|
Notes |
| Blood Meal | 12 – 0 – 0 | 5 – 10 | Can burn plants if over applied |
| Cottonseed Meal | 6 – 0.4 – 1.5 | 10 | May have pesticide carryover unless labeled as pesticide-free |
| Soybean Meal | 7 – 2 – 18 | 8 |
Feed stores will often sell these products. Colorado State University has an excellent publication on organic fertilizers: Organic Fertilizers.
Transplant Solutions and Sidedressing
Transplant solutions are mild fertilizer solutions that are applied to newly transplanted vegetables and flowers. Transplant solutions are also called starter solutions or root stimulators. Early-season plants not given a transplant solution often develop a purplish tinge to the leaves caused by a phosphorus deficiency. Surprisingly, the soil may have plenty of phosphorus, but plants often have difficulty taking up nutrients in cool soils. The starter solution places soluble nutrients near the roots so the plants get off to a good, strong start.
For a different take on root stimulators and transplant solutions, search for willow water. There are many recipes. The one I was taught is to take freshly cut willow branches and stand them in a bucket of water until they start to root. When that happens the water is infused with rooting hormones (indolebutyric acid (IBA) and salicylic acid) from the willow tissues. Try with and without.
Transplant solutions (root stimulators) are available for sale, but it is also possible to make your own transplant solution from a fertilizer that contains more phosphorus than nitrogen or potassium — such as a 5-10-5, 10-20-10 or 11-15-11. Mix 2 to 3 tablespoons of one of the above fertilizers in a gallon of water several hours before use. The fertilizer won’t completely dissolve but enough will go into solution to get plants off to a good start. Use about 1 cup of transplant solution for each transplant.
Here’s an interesting piece on making woody plant cuttings: How to Make a Rooting Tonic
Sidedressing is a fertilization done after the plants are established. A fertilizer containing primarily nitrogen is used to keep plants growing and productive. Nitrate of soda (16-0-0) is often used at the rate of 2 pounds fertilizer per 100 feet of row. More commonly available lawn fertilizers such as a 30-3-3, 29-5-4 or something similar can also be used, but cut the rate in half. Be sure any lawn fertilizer used does not contain weed preventers or weed killers.
Note on Compost
Compost is a great low fertility addition to your garden. Although it probably doesn’t add sufficient nitrogen, it adds trace minerals, and other nutrients that are easily assimilated by plants. Most importantly, compost increases the organic matter in the soil and, if it’s homegrown, also adds microorganisms that help plants make better use of the nutrients that are already present in the soil.
Do combine compost applications with soil aeration techniques for optimal results.
–Adapted from Virginia Cooperative Extension, Oregon State University, and Ward Upham, Kansas State University