On a cellular level, all life forms are not much different than the singular-celled organisms that evolved from the ocean. In fact, cell fluid is most similar in composition to sea water than any other substance on Earth-especially the presence of those essential micro-nutrients often ignored by coarse approaches to nutrition. In my diet and in my gardening practices I like to go back to the ocean.
The N-P-K ratings (the three numbers you find on fertilizers that tell you how much nitrogen, phosphorus and potassium a fertilizer delivers) look low. But most organic fertilizers rate low because they are feeding your plants differently than synthetic fertilizers. Kelp feeds microorganisms where chemical fertilizers kill them. And organic fertilizers like kelp don’t go running off into the water supply like chemical fertilizers do. They supply a steady, stable supply of food for both your plants and the soil. In other words, low N-P-K ratings don’t necessarily reflect how effective a plant food is. That higher N-P-K rating is reflected mostly in the water soluble, “available” nutrients. Even when a synthetic fertilizer has a lot of nitrogen, it doesn’t stay in the root zone of the plants. It is often suggested that low-rated fertilizers are less effective for this reason, but really, the opposite is true. Plants often cannot suck up enough water soluble fast enough before the fertilizer runs off. What I am saying is, slow and steady wins the race. Let nature feed your plants. Nature has been doing it for a LOT longer than we have.
The nice thing about kelp meal is that is is appropriate for most crops. Plants that want less nitrogen (like peas, tomatillos, and root crops) won’t react negatively to occasional feedings of kelp. Kelp is an excellent food for both beneficial soil bacteria and fungus. I also use kelp powder in my compost and compost tea.
I am very strict about my food sources for plants. Some kelp products have sulfur added (usually the liquid forms) that are not good for microorganisms. While some of this sulfur might be diluted when adding kelp to water, I am still uncomfortable with using such products. I use powdered forms of kelp that don’t require additives.
A 50 pound bag is available at Nature’s Way Probiotics‘ Farm Store for $50.00. That is a lot of kelp that will last a long time. For use in compost tea, I use a higher grade, water-soluble version. Nature’s Way makes an excellent product specifically used for compost tea. It’s more expensive than most kelp, but for compost tea you don’t use a lot anyway.
As far as application rates go, it’s a very inexact science. I just eyeball it in a very general way. Sometimes… I even read the instructions on the bag… Because it is safe and organic, it is a challenge to overdo. But I suppose it could be done. So maybe you SHOULD follow the instructions for the brand you purchase.