As everyone realizes, growing plants on soil means that the plants will draw out nutrients from that soil. Some soils start out in fertile condition, offering a high level of essential nutrients – and some don’t. But in any case over time, there will be a draw-down of nutrients – mainly nitrogen, phosphorous, potassium, calcium, and sulphur – but “minor nutrients” like copper and boron, as well.

Photo: Joel Russ
Every year, we’ve been adding organic materials to our topsoil. Given the fact that we’re not currently raising livestock on our place, we judiciously use the manure that we acquire, spreading it completely over our smaller “salad garden” and placing it into the rows in the large garden. On both, we apply mulch (mainly straw), in broad coverage in some areas. And in some parts, I’ve been planting fall rye to add organic matter.
To supply extra nutrient to the roots of plants, we sometimes use supplemental materials (like compost we make, or rotted manure) or diluted brews (like fish emulsion mixed in water) in the rows we plant.
I have to say we’ve become a little cautious about the fish emulsion, at least in the later part of the gardening season. Friends of ours in Vallican were using it this past year and found that it attracted a bear or two in early summer. And the intrusions occurred despite the fact that their place, like ours, is fenced to keep the deer out. The bears became pretty troublesome. And this fall we had one climbing over the fence to get to the ripening corn. Not an attraction we want to enhance.
This fall I used an inexpensive NPK soil-test kit, bought locally, to test soil in our gardens for nitrogen, phosphorous, and potassium. I tested the soil from spaces between rows, since I knew we tended to use extra amendment materials within the rows we’d planted in the spring. Nitrogen turned out to be pretty low, and phosphorous – though it varied according to places from which each sample was taken – was pretty low, too.
For the phosphorous, I’ll spread phosphate rock, a commonly available soil supplement, on the gardens next spring. It’s generally acknowledged that nitrogen is the essential plant nutrient most frequently deficient. This page discusses some of the options available for organic supplementation of soils: feather meal, composted manure, alfalfa meal, and vermicastings.
At the moment, I lean toward the idea of using alfalfa meal, due to the fact that it provides other nutrients, including minor or micro nutrients, in addition to the nitrogen.
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