Agriculture Reference
In-Depth Information
Of course, there are lots of things that can be added to your garden as soil amendments. These
organic fertilizers are from mineral, plant, or animal origins and usually contain many micronutri-
ents and trace elements in addition to whatever main nutrients are in them.
Bonemeal.
This supplement is made from finely or coarsely ground bones, usually slaughterhouse
remnants, and is an excellent source of phosphorus and calcium. It usually encourages strong root
growth, which is why you'll hear gardeners say to mix a spoonful into the bottom of a planting hole
for bulbs. It also helps prevent blossom end rot in tomatoes.
Bloodmeal.
Like bonemeal, this fertilizer has an animal origin and is powdered blood. Over
10 percent nitrogen, it is a strong fertilizer that is useful to feed nitrogen-loving plants and leafy
greens. Be aware that spread bare in the garden, bloodmeal might attract dogs or cats to the
garden.
Gypsum.
A common ingredient in plaster and construction drywalls, this fertilizer contains
calcium sulfate and helps supply calcium without changing the pH of the soil. You can use it to
lighten clay soils, often in tandem with dolomitic limestone, but it isn't one of the most effective or
popular fertilizers as not every area needs gypsum.
Feed meal.
Usually soybean meal or cottonseed meal, these fertilizers are high in nitrogen (6 to
7 percent) and potassium or phosphorus. They can be used as a side dressing on vegetable beds to
feed fast-growing annuals. Of interest to those looking for organic backyard farms, cotton crops are
often heavily sprayed with pesticides and most soybeans are genetically modified.
Alfalfa meal.
Alfalfa is a great source of not only nitrogen, but many other nutrients as well, such
as potassium. It's often used as a general fertilizer for feeding both annuals and perennials, but
many self-sufficient farmers are beginning to grow alfalfa as a cover crop to improve soil fertility
without having to apply it in concentrated form.
Seaweed meal or
kelp.
Valued for the diversity of minerals and nutrients it provides, gardeners
can usually find it in liquid, pellet, or powdered form. Applied to soil in the spring and summer,
seaweed applications seem to increase a plant's stress tolerance. It is considered by some to be the
most complete source of micronutrients available.
Rock phosphate.
This is a nice source of phosphate for vegans who want to avoid bonemeal.
However, it is stronger—especially hard-rock phosphate—and it shouldn't be used on alkaline soil
because it will raise soil pH. Soft-rock phosphate is not as strong and breaks down more slowly so
that it lasts for a long time in the garden.
Limestone.
Both ground limestone and dolomitic limestone raise a soil's pH level and supply
calcium. Dolomitic limestone also supplies magnesium and is easy to spread directly onto the soil.
