Amending Your Garden’s Soil

Lately  we’ve been conducting a series of free classes for gardeners.  Call it cabin fever, but gardeners are ready for the growing season to begin based on the response to these classes.  The latest class was on amending your garden’s soil.  So, for those of you who missed the class, let’s have a chat about amendments.

First, what is a soil amendment?  It can be just about anything that will improve the soil for the betterment of a garden’s ability to produce a crop.  There are hundreds of choices available to the gardener, everything from compost to wood ash to alfalfa pellets—some good, others down right detrimental.

For all intents and purposes, the number one thing you can do to improve the soil is the addition of organic matter.  Organic matter can be anything from last autumn’s leaves to bagged grass clippings; the key is it is derived from plants.

In Wyoming, most of our soils are deficient in organic matter content.  That shouldn’t surprise anyone as just one look at our short grass prairie would suggest it doesn’t produce much vegetation.

Adding organic matter to your garden improves water infiltration, opens up heavy clay soils, and is an energy source for bacteria, fungi and earthworms that live in the soil.  It is this web of life that enhances the soil to produce a crop.  Adding organic matter for most gardeners should be done at least annually if not more.

By and large organic matter is not a fertilizer.  Sure it contains some fertilizer components but usually at levels so low that it won’t make for a bountiful crop.  Even cow manure, aged appropriately for a year or so and applied to the garden has very little fertilizer in it, ditto for compost.

The take home message is that organic matter improves the soil but don’t think of it as a fertilizer.  That said, adding such things as soybean meal and alfalfa pellets to the soil will provide plant based nitrogen to the soil.

There are a tremendous amount of articles written on soil amendments and a lot of the articles are written for gardeners that have acidic soils.  The problem with following their information in Wyoming is that our soils are the exact opposite—we have alkaline soil.

A common recommendation for gardeners with acidic soils is to introduce lime and wood ash to the garden as an amendment.  Both of these products will raise the pH of the soil and lime will introduce calcium while wood ash will increase the potassium levels, both nutrients usually lacking in acidic soils.

The problem using these soil amendments here is we don’t want to raise the pH of the soil, in fact too much wood ash or lime can sterilize our soil by making it too alkaline for plants to grow. Unless you live on a sand pile our soils are naturally high in calcium and potassium so adding both lime and wood ash are not necessary; we’re already loaded to the gills with these nutrients.

There’s a reason why the old timers always win the blue ribbon at county fairs—they’ve been amending their garden’s soil for years with organic matter.

Originally published in the Casper Star-Tribune, March 1, 2015

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