New Advice on Soil Amendments

Q: I’ve gotten my test results back from the soil lab, telling me to add some organic matter. What’s the best thing to add?

A: In the past, we’d just bop on down to the local garden center and load up a few bags of… something. Soil amendment, composted manure, planting mix, potting mix, top soil, compost… there are hundreds of products, and the names are pretty random.

So are the ingredients. Since there are no legal standards, these bags can contain whatever the manufacturer wants them to. There’s no labeling law, either. If there’s a label at all, often you’ll see something like, “Contains (peat, forest products compost, and/or compost), wetting agent, fertilizer.” You have no idea if this particular bag has peat or compost, much less what went into that compost. And what’s a forest product? Bark? Sawdust? Squirrels?

 

Does Your Soil Pass the Test?

The sun is shining, the lawn is turning green, and the birds are chirping. In fact, it’s a balmy spring day. Surely there must be something you can do to start your garden! As a matter of fact, there is, but it doesn’t involve a single seed.

If you’re like most gardeners, you’ve never had your soil tested. Every year you dutifully spread a layer of compost and/or manure over your garden, dig it in, and plant. After all, that’s what every book, article, and website tells you to do. You might even add some fertilizer, just to be on the safe side. But if you’ve never had a soil test, you’re flying blind.

The goal for most gardens is 5% organic matter (natives prefer leaner soil). But we gardeners tend to think that if 5% is good, 10% is better! And everybody knows that you add manure to create fertile garden soil—right?

Well, apparently not. We really do want 5% organic matter, and more is not better. Too much compost can cause major problems, and too much manure can be even worse.

 

Fall is for Compost

Q: I’m curious about home compost, both in terms of reducing yard and garden waste sent to landfills, recycling kitchen waste, and improving my garden soil. This year’s gardening season is over, but I’m anxious to do what I can to get ready for next season.

A: El Paso County garden soils vary greatly—some are clayey, others are sandy. All are notoriously lean—low in organic matter. Amending soil with compost is a great way to improve any soil. It attracts beneficial soil organisms and releases nutrients while breaking down. Compost helps the soil hold moisture and makes it available to garden plants.

Commercial compost can be a combination of plant residues, manure, animal by-products and possibly bio-solids, and can be at any stage of decomposition. Colorado does not regulate compost. While these products will provide a long-term release of nutrients, add organic matter, and improve soil properties, they may also increase the salt content of the soil. If the contents have not been thoroughly composted, they can be “hot” with high ammonia levels, which will burn tender plant roots.

Homemade compost offers a great solution by improving the quality of our garden soil while recycling our “green waste.” In addition, composting at home allows the gardener to control the content of the compost, avoiding weed seeds, diseased plants, and salt problems.

 

Encourage Earthworms

Q: Earthworms gross me out. What good are they?

Photo: Joseph Berger, bugwood.org

A: We hardly notice them most of the time… they’re out of sight, underground, aerating the soil, creating humus, increasing fertility. It’s only after a rain storm, when the ground is saturated, that they come up for air. Then we see their desiccated carcasses strewn across the pavement. Robins eat them, anglers use them for bait, and little kids bring them home in their pockets as pets. Most of us dissected one in biology, carefully counting the five aortic arches while debating the coolness of being squeamish. Yet, for all their inconspicuous habits, earthworms play a major role both in our gardens and in the wild.

 

Amending Soil (by Ross Krummel)

Just a few eons ago, ocean waves lapped against the rocks of Garden of the Gods Park. Rivers flowed out of the mountains, carrying sediment to the shallow inland sea, building deltas. Finer shale and clays settled to the bottom of deeper waters.

Now, gardeners wonder what their soil is like in the Pikes Peak region. You guessed it: we have gravels, sands and clays. We do not have the rich, dark soils built from ancient, decaying forest floors. On the contrary, our soil grossly lacks humus content, and either percolates water too quickly (sand) or hardly at all (clay).

To help gardens in this area succeed, an aggressive soil-amending program may be necessary to make our soils more productive. Healthy soil has many different components to it: minerals, air, water, and microbes.

 

Soil Tests Provide Good Information (by Deb Ross)

Q: I’ve heard about soil tests. What are they and should I have one done?

A: Soil is like an all-you-can-eat buffet for plants. Soil provides food to plants and different kinds of plants need different kinds of nutrients. A soil test can help you decide what fertilizers and organic amendments you should add to your soil when starting lawns, flower beds, or vegetable gardens.

If the plants in your home landscape are struggling, the problems are not always soil related. A standard soil test will not identify the most common garden problems such as over-watering, under-watering, poor soil drainage, soil compaction, diseases, insects, weed competition, too much sun or shade, poor plant varieties, or just neglect.