Gardening Guy: Good Time to Test and Improve Soil | Weekend magazine


Now is a good time to beat the rush and get your soil tested so you can improve your soil before you start planting.

Most New England states have soil testing labs available to gardeners. Finding one is as easy as searching for “Soil Testing Lab Near Me” in your browser. Your first choice should probably be one run by the state university’s extension service. Most offer a variety of options as to what gets tested, and their websites will explain your options, what each costs, and how to take a sample. Most tests require one or two cups of air-dried soil of roots and rocks.

Most state labs are very busy in the spring and a wait of 14-21 days is typical. If you’re in a rush to get your soil test results, you can try Logan Labs, a commercial lab in Ohio. They can usually email test results within a few days and also have a soil scientist available to talk to you (for a fee) to make recommendations.

Unless you live where there are natural deposits of limestone or marble — parts of Vermont, for example — your soil is probably acidic. Why? Coal-fired power plants send sulfur into the air, which reacts with water to form sulfuric acid, which is released by rain. Most plants do best with a soil pH between 6.0 and 6.8. A pH of 7.0 is neutral and above is alkaline. Soils rich in organic matter and microorganisms tend to buffer soil pH, making it less acidic.

Soils are essentially composed of three elements: crushed rock represents around 45%, air around 50% and organic matter around 5%. The particle size of the rock component is what determines the texture of the soil: large particles are found in sand, medium particles in silt, and very fine particles make up clay. Good soil has particles of all three sizes, but it’s mostly silt.

You can see what’s in your soil by filling a jar half full of water and adding a few cups of soil, then shaking it well. The sand will fall to the bottom almost immediately, and the silt will then fall. Finally, after about 24 hours, your clay will form a layer. Each will likely be a different color and fairly obvious. Organic matter often floats to the surface, but usually mixes with the silt layer.

Clay retains soil minerals and moisture better, but it can stay soggy and also compact. Sand particles are not electrically charged, so they do not hold minerals like clay or loamy soils, but the sand helps with drainage. You can get a feel for your floor by rubbing it between your thumb and finger after you wet it. The clay soil is sticky. You can smell the grains in sandy soil.

If your soil has a pH of 6.0 or less, you should add garden lime or wood ash to “soften” it. If you get a soil test, it should tell you how many pounds of lime to add, expressed in pounds per 100 square feet – a 10 foot by 10 foot area. I weighed a quart of garden lime in a yogurt pot and it weighs just over 3 pounds. Wood ashes are roughly equivalent in what they do. But it’s not rocket science – you don’t need to be specific.

Lime is ground limestone and is sold in bags at the garden center. It comes in the form of powdered lime or granulated lime, which is less messy. If you buy powdered lime, wear a mask when spreading so you don’t inhale it.

All fertilizers add nitrogen (N), phosphorus (P) and potassium (K). The amount of each is expressed as a number which is the percentage of the active ingredient by weight. A 10-10-10 fertilizer contains 10% each and 70% filler. The minerals in chemical fertilizers are in the form of salts and excessive use can damage the roots. The salts in chemical fertilizers are water soluble and can be dissolved and washed away by heavy rains.

Organic fertilizers, on the other hand, are made from natural ingredients and minerals from crushed rocks. My favorite organic fertilizer, Pro-Gro, is made in Vermont and contains peanut meal, cottonseed meal, ground oyster shells, feather meal, crab meal, dried blood (for nitrogen) and rock phosphate. I like to compare it to a 7 course meal for plants.

The ingredients of an organic fertilizer must mainly be digested by the microorganisms present in the soil, and then shared with the green plants. They are softer and slower to release their treats. Pro-Gro’s mineral content is listed as 5-3-4, which is lower than most chemical fertilizers, but delivers all those micronutrients not found in chemical fertilizers.

Of course, you can go the old fashioned way and add animal manure to improve your soil. They work, but some can also introduce weed seeds. I don’t recommend using fresh horse or cow manure because of this, but manure that’s a year or two old has fewer seeds. Rabbit, sheep and goat manure has fewer weed seeds and adds a lot of organic matter which helps with texture and texture.

If you add compost to your garden and work it, it will become more biologically active – full of beneficial microorganisms. It will drain much better, but will also retain moisture better.

Having good soil is one of the keys to being a good gardener. Maybe testing and improving your soil will help you get that elusive green thumb. It’s worth a try.

Henry Homeyer can be contacted by email at [email protected] or by USPS at PO Box 364, Cornish Flat, NH 03746. His website is in line.


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