Organic Solutions for Improving Your Soil
The key to successful gardening is right below your feet. Focus your efforts on building healthy organic soil and your plants will have what they need to thrive naturally. As organic gardeners like to say, “feed the soil, and let the soil feed the plants.” This process is not complicated or even labor-intensive—rather, it’s an ongoing effort that you invest in throughout the growing season.
All you need is a little information about the attributes of healthy soil, a few simple strategies, and a couple of handy products. You will begin with soil sampling and soil testing so you can find out about the reasons for imbalances in the soil. You will get a reading on its pH and check in on the vitality of the soil food web. When you’re ready, you’ll have guidance on improving the soil.
Balancing Soil
About 40 to 45 percent of soil’s volume is solid mineral particles—sand, silt, and clay. Sand and silt provide a skeleton for the soil but retain little if any water and nutrients for plants to take up. Clay holds onto water and nutrients for plants to absorb, but it becomes dense when wet, so roots stay soggy and may even drown. Loam has a balanced mix of all three types of particles and offers the best conditions for most garden plants.
Much of the remaining volume of soil is made up of pore space, or air pockets between the particles, which allow essential oxygen and water to reach plants’ roots. About 5 to 10 percent of healthy soil is organic matter—the decomposing residues of plants (mostly)—and the complex ecosystem of organisms that feed on the decay, from earthworms and beetles to microscopic fungi and bacteria.
Soil food web
Those billions of living things in every teaspoon of healthy soil make up what’s known as the “soil food web.” They break down organic matter into nutrients for plants to absorb, open the pore spaces in soil, ward off plant diseases, and help to trap carbon from escaping into the atmosphere. By nourishing the soil food web with organic matter, you help to supply your plants with nutrients in the exact form they have evolved to absorb.
The pH factor
The soil’s mineral content determines how acidic or alkaline it is. This is measured by pH, on a scale that ranges from 1 to 14—readings below 7.0 are acidic and above are alkaline. The relative pH impacts plants’ ability to absorb different nutrients from the soil. Most garden plants fare best in slightly acidic soil—between 6.2 and 7.0—but soil that’s too acidic can hamper their growth.
Reasons for Soil Imbalance
- Top soil removal: In many new housing developments, construction crews level the ground by pushing aside or removing the top 6 to 8 inches of soil. This is where most of the organic matter and microbes are found.
- Excessive clay or sand: Outside of the most fertile agricultural land, most garden soils are not naturally loamy. They’re either predominantly high in clay content or sand.
- Constant compaction: Daily pressure from foot traffic and equipment such as lawn mowers squeezes out the pore spaces in the soil. This compaction makes it hard for plants’ roots to spread out and gather water and nutrients.
- Too acidic or alkaline: When the soil’s pH is too high or low, certain essential minerals become inaccessible to the plants.
- Depletion: Gardeners often plant their crops in the same spots every season. Over time, the soil’s organic matter and natural storehouse of nutrients in those places can be depleted by the years of crops using them up, if they are not replenished
Soil Testing
Investigating your own soil
Before you can determine how to optimize the soil in your garden, you need to learn more about it. A test you do yourself can inform you about your soil structure and drainage. Begin by using a shovel or post-hole digger to make a hole at least 12 inches deep and 4 to 12 inches wide. Fill the hole with water and let it drain. Right after the water drains for the first time, refill the hole with water. Measure the depth of the water with a ruler and after 15 minutes, measure the drop in water in inches. Multiply this number by four to calculate how much water drains in an hour.
Soils that drain 1 to 3 inches an hour are desirable for most plants. Soils that drain less than 1 inch per hour have poor drainage, while soils that drain more than 4 inches of water per hour can be too dry for plants to absorb the moisture they need before it is gone.
When you want to know about the nutrient content of your garden soil, Burpee’s Deluxe Garden Soil Testing Kit is easy to use and provides you with everything you need to perform 15 tests each for available nitrogen, phosphorus and potassium, and 30 tests for soil pH. The handy, battery-free Electronic Soil Tester gives you instant readings on fertility and pH during the growing season.
Soil sampling
You also can get an inexpensive, detailed test with the cooperative extension service of the state university where you live or pay a privately run laboratory. Whether you use the kit or a lab, the value of your results depends on the quality of the soil sample you test.
Follow these steps to ensure your sample accurately reflects your garden conditions:
- Scrape away any surface litter or plant growth from a small area of soil. Use a soil probe to cut a core of soil or dig a hole with a stainless steel trowel or other tool (if you don't have stainless steel tools, use a large stainless steel spoon) and collect a slice of soil from the side of the hole. For cultivated areas, collect a core or slice to a depth of 6 inches.
- Repeat the sampling procedure at six to eight different locations around your garden.
- Don't touch the sample with soft steel, galvanized or brass tools or with your bare skin. The content of some minerals in soil is so minute that any particles picked up from these metals or your skin could throw off test results.
- Mix the soil samples together in a clean plastic or stainless steel container.
- Place the mixed sample in a plastic container or bag to send off to the lab.
- Be sure to write on the information form that you want recommendations for organic soil amendments.
Improving Soil
The test results give you insight into any deficiencies in your garden soil and can guide you to the ingredients needed to achieve your perfect soil mix.
Phosphorus is critical for root growth early in the season and flowering and fruiting later. If your soil test shows low levels of phosphorus, bone meal is an easy-to-apply organic solution. It comes with calcium, which plants need to build new cells and other functions.
Plants need a steady supply of nitrogen, the nutrient that fuels leaf and stem growth. Instead of fertilizers made with synthetic sources of nitrogen, organic gardeners rely on natural soil amendments such as blood meal In addition to powering plant growth, blood meal nurtures the soil food web.
Did your test say your is too acidic? An application of garden lime garden lime garden Lime will help bring it to the optimal level of about 6.0 to 6.5.
Many experienced organic gardeners today are adding biochar biochar to their garden soil mix. It’s a by-product of burning wood and plant debris in sustainably managed forests. It helps soil retain moisture and activates the microorganisms that plants depend on.
The ideal soil conditioner for your garden is organic compost. It holds and slowly disperses moisture, gradually releases nutrients to plants in the form they can easily absorb, nourishes the soil food web, and helps to bring the pH to the optimal level. Compost loosens compacted clay soil and it helps sandy soil retain nutrients and water. Spread a half-inch of compost on top of your garden soil each spring and your plants will get off to a strong start. The Aerobin 400 transforms ordinary kitchen scraps and yard debris into healthy compost for your garden.
The Ruth Stout Method
Named for a popular garden writer who wrote a series of books about no-till gardening half a century ago, the “Ruth Stout Method,” is an easy way to refresh your soil. Stout"mulched in place," piling straw, leaves, garden debris and other natural materials around her vegetables. As those dead and decaying plants decompose, they nourish the soil food web.
This approach is convenient in vegetable beds and in natural shrub borders because you don't have to bag clippings or leaves, turn a compost pile, till the soil or weed the beds. Plants need less watering, and earthworms are abundant and actively aerating the soil and fertilizing with their castings. Take care not to use plants infested with pests or diseases so they don’t spread in your garden.
Check out Burpee’s selection of soil improvement products.