Your garden soil is where your plants live and produce. Great soil makes having a great garden much easier; poor soil makes having even a good garden a burdensome challenge. So the very best thing that you can do for your garden this year is to improve your soil.
Soil’s Basic Components
All soil consists of mineral particles, organic matter, air, and water. Mineral particles come from dissolved and weathered rock materials. Organic matter consists of decayed plant and animal products, as well as living organisms. Air and water come naturally from the atmosphere and circulate among the mineral and organic particles.
Minerals have two important functions they supply nutrients and give shape to the soil. Organic matter supplies nutrients as well, and it effects how well your plants are able to use the other three basic soil components (minerals, water, and air).
Your garden soil texture is determined by the mineral particle size. Sandy soil is the result of larger mineral particles. Clay soil is an abundance of very small mineral particles. And, silty soil is made of particles that are smaller than sand particles and larger than clay particles.
For almost all garden plants, the ideal soil has a good combination of sand, silt, and clay particles. The geometry of the sand components provides spaces for water absorption and drainage, while the clay and silt components hold some moisture which is necessary for both your plants and for the organic components of your soil.
Soil structure is defined as how well the soil particles stick together to form larger groups. When a handful of moist soil can be shaped into a nice ball that can easily be crumbled, you have good structure. If your soil is too sandy, you can’t form a ball. If your soil is heavy clay soil, you can’t crumble the ball. Good soil structure promotes good root development and relatively free movement of air and water.
Organic Matter in Your Soil
Two types of organic matter are essential to good soil:
1. Dead plant and animal matter in various stages of decay, and
2. The living organisms – from microscopic soil bacteria to earthworms – that break down the organic matter.
As organic material decays, it becomes a dark, sticky material known as humus. Acting like glue, the humus holds individual mineral particles together in larger groups. Humus also contributes to soil fertility.
Soil Chemistry, Part 1 – Nutrients
The three major soil nutrients are: Nitrogen (N), Phosphorous (P), and Potassium (K). Virtually all garden fertilizers are labeled according to their N-P-K concentration. A fertilizer that is labeled 10-10-10 contains 10% Nitrogen by weight, 10% Phosphorous, and 10% Potassium. (The rest of the weight is filler or carrier that facilitates spreading the fertilizer.)
Nitrogen affects good leaf and stem growth; it also causes the quick greening of newly fertilized lawns. Too much Nitrogen, however, can “burn” plants and actually kill them.
Phosphorous is important to root development and plays a key role in fruit ripening.
Potassium’s key role is that it enhances resistance to disease.
All other soil nutrients are called “minor elements” even though some are either very important or somewhat toxic to various plants. Copper (Cu), sulfur (S), and boron (B), for example, are very helpful for fruit trees; but, even small amounts of boron can be harmful to vegetable garden plants. Other micro-nutrients, sometimes called “trace elements,” include: Magnesium (Mg), Iron (Fe), Manganese (Mn), Zinc (Zn), and Calcium (Ca).
Soil Chemistry, Part 2 – pH
The pH scale ranges from 1 to 14, with 1 representing the most acid, 14 being the most alkaline (or basic), and 7 being neutral. Very rarely will soil have a pH outside of the range of 4-to-8. The soil’s pH affects how well the soil microbes perform as well as how well the plants roots absorb nutrients.
Areas with abundant rainfall typically have more acidic soils; and, all garden soils tend to become more acidic over time, as acids are created when organic matter decays. Thankfully, most garden plants tend to do perform very well in slightly acidic soils… at about 6.5 on the pH scale, the point at which minerals are most soluble and therefore readily available to the plants as nutrients.
Checking Your Soil’s pH
If last year’s garden performed very poorly, you may want to check the soil’s pH. Most soil experts recommend a professional test. Home test kits are simply not very accurate and this is one instance where bad information may be worse than no information at all. If you’re going to amend your soil with anything other than good compost, make sure that you know what you have, and what you need!
You can find a lab or lawn care service online. You can also purchase a soil test kit at your local garden center or online. Most soil tests will include both a pH reading and a nutrition analysis.
You Can Make Your Soil Better
You can easily build and maintain better soil for your gardens. Better soil will have depth, tilth, and abundant nutrients for plant growth and health. Better soil enables garden plants to develop good root systems, which means they’ll thrive even when other conditions, like rainfall, aren’t ideal. And, better soil results in plants having the ability to better resist diseases.
From Sandy Soil to Loam
If your soil is sandy, you can create better soil texture by adding top soil, dehydrated manure, or compost. You can simply add several inches of compost to the soil surface, then use a small tiller to work the compost into the soil to create a uniform mixture.
Compost is, by far, the single best soil additive because it contains both solid mineral particles (for texture and nutrition) as well as organic matter (for structure and nutrition). Compost also contains millions of microorganisms that that help keep soil “alive” by continuously breaking down mineral and organic matter into the proper form of nutrients for your plants.
Turn Clay Soil into Garden Loam
If your soil is mucky clay, you can improve its texture and structure by adding sand and compost. Sand will quickly improve the texture by separating some of the smaller mineral particles and allowing more openings for air and water circulation.
Compost will improve the structure by providing humus, which builds more loosely compacted soil crumbs. And, compost will significantly boost your soil’s nutrient content and help plants resist disease.
If You Already Have Loamy Soil
If you are blessed with, or if you’ve created a healthy loamy soil, you still need to maintain it. Plants take nutrients from the soil, and traffic contributes to compaction which makes the soil denser. Even if you have good soil, you can probably improve it. The best way to maintain and improve soil is, of course, to add compost.
Compost is the single best additive for your soil because it contributes to texture, structure, nutrition, and helps regulate pH. “Hot,” or aerobic, composting occurs when a mix of “brown” materials and “green” materials quickly decomposes with the help of microorganisms, air, water, and sometimes worms.
If you don’t already have a compost pile or bin, it’s easy to start. You can buy a bin, or build an enclosure for leaves, dead garden plants, kitchen waste, and grass clippings. You can create your own premium soil builder and reduce the amount of waste you put into the trash steam. With just a little practice, you’ll soon discover that composting can be very rewarding.