04 November 2010

Dirt or Soil? That's the question.

A successful garden includes plants suited to your geography, correct placement, insect and disease control, right amount of water, plus healthy soil.

The first year of efforts in making a new garden can be disappointing. Over time, gardens make a turn for the better. Seeds come up, perennials grow healthier, flowers bloom for a longer season, and fewer problems arise. The change is not only that the gardener is learning about their conditions, but that the soil quality is probably improving.

Soil is basically made of air, water, deteriorated rocks, plus broken down organic matter such as leaves and twigs. Tiny animals that live in soil, called organisms, make the dirt healthy enough to support plant growth.

Soil texture matters. Half of most soil is broken down rocks, sand is large particles, silt is medium size, and clay is made of small, flat, particles.

Organic matter makes up less than 10 percent of dirt, yet it has a critical role in garden success. It makes those rock bits capable of allowing air and water to flow, and provides food for microorganisms. Gardeners put aged manure, compost, cover crops, and mulch into the top 6-inches of the ground to increase organic content.

Austrian peas as winter cover crop in our veggie garden


Soil organisms, bacteria, fungi, protozoa, nematodes, mites, springtails, earthworms and other creatures, are essential for plant health. These invisible helpers convert organic material into vitamins, plant protection, plant nutrients and minerals. The secretions and excretions of these animals help bind the soil into crumbly bits.

A gardener's job is to feed the soil organisms so they can make healthy plants. They need food, soil aeration for air and the amount of water that will help with their digestion but not drown the oxygen out of the soil particles.

Great garden soil is 25-percent air, providing space between the soil crumbs, so avoid walking on planting areas and don’t dig when the ground is wet.

The ideal moisture level is 25 percent. Water runs straight through sandy soil and cannot escape the fine particles of clay soil.


In the spring, we dig a trench and put all the winter-grown legumes in the trench, cover it with soil and plant the first spring crop - usually snow peas.


An easy way to diagnose the quality of the soil you are working with is to fill a one-quart jar one-third full of soil taken from the top 3 inches of your planting bed. And then fill the jar with water.

Put the lid on the jar and tighten it. Shake the jar until all the soil is dissolved into the water. Put the jar on a windowsill and watch the soil settle. After a few minutes, the sand will settle. Draw a line with a marking pen, indicating the percent of sand in your soil. In a few hours, the next level will settle with different colors of particles.

Overnight, the fine, clay particles will settle. Mark the clay level on the jar. The organic material will settle on top of the clay silt. Your soil’s organic
material also may float in the water.

To aid sandy soil, add composted manure and compost. Plant a cover crop this fall and then dig it into the soil next spring.

If you have clay soil that becomes hard when drying after rain, add organic matter.

If you want to plant a garden before the soil has time to improve, build raised beds and put good dirt into the beds. Over time, the clay under the beds will improve so deeper rooted plants such as carrots can grow in it.

Planting green manure crops in the fall is an easy way to improve next summer’s garden. A green manure crop prevents weeds from planting themselves over the winter, plus gives you ready-made, nutrient rich soil food.

Green manure crops include Austrian peas, rye, vetch, soybeans, alfalfa and buckwheat.

2 comments:

gourdphile said...

This is such a great posting! You have shared great information and put the components of fecund soil in understandable perspective. I'm going to try the jar thing.

Thank you!

Martha said...

Thanks for your kind words.
How did your soil test in a jar turn out? How much clay?
May I add one more chore to your busy schedule? Put down mulch, even if it's just newspaper topped with cotton seed meal or alfalfa hay (both are cheap at the farm store).