From the ground up
Soil: a growing medium
What is soil?
Soil is made up of number of components such as decayed & organic matter, (which makes composting/humus), mineral & rock particles, is one of the most important elements for achieving success in the garden. Of course, other elements such as location, water, sunlight and maintenance are also important for gardening success.
Living organisms, although microscopic, work hard beneath the ground to enrich the soil producing a high quality medium for planting. One such organism is the Earthworm, which as they burrow, they consume soil, extracting nutrients from decomposing organic matter like leaves and roots. Earthworms are vital to soil health because they transport nutrients and minerals from below to the surface via their waste, and their tunnels aerate the ground. An earthworm can eat up to one third its body weight in a day (1). Other contributing factors for quality soil is air and water. Earthworms are the most easily recognized soil organism and are viewed as a sign of soil health. New no-tillers eagerly document the increase in worm numbers as a sign of improving soil health — and they are right to make that assumption. In fact, worms are often studied as an “indicator species” for monitoring changes in soil quality(2).
Types of soils:
- Sandy soil is made up of large particles, which allow water to drains quickly and can often take valuable nutrients with it.
- Clay soil is composed of very small particles,have the ability to hold water and nutrients but air cannot penetrate between these spaces, especially when they are filled with water. Poor drainage and aeration are characteristics of clay soils. Wet clay soil is difficult to work while dry clay is very hard.
- Silt is composed of particles sized between those found in sand and clay and can cause drainage problems, especially when its wet. Silt tends to be dusty and powdery when dry.
- Loam is the ideal blend of particle sizes. It is a balance of sand, clay and silt. Loam has the ability to hold water. Any excess water can drain away enabling air into the soil to provide the necessary oxygen to plant roots and the organisms found in the soil. It is easy to work, holds nutrients, and has good aeration and good water-retention capacity.
Adding compost improves water and nutrient retention in sandy soils, and improves drainage and aeration in clay soils and silt.
Nutrients for your soil
Plants need macronutrients and micronutrients which is provided by healthy soil.
- The macronutrients include: nitrogen (N), phosphorous (P), potassium (K), calcium (Ca), magnesium (Mg) and sulphur (S). They provide the main nutrients for plants. The first three – N, P, K – are used in the largest amounts by plants, each providing specific benefits including leaf and stem growth (N), root growth (P and K), flower and fruit development (P) and overall vitality (K).
Plants need micronutrients, also called trace elements, such as iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn). Their presence in very small quantities is essential for plant life. The balance and level of these micronutrients is critical as excesses are harmful to plants. Compost provides an available, balanced supply of these micronutrients.