Soil properties and processes

Soil Types and Their Properties

There are primarily three types of soils: sandy, silt, and clay, each having distinct properties.
Sandy soil has the largest particles and feels gritty. This type of soil doesn’t hold water well.
Silt soil has medium-sized particles and feels smooth, but not sticky. It retains water longer but does not contain a lot of air.
Clay soil has the smallest particles and feels sticky when wet. It drains slowly and holds water but not much air.

Soil is generally composed of mineral particles, organic matter, water, and air.
The mineral particles mainly include sand, silt, and clay.
Organic matter in soil is derived from decaying plant and animal material and is vital for soil fertility.
The amount and type of each component varies in different types of soil, affecting its texture and fertility.

Soil pH is a measure of soil acidity or alkalinity and it greatly affects soil health and productivity.
Acidic soils (pH less than 7) may need lime to neutralise the acidity.
Alkaline soils (pH larger than 7) may need the addition of sulfur or iron to decrease alkalinity.
Most plants prefer a pH range between 6 and 7.5, but tolerances can vary.

Soil water holding capacity refers to the volume of water that the soil can withhold after drainage.
Soils with higher sand content have low water holding capacity as water drains away quickly.
Conversely, clay and silt soils retain more water due to their smaller particle size.

Soil erosion refers to the wearing away of the topmost soil layer due to various factors like wind, water, and human activity.
Soil conservation practices like crop rotation, contour planting, and careful land-use planning can help prevent soil erosion.

Healthy soil contains several essential nutrients like nitrogen, phosphorus and potassium, required by plants for growth.
Nutrient availability is affected by factors such as soil pH, moisture content, and the presence of organic matter.
Soil fertility can be improved by adding compost, manure, and inorganic fertilizers.

Soil health is significantly affected by the presence of a variety of organisms, also known as soil biota, which include bacteria, fungi, insects, and earthworms.
These organisms help break down organic matter, recycle nutrients, improve soil structure, and control pests and diseases.