The simplest soils have three horizons: topsoil (A horizon), subsoil (B horizon), and C horizon.

These are called the horizons of a typical soil profile.

• The uppermost horizon is called the “organic” horizon or “O” horizon.
• Just below the O horizon is “topsoil” or “A” horizon.
• Below is the “B” horizon or subsoil.
• The “C” horizon is the lowest layer.

Topsoil – Topsoil is considered the “A” horizon. It is a fairly thin layer (5 to 10 inches thick) composed of organic matter and minerals. This layer is the primary layer where plants and organisms live. Subsoil – Subsoil is considered the “B” horizon.

Soil Horizons (layers): Soil is made up of distinct horizontal layers; these layers are called horizons. They range from rich, organic upper layers (humus and topsoil) to underlying rocky layers ( subsoil, regolith and bedrock).

The layers of weathered particles of earth material that contain organic matter and can support vegetation are defined as soil. Soil can be all or just part of the sedimentary material that covers the bedrock. Loam contains sand, silt, and clay with abundant organic material.

Soils typically have six horizons. From the top down, they are Horizon O,A, E, B, C and R. Each horizon has certain characteristics.

The layers of the soil are called horizons. The uppermost horizon is called the topsoil layer. The topsoil layer is a mixture of sand, silt, clay and broken down organic matter, called humus. Humus is rich, highly decomposed organic matter mostly made from dead plants, crunched-up leaves, dead insects and twigs.

Like a biography, each profile tells a story about the life of a soil. Soil Changes with Age – As a soil ages, it gradually starts to look different from its parent material. That’s because soil is dynamic. Its components—minerals, water, air, organic matter, and organisms—constantly change.

Soil Erosion

Carbaryl has a soil half-life of 7-28 days; plant surface residues (unspecified levels) usually last less than 14 days. Microbial insecticides are those which include living microorganisms such as bacteria, fungi, or viruses.

Indian researchers have recently shown that siderophores are efficient washing agents that can remove arsenic from contaminated soils. These small organic compounds secreted by micro-organisms are able to remove up to 92.8% of arsenic in contaminated soils after 5 washings.

The only sure way to tell if soil is contaminated is to sample the soil and have a certified laboratory test it….Soil Contamination Inspection

1. The primary source of lead contamination in soil is from paint that contains lead.
2. Arsenic is another contaminant that is commonly found in residential soil.