CHARECTERISTICS OF IDEAL SOIL
What is Soil:
Soil is a natural medium of plant growth comprising a tri-phasic mixture of Mineral & Organic matter, Water and Air (Solid, Liquid & Gas).
The mineral matter, a result of several thousand years of weathering of rocks, is made up of Sand, Silt and Clay particles. The arrangement of these particles and their relative proportion give soil its Structure and Texture.
The organic matter, a result of several years of decomposition of plant & animal residues, binds the soil particles together into aggregates and serves as a source of food & energy for the microbial population.
The air facilitates gaseous exchange between the soil & plant roots.
The water serves as a solvent thereby facilitating transport of solutes (which are essentially nutrients) to the plant.
- Help plants in anchoring themselves in the soil
- Store and supply nutrients
- Store and supply water
- Facilitate gaseous exchange (of CO2 & O2)
What is an ideal Soil like:
In terms of its constituents, an ideal Soil should be made up of (by volume)
- Mineral Matter – 45%
- Organic Matter – 1 to 5%
- Pore Space – 50% (filled with 50% water & 50% air – a desirable condition called Field Capacity)
In terms of its properties, an ideal Soil is characterised as one with
- A loamy texture for ease of air & water movement into the soil
- An organic matter content sufficient to sustain microbial populations
- Textural & organic matter traits that contribute to good tilth
- A soil structure that promotes proliferation of plant roots into the soil mass, ease of water drainage and air exchange at the soil surface
- Sufficient clay (as well as organic) colloids to hold reserve essential plant nutrient elements and soil moisture
- A deep soil profile with a permeable subsoil allowing for root penetration and normal soil water drainage
- A subsoil fertility (pH and level of essential plant nutrient elements) that promotes root growth