SOIL PROPERTIES AND IMPORTANCE OF SOIL TESTING
Soil Properties & their significance
Soil Texture: Influences Water Holding Capacity, Nutrient Holding Capacity, Drainage & Aeration.
Desirable: Sandy Loam
Soil Structure: Influences Tilth, Ease of Manipulation, Water Infiltration & Drainage Rates, Air
Exchange. Desirable: Granular
Soil pH: Single most important property that influences nutrient availability.
Desirable: 6.5 – 7.5
Soil E.C.: Influences Water Uptake by plants. Desirable: Less than 0.80 dS/m
Organic Carbon: Indicator of the Organic Matter content which exerts its positive influence across the entire spectrum of soil properties. Desirable: Greater than 0.41%
Calcium Carbonate: Influences pH and availability of Phosphorus, Iron, Manganese, Zinc, Copper & Boron. Desirable: Less than 5%
Soil Fertility: Capacity of Soil to supply essential nutrients to plants. The Soil supplies 13 of the 16 essential nutrients. Desirable: A individual Nutrient level of Medium and above, in the six-tier system
A brief look at the 16 Essential Plant Nutrients & their Bio-chemical Role
|ESSENTIAL ELEMENT||FORM UTILISED BY PLANTS||BIO-CHEMICAL ROLE|
|Carbon, Hydrogen, Oxygen||CO2, H2O||Combined in the process of Photosynthesis to form a Carbohydrate that becomes the physical structure / framework of the plant|
|Nitrogen, Sulphur||NO3–, NH4+, SO42-||Combine with carbohydrates to form amino acids & proteins that become involved in enzymatic processes|
|Phosphorus||PO33-, H2PO4–, HPO42-||Involved in energy transfer reactions|
|Potassium, Magnesium, Calcium, Chlorine||K+, Ca2+, Mg2+, Cl–||Involved in maintaining osmotic potentials, membrane permeability & electro potentials and balancing anions|
|Iron, Manganese, Zinc, Copper, Molybdenum||Fe2+/Fe3+, Mn2+, Zn2+, MoO42-||Enable electron transport by valency change|
|Boron||H3BO3, BO33-||Involved in Carbohydrate reactions|
Deviation from these normal / desirable traits results in an imbalanced soil.
How does one know, to what degree, a given soil is close to the ideal or desirable?
The answer unequivocally will be SOIL TESTING!
What is Soil Testing:
Soil Testing is a scientific process of subjecting a soil to various physical and chemical tests in a lab to study its suitability for growing crops and in the process estimate its production potential in terms of its physical, chemical & biological properties.
A Soil Test Report serves as an important management tool to mitigate production risks in agriculture. It recommends measures to be undertaken by a grower to correct deviations in the soil properties to facilitate creation of favourable conditions for a good crop growth & development aimed at getting the desired yield.