Contents
What is Soil texture?
It refers to the relative proportion of mineral particles of various sizes in the given soil i.e., the proportions of coarse (sand), medium (Silt) and fine particles (clay)
What is the size of mineral particles present in the soil?
The mineral particles are classified into 4 groups as follows
Course sand
These particles have a size between 2 mm to 0.2 mm
Fine sand
These particles have a size between 0.2 mm to 0.02 mm
Silt
These particles have a size between 0.02 mm to 0.002 mm
Clay
These particles have a size less than 0.002 mm
How are percentages of sand, silt and clay determined?
The textural class of a soil can be accurately determined in the laboratory by mechanical analyses
What are different textural classes?
On the basis of which mineral proportions like sand, silt and clay are present in predominant proportions, soil is classified into textural classes as follows
As per the classification followed in USA, there are twelve major soil textural classes
A. Sandy soils
They have more percentage of sand and further contain two classes
1. sand
2. loamy sand
B. Loamy soils
These basically have equal percentages of sand, silt and clay and further contain the following classes
1. sandy loam,
2. loam,
3. silt loam,
4. silt,
5. sandy clay loam,
6. clay loam,
7. silty clay loam,
C. Clayey soils
These have greater percentage of clay particles and contain the following classes
1. sandy clay
2. silty clay
3. clay
How does soil texture afect soil?
The soil texture is closely related to the following properties
a) Water holding capacity of the soil
b) Irrigation interval and number of irrigations
c) Permeability i.e., ability of the soil to transmit water & air
d) Infiltration rate
Sandy soils have low water holding capacity and facilitate rapid drainage and air movement
Therefore, crops grown on these soils require frequent irrigations with less irrigation water depth at each irrigation.
On the other hand, clayey soils have relatively high water holding capacity, however the permeability for water and air is slow thus resulting in poor drainage and sometimes the soils get waterlogged
Which textured soil is best for majority of crops?
Considering its various effects, the soils with loamy texture are the ideal soils for growing most crops under irrigated conditions
Further reading and references
Introduction to Soil Science – V D Patil & Mali
