Download 2004-ag-1537 (Reclaimation of Salt Effected Soils)

IN THE NAME OF ALLAH, THE COMPASSIONATE, THE MERCIFUL
Reclamation of Salt Affected Soils
by
Rizwan Zahoor
2004-ag-1537
B.Sc. (Hons) Agri.
Agronomy 7th
Objectives of Reclamation:
1. To increase crop yield per unit area
2. To increase WUE
3. To improve farmers’ living standard
Methods of Land Reclamation:
1: Physical Methods
–
–
–
–
–
Sub soiling
Deep ploughing
Sanding
Horizon mixing
Profile inversion
2: Biological Methods
Growing of crops on problem soils and/or their
incorporation at the stage of maximum biomass
productivity.
3:Chemical Methods
It includes the application of
– Gypsum
– Sulphur
– Sulphuric acid
– Hydrochloric acid etc
Prerequisites for Land Reclamation:
• Good surface drainage
• Leveled soils
• Availability good quality water
• Chemical amendments
Reclamation of Saline Soils:
Reclamation of saline soil is done by applying excess
water to the soil surface. The removal of salts may be
accomplished either by continuous ponding of water on
soil surface or by intermittent leaching.
Reclamation Requirement:
It is amount of water required for reclamation, usually
depends upon
– Salts concentration
– Soil texture
– Soil structure
– Trenching
Reclamation of sodic and saline-sodic soil:
Reclamation of sodic and saline-sodic soil is more difficult,
time consuming and expensive than that of saline soil. It
involves not only leaching a soluble salts but also the
replacement of exchangeable sodium with calcium and the
improvement of physical properties of soil. The two most
difficult aspects of the reclamation process are
• Provision of source for replacement of sodium with calcium
• Water for leaching
Sources of calcium for replacing
exchangeable sodium:
– Irrigation water
– Gypsum and lime present in soil
– Chemical and biological amendments
– High-salt water
Replacing exchangeable sodium:
CaCO3 is insoluble in water. However, the presence of lime
is important in sodic and saline-sodic soil, if it is treated with
acids or sulphur, it provides calcium.
when vegetation is established, CO2 released and converts
the CaCO3 into relatively soluble Ca(HCO3)2.
Crop During Reclamation:
Some
kind
of
vegetation
should
be
grown
during
reclamation, as they help reclamation and also provide
some income to farmers.
Growth of crop helps reclamation in two ways
• The development of roots improve the permeability and
infiltration capacity of soil.
• CO2 released into the soil by roots increase solubility of
CaCO3.