What is dryland soil salinity?

Dryland salinity is the build-up of salt in surface soil in non-irrigated areas, usually because of rising groundwater tables. Groundwater seeps to the surface, bringing salt with it. As the soil surface dries out, salt is left behind.

What are the causes of dryland salinity?

Dryland salinity is caused by rising water tables. Some ways this can occur: Clearing deep-rooted perennial native vegetation and replacing it with shallow rooted annual plants. The shallow roots are no longer able to utilise the excess runoff, and it now seeps past the roots zone to enter the groundwater system.

What are the effects of dryland salinity?

Dryland salinity is closely linked to other soil degradation issues, including soil erosion. Salinity is often associated with prolonged wetness and lack of surface cover and therefore increases the vulnerability of soils to erosion.

What is dryland salinity and irrigation salinity?

Dryland salinity is the accumulation of salts in the soil surface and groundwater in non-irrigated areas. It is usually the result of three broad processes: groundwater recharge (or deep drainage) groundwater movement. groundwater discharge.

How does dryland salinity affect agriculture?

reduced productivity of agricultural land (Figure 7) • reduced agricultural production • reduced farm income • reduced options for production • increased input costs to rectify or reduce impacts of salinity • reduced access and trafficability on waterlogged land • reduced water quality for stock, domestic and …

What are the different types of salinity?

The term “salinity” refers to the concentrations of salts in water or soils. Salinity can take three forms, classified by their causes: primary salinity (also called natural salinity); secondary salinity (also called dryland salinity), and tertiary salinity (also called irrigation salinity).

How can dryland salinity be reduced?

Options may include improved irrigation systems, crop rotations, incorporating perennials into cropping systems, whole farm planning, interception plantings and monitoring of groundwater. There has always been a strong interest in the use of trees and revegetation in the management of dryland salinity.

How can dry land salinity be reduced?

In most recharge areas that are at risk of future salinity, the goal is to minimise recharge. This can be done by planting wide-spaced trees (alley farming), areas of perennials on suitable soils, and by preventing soils from being left without a significant leaf area in winter and spring.

Where does dryland salinity occur?

Dryland salinity occurs in unirrigated landscapes (Figure 1). Primary (or inherent) salinity is the natural occurrence of salts in the landscape for example salt marshes, salt lakes, tidal swamps or natural salt scalds.

What is salinity PDF?

stress · Crop production. 1.1 Introduction. Salinity is the term used to describe the condition when soluble salts get accumulated. in the solution (soil or water) to a level that has a negative impact on the growth and. development of crop plants (Childs and Hanks 1975).

How is dryland salinity different from irrigation salinity?

Common forms of secondary salinity are: irrigation—irrigated areas, either as a result of rising groundwater tables (from excessive irrigation) or the use of poor quality water. dryland—non-irrigated landscapes, generally as a result of clearing vegetation and changes in land use.

What causes dry land?

Drylands are places of water scarcity, where rainfall may be limited or may only be abundant for a short period. They experience high mean temperatures, leading to high rates of water loss to evaporation and transpiration.

What is salinity in geography?

The term salinity refers to the amount of dissolved salts that are present in water. Sodium and chloride are the predominant ions in seawater, and the concentrations of magnesium, calcium, and sulfate ions are also substantial.

What are the 2 types of salinity?

What is the unit of salinity?

g/kg
Ocean salinity is generally defined as the salt concentration (e.g., Sodium and Chlorure) in sea water. It is measured in unit of PSU (Practical Salinity Unit), which is a unit based on the properties of sea water conductivity. It is equivalent to per thousand or (o/00) or to g/kg.

What dryland means?

Definition of dryland : of, relating to, or being a relatively arid region a dryland wheat state also : of, adapted to, practicing, or being agricultural methods (such as dry farming) suited to such a region.

What are the factors affecting salinity?

Factors that Control Salinity

• Evaporation.
• Precipitation.
• The Influx of River Water.
• Atmospheric Pressure and Wind Direction.
• Circulation of Oceanic Water.

What is salinity PPT?

Salinity is the measure of the amount of dissolved salts in water. It is usually expressed in parts per thousand (ppt) or percentage (%). Freshwater from rivers has a salinity value of 0.5ppt or less.

What two factors affect salinity?

The salinity of water in the surface layer of oceans depends mainly on evaporation and precipitation. Surface salinity is greatly influenced in coastal regions by the fresh water flow from rivers, and in polar regions by the processes of freezing and thawing of ice.