WHEATBELT SALINITY

Solutions

Alley Systems

Problem  – Binnu, Midwest West Australia

A wheat and sheep farmer in the Midwest West Australia had a 250 ha paddock that was showing signs of a rising watertable. There was a poor crop yield, rye grass and other weed infestation resulting from the area being moist throughout the year. The boggy site made winter spraying treacherous and ineffective.

Solution

Block planting these areas was not viable as :

  • The fencing would be too costly
  • Too much good productive land would be lost to trees
  • The paddock could become inefficient and unworkable as the farm uses braoadacre seeding equipment and tramline mechanisms

Recommendations

Alley farming was recommended, that is the planting of dense belts of trees above, below and through the problem zones. The introduction of fodder crops like saltbush enabled the trees to be protected from chemical drift and provide summer feed for sheep.
The trees were planted on a lupin rotation. This meant that weed spraying of chemical would have little or no affect on the trees. The belts were positioned so the widest implement (boom spray) could travel between the belts with no overlap.
Alley systems can be incorporated across the landscape to rectify wind erosion.

Outcome

The alleys are now producing exceptional cereal crops. Weeds are now under control. Paddock average has increased 15%

Block Planting  – Lake King West Australia

Problem

This valley floor was showing signs of a rising water tables. The evidence is the barley grass, bare wet spots, poor pasture composition and poor crop yields made the area unprofitable due to salinity as a result of waterlogging.

Solution

The valley floor was planted to salt tolerant trees and shrubs were planted to lower the water table. As they grow they will soak up the water and reduce the spread of salinity.  Where possible saltbush fodder shrubs were planted on the specific soil types.

Directional surface drainage also helped move the water off site and ultimately reduce the effect of waterlogging

Drainage  – Kojonup West Australia

Deep drainage in conjunction with strategic planting will also help reduce the spread of salinity. Drainage needs to be carefully planned with permission from all neighbours and authorities if water is redirected from one property to another.

Drainage cuts into the lower sub soils and allows this water to travel in a direct route to either a river or lake system. Often rock dykes, change in soil types and man-made objectives (tracks and roads) hinder this movement.

A deep primary drain is paramont. From here secondary drains can pick up fingers of waterlogging. The key principle is to ensure the water keeps moving . After construction on going maintainence of the drain is essential to prevent silting up of the drains.

Block planting around these secondary drains will help reduce waterlogging and the spread of salinity up slope

PALS will help with the concept design and assist where necessary with the overall process.