P ART 3-L ESSON 1 Salinity of soils and water

I NTRODUCTION Salinity is the word used to describe the salt content of soil or water. When this salt content is excessive it degrades water quality and land productivity. Soluble salts are often found in water and soil but usually not in sufficient concentrations to affect plant and animal survival.

I NTRODUCTION Salinity is a growing concern around the world. Much of the worlds farm land is becoming to salty for crops to tolerate.

I NTRODUCTION Soil salinity is associated with increased salinity in rivers. Today scientists understand what causes these problems but is it to late to fix the damage already caused?

W ASHING SALT FROM THE SOIL Australia naturally has salinity problems. Visit the site below to learn more about this topic. alinity.html

W ASHING SALT FROM THE SOIL Great inland seas and inward drainage of great river basins have produced areas of naturally saline soil in Australia. Lake Eyre and the south western wheat belt of Western Australia are examples of such places.

W ASHING SALT FROM THE SOIL The salinity problem has steadily increased because of agricultural practices inappropriate for the Australian environment. Farmers within the Murray-Darling Basin are culprits to this problem. For example:

T HE M URRAY -D ARLING B ASIN Irrigation Salinity Diverting water for irrigation causes areas of the river to be lower than normal and increases the water table under the areas of irrigation. The salinity rises in these areas and if water from these areas makes its way back to the river via run-off increases the salinity of the river system.

T HE M URRAY -D ARLING B ASIN Irrigation Salinity Damming areas of the river can encourage salinity because these damns are not flushed out allowing salt to accumulate in these areas.

T HE M URRAY -D ARLING B ASIN Dryland Salinity: Huge amounts of land has been cleared for farming and grazing. Replacement crops with shallow root systems allows water to penetrate down to the water table causing it to rise. This rising water table brings dissolved salts with it.

R EFLECTION Dryland Salinity Caused by the removal of native plants by overgrazing or clearing land for non native plants When large areas are cleared or replaced with plants with shallow root systems water can penetrate through the soil carrying dissolved salts and minerals which would have otherwise been absorbed by plants into the water table. As a result, more water reaches the water table which causes it to rise and carry dissolved salts with it.

R EFLECTION Irrigation Salinity: This is caused by over irrigation. The additional irrigation water causes the underground water-table to rise, bringing salt to the surface. When the irrigated area dries and the underground water-table recedes, salt is left on the surface soil. Each time the area is irrigated this salinity process is repeated.

H OMEWORK Read pages HSC Spotlight Text Update Electronic Vocabulary Complete DOT Point 3.1 pg 61

P ART 3-L ESSON 2 Salinity of soils and water

C OMBATING S ALINITY Salinity has become such a concern communities and governments have come together to combat the problem. Salinity contributes to agricultural losses and environmental damage so this should be a concern for us all.

C OMBATING S ALINITY Different forms of salinity need different management strategies. Any strategy should involve managing the movement of ground water through the subsurface

C OMBATING S ALINITY Local farmers can use prevention strategies that focus on reducing the amount of water reaching the water table. For example: Ensure vegetation covers the entire catchment Constant monitoring of the water table depth Budgeting only appropriate amounts of water to be used for irrigation Use drip irrigation systems to control the amount of water being used Using deep rooted crops Decrease fallow time (the time between harvesting one crop and planting another)

C OMBATING S ALINITY State Governments and Councils can also help combat salinity by implementing strategies on a larger scale. For example: Designing and building drainage systems to divert water before it reaches the water table. Surface drainage management (collecting and controlling water entering and leaving an area to minimise infiltration) Draw up water from the water table through bores to keep it at a level below root systems. The saline water drawn up can be collected in evaporative basins or disposed of appropriately.

C OMBATING S ALINITY The only way to effectively combat this problem is to all work together. We all need to learn from our mistakes and take the appropriate steps to fix the problems.

A CTIVITY Discuss Activities 3.5 and 3.6 (HSC Spotlight Text page ) together

H OMEWORK Read Pages HSC Spotlight Text Update Electronic Vocabulary Complete DOT Point 3.2

P ART 3-L ESSON 3 Salinity of soils and water

C ASE S TUDY In this lesson we are going to process a case study to reduce dryland salinity on a Temora Farm. Follow the steps below to access the study: 1. Go to Earth Wiki 2. Click on ‘Useful Links’ 3. Click ‘ Under the ‘CORE’ heading click on ‘Caring for our country’ 5. Under the ‘Students’ heading, click on ‘identify data sources and gather, process and present information as a case study of a successful rehabilitation program of a salt- affected area, including’ 6. Click on ‘ A case study to reduce dryland salinity on a Temora farm’

C ASE S TUDY Read and discuss the Case Study If time, complete DOT Point 3.3 together (Otherwise its homework)

H OMEWORK Complete ‘To Think About’ pg HSC Spotlight Text Complete DOT Point 3.3 pg 62