Salt affects millions of hectares of farm land in Australia. Students will research the adverse effects that salt has on plants.
Australian Curriculum: Humanities and Social Sciences
Science Inquiry Skills
- Year 4 - With guidance, identify questions in familiar contexts that can be investigated scientifically and predict what might happen based on prior knowledge (ACSIS064)
- Year 5 and 6 - With guidance, pose questions to clarify practical problems or inform a scientific investigation, and predict what the findings of an investigation might be (ACSIS231)
- Year 5 - Living things have structural features and adaptations that help them to survive in their environment (ACSSU043) The growth and survival of living things are affected by the physical conditions of their environment (ACSSU094)
- Wheat seeds (if you have easy access to seeds, this activity can be extended to test salt tolerance of different crops e.g. barley, canola, oats)
- Plastic cups
- Potting mix
- Water bottles
View the photographs on the Department of Agriculture and Food, Western Australia's website: Dryland Salinity in Western Australia
Give students four sticky notes. Ask them to view each image and write a word or comment in response to each photo. Discuss.
Whole class introduction
Dryland salinity is one of the greatest environmental threats facing Western Australia's agricultural land, water, biodiversity and infrastructure. Dryland salinity (non-irrigated land) is defined as salinity at or near the soil surface causing a reduction in plant growth, reduced water quality and damage to infrastructure.
Australian soils have always contained salt which was kept at bay by our highly adapted native species that used the water in the soil profile efficiently and kept the watertable low.
As the native vegetation was removed in the development of agricultural lands and replaced with short rooted crops and pasture, the excess water infiltrates the soil profile and collects as groundwater which over time has risen bringing the build-up of natural salts to the soil surface.
Salinity is usually first noticed when plants grow poorly and yields of farm crops and pastures are reduced by more than 25–30%. In severe cases, bare patches, known as salt scalds, develop with salt obvious on the surface. Where groundwater seepage is apparent, saline areas are referred to as saline seeps or seepage scalds (DAFWA, 2015).
More than two million hectares of broadacre farmland in Australia were estimated to be affected by dryland salinity, with more than half in Western Australia (Australian Bureau of Statistics 2002).