Weedbusters - Activities, Information and ... - Weeds Australia

Weedbusters – Activities, Information and Curriculum LinksSeed bank robbers –How many seeds in a seed bank?AIM: To calculate the number of seedshidden in soilYou will need:• tray with drainage holes, and• spade.This exercise demonstrates the size of a weedseed bank. It is best done in late winter or earlyspring when many seeds will be more likely togerminate.1. Locate an established infestation of weeds.Hold the spade so that the handle is only30 cm from the ground. Carefully push thespade so a scrape of soil about 5 cm deep isremoved and covers the spade. Try not tobreak up the scrape too much.2. Slide the scrape of soil into a shallowcontainer with drainage holes.3. Measure the area of the scrape.4. Place the scrape in a sunny position in yourclassroom and treat as you would the fussiesthouse plant. (Weeds have an annoying habitof not growing well when you want themto.) Do not over water.5. When the seed bank starts to germinate(it may take three to six weeks) keep atally of seedlings that appear over the nexttwo weeks.6. Convert the total to a density measurementusing the following calculation:Density (D) = number of seeds per squaremetreD =no. of seedsarea of scrape (in m 2 )7. Compare your findings with similar estimatesand for the weeds you have alreadyinvestigated. Discuss ways of ‘Robbingthe Seed Bank’ i.e. reducing the numberof weed seeds in the soil.39www.gould.edu.auwww.weeds.org.au