-
Fertile Minds contents page
- Fertile Minds archive (back issues)
- Refer this site to a friend / colleague
March 2008
Welcome to the March edition of Fertile Minds, the monthly newsletter of Sydney Environmental & Soil Laboratory. We know we're a bit late, but we'll be sending the April issue later this month.
Winter is coming, so in the next issue we will begin a series of articles about using the down time to prepare for the growing season.
If there are specific topics that you would like covered, please email your request to info@sesl.com.au.
If you have received our newsletter by mistake or would like to be removed from our mailing list, please go to the bottom of the newsletter you received and click on Safe Unsubscribe. This action will remove you immediately and you won’t hear from us again.
In this issue
- The Loam Ranger – Iron chemistry: Colours in the landscape
- Recycling waste products
- Water-repellent soil
- What is urea?
- Did you know ... ? – Saving endangered wallabies
New price list available
Our new price list is now available. If you would like to receive a copy, please click here.
As usual, if you have any special testing or consultancy requirements, we would be pleased to discuss them with you and tailor a package and price accordingly. Please contact the office on (02) 9980 6554 or info@sesl.com.au with your request.
The Loam Ranger – Iron chemistry: Colours in the landscape
|
Dear Loam Ranger, After the recent heavy rain we've noticed a slick of some orange-coloured slime running across paths and an oily film on the soil surface. Is it harmful?
We've had a lot of calls in the last 6 months from people concerned that they have oil slicks in their creeks or dams or running onto their property, or that their dams have become contaminated. Often this is associated with springs and water leaks they have not seen before. Typically these oily surface slicks refract light and show a rainbow of colours. The first thing we tell callers to do is lightly touch the oily film. If it swirls and flows together again it is likely due to oil, but if it breaks up like shattered icebergs it is due to iron. Click here to read about how drought, rain and iron lead to orange slicks (550 words, 2 minutes). |
 |
Photo courtesy of Megan Davenport, Baulkham Hills Council.Recycling waste products
As they say in Yorkshire, "There's brass in muck." It's possible - and even desirable - to make money out of other people's waste. For purely economic reasons, it's often cheaper to reuse waste than to buy new materials.
When Sydney Airport's Third Runway was built, it was landscaped with soil made from sand dredged from Botany Bay and 55 000 tonnes of composted biosolids, equivalent to about 30% of the sewage sludge produced in a year in Sydney. Biosolids are valued for their high organic matter content, which retains soil moisture, and high nutrient content. In fact, demand outstrips supply. Not bad for a waste product that was once flushed out to sea.
In NSW, more than 1.3 million tonnes of organic materials is recycled each year by licensed composting facilities. Over 80% of councils in the Greater Metropolitan Region of Sydney, the Illawarra, the Blue Mountains and the Hunter collect organic wastes - predominantly green waste - and turn it into compost for landscaping projects and even for sale back to the people who threw it away in the first place!
Click here to learn about the beneficial uses of recycled wastes (640 words, 2 minutes)
Water-repellent soil
Water-repellent, or hydrophobic, soils repel water instead of absorbing it. The water sits on the soil in beads. The reason is organic waxes that result from plant breakdown. The waxes coat soil particles and effectively prevent water entry into the soil. The main sources of the waxes are native vegetation and legume crops and pastures. Organic matter itself can also cause the repellence if it is present in high proportion.
When rain falls, water-repellent soil does not readily become uniformly moist. The water either runs off along the soil surface or enters the soil only in irregular patches. These patches can be seen beneath the surface as wet fingers alternating with dry regions.
In crops and pastures the uneven distribution of water can result in patchy growth, early growth and reduced yield. Lack of cover then exposes the soil to wind and water erosion, the latter focusing runoff.
What is urea?
Urea is a white crystalline substance with the chemical formula CO(NH2)2. It is highly soluble in water and contains 46.7% nitrogen. Urea is considered an organic compound because it contains carbon. It was the first organic compound ever synthesised by chemists; this was accomplished by accident in 1828 by the German chemist Friedrich Wöhlerin.
Click here to learn about using urea fertiliser (500 words, 2 minutes)
Did you know ... ? – Saving endangered wallabies
The brush-tailed rock-wallaby used to thrive in eastern Australia, enough that during the 1890s alone, 144 000 pelts were exported and 66 000 scalp bounties were paid because the wallabies were considered pests. Between 1850 and 1900, both sheep and rabbits proliferated, competing with the wallabies for food, and foxes killed many joeys. Hunting continued until 1930, and in the 1960s goats began competing with the remaining wallabies for food.
By 1998, only 10 brush-tailed rock-wallabies remained in Victoria, and populations in NSW were legally listed as endangered.
Continuing threats to the wild populations include predation, competition, habitat modification by fire, exotic weeds, clearing, drought, inbreeding, human disturbance, illegal shooting, road kills and disease transmission by feral predators.
Fortuitously, in 1870 the then Governor of New Zealand imported wallabies to Kawau Island, off Auckland, for his private zoo. Those wallabies throve, to the point where they became pests! In 2003, 33 wallabies were relocated from Kawau to Waterfall Springs Wildlife Sanctuary. Waterfall Springs, in Kulnura, on the Central Coast of NSW, is a not-for- profit organisation that works with Government departments, major zoos, recovery teams and volunteers to conserve endangered species.
These Kawau wallabies, of the endangered "central form" of the species, have bred well, and offspring have been provided to other breeding programs, with the ultimate aim of reintroduction to parts of their former range in NSW.
To breed up numbers of the near-extinct "southern form" from Victoria, Waterfall Springs uses an accelerated breeding technique called cross-fostering. Ten-day-old joeys are taken from their mother's pouch and placed in the pouch of a surrogate mother of a closely related species. The loss of the joey prompts the mother to breed again. This cross-fostering process adds an additional wallaby to the population every 40 days, and over two dozen breeding animals now exist in Australian zoos.
SESL is pleased to be a sponsor of the captive breeding program at Waterfall Springs. If you would like to become involved too, visit the Web site, http://www.waterfallsprings.com.au/index.htm, for more information. There is currently no government money available for captive breeding programs.