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The Loam Ranger – Cation exchange versus ammonium sorption in zeolites
Our client Brett, in Sydney, was stumped by a large discrepancy between an earlier SESL Australia test result on his zeolites and a recent US laboratory analysis. Specifically, why did the US lab report a cation exchange capacity (CEC) of 55 meq/100 g and SESL report 147 meq/100 g (nearly 3 times the size)?
The short answer is that the US lab tested CEC, which is not appropriate for zeolites, whereas SESL tested the ammonium sorption capacity, which is highly relevant to zeolites.
Click here for the long answer (1000 words, 4 minutes)
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Cut high to help turfgrass establish
The most resilient turf has deep roots that can reach the deep water in the soil profile. New turf must be watered regularly until the deep roots develop. But regular watering discourages the turf from rooting deeply, because the turf gets all the water it needs at the surface. All the while, you’re wasting water.
So what can you, the turf manager, do to speed up the deep rooting and so minimise the irrigation?
Researchers at the Texas A&M University, North Carolina State University and the University of Florida asked this question. To answer it, they grew plugs of turf (couch, Zoysia grass, bahia grass and buffalo grass) in tall clear tubes, and tested combinations of nitrogen (N) fertiliser and mowing height. Two rates of N approximated the lower and higher ends of the normal recommended range. Two cutting heights (which depended on species) represented heavy and light mowing.
Two conclusions were evident:
- The higher N rate encouraged faster rooting.
- The higher cutting height encouraged better rooting.
Cutting height had no effect on the rate of root growth, although it had a big effect on root mass: the low cut greatly reduced root mass.
Bahia grass achieved the best root growth (depth and mass) in the high N, high cut combination. But Zoysia grass did best in the low N, high cut combination. The results depended as much on the species as on the treatments.
Overall, maintaining a high cutting height did far more to encourage rooting that applying high N fertiliser. The authors recommended that turf managers cut establishing turf to the highest height recommended for the species.
Click here for the link to the article (400 words, 2 minutes) |
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Water quality monitoring guidelines
We’ve had several articles recently on water quality monitoring. These all focus on different aspects of why water quality monitoring is critical. In brief:
- Monitoring is a legal requirement of some operating licences – to ensure, for example, that an activity doesn’t release harmful substances into groundwater or surface water and cause problems for people or wildlife downstream.
- Monitoring can be good insurance, even where it’s not a legal requirement, in case of a dispute about who contaminated a water supply.
- Monitoring is essential in the supply of drinking water; water supply authorities, for example, have a legal and moral responsibility to ensure a safe supply.
- Monitoring can warn of adverse effects before the effects show up in wildlife or consumers.
- Monitoring can detect the intrusion of saline groundwater into a previously freshwater supply.
All water quality monitoring in Australia and New Zealand follows the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (usually referred to as the ANZECC Guidelines). This is an extensive document (in 3 parts) that is itself part of a much more extensive set of over 24 documents on water quality, including policies for water quality management, water quality benchmarks, groundwater management, sewerage, effluent, recycling and more. These can all be found at the Australian Government’s “Water publications” Web page.
Click here for links to the Guidelines (500 words, 2 minutes) |
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Sign up now to earn carbon credits
The Australian Government’s new carbon pricing mechanism, which came into force on 1 July 2012, is part of a broader program to reduce Australia’s contribution to human-induced climate change. It joins other mechanisms within the Clean Energy Future plan, of which the Carbon Farming Initiative will be of interest to many of SESL Australia’s clients.
“The Carbon Farming Initiative (CFI) allows farmers and land managers to earn carbon credits by storing carbon or reducing greenhouse gas emissions on the land. These credits can then be sold to people and businesses wishing to offset their emissions.
“The CFI also helps the environment by encouraging sustainable farming and providing a source of funding for landscape restoration projects.
“The CFI is a carbon offsets scheme that is part of Australia's carbon market.”
To explain the CFI, the Government has released The Carbon Farming Initiative Handbook, which can be downloaded now. The Handbook “contains information about the [CFI] and how it operates. It will also help you decide what type of CFI activity might be right for you, your business or your organisation.”
Click here for more details and links (450 words, 2 minutes) |
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| Efflorescence typically appears as whitish patches. |
Crazy pavers – why pavers go white
We’ve all seen them somewhere – pavers coated with patches of white salt. This unsightly problem is easy to avoid, though harder to fix.
If you’ve ever sat on the grass at a picnic and stood up with a damp seat, you’ve experienced capillary action first hand. Capillary action is the ability of very closely spaced solids to lift water on account of the surface tension of the water. A sheet of paper on a kitchen bench shows capillary action if you drip water at its edge.
So long as there is an unbroken length of closely spaced particles, soil moisture will be conducted to the surface of whatever is laid on the ground. Like pavers.
All soils have salts in them, as a result of natural weathering, deposition of trace amounts of sea salt in rain, and fertiliser application. Salts, being dissolved in the soil water, will therefore also rise to the surface, where the water evaporates, leaving them behind.
In the “good old days”, pavers were always laid in a bed of sharp river sand, which used to be easy to come by and cheap. The sand grains, being of nearly uniform size, have few points of contact with each other, and so capillary action is hindered. This is the crucial point: without capillary action, the soil water can’t rise very far. Salt stains on pavers were uncommon.
Today, sharp sand is expensive, so landscapers look for cheaper alternatives.
Click here for what happens and how to avoid it (400 words, 2 minutes) |
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| Mantis shrimp have 12 different colour receptors and can discern possibly 1 000 000 000 000 different colours. Photo: Wikipedia |
Did you know ...? – Colour vision
Most of us take colour vision for granted. With three types of colour photoreceptor cells (cones) in the eye, some primates, including humans, can perceive millions of different colours. Although these three colour photoreceptor cells are thought of as responding to red, green and blue light (the colours used in television screens and computer monitors), in fact they all respond to most wavelengths, and colour is discerned in the brain from the balance between the three signals and their intensities.
Primates are the only placental mammals to have three colour receptors – they are called trichromats.
Evidence is emerging that marsupials are also trichromats. Surprisingly, their colour vision may be different from ours. Our ancient vertebrate ancestors had four colour receptors, and birds and fish today retain those (making them tetrachromats). Our early mammalian ancestors lost two of those receptors, but our early primate ancestors acquired an extra one (through a mutation of one of the others). The marsupials appear to have retained three of the four ancestral receptors. Because at least one of these is different from ours, it is likely that they see different colours from those we see.
Most of the rest of the placental mammals make do with two receptors – they are called dichromats. (Whales and seals are monochromats, seeing only in shades of grey.) In consequence, your dog or cat can see in colour, but cannot see red.
Some species of bees are also trichromats, and can see ultraviolet but not red. This implies that red flowers are not attractive to bees; instead, they attract birds.
A few people are true monochromats, being unable to perceive colour. Instead, they tend to have unusually acute vision, being able to detect objects too indistinct for the rest of us to see. More commonly, people who are colour-blind can see in colour but are unable to distinguish between red and green (the most common form) or between blue and yellow.
At least two possible tetrachromatic humans are known, both women. Because two cone pigment genes are located on the X chromosome, and as females have two X chromosomes, it is possible that a small percentage of girls and women are tetrachromats. What colours these women are capable of seeing, the rest of us can only guess.
The winners appear to be the mantis shrimp, which have 12 different receptors, responsive to colours from red to ultraviolet, giving them the potential ability to discriminate 1 000 000 000 000 different colours. |
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Yours sincerely,
Murray Fraser and Simon Leake
SESL Australia ABN 70 106 810 70
Tel: 02 9980 6554, Fax: 02 9484 2427
16 Chilvers Road | Thornleigh | NSW | 2120
PO Box 357 | Pennant Hills | NSW 1715 | Australia
www.sesl.com.au |
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