Sunday, October 31, 2010

Phytoremediation with Napier grass

Napier grass for Phytoremediation

Phytoremediation often seems a simple but slow and unobtrusive process. Not visually obtrusive, no flash pumps nor any drill rigs, but a simple plant, just growing and doing its thing to improve soil quality.

Recent research by a group that involves the Australian CRC, CARE – based in Adelaide – has shown that a commonly used tropical pasture grass – Napier grass , Pennisetum purpureum may offer some simple options for phytoremediation of soil in the tropics.

The specific details are detailed in a generic way in the following link on the ABC web site :

although more details are on this link, direct to the CRC CARE:
but the potential seems to operate through metal uptake from soils as well as degradation of some hydrocarbon materials.

Napier grass is a fairly common perennial pasture species used in the tropics, particularly in those regions with rain most of the year. Napier grass which is perennial, has a few relatives in the grass genera that are very deep rooted and do grow on poor, dry soils for example – pearl millet, an annual species. It would be interesting to see how these species perform in the tropics.

There are not many plants considered suitable for phytoremediation use in the tropics so another candidate species is very welcome.

Cannot understand why it is being imported into Australia though, unless these characters are very specific to a new cultivar as would have thought the generic plant was readily available in northern Australia. Bana grass [ same species ] is used commonly as a windbreak grass in north Australia, and there is at least one Australian derived cultivar. See the following for more information:
and there is plenty more online.

Vetiver grass [ Chrysopogon zizanoides] also has a reputation as a species with metal accumulation properties, as well as being a great erosion control species and one that will colonise on tough soil conditions. Plenty of information on the web site

Friday, October 22, 2010

Endosulfan Registration Cancelled in Australia

Registration of Endosulfan Cancelled in Australia

The Australian Pesticides and Veterinary Medicines Authority (APVMA) on Tuesday advised that it had cancelled the registration of the insecticide endosulfan.

This decision followed a recent assessment of new information by the Department of Sustainability, Environment, Water, Population and Communities (DSEWPC) that the prolonged use of endosulfan is likely to lead to adverse environmental effects via spray drift and run-off.
A full risk assessment conducted by DSEWPC concluded that these long term risks could not be mitigated through restrictions on use or variations to label instructions.

From 12 October 2010, agricultural products containing endosulfan are no longer registered in Australia. The three current approvals for endosulfan have also been cancelled, and the five products containing the chemical will be phased out over the next two years.

Read the Full Report here.

Tuesday, October 19, 2010

Plant Power - Build Better Plants for More Carbon Capture or Bioenergy

WOW!!! Scientific American seems to have woken up to a fact probably well understood by many in the agriculture research area, and also by many farmers.

Better plants for carbon capture, biofuels, or for that matter almost anything else requires an investment in R and D, specifically some decent plant breeding and genetics. Along with some public policy work to see that the plants get used.

The article below appeared in in mid October 2010, and at least the review does build a case for a decent and ongoing investment in plant research, something that seems to have been over looked in the rush to develop geosequestration of carbon. Algae also probably has a place, especially for coal power stations, as does agrichar.

The comments about a price for carbon are very US-centric, and reflect what I would consider as "head in the sand" thinking by many US policy gurus, as another study, on mainstream media reports today, has indicated that many countries already have an explicit or implicit carbon price, including China and the EC countries, and that the US is probably out of line in its current thinking.

The article really says little that is new, but getting this approach into the mainstream thinking is very necessary to ensure the $$$$ do flow into a very useful avenue of development, in a time when agriculture seems to be less endowed with investment for long term progress.

Review article below.

Flower Power: Genetic Modification Could Amply Boost Plants' Carbon-Capture and Bioenergy Capacity
A new review sums up options for increasing global carbon-sequestration by flora, and speculates that genetically engineering crops and trees could enhance the process, trapping gigatons of the greenhouse gas as well as increasing bioenergy production.

Human activities currently add about nine gigatons of carbon to the atmosphere yearly.
Photosynthetic organisms on land and in the ocean absorb about five of those gigatons through the natural uptake of CO2, leaving to humans the task of dealing with the rest. But no matter how much carbon there is, capturing it and preventing it from reentering the atmosphere is an immense engineering challenge; even today's best technology is orders of magnitude less effective than photosynthesis at trapping atmospheric carbon.

A new analysis published in the October issue of Bioscience suggests that by 2050 humans could offset between five and eight gigatons of the carbon emitted annually by growing plants and trees optimized via genetic engineering both for fuel production and carbon sequestration.

Bioenergy crops represent an opportunity to mitigate atmospheric carbon dioxide in two separate ways, says lead author Christer Jansson, a senior staff scientist at Lawrence Berkeley National Laboratory's Earth Sciences Division. First, they are a carbon-neutral energy source that could offset the burning of fossil fuels. Second, "if they are the right kind of plants, they have a chance to transfer a lot of carbon underground for long-term sequestration," he says.

Plants take up CO2 and store carbon in their biomasses. Carbon can stay for decades or centuries in leaves, stems, branches, seeds and flowers aboveground, whereas carbon allocated to underground root systems is more apt to be transferred into the soil, where it can stay sequestered for millennia. Therefore, an ideal bioenergy plant would produce lots of aboveground biomass for fuel as well as have an extensive root system. Preliminary research indicates that genetic engineering approaches could be employed to enhance both these traits.

Using genetic modification to enhance photosynthesis and thus biomass yield is a realistic approach, says Stephen P. Long, a professor of crop sciences at the University of Illinois at Urbana–Champaign who was not part of the study. Long notes that transgenic tobacco plants, with simple modifications applicable to other plants as well, have already been shown to be more productive. "We are in a position now where we certainly know enough to where we could engineer quite a few of these changes," he says.

Meanwhile, regarding the problem of coaxing plants to allocate more carbon to their root systems, Jansson says an important difference between perennial and annual plants is a good place to start. "Perennials are more efficient than annuals at hiding carbon underground," he says. That's because annuals, which make up most of the world's food crops, spend much more energy producing seeds, stems and leaves than for building their root systems. On the other hand, perennials like switchgrass and Miscanthus have more extensive root systems—necessary because they remain dormant for part of the year and then must grow up again from their roots.

Whereas it may be exciting to imagine a bioenergy or food crop that produces lots of aboveground biomass and has large, carbon-sequestering root systems, research into whether this goal is realistic is still in its early stages. "Perenniality is a complex trait," Jansson says. He suggests it may end up being easier to modify perennials so they possess desirable annual-like features, as opposed to the other way around—but it's too early to tell. For the short term Jansson is confident that science can modify plants so they are more drought resistant and salt tolerant. Crops that could be maintained with brine or brackish water, such as industrial wastewater or seawater, would help preserve freshwater supplies. "These are important traits that need to be introduced into food and bioenergy crops," Jansson says, adding that "we will see this sooner" than enhanced photosynthesis or perennials with annual traits and/or vice versa.

The authors stress that genetic engineering should not be viewed as a cure-all, but rather part of a larger breeding effort. Further, Jansson says, "One problem is that the different aspects we mention—increasing photosynthesis, improving bioenergy crop yield, and putting more carbon into the root systems—are highly interlinked, and thus not necessarily additive." It could be, for example, that a modifying a plant to grow more roots takes away aboveground biomass production. Again, research in this area is too preliminary to tell.

Allison Thomson, who studies climate change and land use at the Joint Global Change Research Institute in College Park, Md., also expressed the need for caution when interpreting the study's projections. They are valuable in principle, she says, but also based on many assumptions regarding future economic conditions, land availability, and the size of bioenergy's role in a larger future energy strategy. For example, she says, "you can't really say how much bioenergy we are going use if you're not also considering other available energy sources and how much they emit." Furthermore, she points out, whether or not there is a price for carbon, which is hard to account for at this point, will figure heavily into future energy scenarios.

Also important to consider are potential land-use issues related to increasing demand for food. "When we do modeling, that's the one demand you can't ignore," Thomson says. "People want to eat before they want bioenergy."Besides all the unknowns, there is also existing regulatory policy regarding genetically modified organisms, which imposes high costs of compliance, thereby making it difficult to assess whether the ideas discussed in the paper are all doable.

Long says: "The bottleneck and damper on all this is really, 'How do you get transgenics out there, and meet all the regulatory requirements and costs?'"

Sunday, October 10, 2010

Rainwater Harvesting in the Tropics

Rainwater Harvesting in the Tropical north

In north Australia where rainfall is mostly very seasonal, with relatively well defined wet and then drier periods of the year it is possible to collect significant amounts of rainfall – rainfall harvesting. The hardest issue to contend with is the need to store relatively larger percentages due to the seasonally dry conditions.
This is particularly so in the north west of Australia – Darwin and areas west around the Kimberley coast where 4 – 8 months may have zero rain, and rainfall declines as you move away from the coastal areas.
However..............look at the data. Columns 2 and 3 show the amount potentially falling on the roof, in Kilolitres [KL] under a range of roof areas , for two different annual rainfall amounts

Roof area [sq metres] Rainfall – 1000mm/yr Rainfall - 1500mm /yr
200 200KL 300KL
250 250KL 375KL
400 400KL 600KL

If you assume a capture rate of 80%, the amounts potentially available are shown in the tables below. A capture rate of 80% could be considered in the low range area, as in the tropics much of the rain falls in significant storms, and in this situation a smaller proportion is wasted in first flush diversion or similar systems that divert the first smaller volumes of rain to ensure clean water is captured and goes into storage.

Roof area – sq m 80% capture of 1000mm/yr -KL 80% capture of 1500mm/yr-KL
200 160 240
250 200 300
400 320 480

The roof areas selected have been used as examples of small, medium and medium/large areas under roof with gutters and collection systems, and include the additive potential from a house roof, garage and sheds. They apply equally to urban and semi-rural locations.

For straight “in house” domestic use, with sensible management, a family of four could use less than 100KL. And there are a lot of options and management ideas to be considered.

For use outside the household areas, a modest lawn and garden could be developed with usage in the 100 – 200KL/year, especially if sensible grey water and effluent use was practised, using systems that allow subsurface disposal of these products.

One option is the use of KISSS subsurface irrigation systems [see] along with a range of approved alternative wastewater treatment systems – that is, a system somewhat superior to the older style septic tank, which treats effluent at least to secondary standard or better.

There are a wide range of these, and in Australia each State or local government region has approval systems for various brands and types, so you need to check what is legally available and approved.

The really tricky part is to work out how much you need stored around the end of the rainy season.

Some sort of monthly water balance is required, to calculate input and usage, but as a very broad guide, somewhere between 100 and 150KL would be needed at around the end of the rainy season.

More storage allows more extensive outside greenery development, naturally. Also remember that this stored water is a valuable resource for any fire fighting, and bushfires can be a threat in the drier months.

Tank Management

A few short comments.......
· Many users of tank water do not worry about water treatment, but there are some simple treatments if needed. Use in line or in tank UV treatment – this seems to be now seen as the most efficient way to kill any nasties in the water
· Clean water in – means clean water in the tank, so keep gutters clean and use pre treatments such as first flush diversion, leaf guards and similar systems.
· Keep mosquito larvae out of the tank.......screening has usually been seen as a simple solution, and of course this also keeps some particles out of the tank. The screen must be cleaned regularly to allow easy flow of the water into the tank, and two stage mesh systems do work well. In parts of Asia some areas use copepods [small animals that eat mosquito larvae] in tanks to prevent development of larvae.

Mosquito and mosquito larvae management is vital in those areas known to have the dengue mosquito present.

This is not a complete guide to using rainwater and tanks, but to show it is very definitely possible in this region, based on rainfall, and usage patterns and known areas of roof cover.

Even if there is no need to provide all of a households water needs, there are opportunities to collect and store rainwater for outside use – filling swimming pools, washing cars, garden watering to reduce using expensive treated potable water.

If planning a new house..........a suitable place for a tank may be under the driveway or under the lawn areas, rather than an above ground object in the yard! Many designs allow for traffic across the top of the tank.

It is not always difficult and can be an option where groundwater supplies are poor, or there are other issues around groundwater usage.