Thursday, April 26, 2012

The slash-and-burn method: useful or not for agriculture and biodiversity improvement??

Ancient farming method may help conserve savannahs

A fire-free farming method practiced by early inhabitants of the Amazonian savannahs could help inform efforts to conserve and rehabilitate these important ecosystems around the world, a study has found.
The research provides greater historic context for findings presented at a conference earlier this year (26 January), which suggested that slash-and-burn — in which trees are felled, left to dry and then burned to prepare land for farming — provides better growing conditions for valuable trees such as mahogany.
This latest study, published in Proceedings of the National Academy of Sciences (9 April), found that 800 years ago, prior to European settlement of Latin America, indigenous farmers had developed a technique known as 'raised-field' farming to manage land sustainably without using fire.

The method involved constructing small agricultural 'mounds' which promoted drainage, soil aeration and moisture retention. It conserved soil nutrients and organic matter, and preserved soil structure. 

The ancient technique was studied by researchers, who have created the first detailed picture of land use by documenting the very low frequencies of charcoal particles — an indicator of fire — in the savannahs of French Guyana. 

(Source: Aleida Rueda, 2012,


Slash-and-burn 'improves tropical forest biodiversity'

[MEXICO CITY] Slash-and-burn agricultural practices, banned by governments because of the risk of uncontrolled fires, provide better growing conditions for valuable new trees than more modern methods of forest clearance, a study suggests.

Starting in 1996, researchers cleared 24 half-hectare areas of tropical forest in Quintana Roo state, in southern Mexico, using three methods: clear-felling, where most of the trees are cut down; bulldozing; and slash-and-burn, a practice common among smallholders, in which trees are felled, left to dry and then burned, to prepare the land for agriculture.

Mahogany seeds and seedlings were then planted and, after 11 years, the researchers compared the sites and found that slash-and-burn techniques had provided the best growing conditions for mahogany.
But, more interestingly, many valuable species had thrived in the slash-and-burn plots, said Laura Snook, one of the study authors and programme director at Bioversity International, which conducts research into agricultural biodiversity for the improvement of livelihoods.

In clear-felled areas, more than half of each area contained tree species of no commercial value, Snook said. In areas cleared by slash-and-burn, 60 per cent of species were commercially valuable. Additionally, the largest trees in slash-and-burn areas were 10 per cent bigger than those in bulldozed areas.

Snook was presenting the results of the study — which ended last year — at the annual conference of the International Society of Tropical Foresters, at Yale University, United States, last month (26 January). 

(Source: Aleida Rueda, 2012,


Is the slash-and-burn (uncontrolled fires) really more valuable for biodiversity improvement than controlled fire method?


Friday, April 6, 2012

Getting “smart”: West Palm Beach & Central Florida!

Recent regional media coverage is shining the spotlight on “smart” irrigation technology. Below are two articles detailing advancements in irrigation controllers and water management and how utilities and municipalities are moving to integrate these advancements into their water conservation efforts.

ET in West Palm Beach

Weather-based timer with on-site weather station

On the verge of exhausting its water supply last year, West Palm Beach is now moving to promote the use of weather-based timers by granting residents installing these devices an exemption from watering restrictions.

Above the law: the Orange County irrigation exemption

Currently, Orange County, in Central Florida, grants residents an irrigation exemption (for posting, pictured above) if they participate in a water-saving study (in collaboration with UF) evaluating ET-based timers and soil moisture sensors.

Some of these residents are using this technology to enhance their watering regime, and others operate them “off the leash,” setting their automated timer to water seven days a week, or programming their ET controller with no watering day restrictions, and relying on the technology to keep them safe from high water bills.

Read more about West Palm Beach's irrigation exemption efforts here.

I calculate GPM, therefore I am

Right: Neptune e-coder, smart water meter

Over the past few weeks I’ve spent several days in Orlando working on what is referred to here as the OCU Project. In fact, last week I saw the sunrise from the highway twice on my way there for early site visits! But more on this in a future post.

Recently, while assessing an irrigation system, I was asked by another researcher (graduate student Stacia Davis) to get the gallons per minute (GPM) information from the home's water meter while she ran the system for zone area measurements. Well, I reached for my hand-held device like I’ve done countless times with the Urban Conservation Unit, and she tells me to take a look in the meter box first because these water meters calculate their own GPM data!

No mess, no fuss: smart meter at rest flashes its GPM rate

Sure enough, every 15 seconds, as the digital meter reads the total volume, it also tabulates and flashes a GPM rate. As this rate stabilizes, the GPM calculation is achieved, sans any subtracting or dividing.

Read more about smart water meter use in Central Florida here.

The Growing Season out at C111 Comes to an End

Isaya and I have seen many crops this year, and due to our weekly downloads have had the pleasure of watching many go from seed to harvest.

Isaya and Nicki taking measurements for LAI in a young corn field

Several weeks later same corn field being harvested

With the heat now starting to creep up on us we realize that the season will soon come to an end, and this is exactly what we witnessed on our last download.

Ploughing a field of recently harvested yellow squash

However in the midst of the season wrapping up and the land being cleared their is still, at least for the next couple of weeks, a failry young crop of green beans (they are one of the last seasonal crops that can withstand a bit higher temperatures).

We did not suffer any major frosts or freezes this year so hopefully our farmers had a successful year. We will continue to collect our weekly downloads but we are definitely looking forward to our next growing season!