Posts Tagged Phosphorus
I have had a lot of questions about my posts related to Biochar over the last few months, so I thought I would post this piece from the Economist from University of Florida. I could talk for a few hours on the subject about the truth, lies, snake oil effect and real research that is going on… but this article gives a good overview. Again – not my own article – but I do have the largest supply of biochar from anaerobically digested dairy manure fiber currently in the world. A large portion of my PhD is dealing with the use of biochar as a nutrient recovery tool
The Economics of Biochar
Before the industrial revolution, whole forests disappeared to provide the carbon that ironmakers need to reduce their ore to metal. Then, an English ironmaker called Abraham Darby discovered how to do the job with coke. From that point onward, the charcoal-burners’days were numbered. The rise of coal, from which coke is produced, began, and so did the modern rise of carbon dioxide in the atmosphere.
Ironically, the latest fashion for dealing with global warming is to bring back charcoal. It has to be rebranded for modern consumers, of course, so it is now referred to as “biochar.” There are individuals who think biochar may give humanity a new tool to attack the problem of global warming, by providing a convenient way of extracting CO2 from the atmosphere, burying it and improving the quality of the soil on the way. Many people with an interest in biochar got together recently at the University of Colorado, to discuss the matter at the North American Biochar Conference. They looked at various ways of making biochar, the virtues of different raw materials and how big the benefits really would be.
The first inkling that putting charcoal in the ground might improve soil quality came over a century ago, when an explorer named Herbert Smith noticed that there were patches of unusually rich soils in the Amazon rainforest in Brazil. Most of the forest’s soil is heavily weathered and of poor quality. But the so- called “terra preta,” or “black earth,” is much more fertile. This soil is found at the sites of ancient settlements, but it does not appear to be an accidental consequence of settlement. Rather, it looks as though the remains of burned plants have been mixed into it deliberately. And recently, some modern farmers – inspired by Wim Sombroek, a Dutch soil researcher who died in 2003 – have begun to do likewise.
According to Julie Major, of the International Biochar Initiative, a lobby group based in Maine, infusing savannah in Colombia with biochar made from corn stover (the waste left over when maize is harvested) caused crops there to tower over their char-less counterparts. Christoph Steiner, of the University of Georgia, reported that biochar produced from chicken litter could do the same in the sandy soil of Tifton in that state. And David Laird, of the USDA, showed that biochar even helped the rich soil of America’s Midwest by reducing the leaching from it of a number of nutrients, including nitrate, phosphate and potassium. However, it is the idea of using biochar to remove carbon dioxide from the atmosphere on a semi-permanent basis that has caused people outside the field of agriculture to take notice of the stuff. Sombroek wrote about the possibility in 1992, but only now is it being taken seriously.
In the natural carbon cycle, plants absorb CO2 as they grow. When they die and decompose, this returns to the atmosphere. If, however, they are subjected instead to pyrolysis – a process of controlled burning in a low-oxygen atmosphere – the result is char, a substance that is mostly elemental carbon. Although life is, in essence, a complicated form of carbon chemistry, living creatures cannot process carbon in its elemental form. Charcoal, therefore, does not decay very fast. Bury it in the soil, and it will stay there. Some of the terra preta is thousands of years old.
Moreover, soil containing biochar releases less methane and less nitrous oxide than its untreated counterparts, probably because the charcoal acts as a catalyst for the destruction of these gases. Since both of these chemicals are more potent greenhouse gases than carbon dioxide, this effect, too, should help combat global warming. And the process of making biochar also creates beneficial by-products. These include heat from the partial combustion, a gaseous mixture called syngas that can be burned as fuel, and a heavy oil.
The benefits of the soil should be enough to persuade some farmers to make and bury biochar. Others, though, may need more incentives – probably in the form of carbon “offsets”that compensate for emissions elsewhere. In the developing carbon-trading economy, CO2-emitting industries could pay farmers to buy stoves to char and sequester farm waste. Farmers in poor countries could get in on the act too, through the Clean Development Mechanism, a United Nations’ program that allows emitters to buy offsets in the global market. (The Economist, 8/27/09).
I retrieved Thursday November 19 at 6:30am from http://pested.ifas.ufl.edu/newsletters/2009-10/biochar.htm
I was ask to include a little of my work in a blog so here goes…I do encourage your input.
Phosphorus is a macronutrient needed for life to exist. Phosphorus is primarily made available to plants through the mineralization of organic material (biomass, organic matter, plant residue or agricultural by-products) and the dissolution of primary and secondary phosphorus minerals. The fate and rate of the phosphorus availability in a system depends on multiple factors which are ultimately site specific. These factors include soil chemistry, temperature, management practice, pH and the physical soil make up including texture, density and structure. Since phosphorus is becoming the new standard element to be tracked for pollution on dairies and agricultural land it, is important we understand the inputs and outputs intimately. When attempting to account for the phosphorus in the system it is vital to use the appropriate testing methodology. Failure to use the best practices for testing could skew regulation to one side or the other. (Barrow, 1974; Fuhrman et al. 2005; Sims ed. 2005; Rowell, 2003)
When breaking down the testing soils for phosphorus there are three primary approaches to testing: (Toor et al. 2006; NRCS 2008; Davenport, 2007; Arie, 2007; Kuo, 1996)
1) Immediately available soil phosphorus which is considered available to the plant immediately.
Methods include Water Extractable Phosphorus and Ion-Exchange Membranes (Anion Exchange Resin).
2) The labile phosphorus which could be available to the plant throughout the growing season.
Methodsinclude Olsen, Bray, and Mehlich 1 or 3.
3) The non labile phosphorus which is contained in the clays or secondary minerals which is only available to the plant as it is broken down over time, usually a very slow process.
Methods include Sequential Phosphorus Fractionation, Nuclear Magnetic Resonance Spectroscopy and X-Ray Absorption Near Edge Structure Spectroscopy.
For the purpose of this post I would like to explore the pros and cons of these methodologies and which are the most useful to science and agriculture respectively.
Please take a look at these three approaches and give me some feed back on the usefulness of a method and some of the factors affecting your answer. Please indicate if you are referring to a specific cropping system.
References available just ask.