Tropical shifting cultivation practise increases soil fertility - farming in a post-oil world
Earlier we reported about the ancient 'terra preta' technique of agriculture which boosts the fertility of poor soils in the tropics. The technique promises to become the basis for biofuel farming in some parts of the South, because not only does it enhance soils and increase yields, it also offers a strategy for carbon sequestration.
Several years ago, a Duke University doctoral student in botany found another indigenous agroforestry technique, a type of shifting cultivation long practiced on the Indonesian island of Borneo, that can boost the fertility of tropical soils. Deborah Lawrence made her findings during five years of research at a remote Dayak village whose inhabitants periodically clear 2 acre patches of land for rice farming or rubber and fruit tree cultivation. In between cultivating these patches, the Dayaks allow them to revert to native shrubs and trees during 20 year long "fallow" periods, with surprising results. This way, the Dayaks succeeded in cultivating plots of land sustainably for more than 200 years, without any loss in fertility.
Since she published her dissertation, Lawrence has been studying the phenomenon in other places (Southern Mexico and Costa Rica) and the results are largely confirmed.
The fallow and active farming sites of the Dayaks are nested within a matrix of "primary" forest land that has never been cleared for farming -- forming a mosaic of differing land uses. Lawrence's analyses of soils and trees focused on seven grown-over fallow sites that had not been cultivated for 10 years, and three other never-disturbed primary forest sites.
The results show that the Dayak method of shifting cultivation actually makes soils more fertile than those in undisturbed primary forest. Those results themselves are "surprising," she said in a recent interview at Duke, because they contradict negative perceptions of "slash and burn" methods that the Dayaks themselves employ to clear land.
In her newest study, Lawrence found that -- especially when she combined all her data from all her sites -- tree biodiversity was "negatively correlated" with soil fertility. In other words, the less carbon, calcium, magnesium, nitrogen, phosphorus and potassium she found in the soil, the more varieties of trees she found growing in a given study plot.
Each of those elements is an essential nutrient, Lawrence said. Carbon is the building block for all organic life, while nitrogen and magnesium both contribute to the photosynthetic process that uses sunlight to create plant sugars. Phosphorus is essential for energy production. Calcium is used to make plant cell walls. And potassium contributes to plant water regulation.
When she separated the fallow site data from that for the primary forest sites, Lawrence found some interesting differences. Not only was there more tree diversity in the never-disturbed woodlands, she said, but to some extent, the relationship between biodiversity and soil fertility was actually reversed when primary forest plots were analyzed alone:
biomass :: bioenergy :: biofuels :: energy :: sustainability :: slash-and-burn :: agroforestry :: Borneo ::
With increasing fertility, diversity increased in primary forest, whereas it decreased in periodically-cultivated plots. "It's as if cultivation takes the soil over some critical threshold where nutrients increase to the point that they then actually limit diversity in a negative way," said Lawrence, who is specializing in biogeochemistry and community ecology.
Her latest findings offer mixed signals for the prospects of reclaiming former tropical rain forests that have been cleared of their trees. On the one hand, she said, they corroborate a paradoxical finding of other scientists. Tropical rain forests may grow the world's most diverse array of plant life. But conditions are so delicately balanced there that the soils actually contain relatively few nutrients.
That means that subsistence farmers who clear tracts of the rich forests in the hopes of a quick return in bountiful row crops are quickly disappointed. They then must move on to destroy additional rain forest, leaving behind soil too depleted to grow anything but scrub grass.
But Lawrence's findings also suggest that Borneo's Dayaks have found a way to manage rain forest land much more productively by alternating various parcels between rice production, tree gardening, and decades-long resting periods.
"It's a broad mosaic of uses, much richer in species than any other land use system around," she said. "It's certainly richer than tree plantations or oil palm plantations or clove plantations or pulpwood plantations. But, within this land use system itself, there's no doubt that there's a decline in diversity and that it will probably continue."
By improving the soil's fertility, though, Dayak methods may actually create the conditions for the long process of generating the next rain forest, Lawrence added. All that would be needed would be seed from nearby remaining patches of primary forest.
"It means that we don't have to bring fertilizers in to get the forests to come back," she said. "We just have to leave them alone and make sure there are seed sources."
Fluent in Indonesian, Lawrence collected an oral history of the changing uses of each patch of land in her study area by gaining the Dayak's trust over a five-year period. She would ask farmers how many times they had "opened" a given patch for cultivation, knowing that there were intervening fallow periods of approximately 20 years.
She also asked the farmers what they remembered about their parents and grandparents use of various tracts. "I think that by going back three generations you can get a rough but pretty reliable estimate about how many times a patch was used," she said.
Land in her study area around the Dayak village of Kembera has been in continuous though shifting cultivation for at least 200 years.
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Friday, September 22, 2006
EU to subsidize energy crops further as biofuels production in Europe surges
This would involve increasing the maximum area which can benefit from the aid to 2 million hectares from 1.5 million at present. In a further push to encourage the production of biomass feedstocks for renewable energy, the Commission also proposed allowing the member states to grant national aid of up to 50 percent of the costs of establishing multi-annual crops on areas on which an application for the energy crop aid has been made. In the interests of simplifying the management of the CAP, the Commission has also proposed to allow eight member states which joined the EU in 2004 to continue operating the so-called 'Single Area Payment Scheme' (SAPS) for a further two years until 2010. The countries affected are the Czech Republic, Estonia, Cyprus, Latvia, Lithuania, Hungary, Poland and Slovakia.
“We need to do all we can to encourage the production of the raw materials for biofuels,” said Mariann Fischer Boel, Commissioner for Agriculture and Rural Development. “The energy crop scheme has had a good start. Now it’s only fair that we give farmers in all Member States the chance to benefit from this support. Extending the SAPS scheme also makes sense because it has proved a very simple and efficient method of supporting farmers in eight of the 10 countries which joined the EU in 2004. I am looking very closely at all possible ways of adding simplicity to the running of the CAP.”
The proposals accompany the first report on the operation of the energy crops scheme, which found the following:
- The €45/hectare aid for energy crops was applied for the fist time in 2004 to provide an incentive for farmers to grow the raw materials for biofuels. The area for which the direct payment for energy crops was claimed was between 1.2 and 1.2 million hectares in 2006, close to the limit of 1.5million hectares.
- The data on the development of bioethanol and biodiesel production as well as recently constructed capacities show a dramatic increase in the demand for energy crops within the next few years.
- The aid for energy crops is an incentive for farmers to produce crops for energy, instead of crops for food. Such energy crops can be converted both into solid, liquid and gaseous biofuels. Currently, 8 of the 10 new member states which apply the SAPS are excluded from this aid for energy crops, while Malta and Slovenia may receive aid up to the "phasing-in" level only.
- The review of the EU/CAP energy crops scheme has shown that it is appropriate to extend the aid for energy crops to all member states as from 2007 and under the same conditions. This way, the maximum guaranteed hectarage on which energy crops may be grown, should be increased proportionately.
- The data available on biofuel consumption and national indicative targets for the EU-25 show that many new member states have adopted national measures (for example exemptions from excise duty) to suport the production and use of biofuels. These data show that new member states are making significant efforts to comply with the Biofuels Initiative and the Biofuels Directive.
- To strengthen the role of multi-annual energy crops, the member states should be entitled to grant national aid of up to 50% of the costs associated with establishing such crops, for the areas that have been subject to an application for the CAP aid for energy crops.
In February, the Commission adopted an ambitious EU Strategy for Biofuels. Increased use of biofuels will bring numerous benefits, by reducing Europe’s dependence on fossil fuel imports, reducing greenhouse gas emissions, providing new outlets for farmers and opening up new economic possibilities in several developing countries:ethanol :: biodiesel :: biomass :: bioenergy :: energy :: sustainability :: CAP :: subsidies :: European Union ::
Todays’ proposal includes also improvements to certain rules governing direct payments, notably: (1) the possibility for the new Member States using SAPS to continue to use this simple way of granting income support to the farmers until the end of the year 2010, instead of 2008; from the start of 2009, farmers in the countries opting to continue this simplified direct aid scheme would have, as in other Member States, to comply under ‘cross-compliance’ with the statutory requirements in the areas of environment, public, animal and plant health and animal welfare to receive full payments under direct payment schemes and certain rural development measures; (2) the simplification of the eligibility rules under the single payment scheme for land with olive trees; (3) the clarification that the phasing-in of direct payments in the new Member States does not apply to all the direct payments related to the sugar regime.
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