Fertilizers boost crop production amongst smallholders in Zimbabwe
A dangerous myth thriving amongst some NGOs and environmentalists is that Africa can not feed itself because it is overpopulated, its agricultural potential has been completely tapped and it faces water shortages. The contrary is true: Africa has a staggering abundance of land and potential to produce rainfed crops, so much in fact that in theory it can feed the entire continent's rapidly growing population and have enough potential left to produce an amount of sustainably produced biofuels equal to the world's total current energy consumption (400EJ) (earlier post).
What Africa lacks is not land or water or agricultural potential (on the contrary), it is investments in land, in knowledge, in very basic farming inputs and in access to these inputs. Last year, the African Fertilizer Summit, which united some of the world's leading agronomists, made the point: if African farmers were to use the most simple of agricultural techniques (such as using micro-doses of fertilizers), the continent could double and, some estimate, even triple its current output at once. To those with an understanding of the realities of sub-Saharan African agriculture, this is stating the obvious.
People who are concerned with the environment should be staunch advocates of fertilizers: even very modest applications of the nuntrients increase crop productivity considerably and hence allow farmers to get more out of a plot of land. If African farmers - especially the millions of smallholders - are not encouraged or enabled to use such classic farming techniques, the socio-economic and environmental effects will be disastrous: land expansion, threats to pristine ecosystems, biodiversity loss, nutrient depletion, ever lower yields, more land expansion and ever deeper poverty. With deeper poverty comes higher fertility, more population pressure, increased food needs and more land expansion... This is an extremely dangerous cycle, but luckily, fertilizers are a major tool that can help turn this situation 180 degrees.
After four years of careful research, Dutch-sponsored agronomist Bongani Ncube demonstrated this simple idea, as it applies to the many smallholder farms in the semi-arid regions of her home country Zimbabwe. Neither water stress nor lack of crop rotations, but nitrogen availability was found to be the single factor that most limited farmers’ efforts to increase cereal yields. The application of micro-doses showed an increase in grain yields of not less than 100% during a normal rainy season.
With funds from the Netherlands Organisation for Scientific Research (NWO) Ncube studied smallholder farms in the southwest of Zimbabwe. She mapped resource flows and carried out field experiments. The Zimbabwean semi-arid regions are dry and farmers face food shortages every season. Yet not water management but the supply of fertilizer, especially nitrogen, was found to be the most important factor in increasing cereal yields. Zimbabwean farmers in the semi-arid regions hardly use fertilizer and manure at present. Chemical fertilizer is expensive and manure is not readily available. Moreover, little is known about the correct use of these nutrient sources in dry climates:
bioenergy :: biofuels :: energy :: sustainability :: water :: fertilizers :: agriculture :: yields :: food security :: poverty :: Africa ::
Nitrogen
The main issue when cultivating soil is the nitrogen balance. Continually cultivating the same crop disrupts this balance. With field experiments, Ncube demonstrated that a little bit of basal manure, and nitrogen fertilizer added as top dressing improved the maize yield by about one-hundred percent in a good rainy season and by up to fifty percent in drier seasons.
Crop rotation
Crop rotation is another option that could provide a lot of benefit according to Ncube. This is the cultivation of different crops alternately in successive years. Leguminous crops, for example, fix nitrogen. This nitrogen remains in the soil and is taken up during the next season by sorghum, a type of grain that grows well in dry areas. Ncube proved that grain legumes can be grown successfully under the semi-arid conditions in Zimbabwe. These legumes were able to leave enough nitrogen in the ground, which doubled yields of sorghum the following season compared to sorghum-sorghum rotations.
With a simulation model Ncube was once again able to show that nitrogen availability was more important in the rotation. These types of treatments often have a negative impact on water availability, yet here nitrogen was shown to be more important.
In short, Africa's agricultural potential is enormous, but socio-economic, and not environmental or ecological factors limit the concrete realisation of this potential. Policies must be focused on taking down the barriers that prevent African farmers from increasing their productivity: investments in extension services must be encouraged and the creation of fertiliser markets and access to those must be kickstarted. If these simple interventions succeed, the African continent could begin to hope to end the vicious cycle of low agricultural productivity that leads to increased environmental and population-related pressures on the continent's natural resources.
Image: A genuine smile: the application of micro-doses of NPK fertilizer doubled the yields on this woman's farm and consequently strengthened her family's income and food security. Courtesy: African Fertilizer Summit.
More information:
Netherlands Organisation for Scientific Research: Fertilizers help Zimbabwean farmers to increase crop yields - April 10, 2007.
Article continues
What Africa lacks is not land or water or agricultural potential (on the contrary), it is investments in land, in knowledge, in very basic farming inputs and in access to these inputs. Last year, the African Fertilizer Summit, which united some of the world's leading agronomists, made the point: if African farmers were to use the most simple of agricultural techniques (such as using micro-doses of fertilizers), the continent could double and, some estimate, even triple its current output at once. To those with an understanding of the realities of sub-Saharan African agriculture, this is stating the obvious.
People who are concerned with the environment should be staunch advocates of fertilizers: even very modest applications of the nuntrients increase crop productivity considerably and hence allow farmers to get more out of a plot of land. If African farmers - especially the millions of smallholders - are not encouraged or enabled to use such classic farming techniques, the socio-economic and environmental effects will be disastrous: land expansion, threats to pristine ecosystems, biodiversity loss, nutrient depletion, ever lower yields, more land expansion and ever deeper poverty. With deeper poverty comes higher fertility, more population pressure, increased food needs and more land expansion... This is an extremely dangerous cycle, but luckily, fertilizers are a major tool that can help turn this situation 180 degrees.
After four years of careful research, Dutch-sponsored agronomist Bongani Ncube demonstrated this simple idea, as it applies to the many smallholder farms in the semi-arid regions of her home country Zimbabwe. Neither water stress nor lack of crop rotations, but nitrogen availability was found to be the single factor that most limited farmers’ efforts to increase cereal yields. The application of micro-doses showed an increase in grain yields of not less than 100% during a normal rainy season.
With funds from the Netherlands Organisation for Scientific Research (NWO) Ncube studied smallholder farms in the southwest of Zimbabwe. She mapped resource flows and carried out field experiments. The Zimbabwean semi-arid regions are dry and farmers face food shortages every season. Yet not water management but the supply of fertilizer, especially nitrogen, was found to be the most important factor in increasing cereal yields. Zimbabwean farmers in the semi-arid regions hardly use fertilizer and manure at present. Chemical fertilizer is expensive and manure is not readily available. Moreover, little is known about the correct use of these nutrient sources in dry climates:
bioenergy :: biofuels :: energy :: sustainability :: water :: fertilizers :: agriculture :: yields :: food security :: poverty :: Africa ::
Nitrogen
The main issue when cultivating soil is the nitrogen balance. Continually cultivating the same crop disrupts this balance. With field experiments, Ncube demonstrated that a little bit of basal manure, and nitrogen fertilizer added as top dressing improved the maize yield by about one-hundred percent in a good rainy season and by up to fifty percent in drier seasons.
Crop rotation
Crop rotation is another option that could provide a lot of benefit according to Ncube. This is the cultivation of different crops alternately in successive years. Leguminous crops, for example, fix nitrogen. This nitrogen remains in the soil and is taken up during the next season by sorghum, a type of grain that grows well in dry areas. Ncube proved that grain legumes can be grown successfully under the semi-arid conditions in Zimbabwe. These legumes were able to leave enough nitrogen in the ground, which doubled yields of sorghum the following season compared to sorghum-sorghum rotations.
With a simulation model Ncube was once again able to show that nitrogen availability was more important in the rotation. These types of treatments often have a negative impact on water availability, yet here nitrogen was shown to be more important.
In short, Africa's agricultural potential is enormous, but socio-economic, and not environmental or ecological factors limit the concrete realisation of this potential. Policies must be focused on taking down the barriers that prevent African farmers from increasing their productivity: investments in extension services must be encouraged and the creation of fertiliser markets and access to those must be kickstarted. If these simple interventions succeed, the African continent could begin to hope to end the vicious cycle of low agricultural productivity that leads to increased environmental and population-related pressures on the continent's natural resources.
Image: A genuine smile: the application of micro-doses of NPK fertilizer doubled the yields on this woman's farm and consequently strengthened her family's income and food security. Courtesy: African Fertilizer Summit.
More information:
Netherlands Organisation for Scientific Research: Fertilizers help Zimbabwean farmers to increase crop yields - April 10, 2007.
Article continues
Friday, April 13, 2007
Scientists reveal quantum secrets of photosynthesis - may lead to clean energy
The team of researchers reports that the answer lies in quantum mechanical effects. Results of its study are presented in the April 12, 2007 issue of the journal Nature. Their discovery may ultimately lead to the creation of artificial photosynthesis that would allow us to tap into the sun as a clean, efficient, sustainable and carbon-neutral source of energy.
Graham Fleming is the lead author of the study and an internationally acclaimed leader in spectroscopic studies of the photosynthetic process. In a paper entitled "Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems", he and his collaborators report the detection of “quantum beating” signals, coherent electronic oscillations in both donor and acceptor molecules, generated by light-induced energy excitations, like the ripples formed when stones are tossed into a pond (image, click to enlarge).
Electronic spectroscopy measurements made on a femtosecond (millionths of a billionth of a second) time-scale showed these oscillations meeting and interfering constructively, forming wavelike motions of energy ('superposition states') that can explore all potential energy pathways simultaneously and reversibly, meaning they can retreat from wrong pathways with no penalty. This finding contradicts the classical description of the photosynthetic energy transfer process as one in which excitation energy hops from light-capturing pigment molecules to reaction center molecules step-by-step down the molecular energy ladder.
“The classical hopping description of the energy transfer process is both inadequate and inaccurate,” said Fleming. “It gives the wrong picture of how the process actually works, and misses a crucial aspect of the reason for the wonderful efficiency", the professor added:
bioenergy :: biofuels :: energy :: sustainability :: photosynthesis :: light :: quantum mechanics :: plants :: biomass :: biophysics ::
The photosynthetic technique for transferring energy from one molecular system to another should make any short-list of Mother Nature’s spectacular accomplishments. If we can learn enough to emulate this process, we might be able to create artificial versions of photosynthesis that would help us effectively tap into the sun as a clean, efficient, sustainable and carbon-neutral source of energy.
Towards this end, Fleming and his research group have developed a technique called two-dimensional electronic spectroscopy that enables them to follow the flow of light-induced excitation energy through molecular complexes with femtosecond temporal resolution. The technique involves sequentially flashing a sample with femtosecond pulses of light from three laser beams. A fourth beam is used as a local oscillator to amplify and detect the resulting spectroscopic signals as the excitation energy from the laser lights is transferred from one molecule to the next. (The excitation energy changes the way each molecule absorbs and emits light.)
Fleming has compared 2-D electronic spectroscopy to the technique used in the early super-heterodyne radios, where an incoming high frequency radio signal was converted by an oscillator to a lower frequency for more controllable amplification and better reception (image, click to enlarge). In the case of 2-D electronic spectroscopy, scientists can track the transfer of energy between molecules that are coupled (connected) through their electronic and vibrational states in any photoactive system, macromolecular assembly or nanostructure.
Fleming and his group first described 2-D electronic spectroscopy in a 2005 Nature paper, when they used the technique to observe electronic couplings in the Fenna-Matthews-Olson (FMO) photosynthetic light-harvesting protein, a molecular complex in green sulphur bacteria.
Gregory Engel, first author of the study said: “The 2005 paper was the first biological application of this technique, now we have used 2-D electronic spectroscopy to discover a new phenomenon in photosynthetic systems. While the possibility that photosynthetic energy transfer might involve quantum oscillations was first suggested more than 70 years ago, the wavelike motion of excitation energy had never been observed until now.”
As in the 2005 paper, the FMO protein was again the target. FMO is considered a model system for studying photosynthetic energy transfer because it consists of only seven pigment molecules and its chemistry has been well characterized.
“To observe the quantum beats, 2-D spectra were taken at 33 population times, ranging from 0 to 660 femtoseconds,” said Engel. “In these spectra, the lowest-energy exciton (a bound electron-hole pair formed when an incoming photon boosts an electron out of the valence energy band into the conduction band) gives rise to a diagonal peak near 825 nanometers that clearly oscillates. The associated cross-peak amplitude also appears to oscillate. Surprisingly, this quantum beating lasted the entire 660 femtoseconds.”
Engel said the duration of the quantum beating signals was unexpected because the general scientific assumption had been that the electronic coherences responsible for such oscillations are rapidly destroyed.
“For this reason, the transfer of electronic coherence between excitons during relaxation has usually been ignored,” Engel said. “By demonstrating that the energy transfer process does involve electronic coherence and that this coherence is much stronger than we would ever have expected, we have shown that the process can be much more efficient than the classical view could explain. However, we still don’t know to what degree photosynthesis benefits from these quantum effects.”
Engel said one of the next steps for the Fleming group in this line of research will be to look at the effects of temperature changes on the photosynthetic energy transfer process. The results for this latest paper in Nature were obtained from FMO complexes kept at 77 Kelvin. The group will also be looking at broader bandwidths of energy using different colors of light pulses to map out everything that is going on, not just energy transfer. Ultimately, the idea is to gain a much better understanding how nature not only transfers energy from one molecular system to another, but is also able to convert it into useful forms.
“Nature has had about 2.7 billion years to perfect photosynthesis, so there are huge lessons that remain for us to learn,” Engel said. “The results we’re reporting in this latest paper, however, at least give us a new way to think about the design of future artificial photosynthesis systems.”
This research was funded by the U.S. Department of Energy and by the Miller Institute for Basic Research in Sciences.
Co-authoring the Nature paper with Fleming were Gregory Engel, who was first author, Tessa Calhoun, Elizabeth Read, Tae-Kyu Ahn, Tomáš Mančal and Yuan-Chung Cheng, all of whom held joint appointments with Berkeley Lab’s Physical Biosciences Division and the UC Berkeley Chemistry Department at the time of the study, plus Robert Blankenship, from the Washington University in St. Louis.
More information:
Nature, Editor's Summary: Making photosynthesis tick - 12 April 2007
Tobias Brixner, Jens Stenger, Harsha M. Vaswani, Minhaeng Cho, Robert E. Blankenship and Graham R. Fleming, "Two-dimensional spectroscopy of electronic couplings in photosynthesis" [*abstract], Nature 434, 625-628 (31 March 2005) | doi:10.1038/nature03429
Gregory S. Engel, Tessa R. Calhoun, Elizabeth L. Read, Tae-Kyu Ahn, Tomás caron Manc caronal, Yuan-Chung Cheng, Robert E. Blankenship & Graham R. Fleming, "Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems", [*abstract], Nature, 446 Number 7137 pp701-830434, 625-628 (12 April 2007) | doi:10.1038/446740a
Article continues
posted by Biopact team at 11:09 PM 0 comments links to this post