Wednesday, February 24, 2010
The accepted agricultural wisdom is that fertilized fields in which plant residue is left in the field will actually gain soil carbon. Unfortunately, it seems the reverse is true - a study by University of Illinois scientists has shown that in their long term (1876-) test fields, soil carbon levels increased steadily till around 1965, when animal manure was used as fertilizer, and started declining after that, with the use of synthetic nitrogen fertilizers.
With decreasing soil carbon (humus), the soil structure deteriorates, as does the capacity of the soil to hold on to nitrogen. As nitrogen leaches out with water, the land needs more fertilizers to stay productive, creating a vicious cycle.
From the paper Synthetic Nitrogen Fertilizers Deplete Soil Nitrogen: A Global Dilemma for Sustainable Cereal Production
... Overwhelmingly, the evidence is diametrically opposed to the buildup concept and instead corroborates a view elaborated long ago by White (1927) and Albrecht (1938) that fertilizer N depletessoil organic matter by promoting microbial C utilization and N mineralization. An inexorable conclusion can be drawn: The scientific basis for input-intensive cereal production is seriously flawed. The long-term consequences of continued reliance on current production practices will be a decline in soil productivity that increases the need for synthetic N fertilization, threatens food security, and exacerbates environmental degradation.There is an informative article on Grist.org with comments from the authors.
This dilemma calls for an international effort by agricultural scientists to thoroughly review, evaluate, and revise current cereal production and management systems and policies. The immediate need is to use scientific and technological advances that can increase input efficiencies. One aspect of this strategy would be to more accurately match the input of ammoniacal N to crop N requirement by accounting for site-specific variations in soil N-supplying capacity and by synchronizing application with plant N uptake. In the long term, a transition may be required toward agricultural diversification using legume-based crop rotations, which provide a valuable means to reduce the intensity of ammoniacal fertilization with the input of less reactive organic N.
Hat tip to Doug on the Fukuoka Farming group for pointing out the Grist.org article.
Saturday, February 13, 2010
Here's an excellent conversation on the challenges and possibilities for the next 40 years between Vaclav Smil, a professor at University of Manitoba and Andrew Revkin, NYTimes journalist and Dot Earth blogger.
The whole video is worth watching, but at 78 minutes, rather long. So here are some important points:
- 5 % of global population in North America consumes 35% of all resources. If India and China reach the same level of consumption, we need 5 planets.
- Global population may never reach 9 B. Currently there is a 70-80% probability to peak between 8.2-8.5 B.
- The Japanese consume half as much energy per capita as North Americans.
- We have a lot of options for energy (shale gas) and other mineral resources.
- Supercrops (nitrogen fixing, low water requirement, low phosphate requirement) may be possible with advanced genetic engineering*.
- Human beings are amazingly adaptable.
- We are not going to change our personal behavior and economic structure unless we actually undergo a catastrophe.
- China is moving rapidly towards NAm consumption levels. India wants to outdo China.
- Alternative energy resources are currently very inefficient. Carbon sequestration is impractical, but will continue to consume attention.
- Nitrogen fertilizers may become cheaper now due to cheap gas, but cheap and clean sources of phosphates are rapidly depleting.
- Western economies is in grave danger. US is the biggest debtor nation in the history of the human race, and the debt is growing at $2T/six months.
- Read anything and everything you can, become more numerate, and learn about the physical world around you.
- Drive smaller and fewer cars
- Eat less meat (Feed to meat ratios for factory farmed animals: Chickens - 3:1; Pigs - 7:1; Cows - 25:1)
* BTW, definitely check out these articles on Synthetic Biology in NYTimes -
Genetic engineers have looked at nature as a set of finished products to tweak and improve — a tomato that could be made into a slightly better tomato. But synthetic biologists imagine nature as a manufacturing platform: all living things are just crates of genetic cogs; we should be able to spill all those cogs out on the floor and rig them into whatever new machinery we want. It’s a jarring shift, making the ways humankind has changed nature until now seem superficial.and also The New Yorker -
The deeply unpleasant risks associated with synthetic biology are not hard to imagine: who would control this technology, who would pay for it, and how much would it cost? Would we all have access or, as in the 1997 film “Gattaca,” which envisaged a world where the most successful children were eugenically selected, would there be genetic haves and have-nots and a new type of discrimination—genoism—to accompany it? Moreover, how safe can it be to manipulate and create life? How likely are accidents that would unleash organisms onto a world that is not prepared for them? And will it be an easy technology for people bent on destruction to acquire? “We are talking about things that have never been done before,” Endy said. “If the society that powered this technology collapses in some way, we would go extinct pretty quickly. You wouldn’t have a chance to revert back to the farm or to the pre-farm. We would just be gone. ”
Thursday, February 11, 2010
Science Magazine has an excellent overview of the challenges of optimizing food production for 9 Billion people over the next 40 years:
Producing more food from the same area of land while reducing the environmental impacts requires what has been called "sustainable intensification". In exactly the same way that yields can be increased with the use of existing technologies, many options currently exist to reduce negative externalities. Net reductions in some greenhouse gas emissions can potentially be achieved by changing agronomic practices, the adoption of integrated pest management methods, the integrated management of waste in livestock production, and the use of agroforestry. However, the effects of different agronomic practices on the full range of greenhouse gases can be very complex and may depend on the temporal and spatial scale of measurement. More research is required to allow a better assessment of competing policy options. Strategies such as zero or reduced tillage (the reduction in inversion ploughing), contour farming, mulches, and cover crops improve water and soil conservation, but they may not increase stocks of soil carbon or reduce emissions of nitrous oxide. Precision agriculture refers to a series of technologies that allow the application of water, nutrients, and pesticides only to the places and at the times they are required, thereby optimizing the use of inputs. Finally, agricultural land and water bodies used for aquaculture and fisheries can be managed in ways specifically designed to reduce negative impacts on biodiversity.NYTimes has a good summary.
Permaculture design principles can help reach a lot of these goals.