The goal to offset rises in atmospheric greenhouse gas concentrations by increasing soil carbon storage by 4 per mille (0.4%) per year is unrealistic, say scientists in a new article.
…To store additional carbon in the soil, you need other nutrients, such as nitrogen. “You cannot build a house with only a pile of bricks but no mortar. Similarly, you cannot produce soil organic matter with only carbon,” explains Kees Jan van Groenigen, co-author of the paper and senior lecturer at the University of Exeter. “You need enormous amounts of nitrogen, and it is unclear where that nitrogen would come from. For example, to store the quantity of carbon mentioned in the 4p1000 goals, you would need extra nitrogen equivalent to 75% of current nitrogen fertilizer production, and for it to be in the right places. Practically speaking, that is just impossible.”
Does that mean that we should abandon the 4p1000 goals? “Absolutely not,” says Jan Willem van Groenigen: “Let’s not throw away the baby with the bathwater. The 4p1000 goals are a great inspiration to do everything we can as farmers, soil scientists, agronomists and policy makers to help fight global warming and at the same time improve our soils.” Instead, the authors appeal to the scientific community to think about the role of nutrients in reaching the 4p1000 goals. “For instance, this could mean that additional soil carbon should be stored in areas where nutrients are also available,” van Groenigen explains. “In other soils the best approach might be to focus on minimizing emissions of other greenhouse gases such as nitrous oxide and methane.”
Jan Willem van Groenigen, Chris van Kessel, Bruce A. Hungate, Oene Oenema, David S. Powlson, Kees Jan van Groenigen. Sequestering Soil Organic Carbon: A Nitrogen Dilemma. Environmental Science & Technology, 2017; DOI: 10.1021/acs.est.7b01427
Cover crops long have been touted for their ability to reduce erosion, fix atmospheric nitrogen, reduce nitrogen leaching and improve soil health, but they also may play an important role in mitigating the effects of climate change on agriculture.
..cover-crop effects on greenhouse-gas fluxes typically mitigate warming by 100-150 grams of carbon per square meter per year, which is comparable to, and perhaps higher than, mitigation from transitioning to no-till….significantly, the surface albedo change — the proportion of energy from sunlight reflecting off of farm fields due to cover cropping — … may mitigate 12 to 46 grams of carbon per square meter per year over a 100-year time horizon,” Kaye wrote.
…”Farmers and policymakers can expect cover cropping simultaneously to benefit soil quality, water quality and climate-change adaptation and mitigation,” he wrote.
“Overall, we found very few tradeoffs between cover cropping and climate-change mitigation and adaptation, suggesting that ecosystem services that are traditionally expected from cover cropping can be promoted synergistically with services related to climate change.”
Jason P. Kaye, Miguel Quemada. Using cover crops to mitigate and adapt to climate change. A review. Agronomy for Sustainable Development, 2017; 37 (1) DOI: 10.1007/s13593-016-0410-x
Dust from as far away as the Gobi Desert in Asia is providing more nutrients than previously thought for plants, including giant sequoias, in California’s Sierra Nevada mountains, a team of scientists have found. The scientists found that dust from the Gobi Desert and the Central Valley of California contributed more phosphorus for plants in the Sierra Nevadas than bedrock weathering, which is breaking down of rock buried beneath the soil. Phosophorus is one of the basic elements that plants need to survive, and the Sierra Nevadas are considered a phosphorus-limited ecosystem.
…The study may help scientists predict the impacts of climate change which is expected to increase drought and create more desert conditions around the world, possibly including California. If that happens, based on these findings, scientists expect a lot more dust moving in the atmosphere, and likely bringing phosphorus and important nutrients to far flung mountainous ecosystems….
…The percentage of Asian dust ranged from 20 percent on average at the lowest elevation, to 45 percent on average at the highest elevation. The percentages were higher at the higher elevation sites because dust tends to travel high in the air stream and not fall unless it hits an object, such as a mountain. The researchers found that the amount of dust from Central Valley sources was greater at lower elevations compared to higher elevations. That was expected, but they also found that more Central Valley dust was entering higher elevations later in the dry season than just after the spring rains….
…The researchers believe their findings will hold true for other mountainous ecosystems around the world and have implications for predicting forest response to changes in climate and land use.
S. M. Aciego, C. S. Riebe, S. C. Hart, M. A. Blakowski, C. J. Carey, S. M. Aarons, N. C. Dove, J. K. Botthoff, K. W. W. Sims, E. L. Aronson. Dust outpaces bedrock in nutrient supply to montane forest ecosystems. Nature Communications, 2017; 8: 14800 DOI: 10.1038/ncomms14800
Note: Co-author, Dr. Chelsea Carey, is Point Blue’s Soil Ecologist.
‘Relationships’ in the soil become stronger during the process of nature restoration. Although all major groups of soil life are already present in former agricultural soils, they are not really ‘connected’ at first. These connections need time to (literally) grow, and fungi are the star performers here (via Eureka Alert).
….A large European research team discovered that when you try to restore nature on grasslands formerly used as agricultural fields, there is something missing. Lead author Elly Morriën from the Netherlands Institute of Ecology explains: “All the overarching, known groups of soil organisms are present from the start, but the links between them are missing. Because they don’t ‘socialise’, the community isn’t ready to support a diverse plant community yet.”…
…”Fungi turn out to play a very important role in nature restoration, appearing to drive the development of new networks in the soil.” In agricultural soils, the thready fungal hyphae are severely reduced by ploughing for example, and therefore the undamaged soil bacteria have an advantage and rule here. The researchers studied a series of former agricultural fields that had changed use 6 to 30 years previously. With time, there is a strong increase in the role of fungi….
Healthy Soils Program funded after multiple years of advocacy by CalCAN and our partners. $7.5 million will be spent in 2017 to reward farmers and ranchers for increasing carbon stores in their soils and reducing greenhouse gas emissions overall. As the program is designed and implemented, CalCAN will continue to provide input aimed at maximizing its effectiveness, reach and accessibility to a diversity of growers.
19,000 acres saved + 47 billion vehicle miles eliminated, thanks to a $37 million investment by the Sustainable Agricultural Lands Conservation Program (SALC). CalCAN will provide input on an expected 2017 request for proposals and argue for funding sufficient to meet the demand.
Researchers have used digital techniques to predict how one vital soil characteristic, soil organic carbon, may be altered by climate change…The researchers used 12 climate change models to predict how soil organic carbon levels vary with climate change. The models used in the study reflected a full range of projected global climate outcomes. They were also applicable to the specific study region of New South Wales in southeast Australia. Results were varied. “A majority of models showed a decline in soil organic carbon with climate change,” states Gray. “But a few of the models actually predicted an increase.”…The researchers also discovered that the extent to which soil organic carbon changes varied across soil types, current climate, and land use regimes. For example, the projected average decline of soil organic carbon was less than one ton per hectare for sandy, low-fertility soils in dry conditions under cropping regimes. It was 15 times as much for clay-rich, fertile soils in wet conditions under native vegetation regimes….
Jonathan M. Gray, Thomas F.A. Bishop. Change in Soil Organic Carbon Stocks under 12 Climate Change Projections over New South Wales, Australia. Soil Science Society of America Journal, 2016; 80 (5): 1296 DOI: 10.2136/sssaj2016.02.0038
It’s getting hot out there. Every one of the past 14 months has broken the global temperature record. Ice cover in the Arctic sea just hit a new low, at 525,000 square miles less than normal. And apparently we’re not doing much to stop it: according to Professor Kevin Anderson, one of Britain’s leading climate scientists, we’ve already blown our chances of keeping global warming below the “safe” threshold of 1.5 degrees.
If we want to stay below the upper ceiling of 2 degrees, though, we still have a shot. But it’s going to take a monumental effort. Anderson and his colleagues estimate that in order to keep within this threshold, we need to start reducing emissions by a sobering 8%–10% per year, from now until we reach “net zero” in 2050. If that doesn’t sound difficult enough, here’s the clincher: efficiency improvements and clean energy technologies will only win us reductions of about 4% per year at most.
….How to make up the difference is one of the biggest questions of the 21st century. There are a number of proposals out there. One is to capture the CO2 that pours out of our power stations, liquefy it, and store it in chambers deep under the ground. Another is to seed the oceans with iron to trigger huge algae blooms that will absorb CO2. Others take a different approach, such as putting giant mirrors in space to deflect some of the sun’s rays, or pumping aerosols into the stratosphere to create man-made clouds. Unfortunately, in all of these cases either the risks are too dangerous, or we don’t have the technology yet. This leaves us in a bit of a bind. But while engineers are scrambling to come up with grand geo-engineering schemes, they may be overlooking a simpler, less glamorous solution. It has to do with soil.
Soil is the second biggest reservoir of carbon on the planet, next to the oceans. It holds four times more carbon than all the plants and trees in the world. But human activity like deforestation and industrial farming – with its intensive ploughing, monoculture and heavy use of chemical fertilisers and pesticides – is ruining our soils at breakneck speed, killing the organic materials that they contain. Now 40% of agricultural soil is classed as “degraded” or “seriously degraded”. In fact, industrial farming has so damaged our soils that a third of the world’s farmland has been destroyed in the past four decades.
As our soils degrade, they are losing their ability to hold carbon, releasing enormous plumes of CO2 [pdf] into the atmosphere. There is, however, a solution. Scientists and farmers around the world are pointing out that we can regenerate degraded soils by switching from intensive industrial farming to more ecological methods – not just organic fertiliser, but also no-tillage, composting, and crop rotation. Here’s the brilliant part: as the soils recover, they not only regain their capacity to hold CO2, they begin to actively pull additional CO2 out of the atmosphere.
The battle here is not just between two different methods. It is between two different ways of relating to the land
The science on this is quite exciting. A study published recently by the US National Academy of Sciences claims that regenerative farming can sequester 3% of our global carbon emissions. An article in Science suggests it could be up to 15%. And new research from the Rodale Institute in Pennsylvania, although not yet peer-reviewed, says sequestration rates could be as high as 40%. The same report argues that if we apply regenerative techniques to the world’s pastureland as well, we could capture more than 100% of global emissions. In other words, regenerative farming may be our best shot at actually cooling the planet….
Andreas Gattingera, et al Enhanced top soil carbon stocks under organic farming PNAS 2012 vol. 109 no. 44 Andreas Gattinger, 18226–18231, doi: 10.1073/pnas.1209429109