Month: September 2017

Study finds no-tillage not sufficient alone to prevent water pollution from nitrate

Ellie Cohen
  • no-tillage alone is not sufficient to prevent water pollution from agricultural nitrate pollution
  • study suggests that no-till needs to be complemented with other techniques, such as cover cropping and intercropping or rotation with perennial crops, to improve nitrate retention and water-quality benefits.
  • study found the adoption of no-till resulted in increased nitrate loss via leaching due to the frequent occurrence of macropores, such as those created by dead roots and earthworm burrows, in soils that have been under long-range no-tillage management

September 22, 2017 Indiana University Read full ScienceDaily article here

A new study answers a long-debated agricultural question: whether no-tillage alone is sufficient to prevent water pollution from nitrate. The answer is no……The study suggests that no-till needs to be complemented with other techniques, such as cover cropping and intercropping or rotation with perennial crops, to improve nitrate retention and water-quality benefits.

After studying concentration of nitrate — nitrate amount per water volume unit — and nitrate load, or total amount of nitrate, researchers found surface runoff from no-till fields to contain a similar nitrate load to surface runoff from conventional tillage fields.

In contrast, nitrate load via leaching was greater with no-till fields than with conventional tillage fields.

…No-till leaves crop residue on the soil surface and limits soil disturbance except for small slits to add fertilizer. An estimated 20 percent of all croplands in the U.S. are under no-till management. It reduces soil erosion by avoiding tilling year after year, which leads to soil getting washed away into lakes and rivers. Because reducing soil loss reduces nutrient loss, it was assumed that no-till would reduce water pollution, Wang said….

Stefani Daryanto, Lixin Wang, Pierre-André Jacinthe. Impacts of no-tillage management on nitrate loss from corn, soybean and wheat cultivation: A meta-analysis. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-12383-7

Removing nitrate with buffer zones for healthier ecosystems

Ellie Cohen
  • For agricultural nitrogen, slow it down, buff it out
  • Understanding where natural nitrate removal is highest can inform management of streams in agricultural settings
  • Nitrate removal in buffer zones was significantly higher than in stream sediments.

September 27, 2017 American Society of Agronomy read full ScienceDaily article here

In a new study, researchers have identified nitrate removal hotspots in landscapes around agricultural streams.

Nitrogen can present a dilemma for farmers and land managers. On one hand, it is an essential nutrient for crops. However, excess nitrogen in fertilizers can enter groundwater and pollute aquatic systems. This nitrogen, usually in the form of nitrate, can cause algal blooms. Microbes that decompose these algae can ultimately remove oxygen from water bodies, causing dead zones and fish kills.

In a new study, researchers have identified nitrate removal hotspots in landscapes around agricultural streams. “Understanding where nitrate removal is highest can inform management of agricultural streams,” says Molly Welsh, lead author of the study. “This information can help us improve water quality more effectively.”…

….Nitrate removal in buffer zones was significantly higher than in stream sediments. “If nitrate removal is the goal of stream restoration, it is vital that we conserve existing buffer zones and reconnect streams to buffer zones,” says Welsh….

Molly K. Welsh, Sara K. McMillan, Philippe G. Vidon. Denitrification along the Stream-Riparian Continuum in Restored and Unrestored Agricultural Streams. Journal of Environment Quality, 2017; 46 (5): 1010 DOI: 10.2134/jeq2017.01.0006

Nitrogen surplus from agriculture impacts groundwater, according to 70 years of monitoring

Ellie Cohen
  • A 70 years time-series of monitoring data relays a clear message: When farmers apply more nitrogen to their fields than their crops can absorb, the amount of nitrogen in the groundwater increases. When less nitrogen leaches from the soil, due to either improved management or reduced nitrogen application, the amount found in the groundwater decreases.
  • the study also found that socio-economic development stimulates adoption of measures to protect the environment and that economic growth can curb environmental degradation.
September 26, 2017 Aarhus University  Read full ScienceDaily article here
A new study based on 70 years of monitoring data highlights the importance of a consistent national groundwater monitoring program and the need for development of future effective nitrogen mitigation measures in intensive agriculture worldwide in order to protect groundwater resources….

…In the years 1946 to the mid-1980s nitrogen surplus increased continually. Increasing environmental awareness and national environmental plans have since then curbed this trend — while economic growth continues. Like the nitrogen surplus, the nitrate concentrations in oxic (oxygen present) water reached its peak around the turning point in the 1980s….

Birgitte Hansen, Lærke Thorling, Jörg Schullehner, Mette Termansen, Tommy Dalgaard. Groundwater nitrate response to sustainable nitrogen management. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-07147-2

Maximizing successful forest restoration in tropical dry forests

Ellie Cohen
  • tests maximizing success of tree replanting efforts in degraded soils in tropics
  • tree species that were drought tolerant did better
  • soil amendments only helped to get seedlings off to good start

September 21, 2017 University of Minnesota read full ScienceDaily article here

A new study has uncovered some valuable information on ways to maximize the success of replanting efforts [in tropical dry forests], bringing new hope for restoring these threatened ecosystems.

…Over the past century most of these forests, which help keep water clean and provide valuable habitat for wildlife, were replaced by farms and cattle pastures. Now, as conservationists work to replant deforested areas, they’re finding that the already challenging, high-clay soils underlying them have been degraded to an extent that makes it hard for tree seedlings to sink their roots.

…To find out what works best for reestablishing tropical dry forests, the researchers planted seedlings of 32 native tree species in degraded soil or degraded soil amended with sand, rice hulls, rice hull ash or hydrogel (an artificial water-holding material). After two years, they found that tree species known for traits that make them drought tolerant, such as enhanced ability to use water and capture sunlight, survived better than other species. Some of the soil amendments helped get seedlings off to a good start, but by the end of the experiment there was no difference in survival with respect to soil condition…

Leland K. Werden, Pedro Alvarado J., Sebastian Zarges, Erick Calderón M., Erik M. Schilling, Milena Gutiérrez L., Jennifer S. Powers. Using soil amendments and plant functional traits to select native tropical dry forest species for the restoration of degraded Vertisols. Journal of Applied Ecology, 2017; DOI: 10.1111/1365-2664.12998

We must accelerate decarbonization for sustainability and limiting warming to 2C; 66% chance if emissions peak by 2020 and drop by 70% by 2050

Ellie Cohen

  • 66% chance of limiting global temperature increases to below 2C if global energy-related carbon emissions peak by 2020 and fall by more than 70% in the next 35 years

  • Necessitates “deep decarbonisation” of electricity, tdransport, heat, industrial, forestry and agricultural systems across the world

  • Rapid changes in electricity, heat, buildings, industry and mobility are needed including tripling of the annual rate of energy efficiency improvement, retrofitting the entire building stock, generating 95% of electricity from low-carbon sources by 2050 and shifting almost entirely towards electric cars.

September 21, 2017 University of Sussex

…To provide a reasonable (66%) chance of limiting global temperature increases to below 2oC, the International Energy Agency and International Renewable Energy Agency suggest that global energy-related carbon emissions must peak by 2020 and fall by more than 70% in the next 35 years. This implies a tripling of the annual rate of energy efficiency improvement, retrofitting the entire building stock, generating 95% of electricity from low-carbon sources by 2050 and shifting almost entirely towards electric cars.

This elemental challenge necessitates “deep decarbonisation” of electricity, transport, heat, industrial, forestry and agricultural systems across the world. But despite the recent rapid growth in renewable electricity generation, the rate of progress towards this wider goal remains slow…

The Policy Forum provides four key lessons for how to accelerate sustainability transitions.

Lesson 1: Focus on socio-technical systems rather than individual elements…Accelerated low-carbon transitions therefore depend on both techno-economic improvements, and social, political and cultural processes…Traditional policy approaches emphasizing a single technology will not be enough…

Lesson 2: Align multiple innovations and systems…accelerated low-carbon transitions in electricity depend not only on the momentum of renewable energy innovations like wind, solar-PV and bio-energy, but also on complementary innovations including energy storage and demand response. These need aligned and then linked so that innovations are harmonized…

Lesson 3: Offer societal and business support…Public support is crucial for effective transition policies. Low-carbon transitions in mobility, agro-food, heat and buildings will also involve millions of citizens who need to modify their purchase decisions, user practices, beliefs, cultural conventions and skills. To motivate citizens, financial incentives and information about climate change threats need to be complemented by positive discourses about the economic, social and cultural benefits of low-carbon innovations….

Lesson 4: Phase out existing systems…Phasing out existing systems accelerates transitions by creating space for niche-innovations and removing barriers to their diffusion. …

Frank W. Geels, Benjamin K. Sovacool, Tim Schwanen, Steve Sorrell. Sociotechnical transitions for deep decarbonization. Science, 2017; 357 (6357): 1242 DOI: 10.1126/science.aao3760

Winter cold extremes linked to high-altitude polar vortex weakening

Ellie Cohen
  • first study to show that changes in winds high up in the stratosphere substantially contributed to the observed winter cooling trend in northern Eurasia.
  • study lends further support that a changing Arctic impacts the weather across large swaths of the Northern Hemisphere population centers.
  • changes in the jet stream that drives our weather can lead to more abrupt and surprising disturbances-potentially disastrous extremes- to which society has to adapt…

September 22, 2017 Potsdam Institute for Climate Impact Research read full sciencedaily article here

When the strong winds that circle the Arctic slacken, cold polar air can escape and cause extreme winter chills in parts of the Northern hemisphere. A new study finds that these weak states have become more persistent over the past four decades and can be linked to cold winters in Russia and Europe.

…[This study is the] first to show that changes in winds high up in the stratosphere substantially contributed to the observed winter cooling trend in northern Eurasia. While it is still a subject of research how the Arctic under climate change impacts the rest of the world, this study lends further support that a changing Arctic impacts the weather across large swaths of the Northern Hemisphere population centers….

…Despite global warming, recent winters in the Northeastern US, Europe and especially Asia were anomalously cold — some regions like Western Siberia even show a downward temperature trend in winter. In stark contrast, the Arctic has been warming rapidly. Paradoxically, both phenomena are likely linked: When sea-ice North of Scandinavia and Russia melts, the uncovered ocean releases more warmth into the atmosphere and this can impact the atmosphere up to about 30 kilometers height in the stratosphere disturbing the polar vortex. Weak states of the high-altitude wind circling the Arctic then favors the occurrence of cold spells in the mid-latitudes.

….”Jet Stream changes can lead to more abrupt and surprising disturbances to which society has to adapt. The uncertainties are quite large, but global warming provides a clear risk given its potential to disturb circulation patterns driving our weather — including potentially disastrous extremes.”

Marlene Kretschmer, Dim Coumou, Laurie Agel, Mathew Barlow, Eli Tziperman, Judah Cohen. More-Persistent Weak Stratospheric Polar Vortex States Linked to Cold Extremes. Bulletin of the American Meteorological Society, 2017; DOI: 10.1175/BAMS-D-16-0259.1

A better farm future starts with the soil; Opinion on the next Farm Bill

Ellie Cohen
  • With extreme weather events on the rise and farmers and foresters feeling the effects of a changing climate, however, soil health is now at the forefront of our national conversation.
  • Within the next year, the new 5 year Farm Bill will be reauthorized with implications for every aspect of food and agriculture in the US
  • the next farm bill should ensure an ongoing and growing focus on improving soil health and should make sure that USDA has the authority and funding it needs to measure and report on program outcomes…
By Alyssa Charney, opinion contributor — 09/19/17  Read full The Hill piece here

Within the next year Congress will reauthorize the massive amalgamation of legislation we commonly refer to as “the farm bill.” The farm bill, which is reauthorized every five years, has major implications for every part of our food and farm system and covers issues including but certainly not limited to: conservation, nutrition, local food, credit and finance, research and commodity subsidies.

Although healthy soil is one of the essential building blocks of agriculture, historically the issue has not been a major focus of the farm bill – as some farmers would say, soil has been treated like dirt. With extreme weather events on the rise and farmers and foresters feeling the effects of a changing climate, however, soil health is now at the forefront of our national conversation.

….As our most significant package of food and farm legislation approaches expiration on September 30, 2018, many are asking: How can the farm bill support resilient farms, address natural resource concerns and increase productivity? A key part of the answer: promote soil health.….The next farm bill should enhance the long-term funding base for both working lands programs and ensure an ongoing and growing focus on improving soil health. In addition, the farm bill should make sure that USDA has the authority and funding it needs to measure and report on program outcomes….

….The Sustainable Agriculture Research and Education (SARE) program is one of the only USDA research programs with a clear and consistent focus on farmer-driven research. SARE is the leader in cutting-edge on-farm research to develop and test soil enhancement methods, such as regionally specific cover cropping or grazing management systems. The next farm bill should reauthorize and secure direct farm bill funding for SARE to ensure the program’s continued success.

….The farm bill must also underscore the connection between healthy soils and reduced risks for farmers, and ensure that federal crop insurance programs reward producers for advanced conservation activities and provide the appropriate incentives for those who are not currently engaged.

Collectively, reforms to conservation, research and the farm safety net present an enormous opportunity to improve the health of our soils. …

Alyssa Charney is a policy specialist at the National Sustainable Agriculture Coalition, and staffs the Coalition’s Conservation, Energy, and Environment Committee.

Quantifying soil carbon measurement for agricultural soils management: 11 white papers

Ellie Cohen
  • Regardless of what approach is pursued, reliable and cost effective quantification methods are critical to designing and implementing improved management of soil organic matter including soil organic carbon, and C sequestration policies in the land use sector.
Together the group, including Point Blue, produced a set of 11 white papers related to soil organic carbon quantification– see here and below.
• There is heightened interest in increasing soil organic carbon (SOC) stocks to improve
performance of working soils especially under drought or other stressors, to increase
agricultural resilience, fertility and reduce greenhouse gas emissions from agriculture.
• There are many improved management practices that can be and are currently being
applied to cropland and grazing lands to increase SOC.
• Farmers and ranchers are decisionmakers who operate in larger contexts that often
determine or at least bound their agricultural and financial decisions (e.g., crop insurance, input subsidies, etc.). Any effort to value improvements in the performance of agricultural soils through enhanced levels of SOC will require feasible, credible and
creditable assessment of SOC stocks, which are governed by dynamic and complex soil
processes and properties.
• This paper provides expert consensus evaluation of currently accepted methods of
quantifying SOC that could provide the basis for a modern soil information system.

Gassy Cows Warm The Planet. Scientists Think They Know How To Squelch Those Belches

Ellie Cohen
  • Different diets made a difference in how much methane the cows emitted, but …the least gassy family emitted the least methane no matter what they ate
  • Genetics is playing a big role in shaping which microbes exist in any individual cow’s gut

NPR September 22, 2017 Angus Chen Read full NPR story here

… The study, originally published in the journal PLoS Genetics last year, showed that a cow’s genetics determine which microbes populate its gut — and some of those microbes produce the methane that eventually makes its way into the atmosphere…

… It turned out that the different groups differed in the amounts of methane they emitted — by a lot. “The highest [group emitted] 200 grams per day, and the lowest [group’s] methane emission was at 140 grams per day. So there is a large difference,” says Rainer Roehe, the lead author on the study and a geneticist at Scotland’s Rural College.

Roehe says the different diets made a difference in how much methane the cows emitted, but when they ranked the cow families based on how much gas they were expelling, the least gassy family emitted the least methane no matter what they ate. On the flipside, the cows in the family that gave off the most gas were still the biggest offenders regardless of what they were eating. Roehe says that suggests genetics is playing a big role in shaping which microbes exist in any individual cow’s gut and is the reason why some cows belch and fart less than others….

Roehe R, Dewhurst RJ, Duthie C-A, Rooke JA, McKain N, Ross DW, et al. (2016) Bovine Host Genetic Variation Influences Rumen Microbial Methane Production with Best Selection Criterion for Low Methane Emitting and Efficiently Feed Converting Hosts Based on Metagenomic Gene Abundance. PLoS Genet 12(2): e1005846. https://doi.org/10.1371/journal.pgen.1005846