How soil carbon can help tackle climate change

Derek Lynch, Dalhousie University

Maintaining soil organic matter is critical to tackling climate change because soil organic matter is rich in carbon. Soil carbon is also the keystone element controlling soil health, which enables soils to be resilient as droughts and intense rainfall events increasingly occur.

Given this tremendous importance of soil carbon, are economic incentives and programs helping Canadian farmers maintain and enhance soil carbon on their farms?

On the Prairies, farm soil carbon levels have stabilized or increased over the past few decades, largely as a result of adoption of no-till cropping, which avoids disturbing the soil while growing a crop. In Eastern Canada, however, most estimates suggest that the intensity of crop production (especially reduced use of forage crops) is causing soil carbon levels to decline. This situation is made more challenging by the fact that in higher moisture regions such as Eastern Canada and British Columbia no-till cropping does not enhance soil carbon. This contrasting soil carbon performance of Eastern and Western Canadian farms could even be a politically sensitive issue.

My research examines how different farming systems and cropping practices influence soil carbon and soil health. But it is increasingly evident that economic incentives are as important as technical approaches in developing solutions to this issue. Which policy tools, taxes or credits are needed to assist farmers, including those in Eastern Canada, prevent further soil carbon losses and move to a more positive soil carbon status?

Carbon credit markets

Some voluntary carbon credit markets such as Nori and Puro are primarily interested in supporting a reduction of current atmospheric carbon dioxide levels. They provide a marketplace for carbon removal certificates, whether the CO2 reduction is achieved by industrial methods or biological methods such as agriculture.

The funds raised support carbon farming initiatives globally. Farmers are paid where net gains in soil carbon can be verified.

Read more:
Carbon farming: a solution to global land degradation and poverty?

These voluntary (that is, not driven by government regulation) carbon credit markets do not, however, support farms making headway in reducing their soil carbon losses.

Such a limited approach to carbon credits, if widely adopted by voluntary markets, would be unfortunate. Avoiding continued loss of soil carbon, which is often eventually accompanied by the irreversible loss of the soil itself, is critical to global efforts to tackle global climate change.

Carbon taxes

On April 1, 2019, the Canadian government launched a national carbon tax on CO2 pollution from fossil fuel use, commencing at $20 per ton of CO2. This tax will be applied in provinces that don’t have some other economic or pricing mechanism to reduce fossil-fuel CO2 emissions.

Read more:
Here’s what the carbon tax means for you

The impact of this carbon tax on consumers is much debated, but the impact on farmers has been much less discussed. Some have argued that the additional costs of farm inputs from a carbon tax will be difficult to recover by farmers. Indeed, one of the few such studies found the carbon tax in B.C., in place since 2008, negatively affected farm economic performance.

Reduced farm profitability would limit farmers’ options in adopting new soil management practices, or less intensive cropping, to maintain and enhance soil carbon levels. A recent report by the Senate’s Standing Committee on Agriculture and Forestry assessed the impact of climate change and a carbon tax on agriculture.

The study recommended farm fuel costs be exempt from the carbon tax. The report also highlighted the critical need for new mechanisms (offset protocols) to determine soil carbon credits for Canadian farmers in different agricultural sectors, and the need to characterize in detail current farm soil carbon levels in Canada.

Cap and trade markets

Cap-and-trade markets to reduce CO2 emissions, such as those in Québec and California, have generated substantial green funds for climate change programs. In both jurisdictions, green fund dollars support on-farm projects for farmers to test out different farm practices that show promise for improving soil carbon levels.

Details on these programs were outlined and discussed at the excellent recent symposium organized by Regeneration Canada. Regeneration Canada’s mission is to support farmers adopting climate-smart farming and to bridge the gap in consumer awareness of these issues and farm challenges.

Reducing emissions

Declining soil carbon levels and associated losses in soil quality and soil productivity are a critical issue globally. Farmers, including those in Eastern Canada, are challenged in understanding the complex relationship between their farm management practices and their soil carbon levels. They also need support to test out and adopt changes in cropping practices to reverse often declining soil carbon levels.

A combination of innovative economic programs, incentives and credits, supported by all stakeholders including consumers, are needed to support farmers in this key challenge of a generation.

Derek Lynch, Professor of Agronomy and Agroecology, Dalhousie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Soil is the key to our planet’s history (and future)

Derek Lynch, Dalhousie University

The English language is full of phrases — from “bogged down” to “feet of clay” and “dirt cheap” — that reflect how we appreciate the diversity of soil, but value it little.

Soil retains a special place in many cultures. In Ireland, where I grew up, patches of what is known as “hungry ground” are thought to retain the memory of the Irish Famine in the 1800s, and you are advised to carry bread while you cross them. To poet Patrick Kavanagh, the clay of soils sealed the hopeless fate of lonely Irish bachelor farmers:

“Clay is the word and clay is the flesh
Where the potato-gatherers like mechanised scarecrows move.”

But is soil valueless like dirt or replete with mystery? Is it just dirt, or a cathedral of evolutionary and cultural memory? Like an elder among us, soil holds records of our planet’s past and the possibilities of its future sustainability.

A repository of memory

Like a library, soil houses stories written from the microscopic to the landscape scale of human and evolutionary history. Our enormous recent impacts, from the global nitrogen cycle to our use of atomic weapons, can be read as elemental and isotopic traces in soil.

One quarter of all the world’s biodiversity can be found in soil; it is where many plants, bacteria and fungi evolved together. In many cases, plants and soil microbes established mutually beneficial relationships, communicating with each other by sending signals through the soil in a complex dating game. Butterflies and beetles and some bees, too, evolved to need the soil for certain stages of their life cycle.

Soil also remembers its natural vegetation — as seeds that can be used to help restore the native plant diversity and ecosystem, even in an urban lawn setting. For plants, the memory of their interaction with soil microbes may even be transmitted to their offspring.

Ecosystem services

In our urgent search for solutions to climate change, we have realized soils are key to turning back the carbon clock and reversing CO2 accumulation in the atmosphere. Thus we are recognizing soils as far more than just an anchor for growing plants, but as the irreplaceable “skin of the Earth” providing economic, environmental and social services that are essential for life.

Read more:
How soil carbon can help tackle climate change

Now more than ever, the science of soil reflects this appreciation of soil’s keystone role in preserving biodiversity, reversing climate change and sustaining life on Earth.

Understanding soil

The history of soil science has often been a story of international collaboration, including the recent production of a global soil carbon map and an atlas of soil biodiversity, both wonderful examples of important global advances in soil science.

Rapid advances in application of molecular techniques are helping us understand in much greater detail the relationships between soil organisms and the many essential functions they perform. Importantly, too, we are learning much more about soil’s resilience, such as how it responds to, and may recover from, the stresses imposed by human activities or a changing climate.

We are learning more about the services provided by soils in cities, and the unique stresses imposed upon them. According to Canadian soil scientist Henry Janzen, a fundamental goal of soil science and key to global sustainability is to extract the memories hidden in soil.

Managing farm soils

Intensive farming systems are a major driver of land degradation and soil losses, and declines in the abundance and diversity of animals and plants. Applying our improved understanding of soil, an urgent challenge is to develop and support farming systems that are sustainable ecologically while also providing humanity sufficient supplies of food and fibre.

Farmers, as land managers, are on the front lines of this challenge. Many take an agro-ecological approach and consider themselves stewards or caretakers of plant diversity and the soil as much as solely producers of crops.

For example, farmers who plant mixtures of flowering cover crops (buckwheat, phacelia, sweet clover, vetch etc.) benefit pollinators. The crop also protects the soil by keeping it covered over winter. As it decomposes, the abundant cover crop residue improves the soil’s structure and biological activity, while releasing nutrients to the following cash crop.

We need to cherish and learn from soil now more than ever. It holds the keys to our planet’s past and future.

Derek Lynch, Professor of Agronomy and Agroecology, Dalhousie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.