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Climate-Smart, Organic Practices Build Soil and Improve Farming Under Changing Conditions

Soil Health on Organic Farms

Healthy soils are essential for resilient crop production and supporting the ecosystem. They retain water, support a diversity of organisms vital to decomposition and nutrient cycling, provide crops with essential nutrients, and store away carbon, helping to mitigate global climate change. The growing demands for food, feed, fiber, and fuel cannot be met without healthy soils.

Unfortunately, soils in the United States are being degraded by unsustainable agricultural practices. Techniques used by organic farmers can help stop soil health degradation, and even restore health in previously degraded soils, because they replenish organic carbon and preserve underground biodiversity.

Many studies have shown that organic soils tend to score higher when it comes to soil health metrics than conventional soils. Organic soils have greater biological activity and stability, more biomass, and higher diversity than conventionally managed soils. Organically managed soils also tend to have higher water-holding capacity, porosity, and aggregate stability than conventionally managed soils, which can lead to yield advantages in extreme weather events such as droughts and flooding, meaning that organic may fare better as our planet continues to experience climate change.

Healthy Soils Help Mitigate Climate Change

Climate change is causing both gradual and extreme changes in weather conditions like temperature, rainfall, and devastating storms. These changes influence the success of crops by causing stress to the crops during drought, flood, or extreme temperatures. Populations of beneficial biodiversity like pollinators and natural enemies of pests are also impacted, while all kinds of pests and pathogens also change with the weather, typically increasing with more heat and humidity. Farmers are faced with fluctuating extremes in nearly every growing condition, which makes it challenging to produce reliable yields each year.

Carbon sequestration is a critical tool for building soil health and combatting climate change—locking carbon away in soil reserves reduces greenhouse gases. By using farming practices that reduce GHG emissions and draw carbon back into the soil (such as reducing tillage, pesticide use, and reliance on synthetic fertilizer) not only helps mitigate climate change, it also improves the soil structure, which helps farmers cope with changes in weather conditions associated with climate change.

Specifically, storing carbon sequestration:

  • Reduces erosion
  • Reduces compaction
  • Improves aeration, filtration, and water holding capacity
  • Provides a reserve of essential nutrients for plants
  • Supports soil organisms by providing a food source that in turn helps fight soil-borne diseases and supports more above-ground diversity

Organic Soils and Climate Change Mitigation

The Organic Center partnered with Northeastern University to explore how organic farming impacts carbon sequestration in the soil and found that not only do organic farms store more soil carbon in general, they also store more of the type of carbon that stays in the ground for longer periods of time. By analyzing more than a thousand soil samples from organically and conventionally managed soils from across 48 U.S. states, this ground-breaking work found that organic soils had 13 percent higher soil organic matter and 44 percent higher long-term carbon storage than conventionally managed soils.

These results highlight the potential of organic agriculture to increase the amount of carbon sequestration in the soil, contributing to climate change mitigation.

Digging Deeper: Specific Organic Practices That Increase Soil Health and Carbon Sequestration

While a growing body of scientific literature suggests that soil management strategies commonly used in organic systems improve overall soil health, there is less research on specific practices within organic systems that have the greatest potential to build healthy soils and sequester carbon.

However, a recent study conducted by the University of Maryland in collaboration with The Organic Center—and supported by the GRO Organic research fund, Annie’s Homegrown of General Mills, and Patagonia—provides a big-picture understanding of the organic techniques that have the most impact on soil health. The review of more than 150 studies from around the world on the benefits of organic farming to soil health and climate change mitigation illuminates specific organic farming practices that are the best of the best in supporting healthy soils.

The study identifies four practices that are the most critical to good soil health:

  • Planting cover crops
  • Applying combinations of organic inputs
  • Increasing crop rotation diversity and length
  • Conservation tillage

Not surprisingly, these practices have also been found to be important for boosting carbon storage in organic soils.

Another recent collaboration between The Organic Center and University of Maryland quantified how specific organic soil management techniques can optimize carbon sequestration within organic farms to show how organic farming can be used as a tool to move the needle even further in mitigating climate change.

For this meta-analysis, researchers sifted through more than 4,000 scientific articles to find data that put numbers behind the soil carbon-building techniques that organic farmers use. The results show that by adopting best management practices, organic growers can boost their soil organic carbon by an average of 18 percent, and increase microbial biomass carbon by an average of 30 percent.

The second major finding of this study is that organic soil amendments are key players in carbon sequestration—using best practices when it comes to biological soil amendments boosts soil organic carbon by an average of 24 percent. And because much of that carbon was found in the top 50 cm (20 in) of soil, using organic amendments is one of the most impactful strategies to quickly replenish carbon in the soil. Conservation tillage added another layer of benefits and cover cropping showed a significant increase in carbon sequestration after five years, rivaling that of conservation tillage.

The study authors also stress that diversifying key practices makes a difference. While each individual practice has benefits to carbon sequestration, challenges associated with organic farming can be better mitigated by a holistic suite of conservation tools when they are implemented in tandem.

Key Research Gaps

To better understand how organic farming can continue to lead the way in increasing carbon sequestration and soil health, more scientific exploration is needed of the length and diversity of crop rotations, as there is a dearth of research on how crop rotations impact carbon sequestration within organic systems. There is also little information about the impact of climate engineering tools such as biochar. Verification of organic practices through soil health measurements across the broad range of organic cropping systems and regions will also help farmers make informed decisions to optimize their practices and continually improve organic’s ability to build healthy soil to support organic production and the health of our communities.

You can find more soil health and climate related reports at The Organic Center’s Resource Library page at organic-center.org.



This article was originally published in the Fall 2022 Organic Report, you can view the full magazine here.