Organic farming practices boost soil carbon storage

With carbon dioxide levels in the atmosphere rising sharply over recent decades, scientists and policymakers alike are becoming increasingly concerned about the long-term impact on global climate patterns.

As the effects of climate change become more pronounced, there is a growing urgency to develop effective strategies for capturing and holding carbon.

One promising approach focuses on the role of soil in carbon sequestration, where innovative farming practices can help reduce atmospheric CO2 by trapping it within the earth’s natural processes.

Farming practices and soil carbon storage

Researchers from Kansas State University (K-State) are investigating how various farming practices can influence the amount of carbon stored in soil, a crucial factor in mitigating climate change.

The study seeks to uncover how long-term agricultural techniques, particularly in no-till farming systems, impact the soil’s ability to capture and retain carbon over time.

To gain deeper insights, the team utilized advanced imaging technologies at two of the world’s most cutting-edge research facilities: the Canadian Light Source (CLS) at the University of Saskatchewan (USask) and the Advanced Light Source in Berkeley, California.

By analyzing soil from a Kansas cornfield that has been farmed using no-till methods for 22 years, they aimed to determine how different nitrogen management strategies influence carbon sequestration.

Fertilizers and long-term study results

During the 22-year period, the farm employed a range of soil nitrogen management practices, each with distinct impacts on soil health and carbon storage.

These practices included the use of no fertilizer, chemical fertilizers, and organic options like manure or compost fertilizers.

By comparing these different methods, the researchers aimed to identify which practices are most effective in enhancing soil quality and sustainability in agricultural systems.

The findings, published in the Soil Science Society of America Journal, offer valuable insights into the mechanisms of soil enrichment, providing a clearer picture of how specific farming practices can enhance the soil’s ability to act as a carbon sink.

“We were trying to understand what the mechanisms are behind increasing soil carbon storage using certain management practices,” said Dr. Ganga Hettiarachchi, professor of soil and environmental chemistry. “We were looking at not just soil carbon, but other soil minerals that are going to help store carbon.”

Carbon sequestration and imaging insights

Consistent with findings from previous research, the K-State team discovered that soil treated with organic matter, such as manure or compost fertilizer, demonstrated significantly higher carbon storage than soil treated with either chemical fertilizers or none at all.

This highlights the potential of organic fertilizers not only to improve soil health but also to play a critical role in capturing and storing atmospheric carbon.

What sets this study apart is the use of ultrabright synchrotron light, a powerful tool that enabled the researchers to examine the soil structure at a microscopic level.

This advanced technology allowed the team to visualize precisely how carbon molecules interact with the soil, revealing that much of the carbon was preserved in small pores and had bonded with minerals – an important factor in long-term carbon sequestration.

“It was preserved in pores, and some carbon had attached itself to minerals in the soil,” noted Dr. Hettiarachchi.

Microbial diversity and carbon storage

The experts also uncovered another important benefit of using manure or compost as a soil treatment: it led to higher levels of microbial carbon compared to soil treated with chemical fertilizers or left untreated.

This increase in microbial carbon is a clear indicator of greater microbial diversity and activity within the soil.

A thriving microbial community is essential for soil health, as these microorganisms play a critical role in nutrient cycling, decomposition, and overall soil structure, all of which contribute to enhanced carbon storage and long-term soil fertility.

“To my knowledge, this is the first direct evidence of mechanisms through which organic enhancements improve soil health, microbial diversity, and carbon sequestration,” said Dr. Hettiarachchi.

Implications for sustainable agriculture

Because synchrotron imaging is non-destructive, the team could observe soil aggregate (clumps) in its natural state, without needing to disrupt the soil structure. This allowed them to look at the carbon chemistry in situ.

“Collectively, studies like this are going to help us move forward to more sustainable, regenerative agriculture practices that will protect our soils and environment while helping to feed growing populations,” concluded Dr. Hettiarachchi.

“Understanding the role of different minerals, chemicals, and microbes will also help improve models for predicting how various farming practices affect soil carbon storage.”

The study is published in the journal Soil Science Society of America Journal.

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