-Farm News photo by Darcy Dougherty Maulsby
Carbon is a foundational building block of every nutrient in the soil and is essential for crop production, says Dr. Jim Ladlie, founder and CEO of ProfitProAG.

There’s a lot of talk — and debate — about carbon credits and how they might put more money in farmers’ pockets, but there’s another way to build a “carbon wealth account.”

“Carbon is a foundational building block of every nutrient in the soil and is essential for crop production,” said Dr. Jim Ladlie, founder and CEO of ProfitProAG.

About 45% of plant mass is made up of carbon. “Carbon must be managed properly, since it’s one of the most limiting resources in crop production,” Ladlie said.

Carbon plays many key roles in natural cycles that can enhance crop production.

“Beneficial bacteria and fungi love plant-derived carbohydrates and need soft carbon sources like root exudates,” said Al Toops, chief agronomist with BTI Ag LLC.

-Farm News photo by Darcy Dougherty Maulsby
Managing carbon is crucial for long-term sustainability in agriculture. A variety of agricultural practices can help farmers reach this goal, including minimizing tillage and using cover crops, which add organic matter to the soil and help control soil erosion.

The microbes open nutrient pathways in the soil that enhance nutrient uptake into the plants. After the growing season, plant residue decomposition starts the cycle over again.

Soil carbon is “black gold” on a farm. It’s also something that farmers can readily influence.

Stored soil carbon is a bit like a bank account, Toops said. While certain farming practices allow farmers to grow this bank account, withdrawals come from soil erosion and other factors.

“What’s in your carbon bank account?” Toops asked.

Carbon provides

many key benefits

The importance of carbon can’t be overemphasized when it comes to producing healthy crops with stronger yield potential, Ladlie said.

The advantages of carbon include:

• Improved nutrient availability and uptake. Many nutrients in the soil must be processed by microbes before plants can take up the nutrients. Beneficial fungal species break down carbon residue and move it to the soil, explained Toops, who champions the BeCrop Test, which sequences strains of DNA to determine what microbes are in the soil and also measures various factors related to carbon. Beneficial microbes, especially mycorrhizal fungi, are essential in releasing valuable nutrients that are locked up in the soil. When these natural pathways work properly, crops can tap into the goldmine of free nutrients stored in the soil.

• Reduced soil density. Soil compaction is no asset to efficient crop production. It can make seedbed preparation more difficult, hinder water infiltration into the soil, and contribute to poor root growth, which reduces crop yield through poor water and nutrient uptake. An abundance of carbon-rich soil organic matter, in contrast, provides a great environment for all sorts of life to thrive in the soil.

“Soil microbes are like little birds that are always hungry and looking for food,” Toops said. As beneficial microbes and earthworms move through the soil to take in carbon as their source of energy, this helps break up soil density. Less compaction in the soil encourages better plant root development. An improved root system fosters better nutrient and water absorption. This also aids the soil’s capacity to withstand erosion.

• Improved resilience to drought and extreme rainfall. Extreme weather events pose serious challenges to agriculture, but carbon helps here, too. Carbon-rich soils can effectively absorb rainfall to control runoff and erosion. They can also retain water to support crops more effectively during dry conditions. This contributes to greater yield stability, Ladlie said.

Increasing soil carbon may even improve weed control. Carbon stimulates the growth of soil microbial communities, noted Maria Gannett, who focused her doctorate research at Cornell University on the link between carbon and weed control. “As these soil microbes grow, they also take up soil nitrogen. This process leaves less nitrogen available for plants, including weeds.” Many of the most problematic weeds in agriculture grow well in high-nitrogen soils but are less competitive in soils with low available nitrogen levels.

“Managing soils so they have lower nitrogen levels could be one way to combat weeds without tillage or the application of herbicides,” said Gannett, who published the online report, “Can Adding Carbon to the Soil Help us Manage Weeds?” in December 2022.

Managing carbon can boost the bottom line

Managing carbon is crucial for long-term sustainability in agriculture, Ladlie noted. A variety of farming practices can help farmers reach this goal, including minimizing tillage and using cover crops, which help add organic matter to the soil and control soil erosion.

“Cover crops can build 0.1% to 0.2% organic matter a year,” Toops said. Managing carbon properly can also boost farmers’ bottom line in terms of:

n The potential for lower crop input bills. Carbon-rich soils enhance nutrient cycling by boosting beneficial soil microbes that help make soil nutrients available to plants. If nutrient pathways are blocked, however, it’s a serious loss. Toops has seen cases where BeCrop soil tests show 2,700 to 7,000 pounds of nitrogen (N) per acre, but only 40 to 60 pounds of N per acre are available to the crop.

“I’ve also seen situations where 500 to 800 pounds of phosphorus (P) per acre were available, but only 60 to 120 pounds were available to the crop,” he added. When those nutrient pathways are functioning, however, that means more nutrients available to the crop, which can lower fertilizer bills.

• Reduced soil erosion and water runoff. Carbon sources help feed beneficial soil biology that drives the water cycle. “If your carbon cycle isn’t functioning properly, your water cycle isn’t either,” Toops said. This is linked to soil aggregates. Soil particles are arranged together to form aggregates, which are held together by organic matter. Soil microorganisms play an important role in the formation and stabilization of aggregates. Well-aggregated soil lets water enter the soil profile, while small pores within the aggregates hold water tightly enough to keep it around, but loosely enough for plant roots to take it up. Well-aggregated soil can absorb rainfall better, which helps control runoff and soil erosion.

• Long-term productivity. Building healthy soils and managing carbon effectively means playing the long game. Increasing organic matter and soil carbon happens over time. Making more deposits in the carbon bank account than withdrawals will keep agricultural soils productive through the years. Carbon farming practices help maintain soil quality instead of depleting it of its life-giving properties, Ladlie said. “Carbon is a plant nutrient and should be treated like one. The better you understand carbon, the better crop producer you’ll be.”