Farmers interested in tapping into potential carbon markets could see benefits other than an added revenue source.
A carbon economy offers farmers opportunities to sell carbon credits through certain conservation practices they employ on their land. Those practices also can reduce agriculture’s own carbon footprint, currently calculated at creating nearly 10% of the U.S. greenhouse gas emissions.
Soil management is a significant source of those emissions, according to several presenters at a recent “Carbon Farming in Texas” workshop in Robstown, Texas.
Texas AgriLife research agronomist Katie Lewis, Lubbock, said agriculture can play a role in reducing greenhouse gas emissions.
Lewis offered four options to increase carbon stocks in the soil. “Producers can manage soil to increase stocks," she said. “Keys are to minimize soil disturbance, maximize continuous living roots, maximize biodiversity, and maximize soil cover.
"Most soils are far from their carbon saturation threshold,” she said. “There is potential for increased carbon inputs and management that protects carbon stocks to maximize carbon storage.”
Sink and reservoir
She explained that soil can be a carbon “reservoir,” storing carbon but not accumulating it.
She said a carbon sink accumulates carbon and is an ongoing process, increasing the amount of carbon stored in it. Growing plants accumulate carbon.
“Soil is a major carbon reservoir, but it could have the potential to be a sink,” Lewis said. That’s where soil management comes in.
AgriLife Research Agronomist Jamie Foster, Beeville, explained the advantages of soil conservation management practices. “Conservation management decreases soil erosion of most fertile soils. It also decreases evaporative water loss,” she said.
“It increases water infiltration and soil organic mater and results in increased water quality and soil resilience.”
No-till planting and cover crops play important roles in improving soil management, Foster said.
She presented findings from several-long-term research projects. A dryland sorghum and cotton rotation study including conventional and no-till was initiated in 2008 at Corpus Christi. Foster said in two of the 13 years, no-till outyielded conventional tillage in sorghum but there was no difference in 11 of those years. Overall, no-till cotton yields were better than conventional. She also recorded an increase in soil organic matter over the course of the study.
Soil regeneration
“That’s about ¼ inch of rainfall advantage with no-till,” she said. “It takes time to regenerate soil.”
See, Be patient on selling carbon credits
Another Beeville project including conventional tillage, strip tillage, and cover crops, showed no increase in soil carbon over the seven-year study. “It took 10 years to increase soil carbon in the Corpus study,” Foster said.
In the Beeville project, Foster noted, “no effect over time from tillage and cover in sorghum.”
She did see some effects in cotton from tillage, cover, and weather. “In five of the seven years, we saw no yield difference in cotton,” she said.