Soil could be “the next frontier” for carbon innovation and an integral part of meeting the U.S. goal of a 50% reduction in greenhouse gas emissions by 2030.
Cover crops will play a large role in those efforts, says Jake Mowrer, Texas AgriLife associate professor and Extension specialist.
Mowrer, speaking at the December Texas Plant Protection Association annual meeting in Bryan, referred to President Biden’s carbon goal, which includes “cutting edge technology” that will help famers meet this goal.
Mowrer referred to a Biden Administration statement explaining the carbon policy. “The United Sates can reduce emissions from forest and agriculture and enhance carbon sinks through a range of programs and measures, including nature-based solutions for ecosystems ranging from our forests, agriculture soils, and our rivers and coasts,” Mowrer said.
No-till and adding carbon to the soil reduces greenhouse gas emissions. “We can see a two-ton increase in carbon sequestration with no-till versus conventional tillage, depending on soil, year, crop, and rainfall.” Mowrer explained.
Cover crops offer additional advantages. “Cover crops add a lot of temporary carbon, not long term. And it fluctuates with time, so when you sample is important,” he said.
Cover also keeps living roots on the soil year-round, increases soil organic matter, and enhances micro-nutrient populations.
Fertility advantages
Mowrer said farmers should consider a systems approach to get the most out of cover crops. “Planting covers for one purpose only is not the best way to approach the practice. Cobbling together several smaller benefits and summing them up in the on-farm calculus helps a farmer realize the profit potential in cover cropping.
“Carbon alone probably won’t do it. But when you reduce herbicide costs, phosphorus and/or nitrogen costs, conserve water, moderately boost yields, smooth out extreme ups and downs each year, among other advantages, the benefits become more consistently dependable. It requires a systems way of thinking.”
Adding legumes to the cover crop mix also aids fertility and prevents leaching.
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Mowrer said cover crops can be beneficial in black soils that tend to tie up phosphorus. “Cover crops improve phosphorus acquisition.”
With non-legume cover crop options, plants act as “a catch crop to scavenge nutrients,” Mowrer said. “They also prevent nitrate leaching, reduce nitrogen and phosphorus runoff, and redistribute immobile nitrogen and phosphorus.”
With legume or non-legume cover crops, producers can reduce fertilizer costs.