Will Brinton, Ph.D., an environmental scientist and founder of Woods End Soil Laboratory, says “a new approach to farming is urgently needed and includes measuring carbon dioxide activity in soil as part of a new approach to monitoring and managing soil fertility.”
Plants photosynthesize and consume CO2 (carbon dioxide) to produce sugar, the life-blood of plants. Most of that CO2 comes from the atmosphere, but not all; some emanates from the soil and that contribution is always overlooked. And with the interest in improving soil health today, the end result is a greater release of CO2 from the soil up into the crop canopy that will increase photosynthesis.
Traditional Farming: “The normal practice is to provide crops with nitrogen, phosphorus and potassium,” Brinton explained. “We take it for granted that our crops will get the CO2 they need from the surrounding air only, but in fact soils are a big contributor to that pool. But things have changed over the years. Soils have fallen so low in organic carbon that they no longer produce enough CO2 to feed vigorously growing plants.”
It’s important to realize that natural CO2 levels in the air are actually controlled by soil because it originates there, Brinton explained. Microbes hold and release organic matter from the soil as CO2. In fact, carbon scientists agree that topsoil is the greatest storehouse of available global carbon.
“In pre-industrial times, soils were naturally rich in humus, the decomposed plant and animal matter essential to our soil’s health,” Brinton said. “Thus, the amount of CO2 coming out of the ground—right under our crops—was more than sufficient to meet all our plants’ photosynthesis needs. Now that agricultural soils have become so carbon-depleted and crops have become more productive, plants are forced to access more of their CO2 from the air rather than the soil. We don’t know the full extent of this soil biology yet, but some crops may now be limited from lack of CO2, which ensures full growth.”
Crops Are Hungry for CO2: According to Brinton, CO2 needs can be as high as 400 pounds per day per acre. “In a race against time and population growth, we imagine that more fertilizer will produce more crops and feed more people,” he said. “But this equation is far too simple—and may even be dangerous.”
Brinton pointed out that a recent scientific paper showed that in spite of increased fertilizer usage, soils are steadily declining in organic nitrogen reserves, which is held by humus. Long-term plot studies confirm that humus has also declined in agricultural soils by more than 50 percent in the last century. Brinton uses an analogy to explain what’s happening: “We’ve depleted our savings account, and the interest we’ve benefited from is no longer there.”
The Effect on Soybeans, Wheat, and Rice—C3 Crops: Brinton added that a reduction in CO2 affects soybeans, a C3 crop along with wheat and rice. “These crops have been found to respond positively to increased CO2 concentrations with gains in seed yield, total biomass and improved water use efficiency.” He cautioned that most studies on the effects of CO2 on crops employ artificially produced CO2 applied to the plant canopy, rather than selecting soils of varying CO2 potential. “As a result, the other positive effects associated with healthy soil are excluded from these studies. We have yet to perform these studies systematically in an integrated fashion, treating CO2 as a positive influence from the soil.”
A Better Way of Farming: We need to alter the way we measure yield response by paying attention to the background CO2 being released by the soil and organic nitrogen fertility. Brinton says these have been factored out of earlier studies. “Correcting this omission is critical to assuring soil health and high-yielding crops. The 2015 International Year of the Soil seems to be the perfect time to address this issue.”
Solvita soil respiration measurement, invented by Brinton, is a rapid and accurate means of gauging soil biological CO2 activity. “If we don’t start accurately measuring soil carbon biology, I fear we will continue to ignore it in soil management. We just can’t keep starving soil microbes of their food.” He added that the Solvita Respiration Kit, which is manufactured by Woods End, can play a distinctive role in restoring the needed soil/plant/CO2 balance.
For more information on the Solvita test visit http://solvita.com/.
Agronomist Dr. Daniel Davidson posts blogs on agronomy-related topics. Feel free to contact him at email@example.com.