Keeping the soil permanently covered is the best way to increase profits in farming no matter where a producer lives or what kind of soil his fields have, says Juca Sa from Ponta Grossa, Brazil.
Juca is a professor who works with farmers in Brazil, but has spoken to farmers all over the world about no-till farming. Ponta Grossa University was the first school in the world to offer a major in no-till agronomy 22 years ago. The university runs both a research and a commercial operation farm.
Juca spoke to producers at the recent Diversity, Direction & Dollars agricultural forum in Dickinson.
His main points were:
- Soil tillage has a major impact on organic matter.
- It is essential to maintain permanent cover on agricultural soils.
- Organic matter and biomass are the most important components of the agricultural system and they come from growing crops with healthy roots and keeping residue on the soil at all times.
The main lesson nature teaches is that it is vital to manage for soil organic matter to build up the soil structure and give the soil the ability to sustain plant growth, Juca says.
"We need to rebuild the ability of soil functionality," he says.
In undisturbed soils, the increase of carbon is a natural process, he adds. Simply put, plants use the sun to convert inorganic compounds into organic compounds, turning carbon dioxide and minerals into plant material by photosynthesis.
"The litter on the soil surface helps maintain organic matter, which sends carbon back into soil," he says.
Juca explains that inputs occur when carbon comes from photosynthesis and outputs come from plant respiration. Cultivating the soil exposes the root material to oxygen which increases respiration.
"Covering the soil can increase our inputs," he says, adding that without the soil covered, there is significant organic matter loss.
He says tillage done in a field that otherwise has been no-tilled for 20 years would result in the loss of 1 ton of carbon per acre and a reduction in organic matter. Losses can increase as the soil remains uncovered and erosion occurs, he adds.
In native soils or natural vegetation, there is litter plus roots, he says. However, in conventional tillage, there is very low aggregate stability and a mix of old residue with fresh residue.
In a no-till system there is high aggregate stability, Juca says.
Soil aggregates are the basic structural unit of soil, he explains. They stabilize the soil and maintain productivity while preventing erosion and deterioration.
Juca says soil that is pristine, such as in a forest, has larger aggregates which results in soil that has increased infiltration, better oxygenation of the soil, greater carrying capacity and more water storage.
"When we change from conventional tillage to no-till, we are rebuilding and recovering the aggregates," Juca says. "When we do this, we have more profitability on the farm."
He gave an example of farming continuous wheat in three areas over 50 years — Missouri in the U.S., Saskatoon in Canada and Argentina.
After 50 years, 48% of the original carbon in Canada was gone and 58% of the original carbon was gone in Missouri. For Argentina, the data covered only 20 years, but in that time, 24% of the carbon was gone, so it was essentially the same.
In tropical regions where the temperatures are higher, there was 60% loss of carbon in 20 years and in Ponta Grossa, 35%.
Juca says conventional tillage in tropical areas leaves the soil bare and unprotected in times of heavy rainfall and heat. That leads to a greater loss of carbon, and that is why many Brazilian farmers have been going no-till and covering the soil at all times for many years.
He also spoke about the importance of crop rotation, even in a continuous soybean area such as Brazil has been. Included in that crop rotation should be cover crops, he adds.