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Many Canadian farmers rely on tillage, the practice of turning over soil in their fields, to prepare for planting crops like potatoes. Tillage, in some respects, is a double-edged sword. Increased tillage can help reduce soil diseases, but too much can also increase weeds and degrade soil quality making it more prone to erosion or reducing crop yields. The trick is for producers to find the right balance.
Exploring the tillage conundrum
This balancing act is why Dr. Judith Nyiraneza, research scientist at Agriculture and Agri-Food Canada, and Prince Edward Island farmers spent four years studying and testing tillage methods as part of the recently completed Living Lab – Atlantic project – a collaboration where farmers and scientists developed and tested innovative solutions on real farm fields to help increase adoption of environmentally friendly farming practices.
“Potato plants have shallow root systems and to protect those roots, farmers often pile soil up around the plant, a practice referred to as hilling. This hilling requires producers to till their potato fields prior to planting.”
- Dr. Judith Nyiraneza, research scientist, Agriculture and Agri-Food Canada
The traditional tillage method, referred to as moldboard plowing, effectively flips the soil while the residues on the surface get buried at a depth of 20-to-25 centimetres. This method is not only labour intensive with high fuel costs, but it can also reduce soil quality and potato yields. Using the living labs’ collaborative approach to innovation, Dr. Nyiraneza, her team, and Prince Edward Island farmers were interested in comparing moldboard plowing with a regenerative soil management practice, called residue tillage or shallow non-inversion tillage. Residue tillage cuts the residues into small pieces and distributes them within the soil while leaving a portion of the residues on the soil surface which helps to reduce soil erosion and retains moisture in soils.
Several farmers participating in Living Lab – Atlantic had previously purchased residue tillage equipment but were unsure how it would compare to their moldboard plowing equipment.
“This research activity was mostly developed and driven by the farmers involved in Living Lab – Atlantic, and it was one of several activities that took place exclusively on commercial fields. We framed the research around the needs of farmers,” says Dr. Nyiraneza.
Andrew Lawless of Hilltop Produce in Kinkora, Prince Edward Island, was among the first on the Island to purchase residue tillage equipment, even before Living Lab – Atlantic began in 2018.
“We were looking at different ways to conserve soil. The moldboard plow was costly to run and maintain and I heard through our supplier about the potential benefits residue tillage equipment has on soil health,” says Andrew.
“Then once Living Lab – Atlantic began, we wanted hard data to support that and other growers who hadn’t yet purchased residue tillage equipment were keen on the results.”
Dr. Nyiraneza and participating Prince Edward Island farmers, including Andrew, compared both tillage methods in 14 commercial farm fields from 2019 to 2022 and evaluated their short-term impact. Researchers and producers worked together to lay out the plots on real farmland. Andrew explains that lingering questions among producers resulted in choosing to plant potato varieties that are more prone to common scab disease, a disease that causes raised, rough patches of skin on the surface of potatoes.
“The perception at the time was that residue tillage caused more common scab in potatoes. We wanted to see how that played out in the research.”
Tillage was completed in the fall, followed by planting potatoes the following spring, all while studying soil health characteristics.
“After just one growing season, and in subsequent seasons, we saw signs of soil health improvement in all measurements including soil respiration, active carbon, soil aggregate stability and nitrogen availability for crops with residue tillage compared to moldboard plowing. Residue tillage also had no negative impact to potato yields.”
- Dr. Judith Nyiraneza, research scientist, Agriculture and Agri-Food Canada
Reduced tillage on potato disease
Throughout the four-year project, Dr. Nyiraneza’s and the producers' findings determined that residue tillage is beneficial to soil health, but how does it impact disease? AAFC scientists Dr. Rick Peters on Prince Edward Island and Dr. Dahu Chen in New Brunswick worked with producers to answer Andrew’s original idea to explore tillage impacts on potato diseases. Dr. Peters compared the effects of residue and moldboard plowing on common scab, while Dr. Chen studied their effect on early dying disease, a fungal disease that causes yield loss in potatoes.
Of the 10 fields that Dr. Peters studied, neither tillage type affected the incidence or severity of common scab disease in six fields. In three fields, common scab increased slightly under residue tillage.
“While tillage practices can affect the incidence and severity of soil-borne diseases in potatoes, other factors influence this and will be studied further. They include prior crops, irrigation practices, type of potato variety planted, and soil health.”
- Dr. Rick Peters, research scientist, Agriculture and Agri-Food Canada
Dr. Chen compared the two tillage methods to understand their effects on soil population levels of verticillium fungus and root lesion nematodes, that together can cause potato early dying disease, as well as the level of disease. He found that the levels of verticillium were higher in the spring with the use of residue tillage as compared to moldboard plowing. However, these increased levels subsided to the average level of disease over the length of the growing season. Populations of root lesion nematodes were not significantly impacted by the tillage practice. After potato harvest in the fall, there were no major differences in pathogen levels between residue tillage and moldboard plowing. The potato early dying disease severity was not affected by the tillage methods.
Even though residue tillage did not significantly reduce pathogen levels and disease severity, Dr. Chen believes the soil health benefits of residue tillage provide enough incentive for farmers to adopt it over moldboard plowing.
“The residue tillage method is an optimal practice as it improves overall soil health, which is essential to farmers. And if farmers can manage their soil health long term, it can lead to more sustainable agricultural productions.”
- Dr. Dahu Chen, research scientist, Agriculture and Agri-Food Canada
Andrew agrees with Dr. Chen’s assessment.
"From the research trials on my farm, I noticed an increase in potato yield with residue tillage, found a decrease in soil erosion, and the soils are retaining more moisture.”
The future climate for tillage research and innovation
Compared to moldboard plowing, previous research reported that residue tillage decreased farmers’ energy input per hectare and decreased operation time of their tractors. Now, with more knowledge about the soil health benefits and minimal effect on disease, many growers have invested in purchasing residue tillage equipment, at least on Prince Edward Island.
“I am seeing lots of other producers adopt residue tillage now because of Living Lab – Atlantic. We’re getting the word out there,” says Andrew.
The return on investment can be quick based on what Andrew has seen in his own data and the results of the living lab project. “From a cost point of view, it’s a definite bonus. All producers have to do is look at the increase in yield it provides. Plus, residue tillage can cover more ground, in less time – it’s huge.”
Adoption of residue tillage continues to grow thanks to the collaboration between Dr. Nyiraneza, Dr. Peters, Dr. Chen and Prince Edward Island farmers.
“Producers at the beginning of Living Lab – Atlantic wanted to know whether residue tillage was benefitting their soil, and I certainly believe their questions have been answered positively – for the improved soil and economic benefits, through reducing precious time and energy costs compared to moldboard plowing.”
- Dr. Judith Nyiraneza, research scientist, Agriculture and Agri-Food Canada
Agriculture research is constantly evolving so Dr. Nyiraneza and Prince Edward Island farmers are setting their sights on climate change. They will continue to test residue tillage for its capacity to sequester carbon and reduce greenhouse gas emissions, through the next Living Lab – PEI project under AAFC’s Agricultural Climate Solutions.
Key discoveries and benefits
- AAFC research scientist Dr. Judith Nyiraneza and Prince Edward Island farmers spent four years studying and testing tillage methods as part of the recently completed Living Lab – Atlantic project.
- The traditional moldboard plowing method flips the soil while the residues on the surface get buried at a depth of 20-to-25 centimetres. Participants were interested in comparing this method with the residue tillage method or shallow non-inversion tillage. Residue tillage cuts the residues into small pieces and distributes them within the soil while leaving a portion of the residues on the soil surface which helps to reduce soil erosion and retains moisture in soils.
- After just one growing season, Dr. Nyiraneza and participating producers saw that residue tillage had improved soil properties compared to moldboard plowing. Residue tillage also had no negative impact to potato yields.
- Dr. Peters compared the effects of residue and moldboard plowing on common scab – raised, rough patches of skin on the surface of potatoes. Dr. Chen studied their effect on early dying disease, a fungal disease that causes yield loss in potatoes.
- Of the 10 fields that Dr. Peters studied, neither tillage type affected the incidence or severity of common scab disease in six fields. In one field, common scab increased under moldboard plowing while in three fields, common scab increased under residue tillage.
- Even though residue tillage did not significantly reduce pathogen levels and disease severity for potato early dying, Dr. Chen believes the soil benefits of residue tillage provide enough incentive for farmers to adopt over moldboard plowing.
- According to a producer involved, many of his colleagues have invested in purchasing residue tillage equipment, at least on Prince Edward Island, and adoption is growing thanks to the collaboration between Dr. Nyiraneza, Dr. Peters, Dr. Chen and Prince Edward Island farmers.
Photo gallery
Dr. Judith Nyiraneza, AAFC colleagues, Dr. Rick Peters, Dr. Dahu Chen, and Prince Edward Island farmers have spent four years studying and testing tillage methods as part of the recently completed Living Lab – Atlantic project.
Residue tillage, seen here, cuts the residues into small pieces and distributes them within the soil while leaving plenty of residues on the surface to ensure soils stay healthy.
Andrew Lawless, owner of Hilltop Produce, shown here with his sons Max (left) and Vance (right), standing next to their residue tillage equipment.