Soil health can be seen as the continued capacity of the soil to function as a vital, living ecosystem that sustains plants, animals and humans. This definition from the U.S. Department of Agriculture – Natural Resources Conservation Service (USDA-NRCS) speaks to the importance of managing the soil so it can continue to sustain life for future generations.
According to the USDA-NRCS, there are a number of agronomic measures farmers can follow to bolster soil health. They include:
- Minimize soil disturbance
- Keep soil covered
- Maximize the duration of living roots
- Maximize diversity of crops
- Integrate livestock into the system
For this edition of Roundtable, Spud Smart asked the following three experts to talk about these important practices and how they can increase the soil’s capacity for potato production:
- Yves Leclerc, Director of Agronomy, North America, McCain Foods
- Bob Larkin, Research Plant Pathologist, S. Department of Agriculture – Agricultural Research Service, New England Plant, Soil and Water Lab
- Wayne Honeycutt, President and CEO, Soil Health Institute
Minimize Soil Disturbance
As the experts point out, potato production disrupts the soil in a very aggressive way. The tubers not only need to be dug up for harvest, there are also numerous planting and hilling procedures as well as chemical applications during the growing season. All this plowing, tilling and heavy equipment use has a profound effect on the stability and health of the soil.
By breaking up the soil, Larkin says, tillage makes fields much more susceptible to erosion. Tillage can also reduce the organic content of soil by stirring things up and causing organic matter to break down more quickly.
“Organic matter is important for soil structure, in forming aggregates which is important for things like water infiltration and drainage, and making the soil loose and more penetrable by roots and water,” says Larkin.
“When you get more infiltration, then you recharge that soil with water so it’s there when the plants need it in times of drought,” Honeycutt adds. “It also means … you have less run-off of soil nutrients into water bodies.”
Larkin says maintaining a high organic content within the soil helps sustain essential microbial populations, which support crops through such processes as nutrient cycling and making nitrogen available in a plant available form.
“High microorganism diversity and activity keeps all of these processes and cycles active and fully functioning,” he says.
As Leclerc points out, practices aimed at maintaining active microflora and beneficial organisms within the soil can also help ward off potato threats. “The more we can maximize biodiversity in the soil, the more chances we have to be able to fight soil-borne pests and diseases,” he says.
Honeycutt agrees. “The biodiversity in the soil influences its ability to suppress soil-borne pathogens for diseases.”
Larkin says while no-till isn’t possible when growing potatoes, there are steps producers can take to reduce soil disturbance during potato years.
“There’s a lot of tillage that’s in the routine procedures that could be reduced substantially,” Larkin says, adding that potato producers who normally incorporate seven or eight kinds of tillage during the planting, hilling and harvesting processes could reduce this to three.
Larkin stresses, however, that it’s in the non-potato years of a crop rotation when growers can drastically reduce tillage. “You might be able to have just one type of tillage, or in some years maybe even none,” he says. “You can no-till plant a grain crop and then you just let that grain crop go all season and you don’t do any tillage at all to it.”
Leclerc agrees, saying there’s a lesson to be learned in how no-till practices have helped shift the sustainability outlook for grain farmers in Western Canada in recent years.
“We always need to look at what we’re doing and try to improve,” he says. “I would like as much as possible for us an industry to look into including as much no-till as possible in our crop rotation system,” he says. “That would really help minimize soil disturbance.”
Keep Soil Covered
Keeping the ground covered is another key aspect of soil protection. As Larkin points out, “When the soil is not covered for long periods and you just have bare soil like after a crop is harvested, it’s much more susceptible to erosion. Then the erosion decreases that organic matter even more.”
Leclerc agrees. “The concept of keeping our soil covered as long as possible is in my mind the key to prevent soil erosion, whether it is from water or from wind. If we can look at ways to keep our soil covered after a potato crop, and also before the potato crop emerges after planting, that would do a lot to maintain our soil,” he says.
“More and more I think we need to be cognizant that soil is a finite resource. We’re not creating any more soils, and the less we maintain the health of soil the less productive it’s going to be long-term,” Leclerc adds.
The experts agree that when it comes to protecting the soil, cover crops are an obvious answer. Cover crops also help achieve another key objective — maximizing the amount of time there are living roots in the soil.
Maximize Duration of Living Roots
“Maximizing the living roots is … part of what you want to do with cover crops, to keep growing plants on that land as much as possible,” says Larkin. Root systems, he adds, help provide more pore spaces in the ground for aeration and water infiltration, and will also help nurture the soil’s microbiology.
As Leclerc notes, cover crops provide more organic matter that can further enhance soil structure and soil microflora. “The longer we leave living roots in the soil the more they can improve the diversity in terms of soil biology, which is very, very important,” he says.
Maximize Diversity of Crops
One of the things that shape a soil’s microbiology is the diversity of plants growing in it. The experts point out that utilizing cover crops, nurse crops and green manures will all help maximize the diversity of plant material in a field, and they stress that lengthening crop rotations is the best way to achieve this objective.
“Short rotations don’t allow the soil to regenerate much,” Larkin says. “If you’re growing the same crops repeatedly in the same places, you’re not getting that diversity of plant matter that covers the soil, which again reduces your soil microbiology because it’s the same things that are grown continuously and this leads to more disease and pests.”
As well as lengthening rotations, Larkin says, growers should consider adding disease suppressant crops to their systems. “We’ve found that can really make a big difference in reducing these soil-borne diseases,” he says.
Integrate Livestock into the System
Some have suggested potato farmers could benefit from fields being rotated into pastures for cows or other grazing livestock, which would inject additional organic matter from grasses as well as from natural manure into the soil.
“There are a lot of things that could benefit from having at least some integration of that,” says Larkin. But as he points out, there aren’t nearly as many farms that combine both crop production and livestock operations as there used to be.
“Farms used to be much more diversified like that … but in modern farming it’s pretty much gone completely separate so that we’ don’t have that integration,” Larkin says.
Leclerc believes rotational grazing is a practice that could benefit potato growers but he acknowledges the geographic disconnect between animal and crop production that exists in many areas is a barrier to implementation.
He is aware of some large potato operations in North America that are starting to incorporate livestock grazing into their production systems. “There are more and more who are starting to recreate that link that existed in the past,” he says.
Honeycutt says a good example of crop/livestock integration can be found in Maine, where some potato growers have chosen to partner up with dairy farmers. “They swap land back and forth from one year to the next because of the benefits that are provided to potato producers,” he explains.
Honeycutt maintains measures aimed at boosting soil health can provide numerous economic benefits for growers. Healthier soils, he says, can lead to improved potato yields as well as greater yield stability for producers, thereby reducing the economic risk of their investments.
Honeycutt recognizes some soil health promoting practices may require additional costs, like the expense of a no-till planter or cover crop seed. However, he says, these practices can also provide substantial savings, such as reduced fuel consumption using no-till and greater nutrient retention with cover crops.
Larkin says farmers can work together to adopt soil health measures on their farm by pooling resources and saving money that way. He also believes there are additional savings to be had in form of fewer nutrient and pesticide applications when soils in farmers’ fields are in a healthier condition.
Leclerc believes it’s important for growers to keep an open mind and not be afraid to try new ideas and technologies when it comes to fostering soil health. “Yes, we do have a lot of well-proven practices but we can always improve,” he notes. “Looking at what’s done elsewhere or on other crops is a critical way to be able to introduce new concepts at the farm level.
“What might seem costly at first might have a lot of benefits [for soil health] that will actually reduce our costs.”