In the Green Revolution, which began largely in the 1960’s, a myriad of scientific advancements in agricultural technology ushered in a new age in higher yields and greater food security in the Western world.
The introduction of new crop varieties, chemical fertilizers, and crop protection products resulted in massive yield gains, taking farming from the subsistence level to a reality where only 1.3 per cent of Canadians work directly in agriculture, but food is plentiful here. This was a great leap forward, no doubt.
Alongside these advancements in agronomy and crop protection, we’re learning more about how our soils function. New testing capabilities allow us for the first time to better understand the microbial communities that are fundamental to the health of soils.
One of the key learnings in recent years has been that soil organic matter is largely increased through the life cycle of soil microbes, not through the breakdown of crop residues. Soil bacteria and fungi break down crop residues and cycle nutrients, making nutrients available to plants. However, they have symbiotic relationships with plants to get energy (in the form of carbohydrates) from plants.
With more living roots in the ground, microbial communities flourish. Individual microbe lifespans are short, and while they too are recycled, the sheer speed at which particularly bacteria can multiply sequesters carbon dioxide and builds organic carbon in the soil through what researchers often call the microbial “necromass.” This is how healthy soils build or maintain soil organic matter. Beyond simply sequestering carbon, organic matter increases the water holding capacity of soil, improves soil structure, and provides essential plant nutrients, including nitrogen.
Therefore, if we want to grow the soil organic matter in our soils, keeping our fields green with living plants as much as possible is key. In the potato industry, we acknowledge this is more difficult for potatoes than some other crops. We need to make a loose seed-bed free of weeds in the spring, we need to lift tubers out of the ground in the fall, and our growing season is relatively long, making establishment of cover crops problematic in some regions. Nonetheless, there are ways we can maximize living roots in our fields as much as possible:
- Shorter-season varieties and warmer falls provide more opportunities for fall-established cover crops. Winter cereals like wheat and rye are ideal for this, as they not only provide fall cover but provide revenue the following year.
- Integrate cover crops into all parts of the crop rotations. This will vary depending on your rotation and where you farm, but for summer-harvested crops like cereals, peas, canola, mustard, and others, there are more cover crop options. For corn and soybeans, establishing cover crops may be more challenging. Personally, I’m excited about the opportunity that drones may play in seeding cover crops in these types of crops without having to damage or limit the cash crop.
- If performing fall tillage in the year ahead of potatoes, try to follow that with a fall cover. In P.E.I., many farms are terminating forage legumes in the late summer followed by mixes of brassicas and spring cereals. This cover crop establishes fast and creates significant biomass that stays green till the snow flies. In Alberta, many farms are ridging their fields in the fall along with seeding oats to enable faster warm-up in the spring and reduce wind erosion. In both cases, another 8-12 weeks of living roots are present in the field without slowing down potato planting in the spring.
There is no one magic solution that will work in every field across the country. I encourage potato farmers from coast-to-coast to experiment with how to optimize their rotations to keep something green and growing in their fields as much as possible, within the limitations you have (water availability, length of season, etc.). Together, let’s embrace a Second Green Revolution…keeping our fields green as much as possible.
My best to everyone as you prepare to put another season’s promise in the ground.
