| | The irrigated lands of southern Alberta offer the opportunity to grow high-value crops like potatoes, beans and sugar beets. However, these crops tend to increase the risk of wind erosion, which can lead to the loss of topsoil, nutrients and productivity. Now Alberta researchers are opening the door to some new options to protect the soil and sustain production of these crops.
Rob Dunn of Alberta Agriculture, Food and Rural Development (AAFRD) explains that sugar beets, beans and potatoes produce low amounts of crop residue. As well, current planting methods for these crops rely on burying previous crop residues, leaving the surface more erosion prone. In addition, southern Alberta’s winter Chinooks contribute to repeated freeze-thaw cycles that break down soil roughness, increasing the wind erosion hazard through the vulnerable winter and spring period until the next crop is established.
“We can’t eliminate the risk of erosion in these low-residue crops, but we can minimize it,” notes Dunn. Farmers currently use various erosion control methods such as: inclusion of a cereal crop every second year in the rotation because cereals tend to produce high levels of residue; creating ridges or soil clods to increase surface roughness; applying and crimping in straw or spreading manure; and growing a cover crop.
None of these options is perfect for every situation. Although cereal residue reduces erosion and conserves moisture, too much residue can result in cooler soils, which can reduce seedling vigour and increase the risk of frost damage for a crop seeded into the residue. Freeze-thaw cycles and wind can gradually break down soil clods. Applying straw or manure may not be practical for large areas, and the straw or manure must be well anchored. And cover crops aren’t always practical because potatoes, beans and sugar beets are often harvested too late in the year for the cover crop to grow sufficiently to provide over winter cover.
So several researchers are evaluating alternatives. For example:
- Dr. Jim Moyer of Agriculture and Agri-Food Canada (AAFC) at the Lethbridge Research Centre is investigating several winter and spring cereals as post-harvest cover crops. Fall rye broadcast just before potato harvest or seeded immediately after bean harvest has given the best soil protection.
- Dunn is field testing winter wheat planted with a hoe-type drill following beans or potatoes harvested in early to mid-September. The fall-seeded crop isn’t seeded early enough to provide good winter cover, so the surface roughness created by the drill gives some protection.
- AAFC’s Dr. Bob Blackshaw at the Lethbridge Research Centre is studying various crop stubble and cover crop scenarios for no-till planting of narrow-row dry beans. Beans planted directly into a fall-planted fall rye cover crop treated with glyphosate herbicide appears to be one of the best options in terms of yield and weed control.
- The M.D. of Taber teamed up with a local aerial applicator to demonstrate oats as cover crop for potatoes. Oats were spread by plane and incorporated by the harvesting operation. Farmers have used fertilizer spreaders to apply the cereal, but spreading by plane is very attractive given the busy workload at harvest.
Beating soil erosion in sugar beets
An intriguing possibility for sugar beets grown after a cereal crop is called zone tillage. A beet grower southeast of Taber who has been experimenting with this approach caught the attention of Dunn and researchers from Rogers Sugar, which processes sugar beets at its Taber plant.
Zone tillage is used in row-cropping systems. It confines seedbed preparation within strips in a residue-covered field. The beets are seeded into the prepared zone, while the untilled areas provide erosion protection until the beet crop is established.
The Rogers Sugar researchers are comparing zone tillage with a conventional beet production system, measuring such aspects as yields and soil temperature effects. With funding assistance from Reduced Tillage LINKAGES and Rogers Sugar, AAFRD’s Lawrence Papworth developed a zone tillage machine last year for Rogers Sugar to use in its study. The Rogers Sugar researchers have field tested the unit, and now Papworth is fine-tuning the unit’s design.
Along with reducing erosion, Dunn says zone tillage could offer other advantages like conserving seedbed moisture and reducing the risk of seedling injury during a soil blow-out event in early spring. He is also hoping to team up with bean growers to investigate using zone tillage in bean production. |
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