Proper crop rotations sprout range of benefits

Harvesting the hidden benefits of a diverse crop rotation doesn't have to be difficult, but it does require close attention to details, says an Alberta soil conservation specialist.

"Good economics, improved soil conservation, effective, lower-cost weed control and reduced greenhouse gas emissions are among the potential advantages of managing a proper rotation," says Don Wentz, an agronomist with Alberta's Reduced Tillage LINKAGES (RTL) based in Lethbridge. RTL crop rotation demonstrations are being partially funded by the federal Greenhouse Gas Mitigation Program for Canadian Agriculture (GHGMP).

A feature report on the RTL demonstration project can be found on the recently revamped Soil Conservation Council of Canada (SCCC) Web site at: www.soilcc.ca.

"With increased interest in zero tillage and continuous cropping, we're finding a proper crop sequence is important to making the systems work," says Wentz. "Some people can get by with wheat on wheat or canola on canola for awhile, but monoculture systems aren't sustainable. Monoculture cropping systems increase the risk of crop diseases, insect pests and even tougher weed control issues."

While rotating crops isn't a new concept for many producers, it takes planning to manage the right sequence for today's farms.

For example, many producers have already discovered that including a pulse crop in rotation provides several benefits, says Wentz. "As a commodity, dryland peas are quite marketable and because they are a nitrogen-fixing legume, they can help reduce fertilizer costs in subsequent years."

However, producers need to carefully consider where peas fit in their crop rotations. "Peas and some oilseeds are host to similar diseases such as sclerotina and neither peas nor oilseeds produce large amounts of crop residue," says Wentz. In Alberta's Brown Soil Zone, oilseed/cereal/pulse/cereal may be a good four-year rotation.

In the RTL demonstration projects, warm-season forages are also being tried as an alternative to fallow for use within crop rotations. "In a fallow year, a producer could seed a warm-season forage instead to provide good ground cover," says Wentz. "The forages would work particularly well if they were to follow a low-residue crop such as sunflower or some oilseeds."

The crops could also be swath-grazed, and under irrigation, could be seeded as a second crop after winter triticale is silaged in late June.

Timing can also be an important weed weapon when planning a proper crop rotation. Growing different crops with different seeding dates changes the herbicide schedule and keeps weeds 'off balance,' says Wentz. The changing schedule means more effective weed control and the crop mix also allows for herbicide rotation.

"While it sounds easy, trying to schedule four or five crops in proper sequence over several thousand acres takes a lot of management. It's a complex task," he adds. "Still, more producers are realizing the benefit of a proper rotation. It has to make economic sense, but as stewards of the land, producers also want to protect and enhance soil as a resource, and the environment."

The GHGMP supports a broad range of projects across Canada with the goal to promote awareness of agricultural practices that reduce greenhouse gas emissions. SCCC administers the delivery of the soil and nutrient management sector component of the program. For more information on activities, visit the SCCC's Web site at www.soilcc.ca.

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