By Richard Kamchen
Prairie farmers would be well advised to include perennial legumes like alfalfa into their tight crop rotations to avoid crop diseases and improve the quality of soil, Alberta Agriculture urges.
"Annual crop diseases have been on the rise across Western Canada," says Alberta Agriculture livestock-forage business specialist Grant Lastiwka. "Diseases such as fusarium, aster yellows, scald, net blotch, blackleg and clubroot, as well as some insect issues, make growing annual crops a bit more of a challenge for cereal and oilseed growers."
High grain and oilseed yields depend on healthy plants with low disease levels, he explains. Diseases like blackleg can worsen in the second year, and he points out it makes sense to use forages for two to three years in an annual crop rotation instead of solely relying on pesticides to combat disease.
Inoculated legumes also provide nitrogen benefits. Lastiwka says a legume can create a nitrogen store worth $40 to $100-plus per acre. Inoculated legumes are able to capture nitrogen from the air through a symbiotic relationship with rhizobia bacteria. The nitrogen store legumes produce is available to subsequent crops for one to three years. Nitrogen is released more slowly and more effectively over a longer period if a farmer uses glyphosate to remove the legume and employs a zero-till cropping system.
"In as little as two to three years of perennial legume production, the maximum nitrogen capture can occur," says Lastiwka. "Yet another synergistic profit consideration when planning a short-term alfalfa hay 'intervention' in a cereal oilseed crop rotation."
Alfalfa in particular can create soil benefits to annual crops that follow it in rotation for up to 10 years after its removal, according to University of Manitoba's Martin Entz. Subsequent crops are able to use old alfalfa root channels to reach nutrients in the soil.
Further benefit to breaking away from the grain monoculture that's been driven by favourable prices comes from improving hay demand. Greater potential of hay export to the U.S. and abroad could push that demand even higher.
"There is a growing need for high quality forage in other countries around the world where water supply is limited," Lastiwka says. Those countries are working to divert their water away from forage production to food production for humans instead. "With domestic and export hay market potential improving, the net return for an alfalfa crop in rotation is going to be higher with greater stability from year-to-year."
Source: FCC