Many benefits to a diverse crop rotation

By: Delaney Seiferling

As we head into a new growing season, many farmers in Saskatchewan are wondering how they can avoid having another year like the last.

And one of the most common pieces of advice is one we’ve heard before … and will again.

“The most important thing is diversity,” says Clark Brenzil, the Provincial Weed Control Specialist with the Saskatchewan Ministry of Agriculture. “Diversity of crops, and diversity of management of those crops.”

Maintaining a diverse crop rotation leads to a more robust agronomic cropping system, which is then better able to withstand stresses from environmental extremes and pests. And although Saskatchewan farmers are always looking to combat weeds, diseases and insects, one of these diseases in particular is currently a top priority.

Fusarium head blight affected a significant amount of Saskatchewan-grown wheat and durum in the last growing season. The growing presence of this disease in the province further stresses the importance of a proper crop rotation, says Stewart Brandt, Research Manager for the Northeast Agriculture Research Foundation (NARF).

“Fusarium in wheat survives on the residues of last year’s crop and as long as you grow a crop that’s susceptible to this disease, the inoculum levels that cause the disease will remain high,” he says. “If you break those cycles by introducing a broadleaf crop like flax, canola or even legume crops you can break those cycles and decrease risk.”

The same approach is true for all diseases, Brandt says.

“By not growing the same crop every year you break the disease cycle and inoculum levels drop down.”

Employing a proper crop rotation is also a key tool for pest management, Brenzil says.

“When you have a less robust system you open up niches for weeds, disease or insects to flourish. If you have a particular crop that is favoured by a pest, that pest will increase in numbers and it may or may not favour the crop that follows.”

The importance of a four-year rotation

Economic concerns cause many farmers to cut corners when it comes to crop rotation, but a well-planned four-year rotation is still the ideal, Brandt says, especially when you are dealing with fusarium.

“For fusarium management you really need have to get out of cereal crops for more than one year in order to have a big impact,” he says. “Even a three-year rotation – something like wheat followed by peas and then an oilseed crop might be a good choice.”

Farmers who are tempted towards a two-year rotation are cautioned about the longer-term effects this could cause.

“In many cases a single year break between susceptible crops is not enough to bring inoculum levels down so we need a broad diversity of crops in order to do a good job of managing diseases through crop rotation.”

Integrated approach

Overall, as we’ve heard before, the best approach to pest management is an integrated approach that includes growing competitive/resistant varieties, targeting fertilizer to the crop row, increasing seeding rates, seeding in narrow rows, practicing adequate crop rotations to break disease cycles, and using pesticides when necessary.

It’s also important for farmers to think long term when planning their pest management strategies, Brenzil says.

“We’re realistic enough to know that a lot of what farmers do focuses around economic prospects, but we also want to make sure they’re considering the agronomics in a program and the way that the natural system is going to react to their choices,” he says. “We want to maintain the effective management options that producers have now well into the future and not lose them to resistance. There have been no new herbicide modes of action brought to market in the last 30 years and few if any projected on the horizon.”

“We want to maintain those management options into the future.”

A final consideration for farmers when it comes to pest management strategies is to always consider your end-use market and tailor your management practice towards that market, Brandt says.

“If you’re growing hard red spring and you anticipate a significant premium for high protein, you might want to look more closely at your nitrogen management and your crop rotation to ensure you are growing, or have a high probability of growing, high protein wheat,” he says.

If you’re growing wheat for another market where protein isn’t as valued, consider a different management strategy, he says. Nitrogen fixing pulse crops might be good to include, as these have shown to increase protein in subsequent wheat crops.

For more information about best management practices for growing wheat or durum in your area of the province, contact the Ag Knowledge Centre at 1-866-457-2377.