By Rebecca Hort, Extension Agrologist Intern, AAg, Yorkton
November 2024
Crop rotations are an important aspect of crop production. The concept of crop rotation has been around for many years; however, there are still some Saskatchewan farms that do not have a diverse rotation in practice. There are many benefits to incorporating a three or four-year rotation in your grain operation. Having a diverse rotation with several crop types is an effective strategy for managing both diseases and insects. It can also increase crop yields and improve soil health.
Rotating crops can reduce the risk of insects and disease in host crops. Significant crop losses can occur in canola when the field is infected with blackleg or clubroot, two major diseases of canola in Saskatchewan. At least three years between growing canola is ideal to reduce the spore load of blackleg and clubroot, reducing the chance of crop infection. Incorporating crops such as pulses or cereals will contribute to breaking down the disease spores further as they do not host blackleg and clubroot. A longer crop rotation may be needed for breaking down the spores of certain diseases in the soil or crop residue. Aphanomyces root rot can have a major impact on pulse crop production in Saskatchewan, in which case, a six or eight-year rotation may be needed to reduce the inoculum present in the soil.
Crop rotation can also help manage insect pests. Some insects are not very mobile and will remain in the same field year after year, in which case, seeding non-host crops and using a diverse crop rotation will help decrease populations.
An example of a diverse four-year crop rotation that suits Saskatchewan is cereal-oilseed-cereal-pulse. The pulse will fix nitrogen for the cereal to benefit from the following year. This rotation allows three years between canola crops to reduce pathogens such as clubroot and blackleg. The break between cereals helps to manage diseases including Fusarium Head Blight, cereal leaf spots or root rot by giving residue-borne and soil-borne diseases adequate time to break down and reduce the pathogen level before the next cereal is grown. When using a diverse crop rotation, always know the specifics of the products you are using each year as some herbicides have residual effects restricting what type of crop you can seed next year.
There are many other benefits to having a diverse crop rotation. It allows for better management of crop residue. Cereals create a lot of crop residue that can build up over time when using zero-till operations and incorporating alternate crops can help manage stubble. Another benefit to crop rotations is water-use efficiency. Crops such as wheat have deep roots that can reach water deeper in the soil profile, whereas peas have shallow roots and cannot reach the water at depth.
Consider incorporating another crop into your rotation. SCIC has information on what crops grow well in each region of the province. Check out our Soil Fertility and Crop Rotation Planning Guide to help you make decisions on your crop rotation.