Covering crop rotations Many factors come into play when considering what to plant where

Crop rotations date back thousands of years. Back then, farmers may not have understood the science behind rotating crops on the same land from season to season, but they used it in practice for crop production. Since then, science and experience have expanded our agricultural knowledge exponentially. Modern-day farms in Washington state still use crop rotations contingent on location, weather, weeds, disease, and water. 

Crop rotation has many objectives in mind. It can help nourish the soil, break pest cycles, maintain moisture and use valuable precipitation more efficiently, and reduce weeds’ proliferation. Rotations give farmers options to spread production, workload, and market risk and increase farm revenue. Still, there are seasons for fallow fields, that is, fields left unplanted and kept weed free to accumulate soil water for use by the following crop. Also, crop insurance plays a significant role in decisions on what crops to rotate and when. 

In general, one should try to alternate between grass and broadleaf crops, fall-planted and spring-planted crops, high and low residue producing crops, and high and low water use crops. Although often difficult to do, it is also beneficial to alternate between annual and perennial crops. The use of a legume crop can help reduce synthetic nitrogen inputs. 

Ryan Poe is a fifth-generation wheat farmer outside of Hartline, Wash., who farms with his uncle and cousin. Ty Meyer is a production agricultural manager with the Spokane Conservation District who has worked with large-scale producers in Eastern Washington. In this article, we will learn from them about best practices and reasons for crop rotations.

The farmer’s perspective on crop rotations

Poe’s family has farmed in north central Washington for roughly 150 years. It’s fair to say that his family intimately knows the land and understands its flaws and the external forces acting upon it. They specialize in winter wheat, grow winter canola, and raise cattle for beef. They are considered a large-scale dryland farm located about an hour north of Moses Lake and near Grand Coulee Dam. 

For him, crop rotations aren’t necessarily consistent in his area. Factors such as wind, cold, and moisture come into play when determining what to rotate. He also said that in the Palouse, they have more options for different crop rotations. 

“The higher rainfall zones like the Palouse look much different than mine; they utilize more spring-planted crops because of rainfall,” he explained.

Poe also factors in weed control, market demands, and crop insurance coverage. When considering the benefits of crop rotations, he said they look at weed control and how crops like winter peas put nitrogen back into the soil. Over the past six or seven years, they’ve integrated winter canola with winter wheat and fallow periods. Regarding weed control, crop rotations outside of just winter wheat allow him to go after the winter annual grassy weeds that are more difficult to control in winter wheat. 

For a few reasons, the question of when to leave the field fallow can be based on soil health, stewardship, nitrogen, and water conservation. 

“For us in our area, the sole reason for fallow is lack of moisture; we are in a 10-to-12-inch annual rainfall zone, and the only reason to use fallow is we need another year’s worth of moisture for a crop,” he said. 

Poe explained that winter-planted crops, like winter wheat, can perform better economically than spring-planted crops. His farm uses a combination of two main farming practices: chem fallow, which is the use of herbicides rather than tillage to control weeds, in a direct seed (no-till) system and tillage in a conventional tillage summer fallow system. One of the hurdles to transitioning to direct seeding on all acres on their farm has been consistently being able to integrate canola into their crop rotation. He added, “We’ve consistently had better luck getting a stand in the fall in a conventional tillage system. With fallow systems, we are trying to control the weeds to conserve moisture to get a stand for the following year.”

Poe mentioned that spraying technology for chemical herbicides and the ability to use camera-based spot sprayers have helped to reduce the use of chemicals. He said they regularly scout the fields for weeds.  “All fallow ground is sprayed in the spring to control early weeds and throughout the summer to keep the fallow as clean as possible for the following year’s production,” he added. 

Market-related factors that play into what farmers plant in their crop rotations vary and are often based upon auxiliary services, including crop processing logistics like local canola crushers. Farmers must seek out processors who can help take their crops to market. 

The conservation district’s perspective on crop rotations

The Spokane Conservation District is funded through Spokane County and Washington state and helps landowners and constituents manage their natural resources. They have water quality, production agriculture, forestry, and education programs that enable the district to provide the right resources and experts to help with natural resource concerns. The district also provides funding through grants. Each conservation district works on local issues impacting landowners in their district.

Ty Meyer has been with the district for 21 years. He brings a depth of knowledge to regional producers and works closely with the U.S. Department of Agriculture’s Natural Resources Conservation Service. Regarding regional large-scale farmers, he said, “We work closely with them in a good partnership with good funding opportunities.” The district is a resource for landowners to come to for support. He said they are here to help keep topsoil on farms, protect land from erosion, and keep pesticides on the fields and out of waterways. 

Meyer said that crop rotations add diversity to the system. “My work is mainly looking at things from a soil health angle, addressing soil erosion, soil productivity, and ecosystem functions; it is about diversity in the system, getting something in the system to add biodiversity.” 

He advises that fallow wheat rotations help mitigate disease and gather moisture for the following crop. 

“Our thought process on crop rotations is evolving and looking at more diversity. Cover crops are there to build a symbiotic relationship between different plant species to help the soil ecosystem grow.” He added that crops evolve, and so do diseases and insects. “Instead of sitting fallow through the winter months, the folks that figure out how to utilize cover crops will see an advantage in reductions of pesticide use and will build a healthier crop system over time that can fend off different diseases and insects as we build a healthier soil ecosystem.” 

Knowledge sharing is important, he added, “We are learning together from soil health experts who have successfully grown cover crops around the country. When do we start crop rotations, how do we get cover crops in rotation, and how might they fit into our system?” 

Meyer said the big questions are where do farmers put a cover crop in their rotation and when do they terminate it to maximize the benefit while mitigating soil moisture loss for the following crops. He said it can be challenging to figure out. 

“Our soil was not meant to be bare; that’s not what nature intended for soil,” he explained. For example, he said that in central Washington, temperatures in bare soil can reach up to 130 degrees in the summer, making it hard for microorganisms to live in. He said cover crops provide shade and feed biology, but knowing how to fit it into the system is hard. For farmers, “We can’t harm cash crops with cover crops. Even in Eastern Washington, where there is more rain than in central Washington, we struggle with starting a cover crop after harvest. However, finding ways to use them in our crop rotations will ultimately build healthier soil.

Crop rotations versus fallow fields and other crop cover plantings are based on maintaining and improving soil health. However, decisions about what to plant and when must ultimately incorporate market and crop insurance considerations. Experts say that crop rotations reduce the use of pesticides and herbicides and can improve nitrogen and water replenishment in the soil.