Sustainability, soil health, crop rotation and good yields

Plant sprouting in healthy soil

In conversation with Dr. Diane Knight

With increased focus on sustainable food production and optimal yields to feed a growing population, producers find themselves under increased pressure to respond to these changing demands. Decades of research have helped identify ways to modify farming practices to help maintain sustainability and soil health while also finding efficiencies and protecting profitability. To get more insight, Dutch Openers sat down with Dr. Diane Knight, a professor at the University of Saskatchewan and a woman with a valuable standing in the field of agriculture. She is co-chair of the Strategic Research Program (SRP) in Soil Biological Processes with the provincial Ministry of Agriculture. The overall focus of the program is to develop innovative solutions to the problems facing today’s producers.

DO: Sustainability is front of mind for most consumers and that extends to how things are made and the foods they eat. With consumers demanding more sustainable and traceable food production, how has this affected producers?

DK: It’s becoming increasingly important for producers to document what they’re doing on their farms. What are the practices they’re implementing and how long have they been doing them for? This affects production and traceability, which are critical for the packaging and marketing of the end products. We know that some producers out there are already doing this but, over time, as consumer demand increases, it will eventually get to the point that everyone will be required to embrace this model.

DO: Do you think climate change has affected certain farming practices like crop rotation?

DL: The biggest things we’ve seen is that producers are faced with more extremes of everything, from temperatures to rainfall levels.

DO: What actions could producers take to help mitigate these?

DK: Crop rotation will help protect them from the unpredictability aspect. Diversifying crops – which a lot of producers already do – helps reduce risk. We know there’s work being done by plant breeders who are looking at the different varieties of crops that are more resilient to these fluctuations but there are no answers just yet.

DO: When it comes to making plans for which crops to grow and how to grow them, what are two of the most important influencing factors producers should keep in mind?

DK: It will usually be how much time and how much money will need to be invested. This leads to the next question which is how can I (the producer) plant, harvest and sell this crop in an efficient and economical manner? Like any business, unless a producer can realize a profit, it doesn’t make sense to do something. So it’s all about understanding the realities of what producers are up against.

DO: Turning to soil health, you reference two factors – purpose and place. Can you expand on these?

DK: Purpose is about knowing why you’re doing what you’re doing. Do you want to improve your soil? Or do you want to grow an optimal crop? Ideally, producers should try to find a balance of growing an economically productive crop while also protecting the land base.

Place is about understanding the limitations of the soil you’re working with – sandy versus clay, how much organic matter is in there, is it dry or wet, what’s the soil structure and so on. Your goal must match your conditions and a producer should be prepared to make modifications.

DO: Of the 20 soil attributes that are often measured to determine soil health, what is the most important one for you?

DK: The most important thing you want to try and improve on your farm is the SOM or the soil organic matter. You should be monitoring it every five years to see if you’re going in the right direction. You also want to look at what we call aggregate stability, which refers to the composition of the minerals and the sand, silt and clay particles and how they’re bound together by fungus and organic matter.

DO: Why is aggregate stability so important for crop production?

DK: When you have larger aggregates in your soil, there’s better water flow, less crusting and it’s easier for roots to penetrate. This really is a solid measurement of your overall soil health.

DO: How can producers help improve their soil health if they have sandy soil versus clay soil?

DK: If they haven’t already done so yet, they should get their soil tested so they have a benchmark understanding of the breakdown of their soil. Sandy soils are challenging and hard to improve. The organic matter needs to be built up. The best way to do this is to keep crops on as much as you can, such as continuous cropping. Even after harvest, the residues go back into the soil. It’s really about doing as much as you can to conserve the organic matter that’s already in your soil.

DO: What about fallowing?

DK: Years ago, it was thought that fallowing would allow water and nutrients to regenerate but what we found was that, during the fallow period, organic matter was getting broken down and levels were decreasing. As a result, we’ve moved away from it and it’s not recommended very much anymore except in specific areas or certain situations.

DO: How important is crop rotation when it comes to preserving soil health and ensuring a good yield?

DK: Crop rotation should be done regularly for two reasons: not only is it good for the soil but it also helps manage risks as well.

DO What kind of crops should be used for crop rotation?

DK: Legumes are great because they fix nitrogen levels. Canola has gotten a bad rap because it’s a sulphur crop but it’s not as hard on the soil as people think. The good thing about canola is that it has a large system so when you harvest, the roots are still there which means organic matter is remaining in the soil. Wheat does this as well.

DO: What other kind of crop practices are there?

DK: There are cover crops and intercropping. We’ve been a bit slow to embrace these practices. They’re becoming more mainstream now but we’re still behind what Europe is doing. Another option is something called shoulder crops, which are grown after vegetables are harvested but before winter freeze. This keeps ground cover on the soil. We’re finding that it’s important to keep something on the soil as much as you can.

DO: What about including perennial crops in crop rotation practices?

DK: Alfalfa and clover can work but we know that if there’s no market for these crops, it’s a challenge for producers. Legumes are good; you can leave them in for two or three years. Clovers can be used for under-seeding with cereals as this helps boost the nitrogen in the soil.

DO: What are three things that producers could do RIGHT NOW to maintain good soil health?

DK: Number one: employ the 4Rs of fertilizing – the right product, the right rate, the right time and the right placement. Number two: keep a crop on as much as you can and diversify your crops. Number three: manage the stubble because this keeps the organic matter that was produced in the field in the field which is where you want it to stay.