Grain growers of all stripes are taking a look at controlled traffic farming, and it may offer solutions for some of the particular challenges faced by pulse growers.Stubble forms a natural trellis for pulse crops.
CTF proponent Steve Larocque is an agronomist based in Three Hills and farms in partnership with his brother-in-law near Morrin, AB. He studied CTF in-depth as a Nuffield Scholar between 2008 and 2010, traveling to countries like Australia, New Zealand, and England where CTF or variations of it have a longer history.
“The goal of CTF is to separate the area you drive your equipment from the area you grow crop,” says Larocque. At the centre of CTF is an understanding that reduced soil compaction allows the plants to access more nutrients and make better use of water, both when there is too much and when there is too little.
“It creates a really robust farming system because it can handle really wet and really dry,” says Larocque, who helped his family convert their 640-acre operation to CTF in 2010.
Both on his own farm and farms abroad, Larocque has observed the improvements in water usage that are possible when the seed bed remains untouched by heavy machinery tires. Larocque explains that there is a natural aeration process that occurs as the prairie soil freezes and thaws. As long as this aeration is not negated by agricultural traffic, the soil absorbs rain quicker and lets plants build more extensive root structures to access stored moisture during dry spells.
Spring 2013 will see Larocque planting his fourth crop using equipment modified to have matching axel widths so that compaction is limited to the tramlines. Implement widths are multiples of each other. In Larocque’s case, they started with a 30 foot combine, which meant using a 30 foot air drill and a 60 foot sprayer. The drill is pulled with a four-wheel drive Steiger that has been modified to have 10 foot centre to centre axel-widths on single bias-ply tires to match the design of the combine.
Last year, Larocque noted that after a heavy rains, they were seeding their heaviest land two days before any of their neighbours were able to get on the fields. The wet spring continued, but he noted “barely any dead spots” on his peas, which are susceptible to excessive moisture.
Larocque points to the larger root system of plants grown in the controlled traffic area compared to the plants on the headlands as evidence that reduced compaction leads to healthier plants. In 2012, his canola yielded 30 bushels an acre after a heat blast in the summer and a hail storm that caused 55 per cent damage five days before straight cutting.
“I attribute that to better root structure – its ability to take in moisture when the plant is sweating during 30 plus degree heat.”
Just as the plants are able to access more water with better roots, they are also better able to access soil nutrients.
“Phosphorus and potassium are sensitive to compaction,” says Larocque, adding that as the roots work their way through the aerated soil, they are able to absorb more nutrient molecules. For pulse crops, well-aerated soil help rhizobia fix nitrogen.
“Rhizobia thrive in oxygen rich environments,” Larocque explains. “The more compacted your soil is, the more you reduce that rhizobia’s ability to fix nitrogen.”
Along with modifying their equipment, Larocque and his partners added real time kinematic guidance to their operation. Existing GPS guidance systems can be upgraded to this more accurate system for about $12,000 to $15,000. The precision of RTK allows Larocque to seed between last year’s rows. Since he does not have to worry about plugging his drill with stubble, he leaves it tall to reduce evaporation and protect new seedlings by reducing wind speed by up to 70 per cent. Larocque describes inter-row seeding as a “natural part of CTF.”
“A lot of people began with inter-row seeding and then moved into CTF,” he explains. “You get better depth control because the soil is very similar inter row.”
Tall stubble means less residue is spread in next year’s planting bed, so soil warms up faster in the spring and less nutrients are tied up in the trash. Later in the season, tall stubble provides another benefit.
“High stubble creates a trellis, so even if your crop falls over, it still stays off the ground. It allows air flow underneath and you don’t get that disease buildup,” says Larocque. He describes this natural trellis as a “dream for pulse growers,” especially those who have issues combining peas. Last year, a heavy wind and hail storm flattened the peas, but with RTK guidance, Larocque was able to run the lifters between last year’s stubble and this year’s pea row with ease because the pea vines were draped over the standing cereal stubble.
Research supports Larocque’s experience planting into tall stubble. At a Swift Current research station, peas seeded into tall stubble had a 9 per cent yield increase over those seeded into shorter stubble and lentils saw a 21 per cent yield increase.
Tall stubble combined with reduced compaction act as a deterrent to weed and volunteer plant establishments.
“After three years, the only place that weeds or volunteers grow is in the tramlines because they’re not getting seed to soil contact in the seed bed,” says Larocque.
Like any good farmer, Larocque is loath to wish for a drought, but he also wants to see how his fields perform in a dryer than average year. If he gets a year with adequate moisture, he plans to side-dress his crop with liquid nitrogen to push the crop to its full potential. Using coulters, he will be able to put the nitrogen right into the soil between the rows.
“We can increase nitrogen use efficiency because we’ll be able to get it into the ground where it will be available to be taken up immediately,” says Larocque. Whatever the 2013 crop year brings, Larocque will no doubt learn from it.
Originally printed in the Spring 2013 edition of Pulse Crop News, this article was written by Sarah Weigum, a grain farmer and Alberta Pulse Growers Advisor.
