LETHBRIDGE — Beans are big business in southern Alberta.
Up to 50,000 acres of irrigated land are planted each year to pinto, white, great northerns, red, yellow and black beans worth about $60 million.
Alberta Agriculture agronomist Pat Pfiffner said it is the second highest valued irrigated crop on a per acre basis.
Beans, which have been grown since the early 1970s, are seeded in neat, wide rows.
However, Pfiffner told an irrigation production conference in Lethbridge Jan. 21 that recent research shows they could be planted more densely for better yields.
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A four year trial starting in 2010 evaluated seeding rates, row spacing and use of seed inoculants and fertilizer to increase yields.
Beans yield about 2,300 pounds per acre, and they are planted in wide rows 22 to 30 inches apart. Seeding is done with a row crop planter, and the crop is rolled after seeding to smooth out fields. Harvest requires specialized equipment.
The research tried narrow row spacings ranging from seven to 15 inches apart. They also used varying rates of fertilizer because beans benefit from a shot of nitrogen.
“As we increase our nitrogen fertilizer rates, we have a dramatic yield increase,” Pfiffner said.
“Beans are a highly responsive crop to nitrogen fertilizer application.”
More seeds in narrower rows means farmers can expect better seed bed use, which is the percentage of the seed bed occupied by seed.
Research plots were seeded at rates of 10, 25, 40 and 55 seeds per sq. metre on the assumption that more plants would make better use of nitrogen and water and would have reduced runoff.
Closer rows use the space better, but there were challenges with crusted soil and good plant emergence. There may also be more susceptibility to white mould once the plants start to fill in the canopy.
However, researchers found that densely planted, narrow rows tended to have increased yields by as much as 80 kilograms per acre.
Fertility experiments with and without inoculants showed differences in nitrogen fixation. Researchers used zero, 27, 53 and 80 pounds of nitrogen per acre with and without inoculants.
Beans tend to be the least efficient nitrogen fixers among the legume family when fertilizer and inoculants aren’t added. Conversely, fababeans and peas are the most efficient.
Researchers saw as much as a 50 percent improvement in bean yields when inoculants were used, increasing them by as much as 70 kg per acre.
The inoculant invades the root hairs of the bean plant, and the cortex cells begin to multiply to use nutrients and energy to make root nodules.
The bacteria convert or fix different forms of nitrogen within the nodules.
Researchers also learned that nodulation performance is sensitive to genotype, in which one strain of beans fixes nitrogen better than others.
Drought, high temperature and soil nutrient levels affect nitrogen fixation of these plants.
Researchers tried urea and slow release nitrogen products but did not see much difference between the two. Pfiffner said more research is needed because researchers think fertilizer should be applied earlier in the season.
“With in-crop nitrogen application, the timing is critical,” he said.
The concept of tighter seeding rates and solid seeded fields is not new. Fifteen percent of farmers contracted to Viterra are trying this style, but Pfiffner said it is not likely going to take over from row crop farming.
“If you are a grower and this fits into your farming operation, you have to place a value on that.”
