Pick a Peck of Prairie Pulses

By Brenda Frick, Ph.D., P.Ag.

Pulses (dry, edible legume seeds) are widely recognized as a good source of protein, starch, fibre, and B vitamins and are considered a healthy part of a balanced diet. These legumes are valued as high protein livestock feed, whether as seed, for grazing, as hay or as silage. Similarly, legumes are ideally suited to feeding the soil and as a healthy part of a balanced rotation.

On the prairies, the most commonly grown pulse crops are field pea and lentil; though pulses such as dry bean, chickpea, faba bean, and soy bean also have a place.

Field pea
Saskatchewan has long been the world’s leading exporter of field pea, so it’s not surprising that organic farmers on the prairies often turn to field pea as the legume in their rotation. Both yellow and green field peas are grown. They are sold both as food and as feed. The classic food use is in split pea soup, though of course more innovative cooks have developed a greater repertoire of pea recipes. Pea seeds contain up to 25% crude protein, so they are much valued as livestock feed. Much of the prairie organic pea crop is exported, especially to Europe, but a small local market exists for food and especially for feed.

Field pea is best suited to black and grey soil zones on the prairie, where moisture is less limiting and high temperatures are less frequent. Field pea can be grown in the drier regions if seeded early to avoid excessive heat during flowering.

Field pea is often grown at a point in the rotation where nitrogen is limiting. Legumes are able to partner with bacteria to obtain nitrogen from the air. This gives them a tremendous advantage against weeds in low nitrogen soils. Field pea also withstands mechanical disturbance very well. When damaged, the pea plants are often able to regrow from nodes under ground. This gives the pea another advantage in weedy fields, where harrowing, rod weeding or rotary hoeing can be used to good effect. Many producers feel that leafy peas are more competitive with weeds than the semi-leafless varieties, perhaps because they let less light through the canopy. Research results have been inconsistent. Semi-leafless peas often resist lodging better, and this too can improve weed competition.

Powdery mildew is a common disease of field pea in the prairies. Often considered minor by producers, it can reduce yields by 10-15% on average, and the release of spores during harvest can be a risk for combine fires and grain dust allergies. The easiest way to avoid powdery mildew is to select a resistant cultivar. Field pea is relatively free from insect attack, and is not a preferred food of grasshoppers.

Field pea can be used as forage at the early bloom stage, or for winter grazing on pea stubble. Field pea can provide a valuable green manure. Usually the plant material is incorporated into the soil at early bloom. With adequate moisture, field pea can provide over 170 lb N / ac. Small seeded peas, such as 4010 forage pea are available at lower cost per acre.

Lentil
The lentil is a relatively recent introduction to the Canadian prairie. From humble beginnings in the 1970s, lentil production has grown to the point that now Saskatchewan is the world’s leading exporter of lentils. Organic farmers produce a variety of lentil types, including large seeded greens, medium seeded greens, small seeded greens, French greens, and reds. Lentil is primarily grown as food. Dhal, or split lentil, is a staple in India. Lentil recipes are abundant, and range from soups and salads to casseroles and baked goods. Because of their small size and flattened shape, lentils cook quickly. Lentils average 22% protein, and are also an important source of fibre, vitamin A and a variety of minerals.

Lentil is best suited to brown and dark brown soils on the prairie. They are somewhat drought tolerant, but they do not tolerate flooding or waterlogged soil. Lentil, like pea, can access nitrogen through their partnership with bacteria. Lentil is a relatively short stature crop, and a notoriously poor weed competitor. It is best grown at a time in the rotation when weeds are under control, after a strong competitor such as fall rye, oat or barley, or following a green manure. Harrowing lentil is possible, but lentil is more susceptible to damage than field pea.

Lentil breeding on the prairies has focused on disease resistance and quality. Today it is possible to find varieties, especially of reds, that have dual resistance to ascochyta and anthracnose. Beyond these varieties, disease is manageable through rotation, isolation and quality seed. Lentil can be highly susceptible to grasshoppers, which are especially damaging at flowering. It is not recommended to grow lentil in years when there is a high risk from grasshoppers.

Lentil is not generally grown for forage; the straw is of high feed quality, but the amounts produced are low. The very small seeded black lentil was developed as a green manure. With adequate moisture it can produce up to 130 lb N / ac, at a relatively low cost per acre.

Dry bean, chickpea and soy bean
Organic producers grow relatively few acres of dry bean, chickpea or soy bean on the prairies. Dry bean and chickpea are used almost exclusively as food; dry bean, primarily in soups and chilies; chickpea, primarily in hummus, falafels, salads and as flour. Soybeans are valuable in both the food and feed markets.

These specialty pulses require special care. Dry bean acres are limited by temperature. The plants are very sensitive to frost at both seedling and seed set stages, and they require warm temperatures for active growth. Likewise, soybeans tend to require a longer, warmer season than is reliable on the prairies. Both are high value, but high risk crops. Chickpea is better adapted to the drier brown and dark brown regions of the prairie. A major limitation with chickpea is its susceptibility to disease, especially ascochyta. Organic producers rely on a disease prevention strategy, including clean seed, rotation and isolation for success with this difficult crop.

Faba bean
Faba bean is currently grown on few acres on the prairies, but recent breeding efforts may change that. The benefits of faba bean have not been accessible to producers because the very large seed size meant a very high seed cost. The goal is to bring seed size down to that of a pea, with a seeding rate of 1 bu / ac.

Faba bean has tremendous potential as a green manure. With adequate moisture, faba bean and its associated bacteria can fix as much nitrogen as an established alfalfa or sweet clover stand, about 270 lb N / ac. Most pulses will use available nitrogen from the soil before partnering to fix nitrogen. According to Bert Vandenberg, pulse breeder at the Crop Development Centre in Saskatoon, faba bean always produces a positive nitrogen balance; it always adds nitrogen from fixation and is the most efficient nitrogen fixer of the pulse crops.

Faba bean may be ideally suited for flexible cropping in cool and moist areas such as the black and grey soils. The plant has good frost tolerance, and can be harrowed after it reaches 5-15 cm in height. Faba bean is an excellent forage or high protein silage. If the plant is swathed for forage or silage in early August, and if there is late season moisture, it can continue to grow and fix nitrogen well into the fall. Alternately, if allowed to go to seed, it averages about 30% protein.

Dr. Vandenberg suggests that faba bean is “delectable” to grasshoppers, and suggests that it would make an excellent bait crop for lentils. A producer could seed lentil at the usual time in a grasshopper prone area, then later seed the faba bean. At the stage when grasshoppers do the most damage to lentils, during flowering, the faba bean would be a much more attractive crop to the grasshoppers, deflecting them off the lentil. Small seeded, relatively inexpensive faba bean varieties will soon be available. Organic producers may just find them “faba-lous”.

Conclusion
Pulses in partnership with bacteria can pull nitrogen from the air that is in the soil and incorporate it into plant tissue. This vital interaction provides a valuable, high protein feed for us, for livestock and for the soil. On the prairies there are several options that make the most of this pulse potential.

 

This article was originally published by Canadian Organic Growers (COG), and OACC gratefully acknowledges COG for permission to post it on our website.

 

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Posted July 2007