Montana Cool-season Pulse Production Guide
This publication provides current knowledge on best management practices for production of dry pea, lentil, and chickpea for producers in the state of Montana. The authors have included basic information needed for successful production of these pulse crops as well as links to more detailed or current information on the Web. When viewing this document online you can simply click on these links to take you to those websites. All links referred to within the text are listed in the back of this publication. Hard copies of many of the references in this publication are available through Montana State University Extension Publications, and through your local county Extension office.
Last Updated: 01/16by Kent McVay, assistant professor and Extension cropping systems specialist; Mary Burrows, associate professor and Extension plant pathologist; Fabian Menalled, associate professor and Extension weed scientist; Clain Jones, associate professor and Extension soil fertility specialist; Kevin Wanner, assistant professor and Extension entomologist; and Ruth O'Neill, research associate and entomologist
Editor
Kent McVay, assistant professor and Extension cropping systems specialist, Department of Research Centers, Montana State University, located at the Southern Agricultural Research Center, Huntley, Mont.
Contributing Authors
All authors are faculty or staff members of Montana State University. Kent McVay is the principle author assisted by Mary Burrows, an associate professor and Extension plant pathologist in the Department of Plant Sciences and Plant Pathology; Clain Jones, an associate professor and Extension soil fertility specialist in the Department of Land Resources and Environmental Sciences; Fabian Menalled, an associate professor and Extension weed scientist in the Department of Land Resources and Environmental Sciences; Kevin Wanner, an assistant professor and Extension entomologist in Plant Sciences and Plant Pathology; and Ruth O’Neill, a research associate and entomologist in Plant Sciences and Plant Pathology.
Designed by Montana State University Extension Communications.
All photos are © Montana State University or IPM Images unless noted otherwise.
Acknowledgements
The authors would like to thank those who reviewed this publication. Thanks to Perry Miller, Terry Angvick, Eric Eriksmoen, Prashant Jha, and Kathrin Olson. Your edits greatly improved our message and focus. We very much appreciate the financial assistance for printing and distribution by the Northern Pulse Growers Association.
Disclaimer
Common chemical and trade names are used in this publication for clarity of the reader. Inclusion of a common chemical or trade name does not imply endorsement of that particular product or brand of herbicide and exclusion does not imply non-approval.
Pulse Crop Overview
Dry pea, lentil, and chickpea are crops known as pulses. A pulse is an annual legume grown for human or animal consumption. Most define pulses as those grown solely for the dry seed, which excludes crops like green beans or fresh peas. Including a pulse crop in your dryland rotation can bring significant financial and agronomic benefits. The traditional wheat-fallow system of crop production common in Montana lacks diversity, does not efficiently manage precipitation, and leads to declines in soil organic matter (OM) and soil productivity. Growing a pulse crop in rotation with wheat can help bring some balance to soil in terms of health, biological activity, and overall potential productivity.
Pulse crops can be planted and harvested with the same equipment used for small grain production. Because lentil and chickpea produce seed very close to the ground, additional equipment such as a roller (to press rocks down after planting) and a flex head for the combine are recommended.
Recent trends show nearly equal proportions of lentil and dry pea production in the state with just a small percentage of chickpea produced (Figure 1). As of 2012, pulse crops represent more than one-half million acres of the seven million acres in dryland production in Montana. The increase in dry pea and lentil acreage appears to be sustained growth as compared to the short-term run of chickpea from 1998-2003. In the 1990s pulse acreage was primarily located in the intermountain region near Kalispell. But today the northeast and Triangle regions of Montana are the dominant locations for pulse production (Figure 2). The reasons for sustained growth are many, but they include a concerted effort by the Montana Agricultural Experiment Station (MAES) to evaluate these crops across the region as well as a substantial increase in the number of buyers. According to the Montana Department of Agriculture1, by 2012 there were 25 different delivery points for peas, and 23 receiving stations for lentils within the borders of the state.
Lentil (Lens culinaris): The name lentil refers to the shape of the seed which appears like a lens at maturity. Seeds vary in size and color due to genetic variability. The United States Department of Agriculture/Federal Grain Inspection Service (USDA/FGIS) recognizes only one class of lentil, but they distinguish special grades of size, either large or small, based on passage through a 15/64-inch round-hole sieve. Although color is not necessarily a grade by USDA/ FGIS, it is a characteristic important to buyers. Typically buyers will categorize different varieties into browns, greens, and reds; named for the color of the seed coat, not the color of the cotyledon.
Adding lentils to your diet can bring lots of flavor and protein to numerous dishes. In the U.S. brown lentils are probably most common, and the type most likely to be found in the grocery store. They range from light brown to dark black. This type cooks in about 20-30 minutes and holds shape very well. Green lentils can be pale or mottled green-brown (like Pardina). Green lentils have a more robust, somewhat peppery flavor, and take a bit longer to cook. They keep a firm texture even after cooking, which makes them an excellent choice for salads and other side dishes. Red lentils can range in color from gold to orange to bright red. Reds are the sweetest and have a nutty flavor. Cooking times are around 30 minutes. Red lentils tend to get mushy once cooked, making them a good choice for Indian soups.
Figure 1. trend in Montana pulse acreage since 1998 (uSdA-nASS).
Figure 2. distribution of pulse acres in Montana in 2012.
Varietal differences lead to different markets, so when managing grain at harvest it’s important to keep each variety segregated. If different colors or different varieties are mixed, the value of the product is diminished, thus affecting the price offered. Current recommendations are to communicate with your buyer prior to planting the crop. Lentil crops are grown with and without contracts but it’s important to know up front what options will be available come harvest time.
Dry pea (Pisum sativum L.): Dry pea has been grown in Montana for many years, and is very well adapted to the region. The variety arvense, or Austrian winter pea, is typically planted in the fall to establish the plant and is grown only for livestock feed. It then lies dormant through winter and begins growing again in spring. In Montana, typically all above-ground plant material grown in the fall desiccates over winter and regrowth is initiated from crown or sub-crown buds. Winter regrowth has been best when significant warm, dry spells occur in early spring, and worst in dense cereal stubble with prolonged cool, wet growing conditions in April. Seeds of this variety are usually mottled brown and are included in the Mottled Dry Pea class by USDA/FGIS. Spring planted pea is typically either yellow smooth or green smooth, each is in a separate class by USDA/FGIS. In Montana, yellow types tend to outyield green types by about 10 percent, but yield varies strongly among varieties in both market classes.
Pea is very versatile and can be harvested as forage or as grain, or can be terminated by tillage or herbicide and used as cover crop to scavenge residual nutrients and fix atmospheric nitrogen (N) for a following crop. The relatively high percent N content of the forage, typically two to four percent, can contribute a significant amount of N to a following crop. For example, a two-ton forage yield of pea at three percent N provides 120 lb. N per acre. This N is in organic form, but pulse residue has low carbon to N ratios and decomposes rapidly, mineralizing this N into forms available to a following crop. This will be discussed further in the fertility section.
Yellow and green smooth pea are quite nutritious. Protein of the grain can range from 17-28 percent. It contains high levels of carbohydrates making pea excellent livestock feed. Pea has lower amounts of trypsin inhibitors than soybean and can be directly fed to livestock. Dry pea is often cracked or ground as it is added to feed rations to increase digestibility.
Dry pea is also sold for human consumption. The largest market is Asia but demand in the U.S. has steadily grown for the past several years. As recommended for lentil, communicate with your buyer before growing pea. It’s important to know your market.
Chickpea (Cicer arietinum L.): Chickpea is grown as a food crop in many countries. Major producers include India, Pakistan, Turkey, Iran, and Mexico. According to the Food and Agricultural Organization of the United Nations (FAO), world-wide chickpea is the most important pulse crop followed by pea and then dry bean. Most people in the U.S. are familiar with the cream-colored kabuli types found on salad bars. Also known as garbanzo bean, chickpea can be processed and served as hummus, a traditional dish in the Middle East, and increasing rapidly in popularity in the U.S. The smaller dark-seeded types of chickpea are known as desi, which are usually ground into flour (dahl) for use in soups or other dishes. Chickpea is typically contract-grown and brings a good price.
Cultural Practices
Inoculation: Pulse crops are legumes. Legumes fix N from the atmosphere through Rhizobia bacteria that grow in association with plant roots. The same Rhizobia species is effective for pea and lentil, but a different species is necessary for chickpea. Once bacteria are introduced to the soil, a certain population remains viable for years. Because of plant disease risk, Montana State University recommends limiting the frequency of pulse crops to no more than once in three years on any particular field. Because of this long break, it’s a good practice and cheap insurance to inoculate the seed with the proper rhizobium at each planting. These crops need a significant amount of N to produce seed, and if the bacteria is not present, or does not infect plant roots, the plants are at risk of N deficiency (See Box 1). Inoculant formulation can have an impact on the establishment of nodules on plants. Field trials in west-central Alberta found granular soil applied inoculant produced greater yields than liquid or peat powder seed-applied, especially at low applied N rates (0 and 18 lb. N/acre, vs 36 and 71 lb. N/acre) (Clayton et al., 2004).
Box 1. nitrogen is nitrogen.
When bacteria invade the roots of legumes, they set up shop to fix atmospheric N gas (N2). This mutually beneficial, or symbiotic relationship, helps both organisms. The bacteria receive energy from the plant, and in exchange the plant receives ‘free’ N. What happens if the two don’t get together? No nodules develop on the plant roots, and the plant is left to scavenge the soil for mineral N. The N can come from the mineralization of soil-OM, or from inorganic forms like fertilizer-N. The plant will complete its life cycle regardless from where the N is supplied. The bottom line is a shortage of N leads to poor plant growth and low yields.
As a point of reference, over the course of a season, a 2000 lb. lentil crop will assimilate at least 80 lb. N/acre. This N can come from the atmosphere through its association with bacteria, or it can come from fertilizer or other sources. It pays to inoculate your soil!
Cropping Systems: Pulse crops are a good choice for diversifying your rotation. These legumes will get their N indirectly from the atmosphere. This reduces overall input and cost of fertilizer. In addition, pulse crop residue breaks down quickly, providing some N credit to a following crop. This credit is approximately 10–20 lb. N/acre depending on yield, but can be substantially higher if the pulse crop is managed as a cover crop. As a cover crop, N credit given is a function of total tonnage produced (download Oregon State calculator)2.
Fields that have been managed primarily for small grains may have herbicide residues that can prevent successful rotation to pulse crops. Lentil is especially sensitive to background levels of herbicides which use acetolactate synthase (ALS) as found in products such as Finesse, or Glean. For example, the labeled plant-back restriction for lentil following Glean is 36 months, and 24 months for dry pea, but in Montana environments this period may be longer. Before pulse crops can be included in rotations with cereal grains, herbicide management in the small grains phase has to be modified. Post-applied products such as Banvel, or Ally Extra for broadleaf weed control can be successfully substituted for the soil-active herbicides which reduces the plant-back restriction. See the discussion in the weed section for more herbicide choices.
The legacy of decades of small grain breeding work conducted at state universities, by USDA scientists, and by private seed companies has provided many choices when it comes to plant disease management for cereal grains. Pulse crop breeding, by comparison, is still in its infancy. The diseases that damage or kill pulses are typically fungal or bacterial organisms that complete their life cycles on residual crop residue. Most diseases are specific to the host plant, so to prevent reoccurrence or a buildup of disease organisms, the pulse crop residue must be eliminated. In years past tillage was recommended, but no-till systems with extended rotations between pulse crops is just as effective. A more detailed discussion of disease management can be found later in this guide.
In Montana the majority of pulse crop production is under rainfed, or dryland conditions. But irrigated production of pulses is possible. For the past two years dry pea and lentil have been grown under dryland and irrigated production at the Southern Agricultural Research Center. Significant yield increases were seen where irrigation was practiced (Table 1). Disease issues were not a problem in these two years but the potential for disease would be higher under irrigation, requiring more scouting and greater management.
Variety selection: Choosing a variety that excels in your region is as important for pulse crops as it is for any crop. Uniform statewide variety trials for dry pea, lentil, and chickpea have been conducted in Montana for several years. Results are available through Extension Publications3, and online for all locations at the Southern Agricultural Research Center4. It’s important to remember when analyzing variety performance data that results from any one year may not mean much. To gain certainty of performance superiority, compare results from sites that are representative of your location. Results from several different years, or results from different locations averaged across one or several years, should be given preference. Unfortunately not all varieties available to you are evaluated in these trials. If you choose to grow a variety that has not been tested, heed the advice of your contractor, or rely on the experience of your neighbors.
Pulse crops are true varieties, not hybrids. Keeping seed for your next crop can be a good idea where and when legal to do so. The Montana State Grain Laboratory5 can test seed lots for presence of disease.
Table 1. Impact of irrigation management on yield (lb/acre) potential of dry pea and lentil production in south central Montana (Huntley) from 2011-12.
| Crop | 2011 | 2012 | ||
| Dryland | Irrigated | Dryland | Irrigated | |
| Green Pea | 1888 | 4213 | 1482 | 2989 |
| Yellow Pea | 2182 | 4486 | 1630 | 3338 |
| Lentil | 659 | 1270 | 534 | 1744 |
Lentil: Most varieties grown in Montana are spring types, though some winter varieties are available. Most well-drained soils provide good locations for lentil production. Lentil will develop roots in the top two feet of soil. Shallow soils are fine, while deeper soils are also a good choice and will retain a reservoir of moisture for a following crop that may root deeper. Lentil can be successfully no-till drilled on 6- or 7-inch row spacing, placing the seed approximately one to two inches below the surface. Seeding early (similar to spring wheat) is important to encourage more vegetative growth, and taller stature as to set seed higher on the plant. Planting into standing wheat or barley stubble encourages taller plants, and provides some protection from lodging at harvest. Lentil is quite frost tolerant, able to withstand temperatures as low as 21° F. Upon germination, the cotyledons open and the shoot emerges. The cotyledons remain below the soil surface (hypogeal germination) as the first node. A second or ‘axillary’ node then develops and the third node will usually establish at the soil surface (without leaves). If the shoot is damaged, re-growth can occur from the crown or from axillary (i.e. below ground) nodes. The first leaf usually develops at the fourth node (but is called the first vegetative node). After that new leaves are produced on successive nodes approximately every four to five days. The total number of leaves developing from nodes varies from nine to 15.
Lentil plants are short, growing only to heights of 12-16 inches. Land rolling after planting is recommended to push rocks down so they can be avoided at harvest. This is especially true in rocky or rough fields. It’s best to roll soil prior to seedling emergence, but lentil can be rolled any time after planting until the five-node (vegetative) stage. Rolling the same direction as planted and on warmer days rather than cold mornings reduces the risk of stem breakage.
Seed size can vary widely from extra-large green Riveland types with diameters close to eight mm (~1/4 inch), while extra-small reds like Crimson or CDC Impact can have diameters of only three mm. Seeding rates should be adjusted to target a final plant population of 11- 15 plants per square foot. Typically that equates to seeding rates of 40-80 lb./acre (See Box 2 for calculations). Be cautioned that higher seed rates can provide a favorable environment for diseases.
Lentil has an indeterminate growth habit, which means they continue to grow vegetatively after setting flowers. Late summer rains can trigger mostly ripe plants to produce new vegetative growth. This growth characteristic can make harvest more challenging, sometimes requiring chemical desiccation to terminate growth to improve seed quality and uniformity for harvest. See the weeds section for some harvest aid recommendations. Forage types, like Indian head, do not store well for long periods.
Clearfield lentil: Varieties in this category have been selected for their tolerance to the herbicide imazamox (Beyond). This tolerance provides an excellent way to help control certain broadleaf weeds such as shepherd’s-purse, field pennycress, kochia, and mustards, which are typically hard to control in lentil. In addition grassy weeds such as downy brome, Japanese brome, Persian darnel, jointed goatgrass, wild oats, and volunteer wheat can be controlled using imazamox chemistry. Some of the limitations of using Clearfield is the requirement by BASF that you sign a Clearfield Lentil Stewardship Grower Agreement, which among other things restricts the use of this system to no more than twice in four years on any particular field. This is a policy used to help prevent development of resistant weed biotypes. Since a typical Montana crop rotation already restricts lentil to no more than once in three years, this is not difficult unless you are growing other Clearfield crops. Another limitation is that seed cannot be kept for future planting, but must be purchased as certified seed.
Even with these limitations and restrictions, if weed control in a field going to lentil is suspect, Clearfield lentil may be a good choice. In the U.S. Clearfield lentil is marketed through Pulse USA6 located in Bismarck, North Dakota. Varieties currently available include CDC Impala CL and CDC Impress CL, which have performed well in the statewide pulse variety trials.
Box 2. Determining seeding rates
Spring Pea: Pea require more moisture to germinate than small grains because of their relatively large seed size. This makes them a good candidate for no- till establishment where previous crop residue helps to maintain higher surface moisture. If the soil is conventionally tilled, it should be worked just enough to be clod free. Overworked soil can crust, which can result in poor emergence of the seed. Pea should be planted in well drained soils from one to three inches below the surface and always into moisture. Narrower row spacing (six inches) helps with early season competition against weeds, but pea can be successfully raised in rows as wide as 12 inches. A population of eight to 10 plants per square foot is needed for successful grain production (see Box 1 for calculations), which means for pea, seeding rates of 150-200 lb./acre are common.
Early planting dates improve yield potential by helping the plants reach maturity prior to the hot days of mid-July. Pea is fairly resistant to spring frosts and can re-grow from buds at or below the soil surface if frost damage occurs. Plant pea just prior to your time for planting spring wheat, especially if the seed is treated for disease control. Handle pea seed with care to minimize cracking. Split seeds will not germinate.
The semi-leafless pea varieties that are commonly grown can be straight-combined. They have shorter vine lengths and plants tend to knit together as one mass as they ripen. The lower pods mature first on each plant. Pea is physiologically mature once the majority of pods have turned yellow or tan and can be harvested once moisture content drops to 16-18 percent. Harvesting in early mornings or late evenings when humidity levels are higher helps reduce shattering and seed coat cracking. Pea is easy to thresh, requiring low cylinder speeds and open concave settings to limit splitting and damage to the grain. Reel speeds should be reduced to match ground speed so that vines are not batted but are gently moved into the machine. Use the manufacturer’s recommended settings for your combine and adjust settings throughout the day as conditions change, as pea is quite susceptible to shatter. Lifter guards and pickup reels improve harvest efficiency, as will the use of a flex head or draper head which will reduce combine maintenance costs and operator stress.
Pea can be swathed prior to harvest if the field is weedy or uneven maturing is a problem, but swathed pea is highly susceptible to wind damage. Delayed harvest, or lengthy times in windrows can lead to greater shattering and bleaching of seeds, which can decrease the value or marketability of pea. Bleaching is much more of a problem for green than for yellow types. When moving harvested grain, augers should be run at slow speeds, or use belt conveyors to minimize damage to the grain.
Chickpea: The seeds of the large kabuli type can be twice the size of most field pea. Seeds should be placed into moist soil to ensure getting a good stand. Seeds should be planted into well-drained soil at two to three inches. Chickpea is considered a cool season crop, but tolerates delayed seeding as compared to pea or lentil. Target a final plant population of four to six plants per square foot (see Box 2) on 6- or 7- inch rows. Like lentil and pea, following germination the cotyledons remain below the soil surface, with scale nodes developed at or near the soil surface. The first true leaves usually appear on the third node.
There are two leaf forms for chickpea regardless of type. The most common leaves are pinnate or compound (i.e. fern-like), approximately two inches long with nine to 15 leaflets per leaf. Many kabuli varieties (but not all) have a unifoliolate leaf type (Figure 3). On average plants produce a new node every three to four days, and flowering begins usually at the 13- or 14-node stage. Kabuli types have white flowers while desi flowers are pink to purple. Single flowers form on short stems located at the base of the leaf. They generally self- pollinate before opening. In general plants mature in 100–130 days, reaching a height of eight to 24 inches. Mature pods will contain from one to two seeds.
Chickpea develops a deeper and more extensive root system than either pea or lentil, and can extract moisture from soil depths similar to that of wheat. The soil profile following chickpea will be as dry or drier than that following wheat because chickpea tends to mature later than wheat. Lodging is not normally a problem. Seeds are set higher on the plant than on lentil or pea, but rolling is still recommended if rocks are a concern. Chickpea matures about two weeks later than pea or lentil (if planted the same day), usually similar to spring wheat. Drought conditions will hasten maturity, while late season rains will cause plants to green back up.
Figure 3. chickpea leaf-types include fern-like (left) and unifoliate (right).
Chemical desiccation may be necessary to facilitate harvest (See Weeds Section for recommendations). Direct-cut harvesting is preferred. For desi types set the combine similar to that for dry pea. For kabuli types, use the dry bean setting. A bean concave set at a wide spacing may be necessary to reduce damage to the large seed. It’s important to plant disease-free seed and use seed treatments. Large kabuli types are very susceptible to ascochyta and should be sprayed with a fungicide at flower initiation or whenever disease is observed. In most years plan on applying a fungicide.
Soil Fertility for Annual Legumes
General Principles: The key to optimizing yield and quality of annual legumes is to select the right fertilizer source, rate, placement, and timing for your operation (4R Concept). These are usually interrelated; for example, the right rate, placement and timing are very dependent on the source. There are some general principles that can help get it ‘right’, which not only can increase your bottom line but help protect our soil, water, and air resources.
Rate: As with other crops, annual legume fertilizer application rates should be based on a soil test (see Interpretation of Soil Test Reports7). In general, soil tests from samples taken in the spring rather than fall better reflect the nutrients available to the crop in a growing season because of overwinter changes in levels of nutrients, especially N. However, since legumes can fix their own N, and availability of phosphorus (P) and potassium (K) are less susceptible to overwinter change, fall samples are acceptable to determine fertilizer rates for legumes.
The fertilizer rate guidelines presented in this bulletin are based on a “sufficiency” fertilization rate which is the minimum required to optimize net revenue in the current year. If, instead, the fertilization goal is to “maintain” soil nutrient levels, then crop nutrient removal rates can be used to estimate the amount of nutrients needed to replace those removed by the harvest (Table 2). The maintenance strategy does not require soil testing but will generally require higher application rates than the sufficiency approach when soil tests are moderate to high.
Table 2. Estimated pounds of nutrient removed per bushel of chickpea, lentil, or pea seed harvested in Montana or per ton of field pea hay.
| Unit | N | P2O5 | K2O | S |
| Seed (lb./bu)1. | 2.18 | 0.67 | 0.87 | 0.15 |
| Hay (lb./ton)2. | 46 | 11 | 32 | NA |
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2. USDA Nutrient content of crops.
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A third strategy, recommended only for non-mobile nutrients (discussed in Timing and Placement) and when fertilizer costs are relatively low, is the “build” strategy. Building up soil nutrient levels quickly should increase the chance that nutrients will not limit crop growth and minimize fertilizer needs when fertilizer costs are high. One strategy for building nutrient supplies quickly is to add the sufficiency rate to the maintenance rate to determine a total rate.
Tissue Testing: If nutrient levels are below critical tissue nutrient concentrations (Table 3) or plant nutrient deficiency symptoms are observed, in-season fertilizer is warranted if applied before potential yield has been reduced. The critical tissue nutrient concentration is the level at which 90 percent of maximum yield is obtained. Because tissue concentrations change with plant maturity, it is important to sample the correct tissue at the correct time. Sampling times are selected based on when nutrient deficiencies begin to appear. Early detection allows for correction of a potential nutrient deficiency within the growing season. Plant and soil samples taken from an affected area can be compared to samples from a healthy area to help identify a limiting nutrient.
Table 3. Leaf nutrient concentration at which 90 percent of maximum yields were obtained.
| Plant tissue concentration | |||
| Crop | S1. (%) | Zn2. (ppm) | Cu3. (ppm) |
| Chickpea | 0.18 | 17 | 2.6 |
| Lentil | 0.29 | 25 | 4.6 |
| Faba bean | 0.038 | 18 | 2.8 |
Plant nutrient deficiency symptoms can also be used to identify nutrient deficiencies. It is better to rely on soil test recommendations, nutrient removal rates, or early season critical tissue concentrations, if available, because once nutrient deficiency symptoms appear, yield potential has likely already been reduced. Deficiency and toxicity symptoms are illustrated in Plant Nutrient Functions and Deficiency and Toxicity Symptoms8. Be cautious of pseudo-deficiencies, such as disease or herbicide damage that may appear similar to nutrient deficiency symptoms.
Source: The nutrient source, for example granular vs. liquid, or monoammonium phosphate (MAP, 11-52-0) vs. diammonium phosphate (DAP, 18-46-0), often does not substantially affect nutrient availability, but should be selected based on cost per pound of available nutrient, ease of application, and potential germination issues if applied with the seed. Some nutrient sources are slow to dissolve into plant available forms. For example, phosphate rock and elemental-sulfur (S) generally do not provide enough phosphate and sulfate, respectively, within the season. However, they can be used to bank soil P and S levels. Organic amendments such as manure can be an excellent source of many nutrients. Manure is especially high in P. Such sources contain variable nutrient amounts and should be tested for nutrient content to calculate application rates.
Timing and Placement: Nutrient mobility in soil largely determines fertilizer timing and placement. Nitrogen fertilizer and sulfate forms of fertilizer are very mobile in the soil so they should be applied close to the time when needed by the crop (see Nutrient Uptake Timing by Crops: to assist with fertilizing decisions9). They can also be applied as ‘rescue’ treatments, i.e. top-dressed, to be taken up by roots. Potassium (K) is relatively immobile and P is very immobile so both are best applied in the root zone at the time of seeding or earlier. Potassium may be top-dressed very early in the growing season, while top-dressed P is most likely ineffective.
Of the micronutrients necessary for N-fixation, iron (Fe), copper (Cu), manganese (Mn) and zinc (Zn) are very immobile and likely unavailable to the plants if broadcast. Foliar applications may help if plants are deficient; primarily because plants need so little that plenty may enter through the leaf. If mobile micronutrients such as chloride (Cl) and boron (B) are deficient, the crop may benefit from top-dressing these nutrients. Be cautious when using micronutrients as crops need very little.
Legume seedlings are very sensitive to salt, and proper fertilizer placement is critical to avoid injury. Avoid placing N, especially urea or urea-ammonium nitrate (28 or 32 solution), directly with the seed. Phosphorus and K can be placed with the seed in limited amounts (see specific nutrients). Potential for seedling injury from fertilizer tends to be higher in dry or coarse-textured sandy soils.
Specific Nutrients
Nitrogen: Legumes must be properly inoculated in order to develop active nodules for N-fixation. Low temperatures, drought or excess moisture, or more than 25-35 lb. total available N/acre (nitrate plus ammonium N) can inhibit nodulation and N-fixation (Saskatchewan Pulse Growers Pea Production Manual10). If nodules are lacking or inactive (inactive nodules are white, whereas active nodules are red inside) three to five weeks after emergence, then check with an agronomist to determine whether an immediate fertilizer N top-dress is justified.
A small amount of top-dressed N (10 to 20 lb. N/acre) can help young plants initiate N-fixation and gain vigor, especially in soils low in N (less than 15-20 lb. N/acre; Miller et al., 2005). In unfavorable growing conditions (e.g. dry seed bed), a similar small amount of starter N can be placed away from the seed to boost seedling growth before nodules become fully functional. If MAP is used to supply P (discussed later) it will supply a portion of the starter N suggested for soils low in N. Although higher N may appear to benefit the crop in early growth, high N may produce excessive vegetative growth resulting in reduced pod set, seed production, N fixation, and delayed maturity. Starter N may not always increase yields. Of 58 field trials conducted with field pea over four years in Alberta, 24 percent increased pea seed yield in response to 18-54 lb. N/acre starter N, 72 percent showed no yield response, and nine percent showed decreased yields. Yield changes were modest in the study, averaging just nine percent (McKenzie et al., 2001).
Phosphorus: Phosphorus promotes extensive root growth, vigorous seedlings, early and uniform maturity, and increased tolerance to stress. Adequate P is necessary for good nodulation and N-fixation. Base fertilizer P rates on soil tests (Table 4) or removal rates (Table 2). Annual legume P rate guidelines are approximately 70 percent of wheat P guidelines (Fertilizer Guidelines for Montana Crops11). This is because effective rooting depths are shallow for annual legumes (2-3 ft) as compared to wheat (3-5 ft) and available P is highly concentrated in surface soils so legume roots are in a P-rich zone. Additionally, annual legumes lower the soil pH in the root zone which dissolves calcium phosphate minerals, whereas wheat raises the pH in the root zone, decreasing P availability. Note that one Montana study found the increase in P availability following legumes was temporary and did not increase P availability for the subsequent crop (Rick et al., 2011).
Table 4. Phosphorus fertilizer guidelines for chickpea, lentil and pea in Montana based on soil analysis.
| Olsen P Soil Test Level (ppm) | P2O5 (lb/acre) |
| 0 | 35 |
| 4 | 30 |
| 8 | 25 |
| 12 | 20 |
| 16 | 15 |
If soil test is above 16 ppm then consider using removal rate (Table 2). Source: Fertilizer Guidelines for Montana Crops 11
Low amounts of P can be seed-placed to encourage vigorous seedlings that compete well with weeds. Safe rates of seed-placed P depend on the P source, soil, and moisture conditions. While the Saskatchewan Ministry of Agriculture suggest MAP should not exceed 20 lb. P2O5 /acre (Farm Facts: Guidelines for safe rates of fertilizer place with the seed12), others have found up to 26 lb. P2O5 /acre triple superphosphate (TSP) can be seed-placed without toxic effects to seedlings (Karamanos et al., 2003; McKenzie et al., 2001). Seed and seedlings are more likely damaged by MAP than TSP. Diammonium phosphate is much more toxic to seedlings than MAP and requires caution when seed-placed. Safe rates of seed placed P tend to be higher in heavy clay soils, soils with high soil-OM, and with seeding/fertilizer equipment with wide openers which disperse the seed and fertilizer granule in the seed bed. The safe rate is lower in coarser and drier soils.
If soil tests suggest more P is needed than can be safely seed-placed, additional P can be sub-surface side-banded or broadcast and incorporated prior to planting. Pea seed yield was higher when TSP was side-banded one inch below and to the side of the seed rather than seed placed, and the yield response was higher in loam than clay loam soils (Figure 4). Since P can be banked in the soil to reduce risk, consider applying more P with the alternate crop the year prior to the pulse crop.
Figure 4. The increase in pea seed yield is lower when TSP is seed-placed than side-banded (one inch below and one inch to the side of the seed) and varies with soil type (Karamanos et al., 2003).
The addition of P is more likely to increase N-fixation and seed yield when initial soil N and P levels are low. Studies over four years at nine locations in west-central Alberta found 40 lb. P2O5 /acre to be the optimal rate to increase pea yield with an Olsen P soil test less than nine ppm (Figure 4). There was no yield response when Olsen P levels were above nine ppm (Karamanos et al., 2003). Parallel studies found optimal pea seed yields at 26 lb. P2O5/acre on soils with Olsen P levels below 13 ppm and minimal response when Olsen P levels were above 13 ppm (McKenzie et al., 2001).
Potassium and Sulfur: Use soil test results (Table 5) or crop removal rates (Table 2) to determine K2O application rates. Potassium fertilizer is best broadcast and incorporated, or banded at planting. Low amounts of K may be seed placed. Nitrogen plus K2O should not exceed 15 lb./acre when placed with the seed. For example, if 50 lb./acre of 11-52-0 is applied as starter, that provides 5.5 lb. N/acre (50 x 0.11). In this case limit an additional K2O to 9.5 lb./acre (15–5.5 = 9.5) if applied with the seed.
The S need must be based on prior crop performance, S removal rates (Table 2) or plant tissue concentrations (Table 3) because the soil test for sulfate-sulfur (SO4-S) is not a reliable indicator of plant available S. If the prior crop indicates the field may be S deficient, then 15-20 lb. S/acre as sulfate can be applied at planting (Mahler and Murray, 1996). If legume tissue concentrations indicate low S, then use Table 2 to calculate S rate. For example, a 40 bu/acre pea crop removes about 6 lb. S/ acre. This amount can be applied as ammonium sulfate for an in-season rescue treatment. As with P fertilization, soil S levels can be banked by using elemental S, which slowly converts to plant available sulfate. In a central Saskatchewan study, 71 lb. S/acre applied as elemental S during the canola portion of a canola, barley, pea rotation provided sufficient S for optimal pea seed yield three years after the initial application (Wen et al., 2003). In contrast, the fields that received sulfate-based S fertilizer did not have sufficient S for the pea yield by the third year, likely because sulfate was removed by crops or leached prior to the year pea was grown.
Table 5. Potassium fertilizer guidelines for chickpea, lentil and pea in Montana based on soil analysis.
| K Soil Test Level (ppm) | K2O (lb/acre) |
| 0 | 45 |
| 50 | 40 |
| 100 | 35 |
| 150 | 30 |
| 200 | 25 |
| 250 | 20 |
If soil test is above 250 ppm then consider using removal rate (Table 2). Source: Fertilizer Guidelines for Montana Crops11
Micronutrients: The micronutrients Fe, Mn, Zn, Cl, and B have occasionally been found deficient in Montana soils. Because little research has been done on annual legume requirements for micronutrients, suggestions for micronutrient fertilization are presented under the general guidelines at the beginning of this soil fertility section.
Weed Management
Weed management in pulses is of particular importance as these crops are generally considered to be poor competitors due to their slow establishment and limited vegetative growth. Yield losses from competition with weeds can be significant in pulse crops and planning an effective weed management program is a key factor to profitable production.
Growers considering incorporating lentil, dry pea, or chickpea into their rotation should develop an Integrated Weed Management (IWM) plan that considers the entire crop lifecycle from pre-planting to post-harvest. They should also consider the crops utilized prior to seeding pulses as soil residual herbicides can severely damage lentil, dry pea, or chickpea. When developing and implementing an IWM program, producers should take advantage of cultural, physical, and chemical practices to reduce the spread and impact of weeds invading crop fields.
Cultural practices that decrease weed pressure in pulse crops include seedbed preparation, variety selection, proper sowing and crop establishment, insect and disease management, nutrition management, and irrigation scheduling. However, while cultural practices are at the backbone of an IWM plan, they alone may not be enough to secure adequate weed control.
To maximize the effectiveness of any weed management practice and to avoid yield reductions, it is important to target the proper crop growth stage. For example, research conducted at the University of Saskatchewan, Canada, showed that weed control in lentil should start by the five- to six-node stage, and lentil fields should continue weed-free until the 10- to 11-node stage (Fedoruk et al., 2011). While the environmental conditions under which this study took place differ from the ones we regularly experience in Montana, these results illustrate the importance of appropriate timing when developing an IWM program.
Mechanical weed control practices, such as harrowing or rotary hoeing, represent a viable alternative for organic producers, farmers interested in reducing herbicide use, or those facing problems with herbicide resistant weeds. Producers should be aware that mechanical weed control practices need to be applied with caution due to the sensitivity of pulse crops shoots and roots to damage. As a general rule, if harrowing or hoeing is planned, it is recommended to increase seeding rates as mechanical damage may reduce stands. Also, producers should minimize the reliance on tillage due to the increased risk of soil erosion.
Crop rotation is one of the most powerful tools to manage pest problems, including weeds. It is very important to carefully consider the crop rotation history prior to growing pulse crops as they are very sensitive to many of the herbicides commonly used in small-grain production. For example, the high persistence sulfonlylurea (SU) herbicides frequently used in small grain crops such as Ally (metsulfuron), Glean (chlorsulfuron), and Finesse (chlorsulfuron), among others, have often damaged subsequent annual legumes. Producers should be aware that due to the high persistence of these products, it might be necessary to wait up to four years before seeding some pulses, depending on crop, product, and application rate. Moreover, weather conditions and soil properties including pH, moisture, temperature, texture, and soil-OM play a fundamental role in determining herbicide persistence in the soil profile and potential crop injury. In many cases a field bioassay should be conducted prior to seeding a pulse crop to check for existence of residual herbicides. Producers should be aware that bioassays do not forecast sub-lethal yield loss, which is likely the most common type of yield loss experienced and unless bioassays are conducted in field conditions and plants are grown to maturity, results of bioassays could be misleading. Producers interested in learning more about crop rotation restrictions for several herbicides commonly used in small grain crops in Montana should consult Integrated Weed Management in Lentils13.
To minimize the risk of crop damage due to soil residual herbicides, producers should keep records of the products and rates used in their fields. Producers should also be aware that rotational intervals may vary with herbicide rates and environmental conditions. More information on approaches to reduce the risk of crop injury due to herbicides can be found in Getting the Most from Soil-Applied Herbicides14.
Chemical weed control can help pulse crop producers manage weeds. However, research and experience has shown that herbicides are most effective when used as part of an IWM program. For example, the applicability and success of herbicides in lentil fields depends on the cropping system, land preparation methods, soil conditions, and weather conditions. Research has shown that if plants are stressed due to environmental or biological conditions, Sencor (metribuzin) applied at recommended rates can provide effective weed control in lentil, but can cause crop damage in stressful conditions such as cold weather, low fertility, disease, or insect pressure. Although Pursuit (imazethapyr) can be used to manage broadleaf weeds in lentil, cold and wet conditions occurring within a week of application can damage the crop.
While information on commonly used herbicides used to manage weeds in pulse crops is provided below, producers should carefully read and follow product labels prior to using any herbicide. Also, while tank- mix combinations of herbicides can be used to control a broader spectrum of weeds, producers should refer to product labels of the tank-mix partners for specific restrictions. Common chemical and trade names are used in this publication for clarity. Inclusion of a common chemical or trade name does not imply endorsement of that particular product or brand of herbicide, and exclusion does not imply non-approval.
Recommendations by Crop
Lentil: Weed management in lentil is essential because they do not compete well and are highly sensitive to soil-residual herbicides, particularly those from the SU-herbicide family.
Dimethenamid-p (Outlook and other trade names). 0.56 to 0.98 lb. ai/acre (10-21 fl. oz/acre). Apply pre-plant surface or pre-emergence (PRE) to lentil. Good to excellent control of several annual grasses. Fair to good control of certain annual broadleaf weeds such as pigweed, waterhemp, or black nightshade. Adjust rate for soil type and OM. Consult your seed dealer for restrictions on specific varieties to avoid potential injury due to sensitivity. Emerged weeds are not controlled. May occasionally result in temporary spotting or browning of crop leaves. Lentil may be harvested 70 days after application. Refer to label for tank-mix options.
Ethalfluralin (Sonalan). 0.55 to 0.75 lb. ai/acre (1.5-2 pt/acre). Should be fall-applied prior to snow cover into stubble. Incorporate once using minimum soil disturbance with a rotary hoe or harrow. Refer to label for use directions and rotational crop restrictions.
Imazamox (Beyond). 0.031 to 0.048 lb. ae/acre (4-6 fl. oz/acre Beyond SG). Apply post-emergence (POST) only to Clearfield lentil varieties (2- to 6-leaf stage of lentil) to control small, actively growing annual grass and broadleaf weeds including jointed goatgrass, downy brome, Persian darnel, and Japanese brome. Non-Clearfield varieties will be seriously injured