Agronomics of Pulse Production - New Issues

Adrian Johnston, Melfort Research Farm, Melfort, SK

Stuart Brandt, Scott Experimental Farm, Scott, SK

George Clayton, Lacombe Research Centre, Lacombe, AB

Randy Kutcher, Melfort Research Farm, Melfort, SK

Guy Lafond, Indian Head Experimental Farm, Indian Head, SK

Brian McConkey, Semi-Arid Prairie Agriculture Research Centre, Swift Current, SK

Perry Miller, Montana State University, Bozeman, MT

Introduction

Grain legumes, or pulse crops, have become an important component of cropping systems in all parts of the Canadian prairies. While field peas and lentils are the dominant pulse species, dry beans and chickpeas are experiencing a rapid acreage expansion. The ability of pulse crops to fix most of their own N, their N benefit to subsequent crops in rotation, and the marketing opportunities they provide to producers, ensure their place in sustainable cropping systems in western Canada.

The objective of this paper is to provide a summary of the many pulse agronomy projects ongoing across the prairie provinces, and a summary to date on the findings of these research activities. Many of the projects that will be referred to are on-going, so conclusions may not be finalized. I wish to thank the support of my fellow agronomists in the preparation of this paper - it is truly a joint effort.

Field Pea Inoculation

Achieving proper inoculation of a pulse crop requires the application of viable rhizobium bacteria, their survival until root formation, and their survival under the drying soil conditions. While the amount of N fixed by a field pea crop varies with environmental conditions, a farmer should not have to provide any additional N to a well inoculated pea field. The big issue in pea inoculation in the last few years has been the release of granular formulations of inoculant. The main product has been a granule of peat based inoculant, however, clay based forms are close to being commercially available. Research trials conducted across the prairie provinces has shown that where inoculant responses were obtained, the granular product provided grain yields that were equal, or superior, to powdered peat and liquid formulations. On acid (low pH) soils in the Peace River region, and under dry soil conditions in the Brown and Dark Brown soil zones, the benefit of the granular inoculant was superior (Table 1). These results indicate that the granular product provides more viable rhizobia to the pea under stress conditions. Evaluation of nodule formation also indicates that the nodules tend to form on the lateral roots with the granular product, unlike the accumulation of nodules around the crown of the plant characteristic of peat powder and liquid formulations. These nodules on lateral roots are fixing N later in the season, resulting in higher pea grain protein.

Table 1. Grain yield response of field pea to inoculant formulation at various locations in western Canada (all trials grown on fields with no history of field pea production).

Some advantages of the granular inoculants include the ability to meter the product into the seed row at seeding and it avoids application directly to the seed. Disadvantages are the need to invest in a third tank on the air seeder, and cost of using the recommended rates of 5 lb/ac. However, there is growing evidence to indicate that application rates can be reduced, and there is little doubt that inoculation on fields with a history of field pea production will be achieved with less than recommended rates.

Field Pea Seed Fungicides

At the seven Agri-Food Innovation Fund (AFIF) Spoke Research sites in Saskatchewan, a study was conducted in 1997 to determine interactions between seed applied fungicide and inoculant formulation in Carneval peas under zero-tillage. Fungicide treatments were a control, Apron (metalaxyl), and Apron plus Thiram. Inoculant treatments consisted of an uninoculated control, a liquid and a granular formulation. These two inoculant formulations provided a seed applied and soil applied comparison.

The principle benefit of seed treatment is the reduction of seedling disease, resulting in improved

emergence. The results from this study indicate little effect of seed treatment on crop emergence or grain yield (Table 2). At the Canora location the Apron + Thiram treatment increased plant stand over the check and Apron alone, while at Swift Current the opposite was true. Melfort was also the only location where a fungicide response was recorded on grain yield, with the Apron alone treatment being lower yielding than the untreated check. While inoculation had no effect on plant stand, granular inoculant improved grain yield over the liquid and uninoculated check at Indian Head and Swift Current (Table 2). A similar positive grain yield response to granular inoculant was also recorded at Redvers and Scott.

Table 2. Effect of fungicide and inoculant on emergence, nodule score and grain yield of Carneval peas under zero-tillage. Means of 12 observations (4 replicates and 3 treatments).

The results from the first year of this study indicate little benefit to seed treatment in crop establishment or grain yield of field pea. The benefit of using the granular inoculant at inoculant responsive test locations proved to be an economically viable option.

Fall/Dormant Seeded Pulse Crops

Work conducted with fall, or dormant, seeding of cereals, oilseeds and pulse crops at Scott Experimental Farm has shown that peas and lentils are not well suited to this practice. Ken Kirkland and Eric Johnson of Scott report that in the 3 years evaluating dormant seeded pulse crops, they had no emergence in two years, and a few plants emerge in the third year with the addition of seed applied fungicides. It would appear that dormant seeded pulse crops are a little way down the road.

Grain Legumes in Semi-Arid Regions

The adaptation of field pea to semi-arid regions has been evaluated over the past 5 years by Perry Miller and Brian McConkey at Swift Current and Stuart Brandt at Scott, Saskatchewan. Their results indicate that early seeded field pea has a high yield potential under water stress conditions, making the crop well adapted to the region. When ample water is available, pea uses less water

than other crops with exception of lentil (Table 3). When water is limiting, pea grain yields are higher than other crops, including spring wheat (Figure 1). Root measurements have confirmed the pea has less roots below 90 cm depth than spring wheat or canola.

Table 3.Yield, water use, and water-use-efficiency (WUE) by 5 crops from three soil depths when grown on fully recharged fallow at Swift Current and Stewart Valley, 1996-97.

Values within a column followed by the same letter are not different (P=0.05).

As has been recorded in other areas of the prairies, spring wheat has higher yields and protein on pulse stubble than non-pulse stubbles and, among the pulse stubbles, often does best on pea stubble (Tables 4).

Table 4. Yield and protein (basis 13.5% grain moisture) values for uniformly managed CWRS wheat on 7 crop stubbles from 1993 to 1997 at Swift Current and Scott, SK.

• Values within a column followed by the same letter are not different (P=0.05).

Chickpea have become a popular and profitable grain legume on many farms in the semiarid prairie. As a new crop there are several issues surrounding the future success of the crop. There are concerns that we may not be able to sell all the chickpeas, at an attractive price, that we are capable of growing. There are some problems with the establishment of kabuli chickpeas, such as the effect of seed size, seeding rate, and seed zone soil temperatures on grain yield and seed size of resulting crop. Current research at Swift Current is focused on these agronomic management factors. There are few herbicides options for broadleaf control, none for in-crop control. Fortunately, anecdotal evidence indicates that chickpea yields are less sensitive to weed pressure than lentil. And finally, the risk of yield loss due to ascochyta is high and questions about the break down of current genetic resistance under conditions of abundant inoculum and favourable weather conditions is unknown.

Fertilizer Management of Field Peas

The ability to achieve high field pea yields is contingent on an adequate supply of plant available nutrients. While research across the prairies has clearly shown that properly inoculated peas can fix all of the N supply required, there has been some concern about the other macro-nutrients, in particular phosphorus and sulphur. Extensive research conducted by Westco Fertilizers and Alberta Agriculture Agronomy Unit showed that peas were sensitive to high rates (>27 lb P₂O₅/ac) of seedrow applied phosphate fertilizer, however, the actual reduction in plant stand was minimal (Table 6). If the phosphate fertilizer was side banded, plant establishment was unaffected. The same study reported that sideband application provided a very minor grain yield advantage over seedrow placement of phosphate fertilizer. When N was seedrow applied, at rates up to 45 lb/ac, seedling stands were reduced as much as 55%, with subsequent grain yield reductions of 22%. At the Melfort AFIF Spoke research site a fertilizer blend (13-20-10-10) was placed either in the seed row, side banded or spread under a sweep with the peas. The reduction in seedling stand with seed row placement was reflected in lower grain yield in 1997, however, not in 1998 (Table 7). Fertilizer placement with the seed using a 9" spread under a sweep proved to be as good as or better than side band application. However, in both studies little grain yield response was obtained from fertilizer addition, leading us to question the level of grain yield response we can expect from peas under nutrient deficient conditions.

Table 6. Plant emergence and grain yield response of field pea to fertilizer P rate and placement.

Westco Unpubl. Data

Table 7. Plant emergence and grain yield of Carneval pea to fertilizer placement, Melfort 1997-98.

(Johnston, unpubl. Data)

Adaptation of Pulse Crops

The pulse crops currently being grown on the Canadian prairies range in their adaptation, based principally on tolerance to moisture stress. Drought tolerant species like lentil and chickpea are generally recommended for semi-arid regions, while peas, beans and faba beans are usually grown in the sub-humid Parkland or under irrigation. Recent work with peas at Swift Current indicates that they are well adapted to semi-arid regions when seeded early. To assess the production potential of a number of pulse species, a study was designed to evaluate the regional adaptation of five pulse species (faba bean, pea, lentil, dry bean and chickpea) across the agroecological zones of Saskatchewan (Swift Current, Scott, Indian Head, Redvers, Canora, Melfort and Outlook - irrigation). Each of the trial locations grew the same variety of each species, allowing a comparison across regions. The varieties included Carneval and Grande field pea, Aladin faba bean, Laird lentil, Othello dry bean, and Sanford chickpea. While chickpea was found to be well adapted to semi-arid regions, field peas were the best adapted, and highest yielding, pulse species considered at all trial locations (Table 8). While not as high yielding, lentil was also well adapted to all regions in this drier than normal growing season (1997). Lentil was not grown under irrigation at Outlook, reflecting past experience with high yield losses due to disease of lentil under high water conditions. Dry beans were found to have little or no tolerance to moisture stress as was shown by the low yields at experienced under mid-season drought at Scott and Indian Head. It appears that dryland beans will be suited best to the wet Parkland region and under irrigation.

The early results of this five year pulse adaptation study indicate that the broad adaptation of field pea demands that it continue to receive high priority in crop management research initiatives. It is likely field pea, which will be the introduction for most new pulse growers.

Table 8. Crop establishment (plants/m²) and grain yield (kg/ha) for five pulse species grown at various locations in Saskatchewan.

† Numbers within rows followed by the same letter are not significantly different using LSD_0.05.

Figure 1. Grain yield responses of field crops to variation in seasonal water use. The data is from field trials conducted at Swift Current between 1996-1998.