Published March 2022
Background
A plant health issue has been impacting Saskatchewan chickpea production in recent seasons. Initial reports of this chickpea health issue date back to the 2019 growing season and so far its cause remains unknown. More information on the chickpea health issue including symptomology and evaluations during the previous growing seasons can be found in the Saskatchewan Pulse Growers’ 2020 and 2021 chickpea health reports. A wide range of possible contributing factors including disease, root rots, nutrition, soil and plant microbiomes, nematodes, crop management factors, and environmental conditions, have and continue to be investigated.
Based on 2019 and 2020 field season experience, environmental conditions—specifically rainfall patterns—appeared to be one of the most consistent factors of the chickpea health issue. In an attempt to understand the potential influence of environmental and soil moisture conditions on the chickpea health issue, SPG teamed up with Crop Intelligence for a collaborative field monitoring project.
Key Findings
- The symptoms of the emerging chickpea health issue were observed during a season that was generally hotter and drier than average.
- There is still a lot to be learned about chickpea water usage, root development, yield potential and the environmental impact on the initiation and progression of the chickpea health issue.
- Chickpea rooting depth varied between 30 and 70 cm.
- Management Factors for chickpea varied between 2 and 5 bushels per inch of Crop Available Water.
- Chickpea grown at the highest yielding site rooted the deepest, received the most in-season precipitation, and the fewest days and hours of heat above 28°C; the inverse conditions occurred at the lowest-yielding site.
Materials and Methods
Site Descriptions
Five chickpea fields, distributed throughout the region with previously reported chickpea health issues were selected as season-long monitoring sites during the 2021 growing season. Fields were located near Gravelbourg, Mossbank, Assiniboia, Coronach and Ogema, SK. Kabuli chickpeas (CDC Leader) were seeded at all five sites and, with the exception of the Coronach site that was seeded on 2020 lentil stubble, all sites were established on 2020 cereal stubble.
Baseline soil properties and nutrient levels were determined through soil sample collection at benchmark locations corresponding to the weather station installation spots. These benchmark soil samples were collected at 0–6, 6–12, and 12–24 inch depths and analyzed by A&L Canada Laboratories.
Table 1. Summary of baseline soil properties and nutrient levels chickpea monitoring sites.
| Site | Soil Texture | Sampling Depth (inches) | Soil Properties | Macro & Secondary Nutrients (ppm) | ||||||||
| SOM (%) | pH | CEC (meq/100g) | N | P | K | S | Mg | Ca | Na | |||
| Gravelbourg | Clay loam | 6 | 3.2 | 7.0 | 22.2 | 11 | 12 | 518 | 16 | 715 | 2390 | 33 |
| 12 | 2.4 | 7.8 | 32.0 | 12 | 5 | 301 | 25 | 877 | 4740 | 66 | ||
| 24 | 2.0 | 8.3 | 39.8 | 4 | N/A | 234 | 288 | 1174 | 5690 | 260 | ||
| Mossbank | Loamy sand | 6 | 2.0 | 6.3 | 8.7 | 27 | 14 | 144 | 11 | 185 | 1120 | 10 |
| 12 | 1.2 | 6.8 | 8.9 | 12 | 5 | 101 | 8 | 216 | 1130 | 11 | ||
| 24 | 1.0 | 7.5 | 8.4 | 5 | N/A | 89 | 8 | 232 | 1250 | 13 | ||
| Assiniboia | Clay loam | 6 | 2.9 | 7.2 | 28.1 | 6 | 19 | 356 | 8 | 722 | 3970 | 25 |
| 12 | 1.7 | 7.7 | 30.6 | 3 | 5 | 242 | 8 | 1143 | 4080 | 48 | ||
| 24 | 2 | 8.1 | 32.9 | 2 | N/A | 302 | 8 | 1398 | 4050 | 79 | ||
| Coronach | Loam | 6 | 2.6 | 7.5 | 25.9 | 5 | 10 | 233 | 9 | 618 | 4040 | 15 |
| 12 | 2.2 | 7.9 | 28.6 | 4 | 3 | 154 | 7 | 563 | 4700 | 14 | ||
| 24 | 2.0 | 8.3 | 44.3 | 3 | N/A | 169 | 7 | 943 | 7200 | 15 | ||
| Ogema | Clay loam | 6 | 2.9 | 6.5 | 17.2 | 6 | 19 | 400 | 11 | 470 | 2200 | 18 |
| 12 | 2.1 | 7.1 | 27.4 | 4 | 5 | 280 | 9 | 280 | 3530 | 33 | ||
| 24 | 1.8 | 7.6 | 28.4 | 5 | N/A | 224 | 12 | 224 | 4070 | 66 | ||
Weather Station Installment
Precise locations for the weather station installment were selected based on grower recommendations for representative areas within the field and through the use of normalized difference vegetation index (NDVI) imagery. Above and below ground monitoring equipment were installed at the designated sites by a Crop Intelligence technician after the fields were seeded. The date of installation marked the beginning of data collection at these sites with moisture data being updated every 15 minutes. All Crop Intelligence equipment installations target a maximum window of 14 days after seeded to avoid excessive trampling of seedlings around the soil probes which can negatively impact plant development, rooting, and ultimately, soil moisture data.
Source: Saskatchewan Pulse Growers
Due to a large rain event from May 20–24, 2021 that delayed installation, the Ogema site was the only site where the 14 day installation goal was not met. Fortunately, the co-operating grower had an additional Crop Intelligence station in an adjacent field that was installed on April 23, 2021. The above ground data (rainfall and temperature) during May for the chickpea site was extrapolated from this adjacent station.
Table 2. Summary of dates of seeding, equipment installation, & harvest.
| Site | Seeding Date | Installation Date | Days Between Seeding & Install | Harvest Date | Days Between Seeding & Harvest |
|---|---|---|---|---|---|
| Gravelbourg | 11-May | 20-May | 9 | 15-Aug | 96 |
| Mossbank | 07-May | 20-May | 13 | 14-Aug | 98 |
| Assiniboia | 11-May | 19-May | 7 | 07-Sep | 119 |
| Coronach | 07-May | 19-May | 12 | 02-Sep | 118 |
| Ogema | 15-May | 31-May | 16 | 20-Aug | 97 |
2021 Environmental Conditions
Source: Crop Intelligence
All field sites, except Gravelbourg, received above average precipitation during the month of May. Precipitation levels continued to diminish throughout June at all locations, with only the Ogema site receiving rainfall amounts higher than the region’s thirty-year historical mean. By July, the sites had received only 13–71% of the long- term average precipitation but moisture levels increased well above historical means at all locations in August. In-season temperatures were also substantially warm, particularly during July where 17–27 days during the month and 106–206 total hours reached temperatures greater than 28°C.
Table 3. Summary of temperature and precipitation data collected via Crop Intelligence weather stations at five chickpea monitoring sites during the 2021 growing season.
| Month | Environmental Conditions | Chickpea Monitoring Site | ||||
| Gravelbourg | Mossbank | Assiniboia | Coronach | Ogema | ||
| May | Temperature above 28°C (days) | 0 | 0 | 0 | 0 | 2 |
| Temperature above 28°C (hours) | 0 | 0 | 0 | 0 | 5 | |
| Total Precipitation (mm) | 17 | 27 | 39 | 31 | 73 | |
| June | Temperature above 28°C (days) | 11 | 10 | 9 | 9 | 9 |
| Temperature above 28°C (hours) | 71 | 71 | 64 | 92 | 70 | |
| Total Precipitation (mm) | 41 | 75 | 56 | 73 | 86 | |
| July | Temperature above 28°C (days) | 27 | 25 | 22 | 22 | 17 |
| Temperature above 28°C (hours) | 206 | 170 | 112 | 158 | 106 | |
| Total Precipitation (mm) | 7 | 18 | 37 | 12 | 18 | |
| August | Temperature above 28°C (days) | 11 | 13 | 13 | 14 | 12 |
| Temperature above 28°C (hours) | 93 | 86 | 68 | 97 | 65 | |
| Total Precipitation (mm) | 55 | 66 | 101 | 62 | 98 | |
| Total Season | Temperature above 28°C (days) | 49 | 48 | 44 | 45 | 40 |
| Temperature above 28°C (hours) | 370 | 327 | 244 | 347 | 246 | |
| Total Precipitation (mm) | 120 | 186 | 233 | 178 | 275 | |
Root Growth & Water Usage
Crop Available Water (CAW) at the beginning of season varied by site locations. Although yield is not determined by precipitation and soil moisture alone, crop access to water is an undeniably important contributor of yield in any crop. Measuring CAW is crucial to understanding the Water Driven Yield Potential (WDYP) should the crop access all moisture in the profile and receive average rainfall throughout the season. The WDYP is not a static value across all crops, seasons, or farms. These differences are captured through individual Management Factors (MF) which estimate how many bushels can be grown for every inch of available water. These values can vary across farms and seasons but it is typically assumed that lentil has a MF of four and field pea has a MF of six.
Local data on chickpea was limited so the Crop Intelligence team assumed the MF at all sites to be equivalent to lentil estimates (four). As is typical for all Crop Intelligence sites, these MFs were evaluated at the end of the season to ensure accurate baselines were maintained. Generally, most sites aligned with initial MF expectations; however, the most extreme yields at Ogema and Gravelbourg fell outside of the expected baseline with Ogema achieving a MF of five and Gravelbourg only achieving a MF of two. Chickpea grown at the Ogema site yielded an average of five bushels per acre (bu ac-1) for every inch of CAW while the Gravelbourg site only produced 2 bu ac-1 of chickpeas, indicating that Ogema site was more efficient at turning CAW into yield compared to Gravelbourg.
Table 4. Summary of Crop Available Water at beginning of month and amount removed by end of month.
| Month1 | Crop Available Water (CAW) | Chickpea Monitoring Site | ||||
| Gravelbourg | Mossbank2 | Assiniboia | Coronach | Ogema3 | ||
| May | Starting CAW (mm) | 186 | 55 | 143 | 138 | N/A |
| CAW removed (mm) | 5 | 9 | 6 | 3 | N/A | |
| June | Starting CAW (mm) | 186 | 142 | 143 | 139 | 151 |
| CAW removed (mm) | 38 | 25 | 39 | 34 | 60 | |
| July | Starting CAW (mm) | 155 | 112 | 114 | 128 | 97 |
| CAW removed (mm) | 37 | 50 | 42 | 39 | 71 | |
| August | Starting CAW (mm) | 128 | 43 | 72 | 76 | 25 |
| CAW removed (mm) | 10 | 7 | 5 | 5 | 12 | |
1Starting at date of installation in May.
2Mossbank site required a re-installation on June 15 due to insufficient seal around the probe; soil moisture data during May and first part of June not accurate.
3Installation of below-ground monitoring equipment did not occur at Ogema until May 31.
Total amount of water extracted and residual levels of soil moisture appeared to be correlated to rooting depth and yield. Rooting activity to a depth of 50 cm was achieved at all locations except Gravelbourg which only reached its maximum depth of 30 cm by the end of June. Ogema and Mossbank sites surpassed the average rooting depth (54 cm) and had measurable root activity at 70 cm depths by the end of July.
Source: Crop Intelligence
Data from these monitoring sites are insufficient to make conclusions regarding rate of root growth or the extent environmental conditions and soil properties influence root activity. However, data from these five sites do suggest that soil and environment are contributing factors of root development in chickpea. Despite the Gravelbourg location starting out with the highest amount of CAW, chickpea root development was the shallowest at this site. Possible explanations include receiving the lowest amounts of rainfall and longest duration of heat relative to all five sites or elevated levels of dissolved sodium (Na) salts at depth as indicated through baseline soil testing.
Environmental factors may not explain all differences in root development. For instance, chickpea roots at the Mossbank site reached equivalent depths as the Ogema location (70 cm) despite exposure to more heat and less moisture. Similarly, chickpea at Mossbank surpassed the rooting depth of those grown at the Assinibioa location which also received more in-season precipitation and less extreme heat. Differences in soil texture may partially explain the deeper or equivalent rooting activity at Mossbank relative to Assinibioa or Ogema; the Mossbank site was characterized by loamy sand soil textures whereas as the dominate soil textures at the Assinibioa and Ogema locations was clay loam.
Yield
Average chickpea yield across all five sites was 25 bu ac-1 but ranged from 13–35 bu ac-1 with the highest yield measured at the Ogema location and the lowest at the Gravelbourg location. Expectedly, heat and rainfall appeared to have a direct impact on chickpea yield at these sites during the 2021 growing season. Rainfall measured during May–July had a strong positive correlation to yield and the number of days and hours with temperatures above 28°C were both strongly negatively correlated to yield. Comparisons of the environmental conditions between the two highest and lowest yielding sites revealed that chickpea grown at the Ogema site received 112 mm of additional rainfall relative to Gravelbourg and that chickpea grown at Gravelbourg experienced over 100 additional hours and 12 extra days of temperatures above 28°C, primarily during the month of July.
Table 5. Summary of chickpea yield (bu ac-1) and in-season temperature and precipitation.
| Site | Temperature above 28°C | Total In-Season Precipitation1 (mm) | Yield (bu ac-1) | |
| (days) | (hours) | |||
| Gravelbourg | 38 | 277 | 65 | 13 |
| Mossbank | 35 | 241 | 120 | 26 |
| Assiniboia | 31 | 176 | 132 | 29 |
| Coronach | 31 | 250 | 115 | 22 |
| Ogema | 26 | 176 | 177 | 35 |
1(May-July).
Source: Crop Intelligence
Source: Crop Intelligence
Conclusions
The Chickpea Project provided important baseline data for chickpea root growth, water use, and yield responses to environmental conditions during the 2021 growing season. Furthermore, data collected during this study may provide a useful comparison for chickpea development and yield factors during a more typical season when higher amounts of rainfall are received and in-season temperatures are more moderate. Chickpea is generally assumed to be one of the deepest rooting pulse crops and data from this field investigation reinforced that chickpea roots can reach depths of nearly one meter (70 cm); however, deep rooting activity is not a guarantee. These data indicate that chickpea may root as shallow as 30 cm and, therefore, the amount of soil residual moisture following a chickpea crop can be variable with favourable amounts of subsoil moisture remaining for subsequent crops in some situations.
Information from The Chickpea Project indicates relationships between rooting depth, precipitation, temperature, and yield, but a single season does not provide sufficient data to make strong conclusions about these relationships. It is clear that there is much more to learn about how chickpea responds to environmental and soil conditions, and how those conditions influence not only the chickpea health issue but also general chickpea agronomy decisions. For these reasons, Saskatchewan Pulse Growers and Crop Intelligence are very excited to extend this study for a second year during the 2022 season and collaborate on The Chickpea Project 2.0.
Acknowledgements
Saskatchewan Pulse Growers and Crop Intelligence gratefully acknowledge the growers who participated in this study (Craig Eger, Codie Nagy, Dustin DeWulf, Quenton Quark, and Scott Hepworth). Appreciation is also extended to industry agronomists Angie Berner (Richard Pioneer) and Carolyn Wilson (Syngenta) along with SPG summer student, Skylee Woodley, for agronomy support and assisting with in-season monitoring at these field sites.
