Funded by Results Driven Agriculture Research (RDAR)
Introduction
Cocktail crop mixtures (i.e., three or more crop species) are integral components for the feeding regimes of cattle producers as they provide high-quality forage feed to livestock. Apart from this, cocktails with the right proportions and combinations of species can impact soil health. Although many commercial cocktails exist on the market, producers also combine various species to create their own cocktails. However, the question of comparative advantages between the commercial and the producer cocktails over the usual mono-crops needs to be explored. So, in this study, we examined forage productivity, feed quality and water-use efficiency of cover crop cocktails.
Method
This study was carried out at the Fairview Research Farm (NW-5-82-3-W6M) on RR35, MD of Fairview. The field was previously seeded to canola in 2021.
The study used a randomized complete block design with four replications. A total of 13 treatments were used comprising 6 multispecies cocktail samples from local producers in the Peace region, 4 common commercial cocktails, 2 cereal mono-crops as control and a warm-season dominated local cocktail mix. The breakdown of treatments is as follows:
The site was seeded on 27 May 2022 using a Fabro plot drill with disc-type openers on 9″ row spacing at a depth 1″ depth with a soil temperature of 9.6 degrees Celsius. Six rows of 8-metre-long were sown per plot. Bi-weekly volumetric water content measurement was undertaken to assess the moisture availability within the soil during the growing season and to aid in water-use efficiency estimates. The water-use efficiency refers to how adequate plants use water for biomass production. This was determined by dividing the total biomass of forage by the total amount of precipitation during the growing season. The cocktail was subsequently harvested on August 23, 2022 and analyzed for forage productivity and quality.
Results
Forage dry matter yield and quality indicators
The average forage yield for all treatments was 4,852 lb/ac. The CDC Haymaker oats had the highest forage yield of 6,055 lb/ac while commercial cocktail 4 recorded the lowest of 3,374 lb/ac (Table 11). Forage yield for producer cocktails varied between 5,329 lb/ac for producer mix 2 to 3,926 lb/ac for producer cocktail 3. In commercial cocktails, a significantly higher yield of 5,685 lb/ac was noted in commercial cocktail 3, while commercial cocktail 4 had the lowest of 3,374 lb/ac (Table 11). Generally, except for commercial cocktails 2 and 4, all commercial cocktails were better compared to producer cocktails and the CDC Maverick barley. The results for 2022 demonstrated a substantial increase in forage yield compared to the previous year (2021, see PCBFA 2021 Research Report) when the same treatments were investigated.
Crude protein (CP): CP content was highest in commercial cocktail 4 (22.2%), followed by local cocktail mix dominated by warm-season crops (15.8%). The lowest CP was recorded in CDC Haymaker oat (12.1%), producer cocktail 4 (12.2%), producer cocktail 1 (12.4%), and CDC Maverick barley CT (12.6%). Overall, producer cocktail 3 (14.6%), producer cocktail 5 (14.3%), and commercial cocktail 4 (22.2%) were above the average CP content of 14% (Table 11). Generally, the producer cocktails were superior in CP to commercial cocktails and mono-crops. However, all treatments herein had adequate CP contents to meet the requirements of all classes of mature beef cattle (7, 9 and 11% CP) and growing calves (12-14% CP).
Total digestible nutrients (TDN): Energy levels within cocktails ranged between 46% for commercial cocktail 4 to 64.7% for CDC Maverick barley. Except for producer cocktail 1 (48.3%), all producer cocktails were above 60% of TDN (Table 11). On the other hand, commercial cocktails were generally low in TDN (between 46.3 to 48.3%). Only producer cocktails contained adequate energy for dry gestation cows. Overall, TDN in 2022 decreased substantially compared to 2021 when the same treatments were investigated.
Neutral detergent fibre (NDF) and acid detergent fibre (ADF): NDF was significantly different among treatments ranging from 47.3% for producer cocktail 5 to 53.9% for commercial cocktail 4. Commercial cocktails 4 (47.3%) and 5 (47.7%) had better NDF, an indication of better uptake and consumption by cattle. Conversely, ADF was low for all treatments ranging from 30% for producer cocktail 5 to 43% for commercial cocktail 5. Here, producer cocktails 3 (30.8%), 4 (30.5%), and 5 (30%) were the best performers (Table 11). This indicates a better digestibility over the other treatments.
Water-use efficiency (WUE)
The ability of treatments to use water efficiently varied significantly. The CDC Haymaker oat was the highest (3,167 lb/inch of water), while commercial cocktail 4 had the lowest (1,891 lb/inch of water). This is reflected in the observed biomass production during the year (2022). Overall, the average WUE was 2,645 lb/inch (Table 12). Except for commercial cocktail mix 2 (2,246 lb/inch) and 4 (3,215 lb/inch), and CDC Maverick barley monocrop (2,478 lb/inches), the other commercial treatments were above the average WUE. Conversely, with the exception of producer cocktail 2 (2,961 lb/inch) and 6 (2,726 lb/inch), WUE for all producer cocktails was below the mean WUE. Overall, highly multispecies cocktails were better in WUE compared to fewer species cocktails (Table 12).
Soil infiltration rate and normalized difference vegetative index (NDVI)
The soil coverage and greenness (NDVI) of individual treatments were significant during the growing season. The results showed values between 0.69 and 0.76 for all treatments indicating a good growth of plant species. Except for commercial cocktail 5 (0.69), all treatments had values above 0.70 (Table 12). Soil infiltration rate also ranged between 8.4 inches/min for CDC Maverick barley to 63 inches/min for producer cocktail 1. Evidently, producer cocktail 1 had the highest infiltration rate followed by commercial cocktail 1. Generally, soil infiltration rates for producer cocktails were better than commercial cocktails and mono-crops. This indicated that producer cocktails in part improved the soil better than other treatments.
Conclusion
This study showed that the highest dry matter yields were in CDC Haymaker oats, commercial cocktail 1 and commercial cocktail 3. Generally, commercial cocktails yielded higher than producer cocktails and CDC Maverick barley monocrop. Overall, all treatments would provide adequate crude protein for all classes of beef cattle. Only producer cocktails had the right energy levels for dry gestation cows. Forage intake and digestibility would be better in commercial cocktails 4 and 5 and producer cocktails 3, 4, and 5. The CDC Haymaker oat and commercial cocktail 4 used water more efficiently to produce biomass. In addition, sufficient water infiltration rate improvements were noted under producer cocktails.
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