Longevity and Ecosystem Services of Perennial Forage Mixtures 4 to 5 Years Following Establishment

Funded by Results Driven Agriculture Research (RDAR) and Rangeland Sustainability Program (Government of Alberta)

Livestock producers rely heavily on mixed perennial forages, typically grass-legume blends, to meet the bulk of their feed requirements. Evaluating new and emerging forage varieties is therefore essential to ensure producers can select options that optimize production and feed efficiency. This project evaluates the long-term performance of perennial forage stands, both as mixtures and monocultures, across two locations in the Peace Region: Fairview and DeBolt. This report provides the results of dry matter yield, forage nutritive value, and water-use efficiency during the 2025 field season.

Objectives

• Determine the dry matter yield and nutritive value of perennial forage mixtures, monoculture grasses, and legumes over multiple years

• Evaluate the effects of legumes (in both pure stands and mixtures) on water-use efficiency.

• Assess weed suppression, stand persistence, and the rate of stand decline as forage mixtures age.

Figure 1. A glance at the mixture plots at DeBolt site

Figure 2. Forage harvest at the Fairview site

Methods

We continue to monitor perennial forage stands, which were established in 2020 at the Fairview Research Farm (Range Rd. 35) and in 2021 on a producer field at DeBolt  (Township Rd. 740). The field trials were established using a randomized complete block design with four replications in small plots measuring 8 m x 2 m. Seeding was carried out using a 6-row Fabro plot drill equipped with disc-type openers on 23 cm row spacing, complete with side banding.

In Field Observations

At the Fairview Research Farm site, forage stands received sporadic precipitation from early May until early June (1.4 inches). After this, the site experienced drought conditions until harvest (2.3 inches). Monoculture grasses or their sole mixtures were severely affected by the dry weather compared to legumes and grasses in mixtures with legumes. Similarly, although the DeBolt site received ~1 inch more precipitation than Fairview, conditions remained relatively dry. The overarching conditions at both sites affected the performance of plants.

Results

Forage Dry Matter (DM) yield at Fairview and DeBolt sites

Fairview site: The DM yield varied noticeably between the different legume varieties. Among the 27 legume varieties tested, the top five yielding were alfalfa varieties, whereas those at the bottom were AAC Mountainview sainfoin, Bull birdsfoot trefoil, and AAC Glenview sainfoin (Table 2). The DM yield for the top five varied from 3,694 lbs/ac for Rambler alfalfa to 5,742 lbs/ac for AAC Trueman alfalfa. The lowest yielding legumes were in the order of AAC Mountainview sainfoin (896 lbs/ac) > Bull birdsfoot trefoil (885 lbs/ac) > AAC Glenview sainfoin (457 lbs/ac).

The monoculture grass varieties also varied greatly in DM yield. The highest yielding top five varieties ranged between 1,615 lbs/ac for AC Saltlander wheatgrass and 1,046 lbs/ac for Milkway tall fescue. Conversely, the lowest yielding monoculture grass varieties ranged from 596 lbs/ac for Merlin festulolium to 335 lbs/ac for Courtney tall fescue (Table 2). 

The DM yield of forage mixtures followed a similar trend of both monoculture grasses and legumes, with significant differences among treatments. Out of the 24 mixtures tested, the five top performers ranged between 2,455 lbs/ac for a mixture of AC Success hybrid bromegrass +  AC Yellowhead alfalfa + AAC Mountainview sainfoin + Veldt cicer milk vetch (M10), and 2,294 lbs/ac for a simple mixture of AC Success hybrid bromegrass + Spredor 5 alfalfa (M6). The lowest yielding were from M0 < M13 and M15 (Table 2).

Overall, the forage DM yield at the Fairview Research Farm site followed the order of legumes > mixtures > grasses.

DeBolt site: The DM yield obtained for the monoculture legumes showed significant differences among the 20 established legume treatments. Of the established legumes, the top five forage DM yielders were all alfalfa varieties with values ranging between 6,090 lbs/ac for Dalton alfalfa and 5,828 lbs/ac for Assalt alfalfa (Table 3). At the bottom with less than 2,500 lbs/ac were Veldt cicer milk vetch, Bull birdsfoot trefoil, and AAC Mountainview sainfoin.

The monoculture grasses also differed significantly in DM yield. Cowgirl tall fescue had the highest yield (1,536 lbs/ac), while Peak bromegrass produced the lowest (446 lbs/ac)(Table 3).

The DM yield from the 15 forage mixtures varied widely.  Legumaster mix produced the most DM yield with 5,835 lbs/ac (Table 3). Compared to the top five DM yielders (3,908-5,835 lbs/ac), the lowest three yielding mixtures had less than 1,500 lbs/ac (Horsemans forage mixture, grass only, and Pasture mix “0” ).

Overall, in terms of the mean DM yield,  monoculture legumes yielded higher than both forage mixtures and monoculture grasses. The trend of DM yield was monoculture legumes > mixtures > monoculture grasses. 

Forage Nutritive Value

Several forage nutritive value indicators were tested, including crude protein (CP), total digestible nutrients (TDN), and neutral detergent digestibility-48 (NDFD 48).

Fairview site: There were noticeable differences in  CP content within monoculture legumes, monoculture grasses, and mixtures. CP was highest for Bull birdsfoot trefoil with about 20% CP (Table 4). In general, the CP of all monoculture legumes was above 13%, which means that the CP needs of a mature beef cow in mid- and late-pregnancy and during lactation are adequately met and even far exceeded. The CP for monoculture grasses were generally low. However, five of them stood out with slightly high values ranging between 12.5% for Richmond timothy and 11.3% for Chief intermediate wheat grass  (Table 5), indicating the top five monoculture grasses in terms of CP had a sufficient amount of CP for a mature beef cow. The CP in forage mixtures was superior in legume-dominated mixtures. Among the top five treatments, the highest CP was recorded for a mixture of AC Yellowhead alfalfa + AC Success hybrid bromegrass + AC Mountainview sainfoin (Mix 17), at 16.4%. Nonetheless, the lowest CP was found in mixtures made up of only grasses, as observed in a mixture of Fleet meadow bromegrass + AC Knowles hybrid bromegrass + AC Success hybrid bromegrass + Kirk Crested wheatgrass + Greenleaf Pubescent wheatgrass (Mix 0), at 10.8% (Table 6). Overall, CP was highest in legume varieties, followed by grass-legume and all-legume mixtures, whereas the lowest was found in monoculture grasses and all-grass mixtures.

The TDN levels within the monoculture grass, monoculture legume, and mixed treatments showed a significant difference. For monoculture legumes, Bull birdsfoot trefoil had the highest TDN (66%), and the lowest came from Halo alfalfa (63%) (Table 4). The highest TDN for monoculture grasses came from Admiral MB with 63.8% TDN  (Table 5). For forage mixtures, the highest TDN was recorded in Mix 10, with 63.1%. (Table 6). The lowest TDN in mixtures was found in simple mixtures of Fleet meadow bromegrass (Mix 4), with 60.1%. Overall, the TDN trend was in the order of legume > mixtures > monoculture grasses.

The NDFD48 of the top five forage legumes ranged between 55.4 for Bull birdsfoot trefoil and 50.8 for Halo alfalfa (Table 4). The lowest NDFD was found in Dalton alfalfa  (47.8), Spredor 4 alfalfa (46.6), and Peace alfalfa (47.5). For grass forages, the highest NDFD48 was recorded for Admiral MB (58.7) and the lowest was found in Courtney tall fescue (37.0). The NDFD48 for mixtures was highest in all-grass mixtures and grass-legume mixtures. Mix 0 had the highest NDFD48 among the top five mixtures (54.7), whereas the lowest among the poorest three was found in a mixture of AC Success hybrid bromegrass + Spredor 5 alfalfa (Mix 5) (48.7) (Table 6). Comparing grasses, legumes, and mixtures, the NDFD48 was higher in monoculture grasses, while both monoculture legumes and mixtures were similar.

DeBolt site: The CP, TDN, and NDFD48 for monoculture grasses, legumes, and mixtures were significantly different. Among the top five legumes, Veldt cicer milkvetch had the highest CP (18.2%), whereas PV Ultima alfalfa (11.2%), Spredor 5 alfalfa (11.1%), and Anik alfalfa (10.3%) had the lowest (Table 7). The grass forage showed a CP of 10.5% for Rocky Mountain fescue, while the Hktor festulolium (6.0%) was among the lowest three (Table 8). For forage mixtures, Haymix #1 had the highest CP (15.8%). The lowest CP was recorded for Horseman's forage mix (9.4%) (Table 9). Generally, the CP was higher in legumes, followed by grass-legume mixtures, and then monoculture grasses.

The highest TDN for the top five legume varieties was found in Veldt cicer milkvetch (64.3%)  (Table 7). For monoculture grasses, the AC Knowles bromegrass had the highest TDN (62.1%), followed by Killerney orchardgrass (62.0%). The TDN for mixtures was also highest in all-grass mixtures and lowest in legume-dominated mixtures. For example, all-grass mix (Sallinemaster mix) had a TDN of 63.7%, whereas Pasture mix “0” had 62.4% (Table 9). Our results demonstrated that TDN was higher in all-grass forages compared to either monoculture legumes or highly dominated-legume mixtures. 

The NDFD48 of legume forages showed that AC Yellowhead alfalfa (52.0), Veldt cicer milk vetch (49), and Bull Birdsfoot trefoil (47.8) were superior varieties (Table 7). The lowest NDFD48 was reported for Spredor 5 alfalfa (28.6). In grass forages, Killerney orchardgrass recorded the highest NDFD48, followed by both Fleet MB and AC Saltander GWG (56.6, each). In contrast, Cowgirl tall fescue and Fleet Peak bromegrass recorded the lowest (Table 8). For forage mixtures, the highest NDFD was found in Sallinemaster mix (58.7), whereas the lowest was in Legumaster mix (47.3) (Table 9). Overall, the trend of NDFD was in the order mixtures > monoculture grasses > legumes.

Water use efficiency

Water use efficiency (WUE) is a measure of biomass produced per unit of water used by the plant. At the Fairview Research Farm site, Mix 10 had the highest WUE (71.1 lbs DM in^-1), whereas the AC Success hybrid bromegrass recorded the lowest (20.8 lbs DM in^-1) (Figure 1). Overall, stands of grass-legume mixtures had superior WUE compared to all-grass mixtures or monoculture grasses.

A similar trend occurred at the DeBolt site, where a mixture of 55% AAC Mountainview sainfoin + 25% Veldt cicer milk vetch + 20% Spredor 5 alfalfa recorded the highest WUE (189.6 lbs DM in^-1), while a monoculture of AC Success hybrid bromegrass had the lowest WUE (16.1 lbs DM in^-1)  (Figure 2).

Conclusion

The DM yield of forages tested across the two sites indicated that alfalfa varieties were superior to other monoculture legume varieties. In particular, the AAC Trueman alfalfa stood out for DM at Fairview (5,742 lbs/ac), and at DeBolt, Dalton alfalfa (6,090 lbs/ac) recorded the highest biomass. At both sites, the AC Grazeland alfalfa was among the top five. This indicates that AC Grazeland alfalfa can adapt to different agro-ecological zones and still produce high DM yield. Grasses such as AC Saltlander wheatgrass and Cowgirl tall fescue also demonstrated great potential for achieving high forage productivity.

The nutritive values evaluated at both sites showed that CP was high in legumes and legume-dominated mixtures (16.4-19.5%). Conversely, grasses and grass-only mixtures had lower CP content. Overall, all forages tested could meet the CP requirements (7-9-11) for beef cattle categories except for grasses such as Peak brome, Fleet MB, Cowgirl tall fescue, and Hktor festulolium, which had CP values lower than 7% as a result of a slightly mature stage at harvest. 

The legumes and grass-legume mixtures had the highest TDN (>60%). The cicer milk vetch and birdsfoot trefoil were the superior varieties (>64.4%). All mixtures from both sites could satisfy the TDN requirements for beef cattle categories (55% mid-gestation, 60% late-gestation, 65% post-calving). However, not all monoculture grasses or legumes met their needs. The TDN is critical for body temperature maintenance during extreme weather conditions, such as during winter. 

The NDFD48, which measures the digestibility of fiber within 48hr period, demonstrated high values for grasses compared to legumes and mixtures. This was observed in varieties of meadow brome and orchard grasses. This means that when grass and legume forage is fed to cows, the grasses undergo better digestion within a 48-hour period compared to the legumes. However, in terms of the rate of digestibility, legumes are superior. For better utilization of forage, those with low fiber are recommended to aid voluntary consumption and subsequent breakdown to release energy for the beef cattle.

The WUE of forages indicated that grass-legume mixtures are better at converting available soil water into forage yield. Alternatively, grasses are poor at this process. In drought-affected conditions, our results showed that growing mixtures is invaluable for obtaining high yields.

2025 DeBolt Plot Tour