Sod Seeding of Legumes to Improve Forage Production, Forage Quality, and Soil Health
Funders: Beef Cattle Research Council, and Agriculture and Agri-Food Canada’s Agricultural Climate Solutions Program (Peace Region Living Lab)
Collaborators: University of Saskatchewan; The Kinnee Family of Brownvale, AB
Introduction and Objective
Over time, pasture productivity and carrying capacity tend to decline due to overgrazing, depleted soil nutrients, encroachment by low-value species, and challenging weather conditions. Restoring these pastures by incorporating long-lasting legumes can significantly increase forage yield and improve nutritional quality for grazing cattle or baled hay. Legume-rich stands provide multiple advantages, including higher returns per acre, greater total forage production, improved weight gain per acre and per animal, enhanced cow body condition and reproductive performance, and an extended grazing period.
In this project, our goal was to establish legumes within degraded, grass-dominated pastures to improve forage quality and yield, strengthen long-term stand persistence, enhance soil health, and support broader agroecosystem benefits.
What We Did
In June of 2023, a first attempt was made to rejuvenate a grass-dominated pasture on a beef producer’s farm in Brownvale (Legal Land Description: SE 32 83 1 W6) by sod seeding legumes. The seeding in 2023 produced little or no emergence due to a prolonged drought. The same strips were reseeded on June 26, 2024, with much success this time. The following treatments were seeded on approximately 2-acre strips and replicated twice.
T1 – AC Yellowhead Alfalfa at 10 lbs/ac
T2 – Spredor Alfalfa (50%) + AAC Glenview Sainfoin (50%), both at 27.5 lbs/ac
T3 – Spredor Alfalfa (50%) + Cicer Milkvetch (50%), both at 13 lbs/ac
T0 – Control (no seeding of a grass-dominated pasture – left as it was)
A 10-ft Agrowdrill (AD 100 Series, no-till drill) pulled by a John Deere 4440 tractor, was used to seed all treatments. For 2025, the first production year, co-environmental benefit data on soil physical properties (bulk density, water infiltration, compaction, moisture, and temperature), botanical composition, and forage production and quality were also measured at the pre-bloom stage of legumes using standard protocols.
In the summer of 2025, a grazing phase of the trial was conducted. The grazing phase of the trial ran for 28 days, divided into four 1-week strip-grazing periods:
Period 1: 07/04/25 - 07/12/25
Period 2: 07/12/25 – 07/18/25
Period 3: 07/18/25 – 07/24/25
Period 4: 07/24/25 – 08/01/25
A total of 30 Simmental yearling heifers were used for this phase of the trial, and animals were equally partitioned into the treatments and group weighed per replicate just before the start of the grazing phase on July 4, 2025, at 9:00am.
Forage dry matter yields were determined manually by clipping several 1m x 1m quadrats just before and after grazing. Forage samples were sent to A&L Lab in Ontario for quality analysis.
Cattle had free access to water in all paddocks, using watering troughs. The animals also had free-choice access to cobalt-iodized salt and mineral supplements while on pasture. Animals were also provided ad lib access to Rumensin® to prevent bloat. Fecal samples were randomly collected from the strips after each grazing period, pooled, dried down, and sent to A&L Lab for the determination of nutrient composition. At the end of the grazing period (08/01/25), animals were reweighed individually at 9:00 am. Average daily weight gains (ADG) were calculated by dividing animal weight gains by the number of days animals spent grazing.
In the fall of 2025, soil samples were collected at 0-15" and 15-30" with a Wintex 3000® truck mounted soil sampler and sent to the lab for the following tests: i) estimation of microbial biomass C (MBC) and N (MBN) using the Fumigation-Extraction Method outlined by Voroney et al (2008), ii) determination of NO3 and PO4 supply rates iii) a 6-week soil incubation experiment to quantify CO2 production and a proxy for soil biological fertility and efficiency.
Grass-dominated pasture just before seeding with AgrowPlow drill (June 2024)
What We Found
Weather conditions over the 3 years are shown in Table 1. Compared to the LTA average, lower (about 25% less) precipitation was measured in 2023 and 2025, with 2024 having higher (12%) than the LTA. The growing degree days, which measure the heat accumulation used to predict plant development, showed higher heat accumulation (28%, 12%, and 24%, respectively) for all 3 years compared to the past 30-year average. These two indicators most certainly accentuated drought stress on plants and accounted for the poor emergence that was observed in 2023.
Soil Physical Properties
Bulk density ranged from 1.2 to 1.6 g/cm3 and was similar for all treatments (Table 2). However, it varied widely over the 3 years with a noticeable increase from 2023 to 2024 and 2025.
Soil compaction at 4" differed significantly between treatments and between years, with a noticeable decrease with the seeding of the legumes to around 300 psi, the threshold for compacted soil (Table 2). Compaction at 8" and 12" was not influenced by seeding of legumes nor years, as values were all above the 300 -psi threshold.
Soil moisture content ranged from 7.7 to 30.3% and varied significantly between treatments and years, with a significant improvement over the years, even in the control (Table 3).
Soil water infiltration ranged from 2.6 to 3.0 in/hr over the two years, with the Alfalfa + Cicer Milkvetch treatment showing better infiltration rates for both 2024 and 2025. No significant effect of years was observed for this parameter.
T1 – Alfalfa yellow head; T2 – Spredor Alfalfa + Sainfoin; T3 – Spredor Alfalfa + Cicer Milkvetch; T4 – Control.
Soil Chemical and Biological Indicators
Soil samples collected in the fall of 2025 after two years of legume seeding did not reveal any effect of seeding legumes on all soil chemical indicators assessed (Table 4). Nonetheless, there was a significant effect of sampling depth on all soil chemical indicators, with higher values at shallower (0-15 cm) depths than at deeper (15-30cm) depths.
Soil microbial indicators also exhibited similar trends to the chemical properties above: no treatment effects were observed on biological indicators, but a significant effect of depth was evident, with higher values at shallower depths compared to deeper depths (Table 5). Six-week cumulative CO2 emissions from fall-collected soils, which measure how well the living component of soil contributes to nutrient cycling and overall soil function, indicated no significant effect of treatment on soil CO2 emissions at 0 – 15 cm but a significant effect of treatment at the 15-30 cm level, with control showing the lowest CO2 levels compared to legume-seeded treatments (Figure 1).
Forage Dry Matter (DM) Yield and Forage Quality
Forage DM Yield tended to differ significantly between treatments and between years, with an increase of almost 2-3 times from 2023 to 2025 (Table 6). Alfalfa + Cicer Milkvetch produced the highest yields in both the establishment year (2024) and the first production year (2025). The control produced an appreciable yield (≈ 1,500 DM lbs/ac) in both 2024 and 2025.
The protein content did not vary significantly between treatments. Still, it varied significantly between years, as evidenced by the marked increases in pasture protein levels during the establishment year and the first production year.
Energy in the form of Total Digestible Nutrients (TDN) generally ranged from 55–65% and varied significantly between treatments, but not between years.
Botanical Composition
The botanical composition of the sward changed significantly with seeding as the percentage of legumes increased by almost 70 – 90%, indicating the better establishment and growth of the legumes in the establishment year (2024) and the first production year (2025) (Table 6). As expected, legumes were hardly found in the Control over the 3 years of monitoring. Weeds, mostly broad-leaved plants such as Dandelion and Canadian Thistle, were also found in the stands.
Animal Performance
The animal performance (Figure 2), measured as average daily weight gain (ADG), ranged from 0.74 lbs/day to 1.7 lbs/day, with Alfalfa showing the highest ADG, and, interestingly, the Control showed a higher (1.1 lbs/day) ADG than the Alfalfa/Cicer Milkvetch (0.74 lbs/day) treatment. Also, the manure had a higher quality than the grazed forages (Figures 3, 4 and 5), possibly due to the microbial protein fraction contribution.
Figure 2: Average Daily Weight Gains
Figure 3: Quality of Hay and Manure (Protein)
Figure 4: Quality of Hay and Manure (ADF)
Figure 5: Quality of Hay and Manure (NDF)
Animals grazing on strips
Strips divided into paddocks
Summary, Implications, and Plans
Legume seeding improved pasture conditions over three years, notably increasing legume presence, forage yield, and protein content, while reducing shallow soil compaction.
Bulk density and infiltration remained unaffected by legume seeding, though bulk density rose over time.
Soil chemical and biological properties were also not affected by legume seeding, but were higher in the topsoil (0–15 cm) compared to the deeper soil layer.
Forage yields increased two to three times from 2023 to 2025, with Alfalfa + Cicer Milkvetch producing the most biomass. Energy content varied among treatments but was stable across years.
Animal performance differed, with Alfalfa yielding the highest ADG, though the Control outperformed the Alfalfa + Cicer Milkvetch mix.
Legume introduction enhances forage productivity and some soil health properties, though improvements in forage quality do not always translate directly into higher animal gains. Longer monitoring periods are necessary to see greater soil health benefits. Co-environmental benefit data collection on various soil physical, chemical, and biological properties will continue in 2026, with the possibility of a second grazing year to confirm the above findings.
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