Summary
This two-year field trial in Oregon evaluated five perennial forage species—alfalfa, birdsfoot trefoil, red clover, sainfoin, and chicory—grown as monocultures or intercropped with subterranean or balansa clovers in a dryland system. Red clover intercropped with balansa clover achieved the highest DM yields (>11 t ha⁻¹ in 2019, 9.4 t ha⁻¹ in 2020), whilst chicory responded most strongly to selenium fertilisation and had notably high condensed tannin concentrations. Nectar production varied significantly by species and year, with red clover providing the most consistent flowering in 2019 and alfalfa yielding the highest estimated sucrose in 2020, suggesting that forage systems can be simultaneously optimised for livestock nutrition and pollinator support.
UK applicability
Findings from Oregon dryland conditions may have limited direct applicability to UK temperate grassland systems, which typically have higher rainfall and different soil types. However, the intercropping approach and multi-functional evaluation framework (combining forage quality, micronutrient uptake, and pollinator support) align with UK regenerative farming interests and may warrant adaptation trials under UK conditions.
Key measures
Dry matter (DM) yield (t ha⁻¹), forage nutritive value, selenium concentration and uptake, condensed tannin content (mg/g DM), inflorescence density (inflorescences m⁻²), and estimated nectar sucrose yield (kg ha⁻¹)
Outcomes reported
The study compared forage productivity, nutritive value, selenium uptake, and late-summer nectar production across five perennial forage species grown as monocultures or intercropped with self-regenerating annual clovers over two years. Key findings included differential performance of intercrop combinations, species-specific responses to selenium fertilisation, and variation in nectar production and floral abundance across species and years.
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