Tailored cover crop mixtures enhance soil phosphorus cycling but not wheat yield in a short-term column experiment

Background and aims: Phosphorus (P) accumulation as “legacy P” in soils presents a challenge and an opportunity for sustainable agriculture. Cover crops (CCs) have been investigated for their P-acquisition strategies, but studies mainly focus on single species. We examined whether CC mixtures enhance P cycling compared to individual CCs by improving P uptake, soil P dynamics, and supporting subsequent wheat growth. Methods: The CC species Avena strigosa Schreb. (black oat), Phacelia tanacetifolia Benth. (phacelia), Trifolium alexandrinum L. (berseem clover), Fagopyrum esculentum Moench (buckwheat), Linum usitatissimum L. (linseed), Guizotia abyssinica [Lf] Cass. (ramtil) and Sinapis alba L. (white mustard) were cultivated individually or in mixtures in columns containing low-P soil over two 80-day cycles. After incorporating CC biomass, summer wheat was grown to maturity. Measurements included CC biomass and P uptake, soil pH, potential phosphatase activity, P fractions, and wheat P uptake and yield. Results: Five out of seven CC mixtures showed higher biomass than single species, and all mixtures achieved greater P uptake. Mixtures increased alkaline phosphatase activity compared to fallow and single CCs. After the wheat cycle, soil treated with mixtures had the highest labile P and reduced moderately labile P by ~ 35% more than single CCs. Nevertheless, wheat P uptake and yield remained largely unaffected. Conclusion: CC mixtures improved P mobilization, uptake, and phosphatase activity compared to single CCs, but this did not translate into improved wheat performance. The findings highlight the potential of CC mixtures to mobilize P, suggesting enhanced P use efficiency and soil P availability.