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

Abstract

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.

Graphical abstract