Sown Diversity Effects on the C and N Cycle and Interactions with Fertilization Aljazairi López, Salvador Ribas, Angela Llurba, Rosa Ferrio, Juan Pedro Voltas, Jordi Nogués, Salvador Sebastiá, Maria Teresa Plant diversity Forage mixtures Carbon and nitrogen balance Stable isotope A better understanding of the role of plant composition and N cycle on agroecosystems is necessary, as these will be affected by future developments in agriculture intensification. To explore the effect of plant diversity on yield and carbon (C) and nitrogen (N) balances in forage mixtures, identifying potential co-benefits between functions. We analyzed results from a field experiment where plants of three forage species (a grass, a legume, and a non-legume forb) were cultivated in monocultures and mixtures. Three years after sward establishment, dry matter yield, together with δ 15N, δ 13C, and C and N content in plant and soil material were measured. In addition, we analyzed a second scenario to investigate the effect of fertigation with pig slurry (δ 15N = +8.4‰) on the C and N balances of forage species. Results support the hypothesis that C and N allocation is affected by plant diversity. Plant composition affected N source (% N derived from air, % N derived from soil, and % N transferred in mixtures). In addition, sown diversity increased yield and modulated C and N balances. The δ 15N of samples was affected by both plant composition and fertigation. These results are consistent with previous work showing strong plant composition effects on N-balances, and the potential role that legumes play in enhancing nitrogen sources (derived from the atmosphere) into forage mixture systems. This study contributes to the prediction of suitable sown plant community composition and N management for the optimum agriculture with increased productivity and at the same time reduced environmental impact 2025-07-28T10:51:48Z 2025-07-28T10:51:48Z 2025-01-23 journal article Aljazairi, S.; Ribas, A.; Llurba, R.; Ferrio, J.P.; Voltas, J.; Nogués, S.; Sebastiá, M.T. Sown Diversity Effects on the C and N Cycle and Interactions with Fertilization. Agronomy 2025, 15, 287. https://doi.org/10.3390/agronomy15020287 https://hdl.handle.net/10481/105765 10.3390/agronomy15020287 eng http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional MDPI