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The irrigated cropping systems in South Europe could benefit from soybean [Glycine max (L.) Merr.] introduction in their maize (Zea mays L.)‐based crop rotations. However, sustainable weed management strategies are needed for soybean growers under Mediterranean irrigated conditions. This work aimed to assess the weed control efficacy, and the soybean performance, of alternative management practices for single‐ and double‐cropped soybean. Two field experiments were carried out in northeast Spain in the period 2019–2021. Row width narrowing (75–37.5 cm), herbicide application (yes/no), and roller‐crimped rye [Secale cereal (L.) M.Bieb.] cover crop (yes/no) were assessed in the single cropping system experiment (SCS). In the barley‐soybean double cropping system experiment (DCS), row width narrowing and herbicide application were assessed. In the SCS, the presence of rye cover crop reduced weed biomass up to 92% compared to the controls without herbicide and cover crop in 2020. In 2021, no effect of the cover crop on weed pressure was found due to the low amount of rye biomass accumulated (11.8 and 3.4 ton DM ha−1 in 2020 and 2021, respectively). In the DCS, herbicide application attained the expected weed control. Row width narrowing to 37.5 cm did not have an impact on weed pressure nor on soybean yield in either experiment. We concluded that herbicide reduction for single‐cropped soybean under Mediterranean irrigated conditions can be achieved by roller‐crimping a rye cover crop, provided enough rye biomass is accumulated. In the DCS, our results indicated that further research is needed to find alternatives to chemical weed control. Core Ideas: Roller‐crimped rye cover crop controlled weeds in soybean when enough biomass was accumulated.Roller‐crimped rye effectively controlled most weed species, especially Datura stramonium L. and Setaria adhaerens (Forssk) Chiov.Narrowing row width from 75 to 37.5 cm did not improve weed control or soybean yield. [ABSTRACT FROM AUTHOR]

Under Mediterranean rainfed areas, no-till cereal-based systems have been adopted to cope with water availability and increasing input costs. However, the increased risk of biotic stresses, high N-fertilizer dependence, and current EU policies warrant cropping systems re-design. Evaluate diversification and N fertilization as strategies to improve N use efficiency at the cropping system level and quantify its productivity. Four crop sequences combined with four levels of N fertilization were assessed in a three-year field experiment in semiarid rainfed north-eastern Spain. Crop sequences were continuous winter wheat (WCS) and three-year diversified rotations with pea (PCS), faba bean (FCS), or a multi-service cover crop (MSCS) and two years of cereals. Crop, pre-crop and cropping system levels were considered. Agronomic evaluation included crops above-ground biological N fixation (Ndfa), net N balance (Ndfa minus N removed by grain), soil N mineralisation productivity, energy to N tradeoff (ENT), and N use efficiency of protein (NUEp) production. Pea yields ranged from 0 to 766 kg ha−1 and Ndfa from 24% to 54%. Faba bean yield ranged from 1378 to 4251 kg ha−1 and Ndfa from 32% to 72%. Net N balance was close to neutral for pea while in faba bean it ranged from 41 to −21 kg N ha−1. Alternative pre-crops led to greater soil N mineralisation (51 kg N ha−1, on average) and higher wheat yield (564 kg ha−1, on average) compared to wheat as the pre-crop. N fertilization increased protein yields, with FCS presenting the highest yields at all N fertilizer rates. This effect led to a stable NUEp (1.69 kg protein kg N supply−1), as the protein yield increased proportionally to N supply. Diversification improved the succeeding wheat performance and grain legumes N fixation exceeded grain N removal. Introducing legumes into cropping systems led to a decrease in energy productivity compared to the cereal-based system. However, protein production in the FCS was higher than in any other cropping system regardless of the N fertilizer rate. Crop diversification adds challenges and risks in dry Mediterranean areas. However, the study shows that crop diversification with faba bean can decrease cropping system's N-fertilizer dependence and increase protein productivity, contributing to cropping systems' sustainability. • Effect of crop diversification and N fertilization to support N efficient cropping systems. • Multiscale assessment including crop, pre-crop and the cropping system level. • Pea and faba bean supported cropping systems N use efficiency through biological N fixation. • Faba bean cropping system showed the greatest protein yields regardless of the N fertilizer rate. [ABSTRACT FROM AUTHOR]