Relay intercropping of subsidiary legumes with durum wheat (living mulch) can be a viable option to support ecological weed control and optimize nutrient cycling in cereal-based cropping systems. However, the lack of knowledge on suitable legume species is often identified as the main bottleneck for the successful application of legume living mulches. This study aimed to evaluate the suitability of 12 different legumes for relay intercropping with wheat in two contrasting Mediterranean cereal-based cropping systems respectively characterized by low-input and integrated management. Each legume was monitored from the undersowing in wheat until the following spring and we compared direct drilling to broadcast sowing of legumes. None of the undersown legumes showed a negative effect on the wheat grain yield. Relay intercropping of legumes proved to be an effective solution to control weeds before and after the wheat harvest, provided suitable legumes species are chosen. Suitable legumes reduced the weed biomass up to the 90% during the intercropping and up to 94% in the following spring. On the contrary, legumes such as Trifoliumresupinatum, Viciavillosa, Medicagotruncatula, and Medicagoscutellata boosted weed growth in the following spring in comparison with the control. According to the performance of legumes, Medicagosativa, Trifoliumrepens and Medicagolupulina had the most suitable characteristics for relay intercropping with durum wheat at the Ravenna site, in a highly productive region whereas Medicagosativa, Hedysarumcoronarium and Trifoliumsubterraneum performed better in the low-input system near Pisa, where yields are generally lower. This is the first time that such a diversity in legumes species is tested in the same experiment for relay intercropping under diversified environmental and management conditions. The results of this study can support farmers in selecting the most appropriated legume species for their specific cropping systems and local conditions.

Fungicides used to control Fusarium head blight (FHB) are commonly applied at the wheat growth stage considered to be most susceptible, i.e., anthesis. We compared the efficacy of the most commonly used fungicide groups that were applied following two strategies: (i) at pre-defined growth stages, from the first half of heading to the end of flowering (experiment 1, in 2013 to 2015), or (ii) based on timing of infection by F. graminearum, specifically at 10, 7, 4, or 1 day before, or 3 or 5 days after artificial inoculation of the fungus (experiment 2, in 2017 and 2018). Fungicide efficacy was evaluated in terms of FHB incidence, FHB severity, and DON contamination by using generalised mixed models. In experiment 1, all fungicide groups reduced FHB severity and DON but only by <50% compared to an untreated control, with no differences among fungicides or growth stages at time of application. In experiment 2, the efficacy of fungicides was higher for applications at 1 or 4 days before inoculation than at 7 or 10 days before or 3 or 5 days after inoculation, with differences among fungicide groups. Based on our results, the timing of fungicide application for FHB control should be based on the time of F. graminearum infection rather than on wheat phenology.

Decision support systems (DSSs) help farmers and decision-makers to find cropping systems which increase productivity while decreasing the use of fertilizers and irrigation; however, few DSSs exist which integrate soil carbon models, especially in Mediterranean climate. Here, we test whether RothC20_N, a version of the widely used RothC model adapted for Mediterranean and arid climates, can estimate the soil water content (SWC), soil organic carbon (SOC), and soil respiration (Rs), observed in two different cropping systems, one traditional and the other informed by the DSS by Horta Srl. The model was calibrated and tested against two long-term (8 years) field experiments in two different areas in Italy. The two sites showed characteristically dry soils during the summer period; RothC20_N was able to predict correctly the soil water content time series observed in both sites. RothC20_N could predict the measured SOC and heterotrophic respiration time series with Nash–Sutcliff efficiency ~0.3, normalized root mean squared error ~0.4, and Kling–Gupta efficiency > 0. This study shows that the multi-objective calibrated RothC20_N is an interesting candidate for inclusion in a DSS to broaden the potential of the DSS to increase the sustainability of agricultural practices by also addressing soil carbon dynamics while maintaining high agricultural productivity.