Changes of weed seed bank and nitrogen availability in soil subjected to cover cropping and conventional management in a Mediterranean apricot orchard

The increasing intensification of agriculture over the last decades has led to serious concerns mainly related to the depletion of soil organic matter and biodiversity, as well as the increase of soil erosion, nitrate leaching and agrochemicals utilization, which determined negative impact on the ecosystem. Specialized orchards emphasize this framework, especially in Mediterranean areas where low and irregular rainfall require frequent soil tillage and use of herbicides to reduce moisture loss and for weed control. In recent years, a valid option was offered by cover cropping, which refers to the mono- or intercropping of herbaceous plants either for a part of year or for an entire one with the aim of enhancing yields (Mauro et al., 2015). Subterraneum clovers represent the most advisable Fabaceae species for cover cropping in Mediterranean agroecosystems, where soils are generally characterized by low contents of both organic matter and nitrogen, thanks to their self-reseed and N-fixation ability (Mauromicale et al., 2010). The objective of this study was to investigate the effects of Trifolium subterraneum cover cropping, compared with a spontaneous flora and a conventional management, on the quali-quantitative composition of weed seed bank of an apricot orchard. Moreover, amoA and nifH genes, involved in nitrogen cycle, and total N, NH4 + and NO3 - were quantified in soil samples.