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Highlights - One month after rye termination, the weed biomass under mulching is reduced by 4 times, compared with the control. - When rye is terminated early, the weed biomass production is reduced by the allelochemical content in rye tissues. - When rye is terminated late, the weed biomass production is reduced by the amount of rye biomass. - Lambsquarters, redroot pigweed, and purslane growth is inhibited by rye mulching, while velvetleaf is not affected. Abstract Alternative strategies to control weeds are required at field level to reduce herbicides and derived pollution. Rye (Secale cereale L.) cultivation as cover crop is adopted mainly because of its allelopathic weed control, which takes place throughout a strong inhibition of germination and seedling growth in several grass and broad-leaved weeds. The present study consisted of: i) a field trial, focused on evaluation of biomass production and allelochemical concentration in the biomass, and in situ weed control at 30 days after termination (with two termination timings: T1 - heading phase and T2 - 10 days later) of 8 rye varieties; ii) a pot experiment, focused on the inhibition effect of mulches derived by those 8 rye varieties on four summer weeds: velvetleaf (Abutilon theophrasti Med.), lambsquarters (Chenopodium album L.), redroot pigweed (Amaranthus retroflexus L.), and common purslane (Portulaca oleracea L). Results showed that biomass production was the highest with Protector, closely followed by Primizia, Sito 70, Hellvus, Forestal, and Hymonta. In any case, rye mulching always reduced the weed biomass, especially with Fasto and Forestal. The allelochemical concentration in the biomass was the highest with Fasto and Forestal, and decreased on average from T1 to T2 (-38% for total BX and -57% for isovitexin). Conversely, the rye biomass production increased (on average + 77%) passing from T1 to T2. We found also that the reduction of weed biomass, compared with the control, is highly correlated with the allelochemical content in rye biomass in the case of T1 termination, while with the biomass production in the case of T2. In pots, a strong inhibitory effect on seedling growth due to rye mulching was observed for C. album (-76%), A. retroflexus (-56%), and P. olearcea (-84%), while not for A. theophrasti. We concluded that, whatever the variety, adopting rye as cover crop may be considered as a suitable practice to reduce weed pressure at the field level. Among all the varieties tested, Forestal and Protector showed the greatest weed suppression potential, as a consequence of high amount of allelochemicals production for Forestal, and high biomass production for Protector.

Introducing smart and sustainable tools for climate change adaptation and mitigation is a major need to support agriculture’s productivity potential. We assessed the effects of the processed gypsum seed dressing SOP® COCUS MAIZE+ (SCM), combined with a gradient of N fertilization rates (i.e., 0%, 70% equal to 160 kg N ha−1, and 100% equal to 230 kg N ha−1) in maize (Zea mays L.), on: (i) grain yield, (ii) root length density (RLD) and diameter class length (DCL), (iii) biodiversity of soil bacteria and fungi, and (iv) Greenhouse Gases (GHGs, i.e., N2O, CO2, and CH4) emission. Grain yield increased with SCM by 1 Mg ha−1 (+8%). The same occurred for overall RLD (+12%) and DCL of very fine, fine, and medium root classes. At anthesis, soil microbial biodiversity was not affected by treatments, suggesting earlier plant-rhizosphere interactions. Soil GHGs showed that (i) the main driver of N losses as N2O is the N-fertilization level, and (ii) decreasing N-fertilization in maize from 100% to 70% decreased N2O emissions by 509 mg N-N2O m−2 y−1. Since maize grain yield under SCM with 70% N-fertilization was similar to that under Control with 100% N-fertilization, we concluded that under our experimental conditions SCM may be used for reducing N input (−30%) and N2O emissions (−23%), while contemporarily maintaining maize yield. Hence, SCM can be considered an available tool to improve agriculture’s alignment to the United Nation Sustainable Development Goals (UN SDGs) and to comply with Europe’s Farm to Fork strategy for reducing N-fertilizer inputs.

Combining no-till and cover crops (NT + CC) as an alternative to conventional tillage (CT) is generating interest to build-up farming systems’ resilience while promoting climate change adaptation in agriculture. Our field study aimed to assess the impact of long-term NT + CC management and short-term water stress on soil microbial communities, enzymatic activities, and the distribution of C and N within soil aggregates. High-throughput sequencing (HTS) revealed the positive impact of NT + CC on microbial biodiversity, especially under water stress conditions, with the presence of important rhizobacteria (e.g., Bradyrhizobium spp.). An alteration index based on soil enzymes confirmed soil depletion under CT. C and N pools within aggregates showed an enrichment under NT + CC mostly due to C and N-rich large macroaggregates (LM), accounting for 44% and 33% of the total soil C and N. Within LM, C and N pools were associated to microaggregates within macroaggregates (mM), which are beneficial for long-term C and N stabilization in soils. Water stress had detrimental effects on aggregate formation and limited C and N inclusion within aggregates. The microbiological and physicochemical parameters correlation supported the hypothesis that long-term NT + CC is a promising alternative to CT, due to the contribution to soil C and N stabilization while enhancing the biodiversity and enzymes.

Lettuce (Lactuca sativa L.) is a leading greenhouse-grown vegetable. However, nitrate (NO3−) accumulation in leaves remains a major issue. The aims of this research were: (i) to test the modified intermittent Nutrient Film Technique (NFT) in the cultivation of soilless lettuce in which plants are grown on peat blocks in trays and supplied with an intermittent flow of nutrient solution, and (ii) to calibrate the fertilization scheme to increase yield performance, while keeping NO3− concentration under control. Two greenhouse trials were performed between autumn 2013 and spring 2014. Results showed that a 30-day cycle is the optimum duration in terms of fresh biomass yield, both for autumn and spring cultivation. Reducing N fertilization in the last cropping days never affected NO3− concentration in leaves during autumn trial, due to unfavourable growing conditions. Conversely, suspension of fertilization 2 days before harvest had a consistent effect during the spring trial, when NO3− concentration in leaves was highly reduced (from 20 to 36%) without yield penalties. Thus, suspending fertilization 2–4 days before harvesting in intermittent NFT may reduce, on average, NO3− accumulation by 29–58% and the fertilization rate by 7–16%, respectively. Yet, growing conditions are crucial to make this system effective.