Intercropping and rotation with leguminous plants in organic vegetables: crop performance, soil properties and sustainability assessment

This research was carried out in an organic crop sequence of cauliflowers (Brassica oleracea L.) and tomatoes (Solanum lycopersicum L.) intercropped with different cover crop species (burr medic (Medicago polymorpha L) and crimson clover (Trifolium incarnatum L.)) grown as living mulches and cultivated on a ridge system on a site characterised by extreme weather events (floods) in the Mediterranean environment. The objectives of the research were to: (i) investigate the impact of the combination of agro-ecological techniques (cover crops and organic fertilisation) on cash crops yield, biomass production and selected physical properties of the soil; (ii) evaluate the sustainability of the systems by using both energy inputs/outputs analysis and assessment of greenhouse gas emissions (GHG). Six treatment combinations were compared: intercropping with burr medic throughout the crop rotation, with and without organic fertilisers; growing crimson clover as a living mulch in the winter crop within the crop rotation, with and without organic fertilisers; cropping system without cover crops, with and without organic fertilisers. The findings highlighted that the introduction of cover crops in the rotation should be recommended since it resulted in higher crop production levels without negative impacts on soil physical properties, as well as in the best energy use efficiency and carbon efficiency in the system. The results of the soil physical quality assessment indicated that the agro-ecological practices had no significant effects on the soil properties. Therefore, in the Mediterranean conditions, the proposed agro-ecological approaches can be crucial to achieving sustainable organic agro-ecosystems.