Evaluating rye and squarrose clover cover crops for no-till organic tomato production

The omission of tillage operations i.e., no-till, is part of conservation practices that have gained increasing popularity since the 1970s in conventional agriculture. No-till has been recently tested in organic farming as an agroecological way for soil management in combination with cover crops. The choice of cover crop is key to addressing the chal- lenges arising with this technique, often related to weed and nutrient management. A field plot trial was set up in 2019-2020 at the Centre for Agri-environmental Research “Enrico Avanzi” in Pisa (Italy) to evaluate the effects of three cover crops and their resi- dues management on weed suppression, soil N availability and tomato yield. Rye (Secale cereale L.) and squarrose clover (Trifolium squarrosum L.) pure stands and their mix- ture in half rates, were either turned into the soil or flattened via roller-crimper before tomato transplantation. Weedy plots with no cover crop preceding tomato served as a control. At termination time, rye and the mixture had equally the highest dry residues per unit area. The presence of a living cover crop decreased winter-spring weed abun- dance measured in dry biomass. Rye and the mixture controlled weeds better than squarrose clover. Weed control continued during the season till harvest with a notable performance by the mixture in no-till. Weed community composition seemed also to be influenced by tillage regime and cover crop choice. Tomato plant growth and yield meas- ured in fruits number and fresh weight were affected by the cover crop. Tomato plants following squarrose clover and the mixture produced more than the control, while prob- ably N immobilization from rye residues hindered tomato growth and yield. Our work showed that legume-cereal cover crop mixture such as rye-squarrose clover can be a good choice for no-till to be successful in Mediterranean organic vegetable systems-