Increase of SOM by cover crop mixtures

The increase in soil organic matter content is directly associated with the use of plant species or plant combinations with high dry matter production and the consequent accumulation of carbon in the soil. With the recent adoption by farmers of cover crop mixtures (cover crop mixes), it has become necessary to identify which species and how many species per mixture contribute most efficiently to biomass production. The objective of this study was to evaluate the dry matter production of cover crops grown as single species and in different mixed combinations. The experiment was conducted at the IDR-Paraná experimental station in Londrina, Brazil, using a randomized complete block design with 25 treatments, including single-species plantings of Avena spp., Urochloa ruziziensis, Crotalaria spp., Pennisetum glaucum, Raphanus sativus, and Sorghum bicolor, as well as mixtures composed of these species, ranging from 2 to 8 species per treatment. Cover crop biomass production was quantified (kg ha⁻¹) and subsequently subjected to statistical analysis. Preliminary results indicate that sorghum and pearl millet showed the highest dry matter production within the evaluated mixtures. Furthermore, mixtures with a greater number of species did not outperform those with lower species diversity in terms of biomass production, suggesting that appropriate species selection is more important than the number of species in the mixture for maximizing carbon inputs to the soil.