Soil decompacting potential and biomass production of Brachiaria genotypes

Abstract Aims : Grasses of the Brachiaria genus are widely used as cover crops in no-tillage areas of the Brazilian Cerrado. The objective of this experiment was to study the ability of six Brachiaria genotypes to produce shoot biomass and root biomass, and the potential of the root system to perforate a 0.01m thick paraffin hardpan disk with 1.5 MPa soil penetration resistance at 30° C. Methods: The plants were grown in PVC columns with a diameter of 0.1 m and a height of 0.7 m. The column was divided into an upper part measuring 0.25 m (top) and a lower part measuring 0.45 m (bottom). The paraffin disk was positioned between the two parts of the column as a physical barrier to be perforated by the roots. The columns were filled with peaty substrate. The Brachiaria genotypes cultivated were: Brachiaria brizantha cv. BRS Piatã, Brachiaria decumbens cv. Basilisk, Brachiaria brizantha cv. BRS Paiaguás, Brachiaria ruziziensis cv. Ruzizienses, Brachiaria brizantha cv. Xaraés and Brachiaria brizantha cv. Marandu. Results: The cultivar Xaraes presented highest paraffin disk perforation capacity. Decumbens is the genotype with the lowest disk perforation capacity. The Ruziziensis cultivar is the genotype that accumulated the high root dry mass. Conclusions: The cover crop of Brachiaria implantation to reduce the physical limitations of the soil for root growth, in no-tillage, must consider the distinct potential of the genotype's root growth.