Crescimento radicular da soja sob níveis de compactação do solo e mecanismos sulcadores

Abstract

No-tillage system has intensified land use and machine traffic come causing problems related to soil compaction which can be a limiting factor for root system development and therefore in yield. In this context, this study aimed to evaluate the effects of furrowers mechanisms in soil compaction levels on soybean root development. The experiment was carried out in the experimental area at UTFPR campus Pato Branco in a split-plot arranged in a randomized complete block design, where the whole plots were arranged the compaction levels (Level 0 - No-till without additional compaction; Level 2 - No-till submitted to further compaction through two tractor passes; Level 4 - No-till submitted to further compaction through four tractor passes and Level 6 - No-till submitted to further compaction through six tractor passes) and the split-plots the two mechanisms furrowers (double disk and driller shank). Before seeding evaluations on soil physical characterization were carried out through bulk density and penetration resistance. Afterwards seeding depth, soil area mobilized and root development were evaluated. Evaluations regarding root development were given through the collection of root samples at three depths (0.00- 0.10; 0.10-0.20 and 0.20-0.30 m) on the crops row and between rows. These samples were washed, scanned and processed with the assistance of SAFIRA software. Data were submitted to analysis of variance by F test for soil density and seeding quality variables means were compared by Tukey test (p<0.05), whereas the means for root development to LSD test (p<0.05). The penetration resistance was higher as increased soil compaction levels to a depth of approximately 0.20 m. Soil bulk density showed a significant difference only in depth from 0.00-0.07 m for treatment without further compression. The sowing depth was influenced only by furrowers mechanisms and the soil area mobilized not significantly different for both compression and to furrow openers. The volume and surface area of root were influenced by the interaction between the levels of compression and furrowers mechanisms at sowing line to the depth of 0.10-0.20 me by compression levels at depths of from 0.00-0.10 and 0.20-0.30 m. The root diameter was influenced by soil compaction at a depth of 0.20-0.30 m in the row and between line, the root length was also affected by compaction at a depth of 0.10-0.20 m only in between line.