Ronny Sobreira Barbosa

Controle de tráfego agrícola e atributos físicos do solo em área cultivada com cana-de-açúcar

The objective of this work was to evaluate the effect of traffic control on soil compaction in sugarcane areas with mechanical harvesting system. The study was carried out in a randomized complete block design in a split plot arrangement, with the following treatments: traditional mechanical harvesting, mechanical harvesting with traffic control, mechanical harvesting with traffic control and automatic tractor guidance. Soil physical properties were assessed at 0.0-0.1, 0.1-0.2 and 0.2-0.3-m depths, at the planting row, at the wheel tracks, and between wheel tracks. The effects of these treaments on sugarcane yield were evaluated, respectively, too. Agricultural traffic increases soil density, and reduces aggregate mean geometric diameters and macroporosity at the wheel tracks in comparison to the planting row, which leads to cumulative soil physical quality degradation throughout the years. The two years of agricultural traffic control did not influence the studied soil physical attributes.

Compressibilidade do solo e sistema radicular da cana‑de‑açúcar em manejo com e sem controle de tráfego

The objective of this work was to compare the load-carrying capacity of the soil in a mechanically harvested sugarcane area, without burning, in managements with and without controlled traffic farming. Controlled traffic was done adjusting the gauges of tractor and trailer, or adjusting the gauges and using autopilot. Soil samples were collected in volumetric cylinders in plant rows and inter-rows (wheel rows), from 0.00-0.10 and 0.20-0.30-m soil depths. Root density was measured by images, obtained by scanning the collected roots in 0.25x0.10x0.10-m monoliths. The management without controlled traffic showed a higher load‑carrying capacity of the soil in the planting rows, in both soil layers, which indicates a higher compaction. Greater root density occurred in the management with controlled traffic with gauge adjustment and use of autopilot, which made possible a higher load‑carrying capacity in wheel rows, and preserved structural quality in the plant rows, resulting in a greater root system development of sugarcane.

Mapeamento do fósforo adsorvido por meio da cor e da suscetibilidade magnética do solo

The objective of this work was to evaluate the possibility of mapping adsorbed phosphorus through soil color and magnetic susceptibility. The experiment was done in a 380-ha sugarcane area, which included four types of Oxisols, with different texture and natural fertility. Two hundred and forty‑one soil samples were collected at 0.00–0.25-m depth. The soil redness index was calculated from sample values of hue, value, and chroma, obtained with diffuse reflectance spectroscopy. Regression models were adjusted between adsorbed phosphorus and soil magnetic susceptibility or redness index. Data spatial dependence was evaluated with geostatistics. Magnetic susceptibility is significantly correlated to adsorbed phosphorus, which allows it to be used as a component in pedotransfer functions for indirect quantification of soil adsorbed phosphorus. The redness index and the magnetic susceptibility show spatial dependency with adsorbed phosphorus. Soil magnetic susceptibility and redness index, evaluated with diffuse reflectance spectroscopy, can aid in the mapping and identification of areas with different phosphorus adsorption potential.