Comportamento da umidade e indicadores físicos do solo em encosta agrícola com e sem terraceamento

Abstract

Agricultural terraces are a conservation practice for containing surface runoff, thereby reducing water erosion. This alteration of the hydrological flow can contribute to increased soil moisture and increased productivity of agricultural crops. Thus, this work aims to analyze the physical-hydric attributes of the soil, monitor soil profile moisture, and evaluate the effects on soybean crop productivity in a no-till system, with and without the presence of agricultural terraces. The study was carried out in a 1.92 ha field area (with and without terraces) in the experimental area of the Federal Technological University of Paraná – Dois Vizinhos Campus, in southwestern Paraná. The physical-hydric attributes of the soil consisted of evaluating the following variables: soil density (Ds), total porosity (Pt), macroporosity (Ma), microporosity (Mi), saturated hydraulic conductivity (ksat), and volumetric moisture (θv). Moisture monitoring was carried out using FDR sensors (θFDR) for the 96 points allocated in the trenches. Evaluations of the physical-hydric attributes were also performed for the 64 points and 256 samples of the sampling grid. Finally, the productivity of the soybean crop was evaluated for the two areas under assessment. For the grid, sampling was done in 4 layers (0.00-0.10; 0.10-0.20; 0.20-0.30; 0.30-0.40) and for the trenches, in 6 layers (0.00-0.20; 0.20-0.40; 0.40-0.60; 0.60-0.90; 0.90-1.20; 1.20-1.50). The results showed that, for the sampling grid, the mega ST, as well as the CT, presented higher values for density in the more superficial layers of the soil, demonstrating that despite management, this attribute undergoes strong alterations due to machine traffic. When observed in the trenches, the physical attribute that showed the greatest difference was macroporosity, an important variable related to soil drainage. Regarding moisture monitoring, both θv and (θFDR) were higher in the mega CT, with 0.4407 m³m-3 and 0.3940 m³m-3, respectively. The physical attributes, both in the sampling grid and the evaluations carried out in the trenches, demonstrated the importance of this study for decision-making regarding soil management and conservation practices, since they all influence soil structure, water mobilization, and consequently, plant development. The highest values of θv and θFDR were concentrated in the terraced area, reinforcing the efficiency of the terracing technique for water storage and maintenance of moisture in the soil profile. Regarding soybean productivity, there was no statistical difference. Possibly due to the higher values of Ds on the surface, characterizing greater compaction and, certainly, greater resistance to root development.