Agregação por macromorfometria e “high energy moisture characteristic” em latossolo, cambissolo sob manejo intensivo na cafeicultura

Abstract

In tropical soils, studies on the stability of aggregates using the High Energy Moisture Characteristic (HEMC) technique and macromorphometry are incipient as are the use of these methodologies in the assessment of impacts generated by conservationist management systems. Thus, this study aimed at evaluating the effects promoted by a different management system, employed in coffee culture, on the aggregation state of Oxisols and Inceptisols. In the macromorphometric characteristics studies, aggregates were collected at the depths of 0.05, 0.20, 0.40 and 0.80 m in an Inceptisol originated from pelitic rocks, after 17 months of implementing the management system. The aggregate analyses were performed using 2D images obtained at a spatial resolution of 300 dpi by a scanner. The aggregation variables of area, perimeter, rugness, compactness, aspect and Feret diameter were calculated with the QUANTPORO software. In order to determine the aggregation state of an Oxisol which received different doses of gypsum to the soil surface, we used the HEMC technique. Aggregates were collected at the depths of 0.05 and 0.20 m on the coffee row of an experimental area. The treatments were: G-0, no gypsum on the row, G-7, 7.0 ton ha-1 of gypsum distributed in the coffee row, G-28, 28 ton ha-1 of gypsum distributed in the coffee row, CV-0, conventional management without gypsum on the coffee row and without Braquiaria sp. between rows. The aggregates were placed in a Buchner funnel (500 mL) and moisturized (2 mm h-1; 100 mm h-1), using a peristaltic pump with volumetric syringe. Once saturated, the aggregates underwent a gradual increase in the matric potential from the displacement of a water column (ranging from 0 to 30 cm) to obtain the moisture retention curve (M = f (Ψ)), which was the basis for calculating the stability parameters: modal suction, drainable pore volume (DPV), stability index (slow and fast), DPV ratio and stability ratio. The methodologies employed, Macromorphometry and HEMC, showed sensitivity to measuring the aggregate stability parameters and allowed the diagnosis of the effects of tillage systems on the structural quality of the studied Oxisols and Inceptisols.