Variabilidade espacial da resistência a penetração em solo sob diferentes condições de colheita de cana-de-açúcar

Abstract

An inherent characteristic of soils is its heterogeneity; however, plantings, especially the mechanized ones such as perfomed in the sugarcane crop, tend to cause changes that increase even more the variability in the physical attributes of the soil. Based on that, the objective of this study was to evaluate the spatial variability of the resistance to penetration in soil under sugarcane cultivation in the microregion of the northern coast of Paraíba. The study was performed in areas of sugarcane production belonging to the Miriri and Bioenergia S/A industries. Two areas are located in Fazenda Santa Emília II, municipality of Rio Tinto and the third is part of the Fazenda Maria da Luz I, located among the municipalities of Capim, Santa Rita and Sapé, in the state of Paraíba. In order of soil, three areas with different usage conditions were selected: I. Manual harvesting - Second Cut (CMA); II. Mechanized harvesting - second cut (CME) and III. Manual and mechanized harvesting (CMM). In each area of study, georeferenced samples were collected in the lines and between the lines of planting, following a regular sample mesh of 20 x 20 m. The samples were analyzed at the Laboratório de Física do Solo, of the Departamento de Solo e Engenharia Rural (DSER), belonging to the Centro de Ciências Agrárias (CCA) of the Universidade Federal da Paraíba (UFPB). Descriptive statistics and geostatistics were used to analyze the data. The mean was not sufficient to represent the spatial distribution of the analyzed areas; The sampling soil mesh was adequate, within the limits of the study, since it allowed the capture of the spatial dependence in practically all the studied conditions. The CMA area presented the highest penetration resistance (RP) values among the three areas. The CME and CMM areas followed a similar pattern, presenting low RP in the superficial layers and with increasing values at the greater depths. Differently from CMA, the CME and CMM presented a higher mean of RP values in the inter-rows, which can be explained by the fact that it is the part that is mostly affected by the compaction imposed by the intensive traffic of the machines.