Variabilidade espacial de atributos químicos em argissolo vermelho amarelo sob cultivo com abacaxizeiro Pérola

Abstract

Despite the importance of pineapple culture in Paraiba's coastal trays, there is little information about the evaluation of spatial variability of chemical attributes related to the use and management of fertility for this culture, where acid soils and Low natural fertility and do not receive adequate management. However, in order to propose proper management it is necessary to make a diagnosis of the cultivated areas. In this sense, it was aimed at this research to characterize and evaluate the relations between the chemical attributes of the soil in the pineapple crop with four (A4) and eight (A8) cycles of the culture in the soil. The deformed soil samples were collected from of an Ultisol in mesh, with regular intervals of 10 m, totaling 75 sampling points per study area at the depth of 0-20 cm. For the evaluation of the chemical attributes of the soil were measured PH, P, K , in, Ca, Mg, AL, H + al, MO, CTCpH7, SB and V%. The data were subjected to descriptive statistical analysis followed by the analysis of the main components. Subsequently it were adjusted to geostatistical models to relate the variability and the separation distances of the sampling points, used for interpolation by ordinary kriging. To obtain a single sampling scheme optimized for all chemical attributes of the soil in the area with eight cycles of cultivation was used the spatial simulated annealing algorithm (SSA). In the area with four cycles was verified an average potential acidity, low pH value and lower levels of organic matter, sum of bases and saturation by soil bases, revealing a greater need for soil correction practices. In the area with eight cycles the largest organic matter content of the soil allied to the application of fertilizers provided higher levels for the capacity of exchange of cations, sum of bases, saturation by bases, carbon of the soil and pH tending to average acidity. The forms of use and management employed induced spatial variability for most of the chemical attributes of the soil, being larger in the area with four cycles of cultivation with pineapple 'Pérola', showing greater amplitude in the levels of the attributes. From an initial sampling scheme and with the determination of an average scaled variograma it was possible to determine the number of 16 points to be sampled to minimize the variance of kriging in the search area.