Variabilidade espacial dos atributos físicos do solo e da produtividade da cana-de-açúcar na zona da mata norte de Pernambuco

Abstract

The agricultural practices promote changes in the physical properties of the soil, causing alterations in the density, affecting the total porosity, the pore diameter distribution, and the availability of water to the plants. These changes directly affect the development of sugarcane cultivation, affecting the respiration of the roots, the reduction of the porous spaces of the soil, and decrease the water infiltration capacity in the soil. Therefore, the use of soil and water management techniques favors the maintenance of agricultural productivity through precision agriculture. The objective of this work was to analyze the influence of the spatial variability of the physical attributes of in an orthodox Humiluvic Spodosol on sugarcane productivity, variety RB86 7515, in an experimental area, in the Municipality of Goiana, in the region of Zona da Mata North of Pernambuco. Soil samplings and crop productivity were performed at 90 randomly chosen points in the experimental area. Deformed and undisturbed samples were collected in the soil layers of 0.00-0.20 and 0.20 - 0.40 m, in order to analyze the attributes: texture, soil density, field capacity humidity, total porosity, macroporosity and microporosity, according to the methodology recommended by the “Empresa Brasileira de Pesquisa Agropecuária – Embrapa”. For the determination of the total porosity, macroporosity and microporosity, the tensile table was used, and the Richards chamber was used to determine the moisture in the field capacity. Productivity was estimated by the average weight of sugarcane at each sampling point. The data were evaluated using descriptive statistics, geostatistics and simple linear correlation. Sugarcane productivity in the study area was higher than the national average for the 2013/2014 harvest. It was verified through semivariograms that the spherical model was the best fit to the dataset of most of the assessed attributes. It was not possible to detect spatial dependence for the textural fractions of the soil, except for the clay fraction in the 0.20-0.40 m layer that had its data adjusted to the exponential model. Through the isoline maps, it was observed that soil density and total porosity, in the 0.00-0.20 m layer, presented inverse spatial correlation. And that the narrowest area of the study area and with the highest topographic quota had higher values of macropores and lower values of moisture and productivity of the sugarcane. Sugarcane yield did not show a significant linear correlation with soil physical attributes.