Dinâmica da umidade e variabilidade espacial de atributos físicos e químicos do solo em uma bacia experimental do semiárido pernambucano

Abstract

The spatial and temporal variability of soil moisture is widely known and long ago became an object of study on Hydrology. To know the behavior of this variable and to understand its relation with the various pedological and metheorological factors is essential to assist the agricultural management and to promote its best beneficial use. It is necessary to consider that the water content in the soil is subject to various processes such as evaporation, plant water uptake, redistribution, percolation and drainage. In semi-arid regions where water availability becomes limited due to the irregularity in the distribution of rainfall, knowledge of the spatial-temporal dynamics of this feature is even more important. Based on this, the objective of this study was to evaluate the spatial and temporal behavior of soil moisture in a small watershed scale and on a small area of 6,720 m² cultivated with banana, in the city of Pesqueira, Pernambuco, located in Brazilian Northeast. The second chapter describes the soil moisture data for the experimental basin of Riacho Jatobá, held for four months with low rainfall at 32 locations along the basin, covering three types of soils (Yellow Argisol, Regolithic Neosol and Litholic Neosol) and vegetation (pasture, natural dense caatinga and natural sparse caatinga), with representative characteristics of typical systems of semi-arid regions. The monitoring was performed monthly and allowed identifying that the areas with Yellow Argisol showed higher water content, as well as those with a predominance of caatinga. In addition, physical and chemical properties of soil were mapped. Texture maps confirmed the spatial distribution of moisture, with higher content of clay fraction in areas with higher soils moisture. In the third chapter, soil moisture data in a small area cultivated with banana are presented, with 13 monitoring conducted in a two-day interval. The soil moisture was monitored at 22 locations, 11 with the use of mulch and 11 without using the cover. In addition to the spatial evaluation of soil moisture distribution for the different soil coverage the technique of mean relatives differences and standard deviations was applied aiming to find points that could be able to represent the mean temporal behavior of the remaining monitoring locations under the same evaluated conditions. It was possible to identify that the points located in the no mulch sector showed more soil water content and the technique of temporal stability it was showed to be adequate in detecting stable monitoring points over time, being recommended the continuity of data collection to improve the understanding of the dynamics of soil moisture in the region studied.