Effect of localized irrigation on granulometry and chemical attributes of a Quartzipsamment soil cultivated with dwarf coconut

Abstract

The objective of this study was to evaluate the effect of located irrigation on the soil granulometry, pH and nutrient contents of a Quartzipsamments soil cultivated with dwarf coconut. The study was conducted at the experimental station of Embrapa Agroindústria Tropical/CNPAT, located at Paraibapa County, state of Ceará, Brazil. Two areas under fertirrigation using two models of microsprinklers (diffuser and rotative) were selected. Comparisons were made between irrigated area  and non-irrigated area. Soil samples were taken from horizontal distances of 0.30; 0.60; 0.90; 1.20; 1.50; 1.80; 2.10; 2.40 e 2.70 m from each plant in the 0-10; 10-20; 20-30; 30-40 e 40-50 cm layers. The measured soil variables were sand, silt and clay contents; available Ca2+, Mg2+, K+ and P; pH and soil electrical conductivity. In the area adopting diffuser microsprinkler occurred an increase of 1% in the clay content at the soil subsurface, which may be attributed to clay dispersion process due to the presence of available Na+ ions in the irrigation water. The fertirrigation favored accumulation of Ca2+, Mg2+ e P at the neighborhood of the microsprinklers in the soil surface, and increase of available Na+ in the deeper soil layers. The increase of Na+ in the soil profile suggests the increase of potential hazard of soil salinization, thus the management of irrigation must consider not only the type of microsprinkler but also the quality of water used in the irrigation associated to the soil physical and chemical properties.