Caracterização de águas e solos do perímetro irrigado Cachoeira II,Serra Talhada/PE

Abstract

The Northeastern semi-arid region northeastern of Brazil, although possess a high agricultural potential, is harmed by the rain irregular distribution, promoting great risks of salinization in irrigated perimeters. This risk is related to naturally present salts of soil profile and propagated by the water used in the irrigation. The work’s objective was to do an evaluation of the water’s characteristics used for irrigation at the Cachoeira II Irrigated Perimeter, as well as to do a survey of the quality of these waters. The study area is the Cachoeira II Irrigated Perimeter, with its 37 lots, at Serra Talhada city. Water samples were taken at each three months in the used water sources at Cachoeira II Irrigated Perimeter, the samples were collected at Pajeú River, Cachoeira Stream and in the main wells and reservoirs used in the Perimeter. There were 76 water samples collected, and the analyses were added in three groups: group I waters collected in the Cachoeira Stream, group II waters of the wells and group III waters collected in the Pajeú River. In these samples they had been carried the pH and EC measures, determining the concentration of Ca²+ and Mg²+ by atomic absorption spectrophotometer; Na+ and K+ by flame photometry; Cl-,HCO3 - and CO3 2- by titration. It was calculated the SAR for the waters classification and its variations at the studied period. The descriptive statistic was used to analyzed the results. It was observed the sodium chloride water predominance, of the level of salinity, the places and the sources of origin, and that the waters used for irrigation had presented salinization risk and it contains high levels of sodium and chloride. The values of pH had been inside of the normal limits (6.5 the 8.4), already the waters of wells present values of the Cl- superiors to 3 mmolc L-1, arriving the average values of 19.53 mmolc L-1, the biggest average values of the SAR had been found in the third period at three analyzed water sources. The waters of the wells had been the ones that had presented higher values of EC in all the periods, presenting themselves inside of the band of risk for many cultures of economic value.