MENDES, J. S.; http://lattes.cnpq.br/4462862908942172; MENDES, Jacqueline da Silva.
Resumo:
The research was carried out to evaluate the quality of waters used in
agricultural areas of Congo region, Paraiba State, Brazil for the human consumption and in
the irrigation and to characterize soils of the irrigated and no irrigated areas of the related
region. The water and soil samples had been collected in two periods of the year, in other
words, in the rainy period (May/2006) and in the dry period (December/2006). Water
samples collected in Cordeiro dam, in wells and in river, were analyzed according the
described methodology in APHA (1998), and the soil samples collected in the depths of 0 -
20 and 20 - 40 cm (rainy period) and in the depths of 0 - 5 and 5 - 20 cm (dry period) were
analyzed with base in the described methodology in Richards (1954) and EMBRAPA
(1997). The CEw and other chemical characteristics increased in the dry period, except pH,
whose variation was small. The chemical composition of all waters was similar, being
predominantly chloride and sodic, in both periods, except waters of low salinity, which had
relatively high bicarbonate concentrations. In average terms, as much in the rainy period as
in the dry period, the waters of the wells presented more salt of what the waters of the dam
and the river. In agreement with CONAMA/MS/OMS Resolution and with the results of
pH, cations and anions, more of 60% the waters collected in both the periods of this study,
are considered proper for human consumption. According to Richards's classification, in
dry period in 56,25% of waters used for irrigation the salinity varied of high the very high,
while in this same period, 6,25% of waters presented risk of medium sodium. On the other
hand and according to Ayers and Westcot's classification about 2/3 of waters must be used
only for irrigation of salt or ions Na+ and CI" tolerant cultures. In relation to the fertility the
soils presented high Ca++, Mg+ + , K+ and P concentrations in both periods and areas of
study, not existing deficiency of these elements for the plants. As the MO, will be
necessary the application of the same, once in the irrigated areas, in both periods, medium
tenors prevailed. In relation to the soils salinity, in the two periods and the two study areas
predominated normal soils. On the other hand, in the rainy and dry period predominated no
sodic and middling sodic soils, respectively.