Chemical characteristics of soils irrigated with deep-well or Gorutuba river water in Janauba region, Minas Gerais, Brazil.

摘要

In the region of Jana.ba, northern Minas Gerais State, Brazil, banana (Musa) yields are high due to the highly technical agriculture of the region, with intensive use of fertilizers and systematic plant disease and pest control. However, farmers frequently report a decline in banana yields, particularly when water from deep wells is used for irrigation. Therefore, the effect of irrigation water from wells and from the Gorutuba River on soil chemical characteristics of areas with banana cultivation were studied. Soil samples were collected to a depth of 100 cm in adjacent areas with and without irrigation. It was observed that the irrigation water from deep wells was of low quality and resulted in increased pH, Ca2+ and Mg+ levels in the soil. This resulted in high Ca:Mg and Ca:K ratios, which were far above from the optimal range for banana plants. For soils irrigated with water from wells, there was an increase of H2SO4 - extractable P as a result of P precipitation with Ca dissolved in water. The pH values of soil saturation extract were higher than the ones obtained during routine analysis. The concentration of soluble salts in soil solution observed within the soil profile at intermediate depths was due to leaching, especially in the 30-40 cm layer of soils irrigated with water deep wells.