Avaliação da qualidade física de solos cultivados em áreas irrigadas na Chapada do Apodi - CE

Abstract

The objective of this research was to evaluate the soil physical quality of irrigated areas in the State of Ceará, Brazil, through the use of the Least Limiting Water Range (LLWR), the S index and the relative density. Undisturbed soil samples were collected at 5-10 cm and 20-25 cm depth in six areas, area under banana cultivation, area under guava cultivation, area under maize and beans cultivation in succession, pasture area and two areas under natural vegetation, located in the Jaguaribe-Apodi Irrigated District, Limoeiro do Norte, Ceará, Brazil. The LLWR was determined using the water retention curve, the soil resistance to penetration and soil bulk density, parameters needed to obtain the upper and lower limit. The S index was obtained from the water retention curve. The determination of the relative density was determined by the ratio of bulk density and maximum density of the soil (Dm) obtained from the standard Proctor test with reuse of the material. Based on these indicators was found that the areas under cultivation of banana and guava shown good soil physical quality and better conditions for root growth and plant development at both depths, while the areas under maize and beans in succession at 5-10 cm depth and pasture area at both depths showed strong loss of soil physical quality. The LLWR, S index and relative density seem to be good indicators of soil physical quality, and was noticed that soils under cultivation suffered alteration of their structure compared to soils under natural vegetation.