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Deforestation of Caatinga and inadequate land use of these dry environments have impacted soil quality in Northeastern Brazil. The objectives of this study were: (a) to evaluate the effect of deforestation and different agricultural uses on the physical and chemical properties of soil, and humic fractions of soil organic matter in dry environments; and (b) to detect the soil properties that were most affected by anthropic actions. We evaluated four dry areas in Chapada do Araripe, NE Brazil: preserved native vegetation; degraded native vegetation; cassava conventional cultivation; and eucalyptus agro-energy cultivation. Soil fertility, total organic carbon and humic fractions of soil organic matter were lower in the degraded native vegetation area. The best indicators for soil quality evaluation were: macroporosity; bulk density; soil resistance penetration; sum of bases (mainly Ca2+); available P; and saturation by Al3+. Total organic carbon and humic acid fractions of soil organic matter were important in improving soil quality. These properties were influenced by deforestation and agricultural uses, suggesting that the deforestation of native vegetation in dry environments has high capacity to degrade the soil, preventing its regeneration. [ABSTRACT FROM AUTHOR]

Copyright of Revista IRRIGA - Brazilian Journal of Irrigation & Drainage is the property of Revista IRRIGA (Brazilian Journal of Irrigation & Drainage) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to develop a method for extensive pomiculture on marginal soils in semiarid Brazil, a field experiment was conducted to study the impacts of the soil conditioners biochar, clay substrate and goat manure on soil physical parameters of a sandy soil and on seedling performance ofSpondias tuberosaArruda. Manure significantly increased total porosity, soil water content and reduced bulk density of the sandy soil. Water content at field capacity (θfc) and at permanent wilting point (θpwp) were increased due to manure application. Neither biochar nor clay substrate had a significant impact on the soil physical parameters. Biochar combined with clay substrate led to lower soil water content and significantly reduced the period of retaining atmospheric water. Due to a strong correlation (R2 = 0.75) betweenθfcandθpwp, the available water capacity within all treatments remained unchanged. Amelioration and initial nutrient supplies had no effect on seedling survival and stem growth ofS. tuberosaduring the 23-month experiment. This underlines the nondomesticated character of the available plant material ofS. tuberosa. The independence of the seedling performance of soil management makesS. tuberosaan interesting species for low-input orchards and for reforestation within the Caatinga. [ABSTRACT FROM PUBLISHER]

Landscapes formed on Barreiras Formation sediments occupy significant area on Brazilian territory. Many of these landscapes have highly intensive agricultural use, due to favorable climate and topography. The objective of this study was to characterize and to compare soil profiles situated on non-dissected coastal plains from southern Bahia to Alagoas, occurring under natural vegetation (forest) and agricultural use. Seven soil profiles were analyzed and data from six soil profiles obtained in other works were incorporated. Particle size distribution, organic C (OC), Al, Ca, Mg, Al+H, K, Na, P, Fe, Ti and Si were determined. Clay mineralogy was analyzed by X-ray diffraction. Soil profiles occur on flat relief, have yellow color, weak small to medium subangular blocky structure on B-horizon and sub-superficial cohesive character. Texture was the most significant attribute that differentiated soil profiles from each other. All soils have low Fe content. X-ray diffraction results showed kaolinite dominance in the clay fraction. The soil OC was the only attribute tested that significantly varied between the surface materials of forest soils and the cultivated systems (sugarcane, orange, coconut and eucalyptus). [ABSTRACT FROM AUTHOR]