The nutrients in rainwater that reach the soil by throughfall or stemflow may represent significant nutrient fluxes in agroforestry systems with low external input. However, there is no information about these processes in agroecosystems of semi-arid northeastern Brazil. This study was conducted in an alley cropping system with Gliricidia and maize in Esperança, PB, Brazil. The objectives of the study were to quantify: (a) the proportion of rainfall that reaches the soil as throughfall or stemflow and the amount intercepted […]

Soil fertility levels in the Agreste region, state of Paraíba, Brazil are generally low. Usually, animal manure is applied to soils to supply agricultural crops with nutrients. However, depending on the quality of the manure applied, incorporation can lead to soil nitrogen immobilization in the beginning of the growing season. It was hypothesized that planting and incorporating crotalaria (Crotalaria juncea) together with animal manure could synchronize the nutrient mineralization pattern more specifically with crop demand. In 2003, field and green-house […]

Potato (Solanum tuberosum L.) is an important cash crop in the semi-arid region of Paraíba, Brazil. However, potato productivity is limited by low soil fertility and the limited and highly variable precipitation pattern of this region. Animal manure is the main nutrient source for soil fertility amelioration, but farm manure available is usually not enough to fertilize crops. A cover crop could decrease the demand for animal manure. The characteristics of Crotalaria (Crotalaria juncea L.) recommend it as green manure. […]

An in-depth experimental study into heat and water transference in the soil – vegetation – atmosphere complex was carried out in a semi-arid region dominated by Caatinga (Xerophytic) vegetation in the state of Paraiba, Brazil. Results showed that the thermodynamic soil behaviour plays a fundamental role in soil evaporation and sensitive heat fluxes. In this paper we show how the thermal difusivity of the soil was calculated in situ by three different methods with different hypotheses. The harmonic method (HM) […]

Studies from some semi-arid regions of the world have shown the beneficial effect of trees in silvopastoral systems, by promoting the formation of resource islands and increasing the sustainability of the system. No data are available in this respect for tree species of common occurrence in semi-arid Northeastern Brazil. In the present study, conducted in the summer of 1996, three tree species (Zyziphus joazeiro, Spondias tuberosa and Prosopis juliflora: ) found within Cenchrus ciliaris pastures were selected to evaluate differences […]

Sand, silt and clay fraction mineralogy as well as the weathering processes of two soils with excess of sodium (SPL and SS) were studied in the state of Ceará, Brazil. The sand coarse and silt were studied using polarized microscopy and phase contrast, while the fine silt and clay were analyzed by X-ray diffraction. Additional information on the mineralogical transformations that occurred in the horizons of both pedons was obtained using scanning electron microscopy. The Solodic Planosol showed in the […]