Chemical changes in argisols under irrigated grape production in the central São Francisco river valley, Brazil

Abstract

SUMMARYThis study compares the chemical composition of the solution and exchange complex of soil in a 3-year-old irrigated vineyard (Vitis vinifera L., Red Globe cultivar) with that of adjacent clearing in the native hyperxerophyllic 'caatinga' vegetation. The soils are classified as Plinthic Eutrophic Red-Yellow Argisol; according to Soil Taxonomy they are isohyperthermic Plinthustalfs. Detailed physiographic characterization revealed an impermeable gravel and cobble covering the crystalline rocks; the relief of this layer was more undulating than the level surface. Significant higher concentrations of extractable Na, K, Mg and Ca were observed within the vineyard. Lower soil acidity, higher Ca/Mg ratios, as well as lower sodium adsorption and Na/K ratios reflected additions of dolomitic lime, superphosphate and K-bearing fertilizers. As the water of the São Francisco River is of good quality for irrigation (C1S1), the increases in Na were primarily attributed to capillary rise from the saline groundwater table. None of the soil in the study area was found to be sodic. About 62% of the vineyard had an Ap horizon with salinity levels above 1.5 dS m -1 (considered detrimental for grape production); according to average values for this horizon, a potential 13% reduction in grape production was predicted. Differences in chemical composition in function of distance to the collector canals were observed in the clearing, but not in the vineyard. The influence of differences in the elevations of the surface and impermeable layers, as well as pediment thickness, was generally weaker under irrigation. Under irrigation, soil moisture was greater in points of convergent surface waterflow; the effect of surface curvature on chemical properties, though less consistent, was also stronger in the vineyard.

Variabilidade espacial de atributos de solos em unidades de manejo em área piloto de produção integrada de coco

“…Ela também vai diminuindo em profundidade, padrão que pode ser atribuído à maior absorção do Ca relativamente ao Mg, o que permite sua reposição parcial em superfície (Heck et al, 2002). De toda forma, a adição de produtos mais calcíticos se faz necessária para alargar as relações Ca/Mg dos solos locais.…”

Soil Chemical Changes under Irrigated Mango Production in the Central São Francisco River Valley, Brazil

“…Assuming that the balance of the Na increase came from the saline ground water (Table 2), this corresponds to about 140 L m −2 of capillary rise since the introduction of mango. On an annual basis (28 L m −2 or 28 mm), this is approximately half of that estimated for heavier‐textured soils under irrigated grape in the same region (Heck et al, 2002).…”

“…The influence of irrigated grape ( Vitis vinifera L.) production on chemical and physico–chemical characteristics of these Ultisols has been investigated (Heck et al, 2002). The present work examined how the management practices such as tree spacing, irrigation, and chemical inputs associated with irrigated mango production have altered the spatial variability of chemical properties of the solution and exchange complex of these soils.…”