Elemental sulphur was added to three calcareous soils varying in texture, CaCO 3 content, native phosphorus and micronutrient content at a rate of 0.5, 1.5 and 3.0% (w/w). The experiment was carried in soil columns which were intermittentantly leached and incubated at 30~ for 3,6,9, and 18 weeks. Sulphur applied at a rate of 0.5% significantly decreased the pH and increased the EC and the soluble sulphate content in all three soils and their leachates with slight differences among soils. Sulphur application generally increased 0.5M NaHCO 3 extractable P and DTPA extractable Mn, slightly increased DTPA extractable Fe and Cu but had no significant effect on DTPA extractable Zn. The decrease in soil pH and the increase in DTPA extractable P,Mn,Fe, and Cu upon S-addition were higher with lower CaCO3 content, lower CaCO3/clay ratio and with higher extractable content of these nutrients. Most chemical changes occurred at rate of 0.5% sulphur within 9 weeks of incubation and were largely confined to the soil surface where sulphur was mixed with soil. DTPA extractable Fe and Cu, however, were affected only at higher rates of S-application.

No abstract

A field experiment was conducted from 1989 to 1992 to investigate the effect of sewage sludge applications on wheat yield under different irrigation regimes. The sewage sludge was applied at rates equivalent to 0,20 or 601 ha~' whenever the available soil moisture reached 30 or 70%. The results showed a significant response in grain yield and its nutrient content with no significant differences between rates of sewage sludge applied. Much higher responses were obtained under the wet than under the dry regime. Respuesta del trigo a los sedimentos de las aguas residuales RESUMENDe 1989 a 1992 se llevo a cabo un experimento de campo para investigar el efecto de las aplicaciones de los sedimentos de las aguas residuales en el rendimiento del trigo bajo distintos regimenes de irrigacion. Los sedimentos de las aguas residuales se aplicaron en proporciones equivalentes a 0, 20, 6 60 toneladas por hectarea, siempre que la humedad de la tierra disponible alcanzo el 30 o el 70%. Los resultados mostraron una respuesta significativa en el rendimiento del grano y su contenido en nutrientes sin ninguna diferencia significativa entre las proporciones de sedimentos de las aguas residuales aplicadas. Se obtuvieron respuestas mucho mejores en un regimen humedo que en un regimen seco.

No abstract

No abstract