Eskander, A.S.; Matter, M.E.A. and Neamat LGhayad,( 2003). Impact Of Amending Calcareous Soils With Different Organic Wastes On Availability Of Zinc And Copper Under Different Moisture LevelsAnnals OfAgrie. Se. Moshtohor, Vol. 41(1): 475-488 ISSN 1110-0419
Abstract: The new reclaimed calcareous soils are very poor in their physical, chemical and biological properties and consequently fertility, which may be improved by addition of organic wastes. These wastes are potentially valuable resource of essential macro and micro-nutrients to plants. Therefore, an incubation experiment was conducted to follow up the changes that may take place in availability of Zn and Cu in three calcareous soils as a result of amenqing these soils with three different organic wastes (Le. sewage sludge, biogas manure and city compost) at two moisture levels (60 and 100% of saturation percentage, SP). Samples of the incubated soils were taken for analysis of Zn and Cu prior to wetting (time zero), and after 7, 14,28,42 and 60 days from incubation. The results showed that treating the calcareous soils with the used wastes significantly increased the soil contents of Zn and Cu extracted by AB-DTPA solution. The extractability of Zn and Cu was affected by the type of applied
organic waste, soil moisture content and incubation time. Sewage sludge was the most effective organic waste in enriching soils witll both AB-DTPA extractable Zn and Cu followed by city compost and biogas manure. This may be due to its higher contents of Zn and Cu and also, its rapid decomposition and consequently the faster release of different nutrients e.g. Zn and Cu. ,"I Incubation under saturation percentage resulted in higher values of extractable Zn and Cu than the corresponding ones attained upon incubation under 60 % of SP. The response occurred in presence as well as in absence of organic wastes, and was much higher where organic wastes were applied. The coarse te:\.1ured soils recorded greater amounts of released Zn than the clayey one while the opposite was true in case of Cu where the clayey soil showed higher values of released Cu tllan the coarser ones. Desorption of Cu from the calcareous soils seemed to be more affected by their original content of this element and the applied organic wastes tllan their CaC03 contents.
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