الفهرس | Only 14 pages are availabe for public view |
Abstract The current work aims at following up the changes that may occur in availability as well as uptake of some micronutrients (Fe, Mn, Zn and Cu) by barley plants grown on some calcareous soils of Egypt upon treating these soils with some organic wastes. To fulfil the purpose of this study, surface soil samples (0-30 em) varying in their content of CaC03 were collected from three locations along Cairo-Alexandria desert road. The first location is about 100 Krn from Cairo, the second is adjacent to EI-Noubaria Seed Company and the third location is EI-Noubaria Agricultural Research Station. The organic wastes used in the current work were sewage sludge taken from EI-Gabal El-Asfar Sludge Station, town refuse taken from Egyptian Organic Manure Plant (Shoubra) and biogas manure supplied by Moshtohor Biogas Research Station. An incubation experiment and a greenhouse one were conducted. In the incubation experiment, each of the organic wastes was mixed with 100 g portions of the investigated soils at a rate of 2 % under controlled conditions (30°C and either of two moisture levels, i. e. 60 % or 100 % of the F. C.). Samples of the incubated soils were taken after 1, 2, 4, 6 and 8 weeks and extracted by AB-DTPA then Fe, Mn, Zn and Cu were determined. In the greenhouse experiment, plastic pots packed with the investigated soils were grouped in four sets. The first set was used as a control {without -_.._------_. ~---- - - -----~ - 77 - mixing with organic wastes), the second, third and fourth ones were mixed (at a rate of 2 %) with sewage sludge, town refuse and biogas manure, respectively. The pots were cultivated with barley for a period of 60 days, thereafter plants were cut above the soil surface and oven dried at 70°C to determine their dry weight and micronutrients content of Fe, Mn, Zn and Cu. The following is a brief summary for the results obtained: (1) Soils contents of Fe, Mn, Zn and Cu extracted with AB-DTPA increased as a result of incubation with sewage sludge, town refuse or biogas manure. In all the investigated calcareous soils and under both the studied moisture contents, sewage sludge was the most effective organic waste in enriching soil with micronutrients compared to the town refuse or the biogas manure which showed the lowest effect. (2) Increasing period of incubation resulted in increases in soils contents of AB-DTPA extractable Fe, Mn, Zn and Cu, however, the increase was dependent on type of the organic waste, soil properties and period of incubation. (3) Increasing the moisture content at which the investigated soils were incubated with the organic wastes from 60% to 100% of the F.C. increased the AB-DTPA extractable Fe, Mn, Zn and Cu. Extractable Fe was affected by increasing soil moisture mo,re than the extractable Mn whereas the extractable Zn was the least affected nutrient by increasing soil moisture content. (4) Interaction effect between sewage sludge and moisture content equivalent to 100% of the F.e. resulted in the highest values of Fe, Mn, Zn and Cu. |