title: Effects of co-application of biosolids and water treatment residuals on corn growth and bioavailable phosphorus and aluminum in alkaline soils in egypt.
abstract: The co-application of biosolids and water treatment residuals (WTRs) has been previously trialed to reduce excessive bioavailable P in the soil treated with biosolids. However, uncertainty still exists regarding the environmental consequences of the co-application of biosolids and WTRs, especially in alkaline soils in Egypt or the Middle East region. A greenhouse pot study was conducted with Egyptian alkaline soils to (i) quantify the effects of co-application of biosolids and drinking WTRs on biomass production of corn (Zea mays L. cultivar single hybrid 10), (ii) determine the co-application effects on Olsen-P and KCl-extractable Al in relation to their accumulation in plant tissues, and (iii) optimize the co-application ratio of biosolids to WTRs for the best yield and effective reduction of soil bioavailable P. The results show that, among the studied soils treated with 1% biosolids along with various rates of WTRs, the corn yield increased significantly (P < 0.01) with increasing WTR application rate from 0 to 3% (w/w), but decreased at 4% application rate. The corn yield also significantly correlated with soil water holding capacity that increased with the addition of WTRs. Phosphorus uptake by plants significantly (P < 0.01) increased when the biosolid application rate was increased from 1 to 3% in the three studied soils that were treated with 1, 2, or 3% WTRs. The application of 4% WTRs in the biosolid-amended soils resulted in a significant reduction in soil Olsen-P values, but without having observable phytotoxicity of metals (such as Al) to corn during the growth period. The effective co-application ratio of biosolids to WTRs, for increasing corn yield and minimizing the potential for bioavailable P in runoff, was approximately 1:1 at the application rate of 3% biosolids and 4% WTRs in the alkaline soils.
authors.affiliation: Dep. of Soil and Water, College of Agriculture, Alexandria Univ., Alexandria, Egypt.
authors.forename: A M
authors.initials: AM
authors.lastname: Mahdy
authors.forename: E A
authors.initials: EA
authors.lastname: Elkhatib
authors.forename: N O
authors.initials: NO
authors.lastname: Fathi
authors.forename: Z-Q
authors.initials: ZQ
authors.lastname: Lin
mesh_terms: D000468:Alkalies; D000535:Aluminum / Q000032:analysis* / Q000493:pharmacokinetics; D001682:Biological Availability; D018533:Biomass; D004534:Egypt; D010758:Phosphorus / Q000032:analysis* / Q000493:pharmacokinetics; D012722:Sewage; D012987:Soil; D003313:Zea mays / Q000254:growth & development*
chemical_list: D000468:Alkalies; D012722:Sewage; D012987:Soil; D010758:Phosphorus; D000535:Aluminum