Sediment - Induced Changes in the Fertility of Water Spreaders in Fars province.

Conversion of the Gareh Baygone Plain, a sandy desert, into a verdunt scenery through floodwater spreading (FWS) for the artificial recharge of groundwater (ARG) has raised many questions concerning how each of the soil constituents has changed due to the sedimentation of the suspended load on to the waterspreaders . and the soil enrichment by the dissoloved nutrients carried in floodwater. As therehas been an 11 fold increase in forage production of native and introduced species, and also a large yield. Eucalyptus camaldulensis wood due to FWS, this study was implemented to discover some measurable' changes in a' few soil physical and chemical properties which have occ~rred during the 1983 - 96 peiad. Eabh of the first 3 waterspreaders in the Bisheh Zard 1 ARG system was selected as a ,sampling Isite. .Soil samples were collected plots in each waterspreader. One plo\\ of each waterspread~r, which due to its higher possition had remained out of floodwater, was taken as the control. Analysis of variance of the measured factors aSsumed a'fsplit plot experimental arrangement with flooded (treated) and non flood (e:ntrol) as main plots and the three depths as subplots. The 3 waterspreaders were eassinged as replicats. FWS has significantly increased clay content, Zn concentration, EC, pH,SAR and Soluble Na, S?iI salinity has increased significantly in the 0-15 em layer. Organic carbon (O.C) and total nitrogen have incresed significantly in the 0-15 em layer relative to 30-45 cm thickness. There has been a significant Increase in the concentration of soluble Na, Ca and Mg in the 0-15 em layer, SAR has also significantly Increases there; this applies to the C:N ratio as well. Sand content has the lower depths. Although statistical analysis do not point to other significant changes in the rest of. studied characteristics, FWS has improved them all. Micronutrient concentrations have increased due to an increase in the organic matter content and silt and clay percentages and a decre~se in sand Percentage. It seems that the enhancement in soil quality has improved the micro flora and fauna of the waterspreaders. Moreover deterioration of the environm~ntal quality, which usually follows development, has not happend here. Therefore, as the exPonential population growth rates urge us to find environmental friendly ways and means of food production, the mer.!ts of FWS, particularly lor the ARG, become more apparent.