EFFECTS OF ORGANIC AMENDMENTS AND IRRIGATION WATERS ON THE PHYSICAL AND CHEMICAL-PROPERTIES OF 2 CALCAREOUS SOILS IN BAHRAIN

The present investigation studies the effects of cow and chicken manur e and sewage sludge at different rates of addition and with two irriga tion waters of different salinities on two major calcareous soils in B ahrain. The aim was to quantify potential improvements in soil quality , the accumulation of trace metals, and quality of leachates. From the pot experiments it was found that soil waterholding capacity did not change significantly after addition of organic amendments, except in t he case of sewage sludge. Total organic carbon and total Kjeldhal nitr ogen content increased in the 0-5 cm layer. Low salinity water and sew age applications improved aggregate stability. Extractable phosphorus was enhanced by the chicken manure treatment more than others. Additio n of different organic amendments did not affect exchangeable cations. pH values did not show appreciable changes and soils were neutral. Tr ace metals studied were present at non-toxic levels in the 0-5 cm laye r. Zinc and copper were the only metal showing a tedency to leach to t he lower soil layer. In all cases metal levels in the surface layer we re proportional to the quantities added in the amendments and their le vels in the leachate were very low.