JPEG Picture EFFECT OF AEROBIC SLUDGE FROM THE OPAL'S SECONDARY WATER TREATMENT PLANT ON THE SOIL PROPERTIES

Abstract

A field study was carried out on a farmer’s field to ascertain the physico-chemical properties of sandy clay loam and clay loam soils because of aerobic sludge application in tonnes/hectare (t/ha) at low, medium, and high rates from the Opal’s Secondary Water Treatment Plant. Bulk density of topsoil significantly reduced (34%) when compared with the control. The reduction in soil bulk density was probably due to the increased soil aggregation. Other soil physical properties such as effective cation exchange capacity of topsoil increased at low, medium, and high aerobic sludge doses to 70, 60, and 46% respectively, compared to the control. Hydraulic Conductivity showed encouraging results at all the treatments in both depths. Overall, Ks increased from 60-98%. Soil aggregation and organic matter also showed a positive trend, after the application of Opal’s aerobic sludge. Paddock with 52 t/ha showed a 74 and 61% increase in organic matter at upper as well as lower depths. Chemical properties such as pH moved towards neutrality whereas high Electrical Conductivity was observed at the lower depths, showing leaching with time. Total N increased 83% in topsoil at low aerobic sludge dose followed by 60 and 67% at medium and high doses, respectively. In the topsoil, total P increased 65% and 44% at the low and medium aerobic sludge application, respectively. Among the cations Ca and Mg concentrations were the highest on all the aerobic sludge treatment levels on both the soil depths except at the highest dose at the lower depth