Abstract

Sudarshana Sharma1, Poonam Mehrotra2 and A.K. Bhattacharyya

Unorganized land disposal of industrial wastes contaminates land and ground water. The Wazirpur Industrial area of Delhi, a metropolitan city, generates highly acidic (pH 2 - 3.8) and toxic waste, and disposal remains a perpetual problem. This waste contains a high quantity of macronutrients as well as heavy metals because major industries are involved in metals finishing. Wastes of these industries were mixed with municipal waste at roads. Hence a study was undertaken to verify the suitability of land disposal of this toxic waste. The waste was first treated with three doses of lime (0, 0.5 and 1%) and then mixed with two types of soils from two different locations in three different proportions viz. 10, 20 and 30%, maintaining soil moisture level at 50% of water holding capacity. These samples were incubated for 120 days. All three waste amendments resulted in an increase in available phosphorus (AP) in both waste-amended soils as compared to the control soils. It is statistically significant at p = 0.05 level. During the 120 days of incubation highest value (36.41 ± 0.01 ppm for site 1 soil and 30.40 ± 0.03 ppm for site 2 soil) of available phosphorus had been found at 20th day of incubation for both the soils. Lime treatment at the rate of 0.5% gave in 10 and 20% treatments significantly positive result as compared to 0 and 1% treatment. Only in 30% waste amendment 1% lime treatment gave better amount of available phosphorus (27.77 ± 0.01 ppm and 24.84 ± 0.03 ppm for site 1 and site 2 soils respectively). The finding of the study evident that 0.5% lime treated 10% industrial waste can be used as manure for soil. The result is of further interest from a plant nutrition standpoint since the amount of potentially mobile-P measured in this study could be related to the amount of available phosphorous required for crop growth.