Effect of heavy metals on soil respiration during decomposition of sugarcane (Saccharum officinarum L.)trash in different soils

An experiment was conducted to study the effect of heavy metals (Cd, Cr and Pb), soil texture (sandy, loam and clay) and incubation periods (7, 15, 30, 60, 90 and 120 days) on soil respiration (CO2 evolution) during sugarcane trash decomposition in laboratory conditions of the Indian Institute of Sugarcane Research, Lucknow, India. Surface soils (0-15 cm) were collected from agricultural fields and crop residue of sugarcane trash (Saccharum officinarum L.) was taken in the institute farm. Crop residue (10 t/ha) and heavy metals (10, 50, 100, 1000 |ig/g) were mixed and incubated at 30°C ± 2°C in an incubator. The rate of soil respiration (CO2 evolution) decreased with increasing heavy metals concentration. During the 120 days, the toxicity decreased but still remained significant. Maximum soil respiration was recorded at 7 days of incubation period; further, it decreased with increasing incubation period. The highest drop of soil respiration rate was caused by addition of 1000 |g/g Cd, Cr and Pb levels. Clay soils evolved maximum CO2 followed by loam and sandy soil.