Nutrient composition of spent wash and its impact on sugarcane growth and biochemical attributes.

Nutrient composition of crude and digested spent wash and effect of their application on sugarcane growth and biochemical attributes were studied. Higher concentrations of essential nutrients (P, S, Fe, Mn, Zn, Cu) and heavy metals (Cd, Cr, Ni and Pb) were present in crude spent wash (CSW) as compared to the digested spent wash (DSW); sulphur content was the highest (765 μg ml(-1) in DSW and 1,609 μg ml(-1) in CSW) among all nutrients analyzed. Sugarcane (Saccharum spp. hybrid cultivar CoLk 8102) setts grown in soil pot culture conditions with different rates of crude spent wash (5, 10, 20 and 100 ml kg(-1) soil) along with digested spent wash (100 ml kg(-1) soil) showed improvement in bud sprouting (10.5 %), settling height (40 %), root number (9.4 %), root length (13.2 %), chlorophyll a (52.9 %) and b (55.3 %) contents and activity of catalase (98 %) enzyme over control at low rate of crude spent wash (5 ml kg(-1) soil). Whereas, higher doses of spent wash (20 and 100 ml kg(-1) soil) decreased these parameters markedly except peroxidase which was found higher at all the levels of both CSW and DSW. Findings indicated stimulatory effect of low rate of crude spent wash (5 ml kg(-1) soil) on root and shoot growth and inhibitory effect of higher dose (100 ml kg(-1) soil) of both crude and digested spent wash, therefore, judicious application of spent wash will improve crop productivity and alleviate environmental pollution problems.