Effects of Sewage Sludge Biochar (Sewchar) Application on Nutrient Uptake and Yield of African Marigold

The study was conducted in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, Thiruvananthapuram, India to evaluate the effect of sewage sludge (SS), sewage sludge compost (SSC) and sewage sludge biochar (sewchar, SC) on plant growth and productivity. Comparative studies showing the effect of sewage sludge, sewage sludge compost and its biochar on plant growth and productivity are limited. Sewage sludge, sawdust, zeolite (50:30:20) and 2.5 kg of flyash were combined and composted for 60 days to prepare sewage sludge compost. Sewchar was prepared through the process of slow pyrolysis at a temperature of 400℃ for 2 hours. A field experiment was conducted to using marigold as a test crop. Experimental results showed that conversion of sewage sludge to sewchar causes the enrichment of nutrients in them. Field experiment revealed that maximum N, P, K content, uptake and yield parameters such as flower diameter (9.35 cm), flower weight (9.21 g) and number of flowers per plant (98) was recorded with sewchar received treatments compared to other treatments. Gradual release of nutrients from sewchar is important in maintaining the soil fertility and boosting the plant growth parameters and productivity.