Physicochemical properties of an acid ultisol subjected to different tillage practices and wood-ash amendment: Impact on heavy metal concentrations in soil and Castor plant

A field experiment was conducted in 2016 and 2017 cropping seasons to determine the effects of tillage practice alone and tillage practices amended with woodash on soil physicochemical properties and soil concentration, shoot and seed uptake of heavy metals (Fe,Zn,Cu,B,Pb). The experiment was laid out as split plot in Randomized Complete Block Design with six treatments and three replications. The treatments were: Flat tillage alone (FO) Mound tillage alone (MO), Ridge tillage alone (RO) Flat tillage +4 t ha-¹ woodash, Mound tillage +4 t ha-¹ and Ridge tillage +4 t ha-¹. Results of the study showed significant (p = 0.05) increase in soil hydraulic conductivity and total porosity (%) in tillage practices relative to woodash amended tillage practices. Results of the study also showed significant (p = 0.05) increase in soil base saturation, organic carbon, available P, soil total N, effective cation exchange capacity, pH and decrease in exchangeable acidity in wood ash amended tillage practices relative to tillage practices alone. Significant (p = 0.05) increases in heavy metals concentration in soil, shoot and seed of castor but to non-toxic level except Fe concentration in soil were observed in tillage practices amended with woodash and tillage practices alone. On the average RW was observed to have the highest improvement in the studied parameters. Use of woodash as soil amendment at applied rate improved soil properties and did not have any negative effect on soil and crops.