Effect of Pb and FYM Application on Spinach Yield, Pb Uptake and Different Fractions of Pb in Sewage Irrigated Fluventic ustochrepts Soils of Peri Urban Area of Vadodara

A pot house study was conducted on sewage irrigated Fluventic Ustochrepts soils of peri urban area of Vadodara to study the effect of Pb and FYM on spinach yield, Pb uptake and different forms of Pb after spinach (Spinacia oleracea L.). The soils were treated with six levels of Pb (0, 5, 10, 20, 40 and 80 mg Pb kg soil^-1) and two levels of FYM (0,1%). The results revealed that the significant reduction in yield of spinach was noticed at 80 mg Pb kg^-1 soil application. The uptake of nutrients viz., P, K, Fe and Zn decreased at higher Pb level. Amongst the different forms of Pb after spinach, the per cent reduction in Fe-Mn oxide bound Pb and increase in other forms was noticed in sewage irrigated soil. On the other hand, when the spinach was grown on sewage irrigated soil with the application of FYM, percentage of total Pb increased except that of residual Pb. The percentage of exchangeable Pb of total Pb decreased due to Pb addition; and the decrease was comparatively higher in the presence of FYM. The relative abundance of various fractions of Pb after spinach in sewage irrigated soils was in the order: Residual Pb>Fe-Mn oxides bound Pb>Organically bound Pb>Carbonate bound Pb>Exchangeable Pb. The spinach leaf yield negatively correlated with enrichment of carbonated bound Pb (r=-0.763**), organically bound Pb (r=-0.588**) and Fe-Mn oxide bound Pb (r=-0.425**) in the soil. The results indicate that the FYM addition modified the distribution of various Pb fractions leading to reduction in the availability of Pb. Therefore, FYM application could show beneficial effect to mitigate the adverse effect of Pb in the high Pb containing sewage irrigated soil.