Trace Metal Enrichment and Distribution in a Poultry Litter-amended Soil under different Tillage Practices

Abstract

Macro and micro nutrients enrichment from poultry litter amendment, tillage, and crop rotation have been investigated to determine their impacts on crop yield, soil and environmental sustainability. This study was conducted to evaluate the soil arsenic (As), copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn) enrichment that could result from the long term effect of poultry litter amendments and tillage practices on selected soil properties at the Alabama Agricultural Experiment Station, Belle Mina, AL. Soil samples were collected in 2006 from plots established in 1996 that received yearly poultry litter applications with three tillage systems, conventional-till (CT), no-till (NT), and mulch-till (MT); and at three depths (0-10 cm, 10-20 cm, and 20-30 cm) that received poultry litter based on 100 kg total N ha -1 yearly. An untreated control was also included in the study. Soil pH values at the 0-10 cm were greater or equal to the lower depths. Copper and Zn concentrations were significantly higher for all tillage systems at the 0-10 cm depth compared to the 10-20 and 20- 30 cm depths and decreased with increasing depth. For example, at 0-10 cm depth Cu concentrations were 58, 66 and 65 and Zn were 13, 24 and 22 percent higher than the control for the CT, MT and NT tillage practices respectively. These results demonstrated that Cu and Zn did accumulate in the surface soil after 10 annual applications of poultry litter but not at phytotoxic levels in contrast to As, Pb, and Ni regardless of the tillage practices.