Trace elements in dominant plant species of cut grassland following long-term applications of liquid pig and cow manures

摘要

Plant samples were taken from 35-year grassland experiment plots in May 2006 with treatments comprising unfertilized control, inorganic fertilizer control (200kg N, 32kg P, and 160kg(K)·ha<'-1>·y<'-1>), liquid pig manure (50, 100 and 200m3·ha<'-1>·y<'1>), and cow slurry (50, 100 and 200m3·ha<'-1>·y<'-1>) with six replicates. The concentrations of manganese (Mn), copper (Cu) and Zinc (Zn) were determined in the three dominant plant species Lolium perenne, Agrostis stoloni fera and Poa spp. The concentrations of Mn in A. stolonifera were much higher than in the other main species across all treatments except for plots without fertilizer, and decreased with increased application of cow slurry. Plant concentrations of Cu and Zn increased with increased application of slurry, and reached their highest values at the highest rate (200m3·ha<'-1>·y<'-1>) of cow slurry for copper (11.8mg·kg<'-1>) and of pig slurry for zinc (41.1mg· kg<'-1>) in A. stolonifera. This indicates that long-term application of high rates of slurry to grassland may pose a potential risk of Cu toxicity to animals eating first-cut silage.