Response of grass leys to applications of calcified seaweed

Calcified seaweed has long been used as a soil conditioner in northern Euro pe, but supposed beneficial responses have not been experimentally substant iated. Field and glasshouse studies examined treatment responses on the cha racteristics of sandy silt loam Hapludalf soils and on the growth and eleme ntal composition of Lolium perenne. Agricultural lime was a treatment in bo th experiments, being chemically similar to calcified seaweed. Calcified se aweed was applied at 2 t ha(-1) and produced small increases in soil pH and extractable calcium (Ca). Significant increases in Lolium perenne growth w ere found in field studies after both calcified seaweed and lime applicatio ns. Smaller, but consistent, increases in growth were found in glasshouse p ot studies. However, only one harvest showed a significant dry weight yield increase after calcified seaweed application compared with the untreated c ontrol. In pot studies, increases in soil extractable Ca were associated wi th increases in shoot elemental Ca. Decreases in shoot zinc (Zn) and mangan ese (Mn) concentrations were found after both calcified seaweed and lime ap plications. Total shoot element accumulation of Zn and Mn after calcified s eaweed application were similar to those produced by the control, suggestin g that decreases in shoot Zn and Mn concentrations resulted from dilution a fter increased shoot growth. However, total Zn and Mn accumulation decrease d after Lime application compared to the control and calcified seaweed trea tments, probably resulting from fixation of available soil Zn and Mn throug h greater increases in soil pH.