Residual Effects of Lime- and Clay-Amended Biosolids Applied to Coarse-Textured Pasture Soil

摘要

This study investigated whether there was residual effect of application of lime- and day-amended biosolids (LaBC~®) on ryegrass growth and soil microbial biomass in a coarse-textured, acid pasture soil. Reapplied LaBC~® increased fertiliser-use efficiency and plant growth in this glasshouse experiment. Soil management history was established with a single application of LaBC~® (501 ha~(-1) wet weight equivalent) with or without inorganic fertiliser (NPK) prior to growing annual ryegrass for 5 cycles. In cycle 6 there was no residual nutrient effect of the original application of LaBC~® but there was a residual liming effect of the previously applied LaBC~®. A nutrient effect of reapplied LaBC~® in plant growth cycle 6, had little residual benefit in cycle 7. The residual concentration of inorganic N remaining in this coarse-textured acid soil after a single application of LaBC~® was negligible and did not appear to be a risk to the environment when applied at 50 t ha~(-1) wet weight equivalent.