Fertiliser-coating technology to improve the efficiency of copper uptake in pastures

Abstract

Current practice for trace element (TE) application is to admix granular trace elements in with macro-elemental fertilisers. Although the correct rate of trace elements per hectare can be applied, the distribution of the trace elements can be variable, depending on the trace element application rate, the macro fertiliser it’s mixed in with, and the particle size of the trace element granule. We report the results of a pasture trial where a polymer-coating technology (Surflex) was used to coat a copper compound (Cu₂O) around the SSP fertiliser instead of the standard Cu addition treatment where the CuSO₄ compound is admixed in with the SSP fertiliser. The Surflex Cu-coated fertiliser significantly increased both pasture plant uptake of copper and use efficiency (18-38% above control Cu levels compared with 12-27% for standard treatment) over 192 days after application. Further work is required to understand the mode of action behind this increase, however, there is an assumption that the probable improvement in distribution of copper across the trial plots, and the use of cuprous oxide, which is insoluble in water, has some influence over the increased nutrient efficiency. In addition to the increased plant nutrient uptake, there were observed product quality improvements at time of dispatch, and when applied by the trial operators. As well as coating the trace element to the SSP, the polymer also binds a large proportion of dust and fine particles. This has benefits both environmentally for a potential reduction in product drift when aerially spread, and health and safety of people handling and loading the product.