AN ASSESSMENT OF CONTROLLED RELEASE FERTILISER IN THE HERBERT CANE-GROWING REGION

摘要

LOSS OF NITROGEN from sugarcane fields is of serious environmental concern and alsolimits sugarcane production. Losses can be significant in high rainfall environments,where nitrogen is subject to surface runoff, leaching and denitrification. Large-scalefield trials were established to compare the efficiency of controlled release (CR)nitrogen (N) (39-0-0 and 37-0-0) fertiliser against urea (46-0-0) in sugarcane cropsgrown in the Herbert valley. Rate response curves for CR N and urea were measured onclay and solodic soils. Fertiliser was applied and cane harvested using commercialequipment. Cane yield and CCS were measured in cane supplied to the mill. Controlledrelease N was significantly (P ≤ 0.05) more effective than urea 46-0-0 on both soiltypes. On the solodic soil, Agrocote® CR N was twice as efficient as urea-N; cane yieldat 80 kg Agrocote®-N was equivalent to that achieved with 160 kg urea-N. On the samesoil type, CR N significantly (P ≤ 0.05) increased cane yields by 10 t/ha above thatachieved with 160 kg urea-N/ha, the maximum recommended N rate under Six EasySteps. Compared to urea, Agrocote® increased (P ≤ 0.05) cane yield by an average of4.8 t/ha on the clay soil. There were no significant yield responses to controlled releaseK. In the Herbert valley, controlled release was an effective tool to increase N-useefficiency and to manage risks associated with N-loss during heavy rainfall events.Controlled release fertilisers may reduce environmental losses and provide productivitygains in high rainfall environments.