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Peter Bishop

Doctor of Philosophy, (Soil Science)
Study Completed: 2011
College of Sciences


Thesis Title
Polymer coated controlled release agrichemicals as mititgation tools in pastoral farming

Read article at Massey Research Online: MRO icon

Mr Bishop developed and tested a number of polymer-coated, granular, controlled-release urea and nitrification inhibitor products designed to reduce nitrate leaching from pastoral farming. He has shown in a field trial that coated, controlled-release urea can be applied in a single application of up to 150 kg nitrogen per hectare without increasing nitrate leaching and without creating nitrogen surpluses in pre-grazed pasture. Avoiding nitrogen surpluses in pasture decreases urinary nitrogen concentrations and decreases indirect nitrogen leaching from urine patches. By polymer coating the nitrification inhibitor dicyandiamide (DCD) its longevity in soils was increased and therefore the inhibitory effect lengthened. A simulation model was constructed to explain the controlled release of DCD and its inhibition of nitrification of urine nitrogen. This model was useful in predicting the long-term effectiveness of polymer-coated DCD and illustrating the commercial potential of such products.

Professor Michael Hedley
Associate Professor Paripurnanda Loganathan
Professor Jim Jones

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