Review of historical land use and nitrogen leaching: Waikato and Waipa catchments

TR 2018/35

Report: TR 2018/35

Author: Neale Hudson, Sandy Elliott, Benjamin Robinson, Sanjay Wadhwa (National Institute of Water & Atmospheric Research Ltd (NIWA))

About this report

This report was commissioned by the Technical Leaders Group for the Healthy Rivers Wai Ora Project Report No. HR/TLG/2015-2016/1.4

This report, commissioned by the Technical Leaders Group, describes what was done to estimate historical changes in nitrogen leaching losses.

Contents
1	Background and scope
1.1	Background
1.2	Scope of this investigation
2	Methods
2.1	Land use change over time
2.2	Nitrogen leaching yields over time
2.3	Current (2012) land use and classes of land use
2.4	Land use before 2012
2.5	Review of historical leaching
2.6	Synthesis of historical trends in leaching yields
2.7	Estimate of historical nitrogen yields
2.8	Trends in total leaching loss
3	Results: Land use
3.1	Current (2012) land use
3.2	Change in land use over time
4	Results: Trends in nitrogen loss
4.1	Review of leaching yield estimates
4.2	Derivation of historical N leaching yields for use in the HR/WO project
4.3	Trends in total nitrogen leaching loss
5	Key findings, limitations and future work
6	References