Ashley Dene is a paired site, growing irrigated and non-irrigated lucerne & #40;Medicago sativa L.& #41; until 2020, then converted to dairy pasture with rotational grazing. It is located on a research dairy station on the Mid-Canterbury plains, South Island, New Zealand, owned and managed by Lincoln University. The lucerne crops and the pivot-irrigation system were established in spring 2015. The flux sites began operating in 2015/16. The research is supported by the Endeavour Fund and the Strategic Science Investment Fund from New Zealand’s Ministry of Business, Innovation and Employment, and for the pasture phase also from the New Zealand Agricultural Greenhouse Gas Research Centre.

Lucerne & #40;2015-2020& #41;
There are two micrometeorological EC flux towers, at ca. 700 m distance from each other. One of them is centrally located in an irrigated lucerne field & #40;labelled "ADwet" in file names& #41;, Fluxnet site name NZ-ADw. Three site-years of data are available in one set of files & #40;1 July 2015 to 30 June 2018& #41;. The first year of data & #40;2015/16& #41; includes the conversion process & #40;oats - bare soil - lucerne& #41;. On 9 March 2020, the lucerne was sprayed off to begin conversion to pasture & #40;see below& #41;.
The other flux tower is in a non-irrigated lucerne field & #40;labelled "ADdry" in file names& #41;, Fluxnet site name NZ-ADn. There, the dataset of meteorological drivers begins on 17 December 2015, after the conversion to lucerne, and flux measurements by eddy covariance started on 20 January 2016. The first 2.5 years & #40;until 30 June 2018& #41; are bundled in one set of data files. This tower ceased operating on 26 August 2020.

Pasture & #40;2020-2022, NZ-ADw only& #41;
A new eddy-covariance system including a multi-gas analyser & #40;with the main purpose of measuring N2O emissions& #41; was installed next to the original system and began operating on 23 January 2020, six weeks before the spraying of the lucerne crop. The original eddy-covariance system operated until 30 July 2020 and the overlap period was used to establish correction factors for the new system. Measurements were terminated on 28 August 2022.
For more site details see the file "Site description for FLUXNET NZ-ADw and NZ-ADn.docx" in this collection & #40;original of 28 Feb 2019, updated 23 Jul 2025& #41;.

XLS and NC files & #40;2015-2018& #41;
We provide data in the standard OzFlux format at Level 3 & #40;NC and XLS& #41; and at Level 4 & #40;including gap-filled meteorological variables, NC format only& #41;. Both lucerne crops were either harvested & #40;machine-cut& #41; or grazed a few times annually, and in order to gap-fill the CO2 fluxes in a meaningful fashion this abrupt change in biomass needs to be represented by a suitable driver. For that, we constructed the variable "Standing biomass" from direct biomass sampling before and after the removal events and interpolated across the regrowth periods. The units of this variable are g dry-matter m^-2 & #40;accidentally omitted in the column headers& #41;.

CSV files & #40;2015-2022& #41;
These files are provided for the complete dataset, both towers, formatted as input files for the FLUXNET2025 database. For NZ-ADw in 2020, data until 23 January 11:30 are from the old EC system; thereafter, from the new system with the multigas analyser. "BIOMASS_AG" is the same as "Standing biomass" explained above. "P_RAIN" is precipitation, "P" is precipitation plus irrigation.