The Ashley Dene flux site is a paired site, growing irrigated and non-irrigated lucerne (Medicago sativa L.). It is located on a research dairy station on the Mid-Canterbury plains, South Island, New Zealand. The research station is 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 and are managed by Manaaki Whenua - Landcare Research. The research is supported by the Endeavour Fund and the Strategic Science Investment Fund from New Zealand’s Ministry of Business, Innovation and Employment.

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 (labelled "ADwet" in file names), Fluxnet site name NZ-ADw. Three site-years of data are available in one set of files (1 July 2015 to 30 June 2018). The first year of data (2015/16) includes the conversion process (oats - bare soil - lucerne). The other flux tower is in a non-irrigated lucerne field (labelled "ADdry" in file names), 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 (until 30 June 2018) are bundled in one set of data files.

For more site details please see the file "Site description for FLUXNET NZ-ADw and NZ-ADn.docx" in this collection (updated 28 Feb 2019).

For the available 3+2.5 site years, we provide here data in the standard OzFlux format at Level 3 (NC and XLS) and at Level 4 (including gap-filled meteorological variables, NC format only). Both lucerne crops were either harvested (machine-cut) 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 (accidentally omitted in the column headers).

Please note that CO2 fluxes during times of cow-herd presence (short intensive grazing events) were removed prior to any processing, because the animal respiration would overwhelm the CO2 exchange between the plant-soil ecosystem and the atmosphere.

In addition, we provide Excel files with processing up to Level 6 (fluxes gap-filled and partitioned), but these deviate from the standard OzFlux format in that the filtering for lack of turbulence at night was done using the standard deviation of wind speed (Uz_Sd) rather than friction velocity, with a threshold value of 0.14 m/s. The rationale for this is explained in Hunt et al. (2016), Biogeosciences 13, p. 2927-2944.