1. Flux investigations for intensive dairy farming, Hamilton Basin, NZ Dave Campbell, Louis Schipper, Paul Mudge & Tehani Kuske Earth and Ocean Sciences University of Waikato

2. Context: Changes in TC and TN within NZ pasture soils Soils collected from previously sampled sites (17-30 yrs ago) had been archived and were reanalysed for TC and TN Sites sampled to date

3. Change in Total C and Total N— initial 31 sites Top 1 m of soil profile: Total C loss was about 1 t ha -1 yr -1 Total N loss was about 90 kg ha -1 yr -1 Schipper L.A., Baisden W.T, Parfitt R., Ross C., Claydon J. (2007) Large losses of soil C and N from soil profiles in New Zealand during the past 20 years. Global Change Biology, 13: 1138-1144

4. Need more data to confirm landuse/land- form findings –Resampling of previously sampled profiles What, where, when? –Hill country around Palmerston North –South Island – Pallic and Semi arid soils –Dairy and drystock –Tussock (native grasslands) Ongoing sampling

5. Quantitative measurements of carbon exchange in relation to different farming practices—applications for EC –e.g. To what extent do the following practices decrease soil C? pasture renewal pugging/poaching irrigation fertiliser feed crop production etc… Research needs

6. Opuatia wetland 2003–05 Landcare Research Moanatuatua wetland 1999–2000 Rukuhia (dairy) 2002–03 Torehape peat mine 2005–06 Previous work Scott Farm (dairy) 2007–

7. Moanatuatua peatland

8. Opuatia peatland

9. Carbon budget for dairy farming on peat soils Nieveen et al. 2005, GCB 11: 607–618 2002-3 C budget

10. Torehape cutover peatland

11. Dairy industry research farm (Dairy NZ) –Focus on increased production vs environmental costs Soils: mod. well drained silt loam Landuse: dairy cow grazing + cut & carry harvesting Research capability (from Dec. 2007): –Open path EC (CSAT3 + LI7500 + CR3000) –Soil CO 2 flux chamber (LI8100) Scott Farm site

14. Hukseflux NR01 REBS Q7

15. Scott Farm immediate research objectives Annual CO 2 –C budget under typical NZ dairy grazing management –3-4 cows/ha (rel. high land pressure) Models of annual water use Case studies of farm management practices: effects on CO 2 fluxes –Cultivation/pasture renewal –Overgrazing/pugging (winter) Long-term: –Simple models of farm soil carbon stocks & changes

16. Scott Farm: Initial results

17. Midday CO 2 fluxes

18. Thanks…… DairyNZ and Scott Research Farm staff