Nutrient Leaching Losses: From the Point, through the Farm, to the Catchment

Transcription

1 Dublin, Ireland, 15 th September 2011 Nutrient Leaching Losses: From the Point, through the Farm, to the Catchment Brent Clothier 1, Steve Green 1, Markus Deurer 1, Alec Mackay 2 & Jon Roygard 3 1 Plant & Food Research 2 AgResearch 3 Horizons Regional Council

2 Nature s Bounty: Capital & Interest Natural Capital: Our stocks of natural materials & energy Ecosystem Services: The beneficial flows of goods between natural capital stocks, or stocks & humans

3 Stocks Services The Millennium Ecosystem Assessment (2005)

4 New Zealanders are highly dependent on our natural capital our waters, soils and biodiversity for sustaining wealthgenerating capabilities 20% of our GDP comes from the top 15 cm of soil Our farming systems are financially and environmentally brittle. 400 Nitrogen fertiliser tonnes 1000 per year Phosphate fertiliser Parliamentary Commissioner for the Environment November

5 The First Step in Scaling Up: Measurement at the Point Rootzone Rootzone mm mm mm mm mm mm 50 50mm mm Wick Wick LL mm mm mm mm mm mm A network of over 350 fluxmeters in Australasia & Oceania

6 Better Vision of Local Processes: State & Fluxes Soil Water Dynamics: Potatoes θ θ mm 200 mm 150 mm 150 mm 50 mm 50 mm Wick WickLL mm mm 0 Jan Feb Mar Apr May Drainage & Leaching: Potatoes High High kg-n/ha kg-n/ha Low 100 kg-n/ha Low 100 kg-n/ha Nov Dec Jan Mar Apr May 1000 mm 1000 mm Fluxmeters Jun 150 mm 150 mm Jun Drainage, mm Rootzone 500 mm Rootzone 500 mm Rainfall [mm] Nitrate [mg/l]/10 Rainfall, mm Nitrate, mg/l ( 10) 0 Dec Drainage [mm] Rainfall, mm Rainfall [mm] θ0-30 Soil water, θ m3 m TDR technology 0.5 Soil water [L/L] 20

7 Measuring & Modelling under Dairy Pasture - Taupo 1500 Cumulative drainage [mm] Modelled drainage Fluxmeters n =30 Cumulative nitrate leached [kg/ha] Jan/07 Apr/07 Aug/07 Nov/07 Feb/08 Jun/08 Sep/08 Dec/08 Mar/09 Jul/09 Modelled N leaching Jan/07 Apr/07 Aug/07 Nov/07 Feb/08 Jun/08 Sep/08 Dec/08 Mar/09 Jul/09 Pumice soil & high rainfall Forty five farmer-owned fluxmeters emptied monthly Leaching more variable then drainage Modelling successful & includes urine spots Upscaling from the point to the farm

8 Soluble Inorganic Nitrogen, g m-3 Looking in the River: Comprehensive Data Manawatu Hopelands River Flow, m3/s ANZEEC Lowland River Standard = g-n m-3 From Data on Concentration & Flows: Modelled Median Load: 745 tonne-n/yr River N-Load is Twice ANZECC Standard!

9 The Challenge: Linking Farm to River Percentage N delivered Alexander et al. (2002) SPARROW Spatially Referenced Regression on Watershed Attributes Fi Nutrient flux in body i Sn,j Mass contribution from source n in water body j exp(- Zj) Proportion delivered to j from landscape Zj - Soil drainage index Soil index : Significant - statistically Loss % Lower Waikato Upper Waikato Taupo Waipa Inverse statistical relation between stream N flux & soil permeability

10 CLUES Catchment Land Use for Environmental Sustainability But Sn is dynamic Best management practices will change Sn And Sn is knowable by measurement & modelling The challenge is here! Elliot et al., (2011)

11 The Challenge On-farm Modelling Landscape Attenuation TRC In-river Modelling

12 Policy to Manage Nutrients in Catchments: Two Case Studies Lake Taupo Horizons Regional Council

13 Lake Taupo Lake Taupo is in trouble The jewel of the North Island is becoming tarnished Some 93% of the Lake s N comes from farming The Regional Council adopted the option: Maintain water quality Reduce existing load Prevent further intensification

14 Policy Adopted: Benchmark, Cap & Trade Regional Plan Variation 5 RPV5 Council adoption March 2007 Environment Court November 2008 Confirmed 17th June 2011 Council adoption 29th June 2011 Operational 7th July 2011 RPV5 Fourteen Policies. Farming a controlled activity 3. Benchmark ( ), Capping by a Nutrient Discharge Allowance 4. Reduce N outputs by 20% 12. Public Fund ($80 M) for permanent land use change through purchase of land and buy-out of N allowances 14. Nitrogen trading for reductions with cap

15 The Manawatu River: A shared natural capital asset

16 Non-point Source Pollution by Agriculture Horizons asked What are best practice acceptable nutrient losses from farms in these WMZs? Fourteen key Water Management Zones

17 Water Quality & Land Use: Modelling for Policy Development Weber Road: Dominated by sheep/beef; some dairy Hopelands: Dominated by dairy, and sheep/beef QW Q H QW qd Ad W q sb Asb W q f A f W qc Ac W qd Ad H W qsb Asb H W q f A f H W qc Ac H W D

18 Modelling the Link: Water Quality - Land Management Weber Road: Dominated by sheep/beef; some dairy Hopelands: Dominated by dairy, and sheep/beef Area of farm-type The impact of farm practices modelled Q d O 1 Ld Ad sb O Lsb Asb 1 Farm leakage modelled by Overseer River water quality Farm-to-river transmission

19 What are the policy options? Cap inputs to limit nutrient losses - A blunt &obvious instrument. Limit nutrient losses from intensive land uses, restrict require mitigations intensification, Limit nutrient-loss for every hectare, regardless of productive capacity Allocate nutrient-loss rights based on natural capital value.

20 A Nutrient-Loss Limit based on Natural Capital Attainable potential livestock carrying capacity is an ecosystem service noted in the Land Use Capability Classification Capability Classes Nitrate leaching lossland byuseluc class N loss (kgn/ha) I II III IV V VI VII LUC class Land Use Capability (LUC) Class is a proxy for Natural Capital

21 Merits of the Natural-Capital Approach Land Use Capability Classes Whole catchment Values the soils natural capital & services Strategic use of the landscape s biophysical resources Not prescriptive & encourages innovation Does not target a land use, intensity, or production Focuses on emissions Focus on outcomes - not inputs Provides future certainty Engagement with community in target setting

22 May 2007: One Plan Notified Intensive farming requires a Resource Consent Schedule J Many submissions lodged!

23 Hearings in early 2010 Decisions in late The LUC approach is not efficient, nor effective, for existing intensive dairying as it is: not based on new technology inequitable & impractical not affordable lacks scientific robustness 5. The LUC approach should apply to dairy conversions as an appropriate precautionary measure The Commissioners set & answered 7 questions

24 Natural Capital in (Amended) Policy Policy 13-2C new dairy farming land must not exceed nitrogen leaching rates based on the natural capital of each LUC class used for dairy farming LUC can used as a proxy for Natural Capital for dairy conversion

25 What Rules then for Existing Intensive Dairying? Rule 13-1 Existing dairy farming land A controlled activity A nutrient management plan must be prepared & provided annually Implementation of reasonably practicable farm management practices for minimising nutrient leaching. Whereas what constitutes a nutrient management plan is defined, there is no definition of either reasonable, nor what is minimal Not surprisingly, given no caps or discharge allowances, this has been appealled by both conservation groups & the farming community. Mediation is underway. Appeal to the Environment Court likely Back to Square One Acceptable Rates! Science is just one player in the policy & regulatory space

26 Possible Non-Regulatory Interventions Soil Natural Capital: The soil stocks of natural materials & energy Ecosystem Services: Policy, Practice & Payment Soil Ecosystem Services: The beneficial flows of goods between natural capital stocks, or soil stocks & humans Footprinting: Eco-verification in the Market Place

27 Value of Ecosystem Services: Dairy Farms in the Waikato Six farm types on Horotiu soil Provisioning Regulating Six farm types on Te Kowhai soil Regulating > 2 times Provisioning From Dominati, Mackay, Green & Patterson (2011)

28 Farms of the Future Some 58% of revenue from payments for ecosystem services

29 We still need to eat. Yet it seems there s a lot of water used in the products we eat (& wear)

30 Three water-colours: Virtual water = green + blue + grey waters Irrigation Evaporation If the soil store runs out, blue water can be used for irrigation Soils leak agrichemicals creating grey water Soil, the green water store captures rainfall which is transpired, or lost as drainage. Leaching

31 The Grey Water Footprint of a Tray of Kiwifruit GreyWFP Effl ( ceffl cnat ) ( ccrit cnat ) Yield Background c is Limit c is Leachate c is Drainage is cnat ccrit ceffl Effl Cnat=0; Ccrit=11.3 A tray of kiwifruit 33 kiwifruit ceffl

32 Appealing to a Discerning & Premium-Paying Consumer Supermarket chains: The new regulators & choice editors

33 Catchment Ecosystem Services Sustaining Returns on Investment into Natural Capital