OVERSEER® Nutrient Management Tool: Present and future perspectives Waikato Regional Council Presentation 25 October 2012 Philip Mladenov Chief Executive

Contents What is OVERSEER®? What does it do? How well does it do it? How is it being used? OVERSEER® and regulation Next steps

What is OVERSEER®?

A short history OVERSEER® started as a simple nutrient budgeting model linked to fertiliser advice 15 years / $15 million invested Today OVERSEER® is a sophisticated nutrient management and decision support platform Key backers – The fertiliser industry (Fertiliser Association of New Zealand) – Government (Ministry of Primary Industries) – Science (AgResearch)

OVERSEER® is based on real data “Data based” model (empirical) Based on real data on nutrient flows on farms Designed for New Zealand conditions and farm systems Long-term equilibrium model – outputs reflect average processes over time Continually evolving and improving

OVERSEER® 6 – The latest version Improvements based on user feedback Better science and data Handles farming systems better – Single enterprise model (integrates pastoral, cropping and irrigated farming systems) – Better options for managing supplements – Handles differential grazing – Extended effluent management options Modern software

What does OVERSEER® do?

OVERSEER® estimates the flow and fate of nutrients Models the flow of nutrients (N,P, K, S, Ca, Mg, Na) on a range of farming systems (for each block and the whole farm) Estimates diffuse losses to the environment – Amount of nitrogen leaching from the root zone – Risk of phosphorus loss – Amount of greenhouse gas emissions

Nutrient outputs (N and P) Leaching and run off (from root zone / farm boundary)

OVERSEER® Nutrient Budget An irrigated dairy farm with shallow stony soils

OVERSEER® Nutrient Budget A semi-intensive hill country breeding / finishing sheep and beef farm

OVERSEER® Nutrient Budget A dryland wheat farm with silty clay loam, high current Olsen P levels, straw baled and removed, stubble residues burnt

OVERSEER® Nutrient Budget A block of potatoes with silt loam over a stony matrix at 0.1 – 0.2m, high Olsen P (45) and high fertiliser P inputs

OVERSEER® is output focused Inputs Fertiliser Feed Stocking rate Outputs Nitrate and phosphate Input versus output management of diffuse agricultural discharges for water quality

OVERSEER® is practical and cost effective Can estimate diffuse discharges by measurement (lysimeters) – Hundreds of thousands of dollars per farm Can estimate diffuse discharges by modeling (OVERSEER®) – At a marginal cost

How well does OVERSEER® work?

Accuracy of OVERSEER® Often quoted that “OVERSEER® is +/- 20% or 30% accurate” – What does this really mean? Accuracy is best assessed by comparing model output with real ‘unseen’ observations → validation

Validation N leaching from farmlet comparisons Farmlets centred around key centres (Waikato, Manawatu and Southland)

P losses Background P Risk Annual P Loss (kg P/ha/yr) y = 0.99x R 2 = 0.96

Accuracy over time (8 years)

OVERSEER® is valid OVERSEER® provides valid estimates of average N loss over time - Provided: – Inputted data are accurate – Default values used are reasonable (e.g. average rainfall data for the sub-region) – Standard best practice is followed on the farm – Used by a properly qualified person

How is OVERSEER® used?

Uses of OVERSEER® Calculate maintenance fertiliser and lime requirements Develop Nutrient Management Plans – Includes environmental risk and mitigation options Calculate effects of farm management scenarios on N, P and GHG discharge / emissions Benchmarking and reporting tool Contribute information to catchment modeling (e.g. CLUES) For consenting / regulatory purposes

OVERSEER® use as a nutrient management tool is growing rapidly 80% of all dairy farms have a nutrient budget – 56% have nutrient management plans About 700 sheep and beef farms have a nutrient budget – About 300 have nutrient management plans About 46% of all nutrients applied to land managed through nutrient management plans About 950,000 ha of intensively farmed land with a nutrient management plan

OVERSEER® and regulation

Drivers of regulatory use Intense interest in managing water quality – NPS-FW, LaWF, public scrutiny Managing agricultural growth within limits a key issue Best tool available Allows output, effects based approaches Not surprisingly, growing regional council interest in the tool

Where is OVERSEER® being used for regulation? Waikato Regional Council – Used to set N limits and allocate NDAs for Lake Taupo catchment Otago Regional Council – Proposed to use to estimate N discharges against N discharge limits (10, 20 or 30 kg N/ha/yr) Environment Southland – Used to develop nutrient management plans to enhance GMP uptake as a requirement for a new dairy farm conversion Bay of Plenty – Used to set benchmarks and track farm level changes (N and P) for Rotorua Lakes Horizons – Used as a reporting tool to meet specified N leaching maximums set by LUC for sensitive catchments ECAN – Industry called upon to set discharge limits and OVERSEER® would be the tool of choice to monitor against these limits

Next steps

What is needed for OVERSEER® to be a robust regulatory tool? Standards, rules and protocols (national guidance) Ongoing funding for model maintenance and development (core and supplementary) More data for calibration and validation for more farm systems Enhanced delivery model Improved stakeholder involvement Certification of nutrient management advisors Third party audit of input parameters

Certification

Potential OVERSEER® governance and delivery structure 1. HortNZ, FAR, Federated Farmers, Beef + Lamb, Deer Industry, Irrigation New Zealand, New Zealand Pork, DairyNZ, regional councils, etc. Owners: Ministry of Primary Industries, AgResearch and the Fertiliser Association of New Zealand Science and Expert User Panels Stakeholder Advisory Group 1 Providers Contractual Agreements

Thank you