MITIGATION OPTIONS AgResearch Invermay Richard Muirhead Ross Monaghan
MITIGATIONS Source + Transport Mechanism = Contaminants in Water Fertilizer Rain + = Losses to Water
HYDROLOGY 101 Rain Contaminant sources Overland flow Infiltration excess Erosion of particulates Release of Infiltration & dissolved saturation excess contaminants Effective depth overland flow Mole Deposition of interaction network Percolation (leaching) Drainage Ground water Variable source area Subsurface flow
SELECTING APPROPRIATE MITIGATION OPTIONS Value Contaminant Mitigation Attribute Stream Health Swimming E. coli fencing Risk Stream Swimming Sediment Clarity fencing Farm Fishing dairy Ammonia Fish health effluent
CALCULATING THE EFFECTIVENESS OF MULTIPLE MITIGATION OPTIONS Farm Dairy Effluent (FDE) –
EFFLUENT – TRAVELLING IRRIGATORS
EFFLUENT LEAKAGE THROUGH DRAINS Trench Macropores soil 450 mm 600 mm Gravel Mole drain backfill Intercepting pipe drain
IMPROVED DAIRY EFFLUENT MGMT Low rate applicators • Low application rate and low depth • Filtration effect
CALCULATING THE EFFECTIVENESS OF MULTIPLE MITIGATION OPTIONS Farm Dairy Effluent (FDE) – 9% reduction in N Off paddock wintering system –
CALCULATING THE EFFECTIVENESS OF MULTIPLE MITIGATION OPTIONS Farm Dairy Effluent (FDE) – 9% reduction in N Off paddock wintering system – 30 % reduction in N But both < 39% Environmental models – such as OVERSEER – take all of these factors into account
CALCULATING THE COST ‐ EFFECTIVENESS OF MITIGATIONS From the same example Cost of new FDE system will be greater with a off ‐ paddock system than without Other factors Increase debt Increase production to maintain profit Increase feed supply… OVERSEER Farmax
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