Lessons learnt from the dairying Accounting for Nutrients project Warwick Dougherty

Drivers of refined nutrient management Reef Rescue package WA Fertiliser Action Plan Societal expectations

Australian dairy industry increasingly reliant on: –purchased feed –nitrogen fertiliser Nutrients in Australian dairy – a paradigm shift Current and future challenges Infrastructure and innovation

Feed Fertilizer Animals Bedding N fixation Precipitation Crops Silage, hay Animals Manure Milk Irrigation Dairy cows ManurePasture / crops Soil Manure INPUTS OUTPUTS RunoffGaseousLeachingSoil accumulation LOSSES Within - Farm Seed Farm gate nutrient balance = Inputs minus outputs

Feed Fertilizer Animals Bedding N fixation Precipitation Crops Silage, hay Animals Manure Milk Irrigation Dairy cows ManurePasture / crops Soil Manure INPUTS OUTPUTS RunoffGaseousLeachingSoil accumulation LOSSES Within - Farm Seed Farm system nutrient balance

Accounting for Nutrients on Australian Dairy Farms Improve our understanding of nutrient flows, transformations, use efficiencies‘, balances, and potential losses on Australian dairy farms. Define standard methodologies and processes for undertaking nutrient accounting 44 dairy farms reflecting the diversity of production systems

Quarterly farm visits Sampling: feed, milk, manure Cows in Space and Time Farmer diaries Feed purchases, fertiliser, etc Daily records of cow locations Special farm visits Effluent applications, soil sampling, legume sampling.

= 351  101 = 101 ÷ 351

Variation in balance and efficiency

Variation in balance and efficiency 32

1. Do farms that have a higher reliance on imported feed have higher N surpluses? Are there particular farm characteristics that influence nitrogen surpluses and whole-farm efficiency?

Are farms that have higher stocking rates more efficient at using nitrogen?

Are farms that have higher production per ha more efficient at using nitrogen?

Nutrient balance and efficiency in vegetable production systems NPNP Balance (kg/ha/yr)Efficiency (%) Wells et al Chan et al. 2010– –6-10 Ovens et al. 2008~200~80~69~8

Nutrient balance and environmental impact ? Wells et al 2000

Manure capture: Milking, housing, feeding systems Nitrogen transformation inhibitors Optimum soil conditions to reduce nutrient loss Rates, timing and placement of fertilisers & effluent Dairy cows ManurePasture / crops Soil RunoffGaseousLeachingSoil accumulation Milk Crop and pasture selection Manure deposition: non- collected, non-productive areas High fertility areas Lower minerals in feed supplement Diet additives and manipulation Animal Selection Reduce inputs Modified fertilisers Nutrient balances inform management

Conclusions Nutrient surpluses of N (& P & K & S) are potentially high to very high on most dairy farms  Median N surplus is 226, but ranged from 40 – 600 kg N/ha  1 litre of milk = 14 g of N lost to the broader environment Median N use efficiency on Australian dairy farms is 28%, but ranged from 14 – 50%. Modelling of N surpluses suggest that loss pathways are highly dependant on the mgt system, soil & climate conditions Generic opportunities to increase N use efficiency  Reduce fertiliser N, (P, K, S) inputs  Rates, timing and placement of fertilisers & effluent  Greater capture, reuse and redistribution of excreted nutrients  Reducing feed nutrient intakes, reducing excreta concentrations

Lessons for the vegetable industry Need to clearly define objectives Nutrient balance provides data/information but not the answer Nutrient balances are not environmental predictors Spatial definition is critical Temporal definition is important – particularly for P Need standard and comprehensive methods Need benchmarking data – what is acceptable ? Nutrient balances can be powerful source of farm and industry information