Timothy HugginsMSLE, The University of Melbourne

Is it commercially viable to use dicyandiamide on a dairy farm in south-western Victoria?

Co-authors: Kevin Kelly (DPIV), Helen Suter (UoM), Richard Eckard (UoM & DPIV), Richard Rawnsley (TIAR)

Short answer

No. Not at this stage.

Outline

• Aims and objectives

• Background

• Dairy Greenhouse Accounting Framework

• Average south-western Victorian farm

• Results

• Summary and conclusions

Aims and objectives

• Decreased nitrous oxide emissions

• Increased pasture dry matter grown

• Economically feasible

• Barriers to adoption

Nitrous oxide

Dairy6.5 t CO2e/cow10.2 t CO2e/ha

CH4 - Enteric74%

CH4 - Effluent ponds

1%

N2O - Effluent ponds

0%

N2O - N Fertiliser

4%

N2O - Indirect11%

N2O - Dung, Urine & Spread

10%

Adapted from Eckard 2008and Christie 2009

• N2O = 4% of Australia’s GHG emissions

•Predominantly produced by agriculture – 86%

•Major sources are N fertiliser management, animal waste management, and soil cultivation

•Also need to include indirect production (N03

- leaching, run-off and NH4

+ volatilisation)

The power of urine

• Animal urine accounts for 2/3 of the N2O from animal production•Urine patch = approx. 1000 kg N/ha equivalent•Urine patches cover 10-30% of farm in 12 months•Eg. If urine covers 20% of farm at 1000 kg N/ha = 200 kg N/ha on top of 106 kg N applied.•Can be huge excess of N in soil available for N2O production – distribution issue

DCD, nitrous oxide, and the N cycle

NH2OH

• NO3- can be lost

through leaching or as nitrous oxide• Indirect losses also reduced • DCD lifespan depends on soil T, moisture, pH, O.M.• Nitrosomonas goes back to work after 2-3 months•10 kg a.i. Applied twice per year

Dairy Greenhouse Accounting Framework

• Based on Australian National Greenhouse Gas Inventory methods

• Farm Monitor Project (DPIV), Dairy Situation and Outlook Report (DA)

DMD = 78% CP = 23% DM

Source: Australian Methodology for the Estimation of Greenhouse Gas Emissions and Sinks 2006

Average south-western Victorian dairy farm

Herd size 281 cowsMilking area 179 hectaresStocking rate 1.57 cows/hectareAverage production (L) 6200 L per cowAverage production (kg MS) 469 kg MS per cowConcentrates fed 1.3 t DM per cowConserved fodder 1.5 t DM per cowPasture 2.8 t DM per cowPasture grown 7.3 t DM per hectarekg MS/kg DMI 0.08 kg MS/kg DMIN fertiliser used 106 kg N per hectare

Also included 25% >12 months, 20% < 12 months and 3 bulls

Average south-western Victorian dairy farm (FY 09/10)

Results

•Cost of DCD application $165/ha

•2 options to cover this cost•Reduction in nitrous oxide ($4.80/ha)

•Increase in pasture DM ($70-100/ha)

•Total return approx. $105/ha

•Nett result: $165 - $105 = -$60/ha

•More detail....

Reducing nitrous oxide - C trading pays

Increasing pasture dry matter – milk pays

What is possible?• Likely response 0-35% increase from 2 applications (de Klein

and Eckard, 2008)• Eco-N (Ravensdown) advertised as 20% increase = 560 kg DM

in our case (7.6% across paddock)• 560 kg DM = 48 kg MS (0.08 kg MS/kg DMI)• 48 kg MS = $216/ha @ $4.95/kg MS• Nett return = $216 - $165 = $50/ha• BUT... we know that there could be issues with:

– Utilisation (not 100%, probably 60-70% but what about substitution?)– Extra costs associated with turning that pasture into milk (look at marginal

response per litre)

Our trial

• 6 commercial dairy farms in South-west Vic (range in soil, temperature and rainfall)

• Spring (2009) and Autumn (2010) applications• Control vs Urine either at start or 1 month later – all

repeated with and without DCD (6 treatments in total)

• Autumn 2010 schedule:– T1. Nil urine applied.– T2. Nil urine applied + DCD applied April.– T3. Urine applied May.– T4. DCD applied April, Urine applied May.– T5. Urine applied April.– T6. Urine + DCD applied April.

• 4 replicates of each treatment in RCBD, excised from grazing

• Soil testing, nitrous oxide measurements, pasture DM harvesting

Increasing pasture dry matter – our results

What did we find?• 0-15% increase in pasture DM in urine patches• 3 farms in each season with significant increases (but not the

same 3) and mostly in response to the urine at the start• Farms with significant results all had different soil types, rainfall

patterns and N fertiliser usage (background N would be different)

• Only in the second season was there an increase from DCD on control = idea of what happens between urine patches. This farm applied 266 kg N during the season – potential DCD impact on the fertiliser

• Across the whole paddock result = 2.5-3.75% increase in pasture DM (180-270 kg DM/ha)

• Nett return of $70-$100 per hectare without considering additional costs and assuming 100% utilisation

Summary and conclusions

• None of the potential benefits are big enough at this stage – need to show improvement in production/profitability

• Factors that would increase viability– Future research showing larger increases in pasture DM– Increased fertiliser price– Reduced DCD price– Need ETS rather than a C price

© Copyright The University of Melbourne 2008