1. Timothy Huggins MSLE, 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)

2. Decreased nitrous oxide emissions Increased pasture dry matter grown
Aims and objectives
Decreased nitrous oxide emissions
Increased pasture dry matter grown
Economically feasible
Barriers to adoption

3. N2O = 4% of Australia’s GHG emissions
Nitrous oxide
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)
Dairy
6.5 t CO2e/cow
10.2 t CO2e/ha
Adapted from Eckard 2008
and Christie 2009

4. Animal urine accounts for 2/3 of the N2O from animal production
The power of urine
Animal urine accounts for 2/3 of the N2O from animal production
Urine patch = approx 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

5. DCD, nitrous oxide, and the N cycle
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
NH2OH

6. 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 across the farm = 1.46 t DM/ha. If we take it only in urine patches = 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 = $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)

7. Spring (2009) and Autumn (2010) applications
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

8. 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 = % increase in pasture DM ( kg DM/ha)
Nett return of $70-$100 per hectare without considering additional costs and assuming 100% utilisation

9. 2 treatments – DCD or nothing with 35 reps of each
Current grazing trial
70 plots of 10 x 10 m
2 treatments – DCD or nothing with 35 reps of each
Graze, then apply DCD in May and August (3 months apart) followed by a 100 kg application of urea
Measure pasture available before and after grazing with Ellinbank Plate Meter
Soil testing

10. 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

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