By Delwyn Dickey
The results are in for the first year of a four-year trial at the Northland Agricultural Research Farm (NARF) at Dargaville, looking at three future farming systems as the north warms up and becomes more prone to droughts.
The three different farming systems are looking at performance using alternative pastures, reducing emissions on a traditional ryegrass-based farm, and the farming system recently highlighted in their previous trial as being the most profitable, being used as the control.
Run by the Northland Dairy Development Trust (NDDT) the research farm is split into three 28-hectare farmlets, with milk from the different farms collected separately.
- The current/control farm – uses ryegrass and kikuyu pasture, with imported feed – palm kernel expeller (PKE) to fill feed deficits before milk fat evaluation index (FEI) limits are reached, with a stocking rate of three cows per hectare, with up to 190kg of applied nitrogen per hectare. Research from the previous four-year research showed this system was the most profitable.
- The alternative pastures farm has at least 75% of fescue, cocksfoot, legumes and herbs pasture, and also uses palm kernel to make up feed deficits. Stocking rates are also three cows per hectare and up to 190kg of applied nitrogen per hectare.
- Fonterra is providing funding to monitor if there is a difference in milk quality and composition.
- The low emissions farm: This system uses existing ryegrass and kikuyu farm pasture and targeted a 25% reduction in methane emissions and a 50% reduction in nitrous oxide emissions (compared to the current farm). The stocking rate was dropped to 2.1 cows per hectare, with no nitrogen application.
Low emissions farm
Using the Overseer model, the low emissions farm reduced methane compared to the current farm by 33% and nitrous oxide by 47%. There was also an 84% reduction in input CO2, and 9% CO2 reduction per kilogram of milk solids.
There was little feed quality difference in this farm compared to the current farm and there were some unexpected gains with pasture growth not down as much as expected despite no applied nitrogen, likely because of the high nitrogen-fixing clover counts in the pasture, and relatively longer grazing rotation with a somewhat too conservative stocking rate. This also had knock-on effect with some of the results including seeing more silage able to be made, eliminating the need for imported supplements.
Crude protein levels were lower during late winter/spring and saw lower milk production at this time compared to other farms.
Clover was almost twice as high on this farm – between 40% and 50% of pasture during spring compared to the current farm.
Mating results were similar between farms although this farm had a 3% empty rate compared to 11% on the current farm.
But overall, the farm had the lowest milk production on the three farms at 794kg milksolids (MS)/ha or 370kg MS/cow compared to the highest on the current farm with 1284kg MS/ha or 409kg/cow.
Financial analysis using the $9.30/kg MS milk price, with the low milk production saw this farm significantly dropping profit, with an operation profit of $3021/ha compared to the current farm at $5040/ha.
The milk price would have to drop to about $5.00/kg MS before this farm stopped being the least profitable.
Even if the significantly higher cost of nitrogen at the moment remained at $1340/tonne delivered, this farm would still be significantly less profitable than the other two.
The cost of reducing emissions through reducing stocking rate and removing nitrogen application and imported supplements was significant.
The pricing mechanism to encourage farmers to reduce emission has yet to be confirmed, however it is unlikely the emissions pricing will be high enough to compensate for the significant loss in profit shown in this study, researchers found.
Alternative pastures farm
Many farmers in the north are turning to tall fescue and cocksfoot pasture as ryegrass struggles to persist in the dry and heat of the warmer months. Alternative pastures also strongly resists kikuyu reinvasion compared to the three years currently seen with kikuyu and ryegrass pasture.
To get this farm up and running by the trial start in June 2021, 9ha was sown in May 2020 with combinations of fescue, or fescue and cocksfoot, with white, red and Persian clover.
Another 11.6ha was sown in March 2021 with either fescue, or fescue and cocksfoot, or cocksfoot with white clover, red clover, and 1kg/ha chicory.
While the pastures sown in 2020 established very well, establishment on the pastures sown in 2021 was varied and in some areas poor. This was mainly due to competition from poa annua. As a result, 4.2ha was resown in autumn 2022.
In some respects this puts the alternative farm at a disadvantage as the kikuyu and Italian ryegrass pasture on the other two farms is mature and well established.
Pasture feed quality was higher for the alternative farm through the year except for spring. This is likely down to chicory in the pasture becoming dominant over summer and autumn. The chicory is also likely behind the highest levels of protein seen in this trial over these seasons.
Pasture cover for this farm was significantly down from late spring to autumn.
About 800kg DM/cow of supplement was used by both this farm and the current farm.
Milk production was somewhat down compared to the current farm at 1213kg MS/ha and 397kg/cow but well above the low emissions farm.
Financial analysis also saw the farm slightly behind the current farm at $4780/ha operating profit.
Emissions were slightly down on this farm compared to the current farm but methane emissions were about a third higher than the low emission farm and nitrous oxide twice as much.
Results from next year once the alternative pasture has established better may well give a better representation of performance, particularly compared to the current farm.
Current farm
This farm kept its position as having the highest milk production at 1284kg MS/ha as well as being the most profitable with $5040 operating profit/ha.
It has 70% kikuyu with mulching each autumn and drilled with Italian ryegrass.
The 190 kg allowance of nitrogen/ha saw 1376kg DM/ha more than the low emission farm. With three more years of this study to run, the farming systems will be tested over different climatic conditions and will show if any of these effects – like the presence of clover – compound over time.
Stocking rates on the Low Emissions farm will increase by 0.15 cows/ha in this coming season.
Full results can be found at www.nddt.nz under current trials Future Farm Systems Financial Results year 1.
The project is funded by DairyNZ, MPI (Sustainable Farming Fund) and Hine Rangi Trust.
