The Waikato-based Scott Farm project comes to an end in February after four seasons of trialling a “current” stocked 13ha farmlet against a “future” farm operation (see table for farmlet details).
The project’s aim was to increase average milk production per hectare by 200kg MS, increase profit, and reduce nitrogen losses from an average of 45kg/ha/year, to 20-30kg N/ha/year.
Data for the first three years indicates the trial had mixed success in achieving its goals.
Project lead scientist Kevin Macdonald said comparisons between the two farmlets in terms of milksolids production had the two systems running close. The current farm yielded an average production of 1186kg MS/ha, against the future farm’s production of 1158kg MS.
Macdonald said the challenge for achieving the increased production was made more difficult by having to achieve those gains against a current farmlet that was already operating at a high level of efficiency, achieving 1150kg MS/ha against the Waikato average of 1051/ha.
Profit levels also tracked closely between the two farmlets, with the future farm’s operating profit averaging $4080/ha, only 5% less than the current farm.
However, the targeted nitrogen losses were achieved. Ceramic cup collection and analysis of nitrate losses between the two farms recorded significant declines in losses, of 56% and 43% over 2013 and 2014 in nitrate leached from the future farm, compared with the current.
This reflected the lower stocking rate (2.6 cows/ha versus 3.2), and the lower nitrogen inputs, with the current farm receiving 137kg N/ha, compared to only 46kg N/ha on the future farm.
The future farm also recorded lower drymatter growth levels. These averaged 1.6 tonnes drymatter (DM)/ha/year less over the three years, attributed largely to the lower nitrogen inputs.
But total intake per cow in the future herd was 14% greater than that of cows on the current herd, resulting in an extra 75kg MS/cow which helped compensate for the lower drymatter grown and eaten per ha. Drymatter intake was 5.1t DM/cow/year on the current farm, compared with 5.8t DM/cow/year on the future farm.
Supplement levels on the future farm included maize grain, fed to help reduce nitrate losses from the herd.
“This also proved quite an expensive input, but one that did have a level of convenience with it, given its ease of storage, compared with maize silage where you may be required to seal the stack again, and ensure quality is maintained,” Macdonald said.
Holding cows off paddocks for extended periods required a woodchip-based pad, draining into the farmlet’s effluent system.
“This came with costs in terms of both time and money.”
The pad attracted an annual cost to the farmlet of $202/ha, of which $130 was maintenance and $72 was depreciation expenses. Maintenance of the pad was significant because of the time the herd spent on it.
Typically, cows would be stood off from March after the morning milking and would graze only after the evening milking. Once dried off they would be on the pad for 16-17 hours a day.
“The design and management of the pad becomes critical, and often supplement will also be fed on it. As a design, however, with lining and woodchip it is one of the cheaper, more practical options open to farmers, and it is scalable from the farmlet design to a commercial herd size.”
While the future of the Scott Farm project is still to be determined, researchers have come away with some useful insights to nitrogen, stocking rate and feed interactions.
The lower nitrogen losses have been a practical confirmation of work that had until then been based on modelling. The trial also highlighted the cost of standing pad construction and maintenance, and additional factors such as cow movement to and from the pad.
DairyNZ lead scientist Chris Glassey said a lowered payout environment should also give farmers pause for thought not only about how much the bottom 10% of their herd was contributing to profit or loss, but also the additional nitrogen load those herd members bought.
“The last few tonnes of nitrogen that is circulating because they are there is like another cost, on top of their lack of profitability.”
