Having data at his fingertips has held Central Hawke’s Bay farmer Murray Howarth in good stead, as he pursues his goal of converting his sheep and beef farm to dairy.
The Hawke’s Bay Regional Council’s proposed legislation – known as Plan Change 6 – to limit leaching losses for farms in the Tukituki River catchment, will affect all farms in the area including Howarth’s 200ha (effective) property.
A family farm
Howarth’s son Steve previously worked as a senior technical specialist at Farmax and has been modelling the family farm and forecasting the various outcomes, using Farmax and OVERSEER.
“My great great grandfather settled on the property in the 1870s and my parents began with a lease in 1985,” tells Steve.
“We are running a mix of sheep, bulls, dairy heifers and winter cows on flat to rolling country. We run 700 ewes, weaning 160 per cent lambs, finishing most of them.
“We also have a flexible bull policy buying calves in the spring and store bulls for their second winter.
“The dairy heifers are on a May to May contract, putting on about 230kg LW over that period. Winter cows are a new addition to our operation. They are wintered on kale and returned to the farmer before calving."
Working with legislation
Steve says the medium-term goals for the farm are to improve profitability, increase the cattle ratio and reduce labour input. To achieve that, there is an ongoing drainage/cultivation/cropping and pasture improvement programme.
“We were concerned about Plan Change 6 and how it would impact on these goals. It is generally recognised that increasing cattle numbers or converting to a dairy farm will increase the nitrogen and phosphorous losses,” said Steve.
“To quantify the impact, we created a model of the current farm system and performance in both Farmax and OVERSEER and this baseline reflects the actual grass production.
“From this base we can then model alternative policies including more cattle or full dairy conversion.”
Modelling the outcomes
For those alternatives, Steve said Farmax was used to quantify the feasibility, i.e. the feed budget and profitability, while OVERSEER quantified the environmental impact around the nitrogen and phosphorus losses.
He said the first round of proposed legislation used a grand parenting scheme which meant farms would be benchmarked on their current nutrient losses and couldn’t exceed that going forward.
However the commission of enquiry recommended the implementation of a Land Use Classification (LUC) system, and this was a major change.
The LUC looks at the natural characteristics of the soil and its capability to sustain different types of land uses. These classifications are based on soil maps across New Zealand and are freely available (check the website out at https://lris.scinfo.org.nz/layer/76-nzlri-land-use-capability/).
“This was important for us because under Plan Change 6 the leaching allowances vary based on soil class. From the maps we were able to quantify what the acceptable losses were for the whole farm and compare this with the predictions from OVERSEER.
“A number of different farming systems have been modelled and the profitability and leaching losses quantified, also checking that the proposed system is compliant with plan change 6.”
Steve said the results only pertain to the Howarth farm as each property has a different mix of land classes and rainfall.
“The story hasn’t finished yet but having Farmax and OVERSEER at our disposal has allowed us to put real numbers behind proposals and to look at the feasibility of farming systems for the future.”