A Pastoral 21 Project on Sustainable Dairying

The Pastoral 21 programme on Scott Farm is a collaborative venture between DairyNZ, the Ministry of Business, Innovation and Employment (MBIE), Beef + Lamb New Zealand, Fonterra and the Dairy Companies Association of New Zealand (DCANZ). The research is led by AgResearch.

Over the last five years the project has centered on four regionally-focused trials in the Waikato, Manawatu, Canterbury and South Otago. The aim is to show how farmers can reduce losses of nitrogen (N), phosphorus (P) and sediment.

Each regional project has a slightly different approach, but overall Pastoral 21 applies three central principles to reducing nutrient loss. These principles are decreasing N inputs, capturing urinary N and managing critical source areas.

The Pastoral 21 farm system research is taking place at Scott Farm in Hamilton, Massey University in Palmerston North, Lincoln University Research Dairy Farm and Ashley Dene Farm in Lincoln, and Telford Farm near Balclutha. The whole point of those farmlets is that they are in four key dairy producing areas, therefore the system is adapted specifically to how that region farms.

The study at DairyNZs Scott Farm in Hamilton aims to show what a future Waikato farm could look like if it used high breeding worth cows (on this trial theyre called future cows) and a different management approach.

Senior scientist at DairyNZ, Kevin Macdonald says the key question was can a farm system achieve high profitability and high efficiency while lowering the farm nutrient footprint.

Before the project started, computer modelling helped determine the best combination of system components - supplements, stocking rates, higher per cow yield, reduced replacement rates and greater pasture diversity.

The Waikato study started in June 2011. It has compared two 13ha farmlets, labelled the current and future farmlets.

The current farmlet represents a typical Waikato farm, with a stocking rate of 3.2 cows/ha. The other, with a stocking rate of 2.6 cows/ha, represents an option for the future.

The future farmlet has higher breeding worth (BW) and production worth (PW) cows, a lower replacement rate and lower N fertiliser input.

The herd is also offered up to 3 kg DM/cow/day of grain, to improve the energy intake when pasture growth or pasture quality is low.

Cows on the future farmlet are also stood off pasture for between eight and sixteen hours per day from March until July to reduce urine patches on pasture and protect pastures. The cows on the current farmlet are only stood off pasture in wet conditions.

Fertiliser inputs were up to 150 kg N/ha on the current farm and up to 50kg N/ha on the future farm.

There were two strategies to reduce N leaching lowered inputs and standing cows off pasture. Kevin says AgResearch was also involved in urine patch modelling capable of predicting N leaching.

Diana Selbie is a soil scientist at AgResearch. Her research area is nitrogen cycling in pastoral systems, particularly urinary N.

AgResearch was measuring N leaching during the course of the P21 trial.

The trial shows that holding onto production and profit is possible while lowering N leaching.

In the future farm system, N leaching had been reduced by 40 -50% via a decrease in N inputs, a more efficient use of inputs, lower urinary N onto paddocks and the standing off of cows in autumn and winter.

After three seasons the future farmlet was about 5% less profitable but both farms performed well above the median for Waikato dairy farms.

Analysis of drainage volumes and N concentrations revealed significantly less N leaching on the future farmlet which confirmed modelling predictions.

Initial results also indicated more production per kg liveweight. There were fewer cows on the future farmlet but those high BW cows spent more days in milk.

Kevin says there is further research that needs to be done with the standoff pads. The trial at Scott farm indicates there needs to be work done to trial different types of standoffs looking for cheaper alternatives.

What the Scott farm trial showed is that reducing N leaching was/is achievable with a combination of strategies including lower N inputs, greater per cow production, use of a standoff, lower replacements and good pasture management. The next steps are to identify how the management interventions used to reduce N leaching can be easily implemented at a commercial farm level.