Forages for Reduced Nitrate Leaching, Campbell and Martine Tait (Canterbury)

The Taits have a strong focus on sustainability balanced with profit, and enjoy trying new ideas. Managing their fertiliser N use and tweaking their wintering system have been recent focuses to reduce their N losses.

Tait family farm

Tait Family Trust is an intergenerational family-owned dairy business based in Lowcliffe, Ashburton. The home farm (275ha) was previously operated as a sheep farm with some cropping and beef. The property was converted in 2010/11 and started milking in the 2011/12 season.  A 123ha support block, 1km east of the dairy, was purchased in 2014 providing dairy support to the business and allowing livestock numbers to increase.

The business aims to operate at a high performance level, particularly in the areas of people, environment, animals, and profit. Operating a self-contained system is important for risk management, and everyone is encouraged to be involved in the community.

Challenges for the farm include light soils that are prone to nitrogen loss. There is an area of gun irrigation on the support block that contributes to significant N loss through high drainage – plans are in place to replace the gun systems with pivots.

Mitigations to reduce N losses implemented to date

Fertiliser N use

The Taits use a range of methods to apply N fertiliser, including solid and liquid forms. Because of the range in application methods, keeping track of the use in different areas is complex. Campbell manages this himself by breaking the farm into 14 management zones which cover the milking platform and cropping areas. These are kept on a spreadsheet, and applications are recorded as they are made. Use in 2019/20 season averaged 190-200 kg N/ effective ha on the milking platform, and Campbell is looking to drop this slightly in 2020/21. The farm has applied higher levels in the past, and Campbell has found these tips have helped to reduce their use down to their current levels:

• Setting the pasture cover up well at drying off, to carry feed through to spring and reduce the need to apply fertiliser early. “In the 2019/20 season we were a bit short on pasture cover, and we also tried to reduce the N rate in early spring,” says Campbell. “That bit us, and so in 20/21 while we got the pasture cover right, we were nervous to drop the N back, but in hindsight it would have been ok. The key is getting the pasture cover right, and then having the confidence to drop the N a little if you’ve set up well.”
• Focusing on what the feed situation will look like in 4-6 weeks and making N decisions based on that, rather than what is happening in the paddock today.
• Using liquid fertiliser to allow lower rates of N to be applied at certain times, such as in the summer months where the response to N is lower. In summer, they have also applied other nutrients such as Potassium and Sulphur in combination with granular N fertiliser. This allows application of lower rates of N, while spreading enough product to achieve good uniformity in their applications.

Winter crops

The Tait’s have winter crops in the same block as the milking platform, as well as on a nearby support block. “We have focused on keeping the crop area away from the lighter soils on the farm, to reduce the N loss impact,” says Campbell. “This takes a higher level of decision making, but is something we can do if we plan well.”

The farm is now using all kale for wintering. While this initially increased their crop area compared to fodder beet, they’ve now been able to reduce the total winter crop area further, to around 45 hectares. This reduction in area has been partly due to an increased focus on getting cows close to target Body Condition Score (BCS) before winter. When cows are close to their target BCS, they can be fed at maintenance levels over winter, reducing total crop demand. They have also increased the pasture area allocated to cows that need to gain condition over winter.

Future N mitigations and ideas

Within-paddock nutrient management

The Tait’s first did within-paddock soil testing four years ago after seeing another farmer get good results from this approach. Individual paddock soil testing had been done already to ensure that other nutrients weren’t holding back pasture production, as Olsen P was below the optimal range in some areas. By moving to within-paddock testing, Phosphorus and Potassium capital applications have now been targeted to get all areas of paddocks within the optimal range.

“After we started talking about nutrients within paddocks, I thought about the patterns of down cows that we had last spring,” says Campbell. “Typically we would have your usual milk fever issues at the fronts of paddocks where K is likely to be high, and cows with low Phosphorus when we were in the backs of paddocks. That’s what made me decide to get smarter around how we apply nutrients within our paddocks.”

Some silage is made on the milking platform, and they have usually taken whole paddocks for silage when they are in a surplus. Campbell is now considering using only the fronts of paddocks to harvest silage. This would allow them to remove some of the potassium build up from the front sections.

Campbell is planning to repeat within paddock soil testing next winter, to assess improvements and plan future fertiliser applications, and targeted silage areas.

'Relay cropping'

Campbell enjoys thinking outside the box and trying new ideas. One that is in the pipeline is using a combination of Italian ryegrass and Raphno, sown in alternating strips within a paddock. Raphno is a brassica that is a hybrid between kale and radish, and can be grazed and regrown multiple times. There are a number of reasons Campbell wants to try this as a winter feed option:

• The crop can be grazed multiple times
• It makes excellent use of sunlight to grow feed by increasing the time the crop is at canopy closure
• By combining the Italian ryegrass with the Raphno, the Italian is already at a mature stage which would allow it to uptake N from urine as soon as it is deposited
• Cows won’t be on bare soil following the grazing of the crop, and it would allow them to get more of their diet from pasture

Campbell has access to a contractor’s strip sprayer, and a drill to plant Raphno in the sprayed strips.

After a normal crop of kale has been grazed for winter, they are planning to sow a combination of oats and Italian ryegrass at the same time as a usual catch crop. After it is harvested for silage, the Italian ryegrass would remain, strips would be sprayed out in the Italian ryegrass, and the Raphno sown.

There would then be three grazings of the Italian ryegrass/Raphno combination in late summer, autumn, and late winter, before the paddock was moved to the next crop.

Challenges and risks that are being considered are:

• Whether grazing timing will work for both crops without compromising future growth and/or quality of feed, and whether this will match animal demand.
• Weed/pest control issues with planting as strip crops.
• Whether this approach will fit into the current farm system with rotation plans, and if the land area needed is too large.

Campbell says that they are always looking for new ideas. “This is one that we can try at a relatively small scale first and see how well it works for us.”

The Taits are one of 50 farms who are partnering with the DairyNZ funded Selwyn/Hinds – Meeting a Sustainable Future Project. They are exploring the options for reducing their farm’s environmental footprint (water quality and greenhouse gases) while maintaining profitability and considering the strategic objectives of their business. As part of the project, these 50 farms are sharing a range of ideas, learnings, case studies and analyses as the project progresses.