Forages for Reduced Nitrate Leaching, Tony Coltman (Canterbury)


7 min read

Farm facts Getting out of FRNL programme Deciding to join the programme Why is it important? Farm & Industry Benefits Annual summary Management and experience

Tony Coltman dairy farms near Dunsandel with a vision to lead in all areas of the dairy industry, including production, financial returns, environmental standards, and staff wellbeing. Since joining the FRNL programme, Tony has made various changes to his farm. He's grown more fodder beet, used more plantain in regrassing, and expanded the farm area. He's also reduced the use of imported supplements and decreased nitrogen fertiliser application, resulting in a significant reduction in nitrogen surplus and leaching. By participating in the programme, Tony aims to understand his farm's environmental impact better and contribute to sustainable farming solutions with real, practical data.

Tony Coltman dairy farms near Dunsandel. At the start of the programme the dairy farm had an effective milking platform area of 335 ha. This was 100% irrigated, at a stocking rate of 4.1 cows/ha. The farm also has a 155 ha leased support block providing winter grazing.

Since being involved in the FRNL programme, Tony has:

  • Introduced fodder beet onto the milking platform
  • Included plantain in regrassing regime
  • Increased farm area by 172 ha and increased peak cow numbers, but reduced stocking rate
  • Utilised feed pad in spring and autumn.
  • Decreased imported supplement by 31%
  • Increased home-grown feed by 2%
  • Decreased N fertiliser applied by 35%

Despite now growing fodder beet on the platform, which can be associated with higher nitrogen (N) leaching losses than from pasture, other changes such as the decrease in N fertiliser use and decreased imported supplement, with associated lower stocking rate, have resulted in a reduction in purchased N surplus of 52% and a reduction in estimated N leaching of 36% since the start of the monitoring period.

Farm facts


335 ha effective milking platform

Area ( in 2018/19 season):

increased to 507 ha

Dominant soil:

Lismore silty loam, Mayfield silty loam

Average rainfall:

approx. 660 mm

Supplements fed:

2.2-3.9 t DM/ha

Cow numbers:

1367-2058 peak milked


1925-2147 kg MS/ha, 477-502 kg MS/cow

Support block:

155 ha leased

Pasture harvested:

17.8-18.6 t DM/ha


Canlac Holdings 2014 Limited

What did you get out of the FRNL programme?

  • The biggest gain is around the knowledge I am gaining to be first off the rank with sustainable and profitable farming practices.
  • The discipline of monitoring and seeing the improvement in N loss we are achieving through on-farm change.

Why did you decide to join the programme?

To understand the environmental footprint of our business better and to contribute to the industry’s understanding of the whole environment issues at a practical farming level with REAL NUMBERS.

Why do you think it's important?

Because there are a lot of organisations and regulatory organisations out there wanting to change things and they don’t have all the facts or understanding of the implications for farming businesses and families. We don’t want to just stand around and complain about the issues and blame everyone. I wanted to contribute to finding a solution.

How will farmers and the industry benefit?

They will have REAL NUMBERS and PRACTICAL SOLUTIONS to the problems we are facing, and regularity organisations and industry will have some more factual information to base decisions on.

Management and experience with implementing FRNL options


Utilised feed pad, increased cow numbers and nitrogen (N) fertiliser, decreased supplementary feed imported and fed lifted fodder beet from support block on the milking platform in autumn.

A small amount of intensification occurred on farm in the 2015/16 season. Changes included:

  • Cow numbers increased by 20 cows (1.5% increase)
  • Increase in N fertiliser use by 21 kg N/ha
  • Imported supplementary feed decreased from 802 to 729 kg DM/cow
  • Increased pasture harvested from 17.8 to 18.5 t DM/ha.

This resulted in milk production increasing by 38 kg MS/ha, a slight decrease in the purchased N surplus, and a slight decrease in the amount of estimated N leaching.

This season was the first where the newly constructed feed pad could be utilised during spring and autumn. Fodder beet was lifted from a support block and transported back to the milking platform and fed on the pad during autumn. Utilisation was good from the feed pad and saved a lot of feed wastage.


Growing fodder beet on the platform for autumn feed, reducing N fertiliser use, increasing imported supplement and continuing to establish plantain as part of a mixed sward.

This season had an increase in stocking rate and intensity, however with the use of low N feeds, less N fertiliser and increased milk production, purchased N surplus decreased by 19% and estimated N leaching decreased by 16% from 2015/16 levels.

This demonstrates that multiple changes drive improvements in environmental outcomes. The use of low N feeds (e.g. fodder beet, maize) and plantain increase the efficiency with which N can be used in the system, but simultaneously N inputs must decrease to capture the benefit of the greater efficiency.

System changes on Canlac during the 2016/17 season included:

  • Continued to introduce plantain in the regrassing regime. The use of plantain is not yet reflected in Overseer, apart from its potential effect on improved N use efficiency.
  • Introduced fodder beet onto the milking platform.
  • Increased imported (low N) supplement from 729 kg DM/cow to 905 kg DM/cow.
  • Increased cow numbers by 46 from 2015/16 (3% increase).
  • Maintained pasture harvested at 18.6 t DM/ha.
  • Increased milk production per hectare from 2082 to 2147 kg MS/ha (3% increase).
  • Decreased N fertiliser use by 49 kg N/ha (17%). The last application was 24th April 2017.


During the 2016/17 season fodder beet was grown on the milking platform, which was used in autumn to extend the grazing rotation and begin transitioning in preparation for wintering on fodder beet.

  • On the milking platform, fodder beet was sown in one paddock (12 ha, 4% of platform).
  • The fodder beet was grazed from the 20th of April. Yield was 24 t DM/ha.
  • Two strips were lifted down the sides of the paddock, with a headland at each end. Tony was running two once a day (OAD) herds and a twice a day (TAD) herd. The two OAD herds were grazing the fodder beet in situ, and the TAD herd was getting lifted fodder beet on the feed pad.
  • The paddock was resown on 15th October in a mix of perennial ryegrass/clover/plantain.


Tony established plantain on the milking platform for the first time as part of pasture renewal in two paddocks (25 ha, 7% of platform).

  • Paddocks were established in October and December, via direct drilling into a sprayed-out paddock, without cultivation. The mix contained 1 kg/ha of plantain seed. The resulting sward was 25-26% plantain in both paddocks.
  • Tony has been managing his paddocks of plantain the same way as his regular paddocks. He’s observed the main difference that required getting used to is the visual difference in late spring/summer when the plantain goes to seed. During this time the paddocks look visually untidy, and he had to resist the temptation to top them. Despite the untidiness no change in milk production has been observed.

Plantain establishment trial

It will be difficult to achieve the levels of plantain needed to reduce N leaching across the farm through pasture renewal alone. A trial was run to investigate the cost-effectiveness of different methods of establishing plantain into existing pastures on Canlac and two other monitor farms.

  • Three establishment methods were tested in one paddock on farm:
    • Graze at 21 days post sowing
    • Pre-graze mow at 21 days post sowing
    • Pre-graze mow at 30 days post sowing
  • All treatments were direct drilled post grazing at the end of December at a rate of 8 kg/ha of plantain seed.
  • At the end of October 2017, a moderate amount of plantain had established:
    • 4% for grazing at 21 days post sowing
    • 10% for pre-graze mowing at 21 days post sowing
    • 4% for pre-graze mowing at 30 days post sowing

Even though these percentages were low, on the other two monitor farms the treatments were sown in February and establishment was poorer still.

In the next season, plantain content had increased to approximately 20%. Other farmers notice this as well – expect the results to become visible in the next year.


Decreased N fertiliser use and continuing to establish plantain as part of a mixed sward.

The farm system in 2017/18 was very similar to 2016/17. Changes include:

  • Established plantain as part of a mixed sward following last season’s fodder beet (12 ha).
    • Fat hen proved problematic as weed due to limited herbicides being available to use with plantain. This was eventually overcome through mowing.
  • Decreased N fertiliser use from 243 to 224 kg N/ha across the whole farm area. This was achieved by minimising the N going on paddocks receiving effluent and reducing the number of applications over the season by one.

These changes decreased the purchased N surplus by 11% and the estimated N leaching by 13% compared with 2016/17 levels.


Increased farm area, increased the area of fodder beet grown on the platform, winter milking, catch crop of oats grown, decreased stocking rate, decreased imported supplements and N fertiliser.

In general, 2018/19 was a good growing season. This year more land was integrated into the farm which increased the effective area from 335 ha to 507 ha. Other changes include:

  • Increased the area of fodder beet grown on the milking platform to 18.4 ha for transitioning and milking about 300 cows through winter as a way of building numbers for the new land.
  • Established a catch crop of oats in July on 6 ha of the fodder beet area, this was grazed in spring.
  • Did not establish any new plantain this season. Last year’s fodder beet paddock was in fodder beet again and no regrassing was done.
  • Decreased stocking rate from 4.3 to 4 cows/ha.
  • Decreased imported supplement from 878 to 551 kg DM/cow.
  • Decreased N fertiliser from 215 to 184 kg N/ha across the whole farm area.

This resulted in a 31% decrease in purchased N surplus and an 11% decrease in N leaching for 2018/19, compared with the 2017/18 season.

Concluding comments

Tony Coltman

Tony Coltman: "We are continuing to refine what we do everyday. The large gain or low hanging fruit have been achieved, it is now small incremental gains. E.g. reduce N usage during summer months when clovers are more active for example. We might look at getting effluent to the whole farm. We are really looking to the industry now to help us find some technological things we can do to make more improvements."

Footnote: The potential effects on N leaching of the FRNL options implemented on the farm (plantain, fodder beet and catch crops) are not yet reflected in Overseer. FRNL researchers and Overseer are working together on updating the model and providing the necessary background information to users and other stakeholders, such as policy makers and regulators.

Canlac are continuing their contribution as partner farms in the Meeting a Sustainable Future project.

Last updated: Aug 2023
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