Forages for Reduced Nitrate Leaching, Bill and Shirley Wright (Canterbury)


8 min read

Farm facts What are you getting out? Why did you decide to join? Why it's important? Farmers & industry benefit Summary of management Summary of farm performance Weather information Management and experience

Bill and Shirley Wright own a sheep and beef farm in Cave and are part of the FRNL research network in Canterbury. Their farm spans 360 ha, with specific soil types and an average rainfall of 600 mm. They grow crops like kale, fodder beet, barley, and maize, and keep a variety of livestock. The FRNL project helps them adopt best practices, reduce nitrogen leaching, and improve understanding of environmental impacts. Nitrogen leaching varies with rainfall, soil, and livestock interactions. In 2015/16, variable weather caused changes in pasture production, leading to a drop in beef production and less nitrogen leaching.

Farm facts


360 ha effective, 378.8 ha total

Dominant soils:

Claremont silty loam, Mairaki silty loam over clay

Dominant soils (others):

Glasnevin stony silty loam

Average rainfall:

approx. 600 mm


1000 breeding Coopdale ewes, 130 R1 bulls, 60 R2 bulls

Animals (Heifers):

230 R1 dairy heifers, 230 R2 dairy heifers

Crops grown:

Kale and fodder beet for winter feed, followed by catch crops

Crops grown (late summer/early autumn):

barley and grazing maize

What are you getting out of the FRNL project?

  • Ensuring we continue best practises meeting ECan’s Good Management Practice requirements.
  • Monitoring/measuring of pasture and animal performance that can be benchmarked against industry.
  • Being continually challenged on current farm practises and getting ideas to change or adopt new science or ideas.
  • Being challenged to adopt best environmental standards to minimise nutrient losses.

Why did you decide to join the programme?

“This programme offered the opportunity to progress our business and to learn best practise to reduce N leaching. As a dry sheep and beef property with dairy grazing the environmental impacts of our business were not yet fully understood. Profitability is driven by innovation and this programme provided that.”

Why do you think it's important?

"With the direction the industry is heading, legislation, catchment allocation etc. it’s important to have as much information as possible."

How will farmers and the industry benefit?

“Gaining understanding and appreciation for a) what we are doing now and b) what we can do going forwards.

The results of the programme inform industry on making better management and crop decisions to increase nutrient uptake and reduce run off.”

Summary of management and farm performance

The rainfall, soil types, plants and livestock all interact and result in nitrogen (N) leaching. For the years studied, N leaching losses on Bill and Shirley’s farm were low and moderately variable between years. Higher rainfall meant more dry matter production and more stock, which all resulted in greater leaching in better seasons.

Reducing N leaching levels was very difficult, although productivity gains were possible within current leaching levels.

The stand-out year was 2015/16. The low N loss estimate for this season was a result of variable weather which required continuously changing decisions. The summer was dry pre-December, so stocking rates were reduced early, but prolonged rains delivered substantial moisture later in the summer, so lambs were brought onto the farm in the new calendar year. As a result of the weather, pasture production decreased and this was not offset by crops and supplement, leading to a decrease in beef production by 38%. This contributed to a decrease of 27% in N leaching, compared with the previous season.

Total production and estimated N leaching were fairly similar for the other years.

Summary of farm performance

Farm details 2014/15 2015/16 2016/17 2017/18 2018/19
Beef (kg)1 90,145 51,652 90,788 92,210 75,740
Sheep meat (kg) 26,233 28,288 23,545 29,547 25,797
Wool (kg) 7,463 6,784 7,114 8,767 5,551
Total animal production (kg) 123,841 86,723 121,356 130,524 107,088
Pasture production (kg DM/ha)2 6,909 5,641 8,307 8,425 8,345
Total Dry Matter Intake (DMI; kg) 2,598,127 1,601,312 2,573,473 2,674,706 2,334,215
Dry matter intake (Overseer 6.3.1; kg/ha) - total 7,217 4,448 7,149 7,430 6,484
Stocking rate (SU/ha) 13.3 9.4 13.3 14.8 11.7
N leaching (kg N/ha; Overseer 6.3.2) 15 12 17 19 18
N leaching (kg N/kg product; Overseer 6.3.2) 0.049 0.054 0.054 0.055 0.064

1 "Beef" means both beef carcass and leaving the farm as live weight gain on grazed dairy cattle.
2 Weighted average from Farmax (natural potential + N fertiliser boosted)

Weather information

Weekly rainfall (blue bars), air temperature (max dashed line, min dotted line) and soil temperature (solid line) from July 2013 to June 2019 based on interpolated weather data from NIWA’s Virtual Climate Station Network (https://www.niwa.co.nz/climate/our-services/virtual-climate-stations)

Management and experience with implementing FRNL options

Grass-based pasture vs lucerne

Production of grass-based pasture and lucerne was strongly affected by temperature and soil moisture across the four years monitored.

  • Production of the grass pasture was affected more by the drought in summer 2015-16 than lucerne with its deep tap root.
  • Lucerne was less productive in the wetter 2016-17 and 2018-19 seasons than the grass pasture.

Growth of grass-based and lucerne pastures on Highlands during 4 years to June 2019.

Plantain in diverse pasture

  • Diverse pastures were only transient under sheep and beef grazing and rapidly transformed into grass-dominant swards.
  • Plantain did not persist under current sheep and beef grazing management and therefore could not be expected to decrease N leaching without substantial changes to current grazing practices.

Plantain was incorporated into diverse mixtures on the farm following discoveries about plantain’s potential to reduce N leaching. Pasture production and proportion of plantain in the mix were measured for the 2017-18 and 2018-19 seasons. These young mixed pastures were very productive in comparison with the older grass or lucerne pastures as shown in the table below.

Total dry matter production (kg/ha) assessed using pasture cages from 12th Sept 2017 to 26th Sept 2018 (2017-18), and 26th Sept 2018 to 17th June 2019 (2018-19).

Name Sown Slope Species DM kg/ha
2017-18 2018-19
Coles cabbage tree 2012 flat Ryegrass 10071 11198
Coles Patersons 1 2013 flat Tall fescue 11872 9736
Coles pumphouse 2 2013 flat Lucerne 10567 7357
Top bottom haybarn 2016 flat Grass-white clover-plantain 13425 10380
Back road flat 2017 flat Grass-white clover-plantain 16614 14182

As shown in the figure below the amount of plantain in the pasture mixes was very low and was never more than 13% of the herbage available in the first season, by 2018 there was very little plantain observed, and none in 2019.

The changes in proportion of plant species in a mixed pasture sown in autumn 2016.

Grazing maize

The use of grazing maize was shown to be more successful on this farm, with its high risk of summer-autumn drought, than growing plantain pastures which have a much lower herbage yield.

The soils and climate on this farm are suitable to grow maize to be used as a forage crop in late summer and autumn. Grazing maize suits this dryland farm very well because feed can be carried from spring and early summer into periods where there is a risk of drought. There is a risk of crop failure, some crops were frosted shortly after sowing but recovered, and in the most recent year a crop was drowned out shortly after sowing. Despite this risk, the crop has given substantial yields in some years, as shown in the table below.

Maize production assessed pre-grazing over five years.

Year Paddock name Date DM kg/ha Area of paddock
Roundhill paddocks 16th Feb 10,288 10.8
Trees 2nd Feb 8,653 8.64
Trees 14th Mar 19,727 (8.64)
End of lane 12th Feb 7,172 2.07
Near Middle creek 14th Mar 11,634 1.28
Stables 14th Mar 9,354 1.92
Stables 1st Mar 4,200 1.92
Bottom triangle 11th Mar 13,820 6.45
James 26th Feb 22,335 3.56
2019 Crop failed

Grazing of maize is not easily represented in the Overseer model. Maize is a low protein feed meaning that the N excreted in the urine is likely to be lower than with pasture.

However, the high crop yields meant that a large number of cattle were required to graze the crop which is likely to leave a significant amount of nitrate in the soil.

On this farm it was best to use the crop in early autumn before the stems resist grazing later in autumn. This also allowed Italian ryegrass or pasture to be sown after grazing, which then functions as a catch crop taking up soil mineral N, reducing risk of N leaching.

Grazing maize

Catch crops

Earlier sowing of catch crops tended to have a yield advantage and greater cost effectiveness. It is worth considering earlier sowing of catch crops wherever and whenever possible.

Catch crops were shown to reduce the risk of N leaching through their ability to take up N remaining in the soil following winter grazing of fodder crops and appear to be the most appropriate tool to reduce the high N loss risk associated with winter grazing of fodder crops.

A catch crop trial was carried out following a 2018-grazed crop of kale. Catch crops, sowing dates and cultivation are summarised in the table below. There were also control plots which were kept fallow. At the start of November plots were split in half and SustaiN fertiliser was applied to one half of each plot. Final harvest was taken when crops were ready to be taken for whole crop silage, this was 21/12/2018 for triticale, ryecorn and wheat, and 7/1/2019 for the remaining crops.

  • Light cultivation assisted seedling establishment and ultimate production from oats. Direct drilled oats that did not receive additional N fertiliser during the growing period were one third less productive.
  • Triticale was most productive when additional fertiliser was applied during the growing period.
  • For those which received no added N, oats with some tillage were very productive compared to other crops.
  • Average levels of soil mineral N in the soil profile were slightly lower at the final harvest (30-40 kg N/ha) than they had been at sowing (40-60 kg N/ha). This indicates that catch crops have the potential to reduce leaching.
  • The season the trial was run was dry prior to sowing and very wet later which meant pugging was minimal. Heavy soils have great ability to hold on to N.

Total dry matter production (kg/ha) assessed using quadrats within plots on three occasions during the growing season for different species and type and timing of sowing, and application of N in the growing season.

Species Timing Method 25/10/18 20/11/18 Final harvest
+N No N +N No N
Fallow - - 1,163
Ryecorn 1/8/2018 Tilled 1,189 7,626 5,392 10,903 7,695
Triticale 1/8/2018 Tilled 3,000 7,382 7,061 16,563 10,276
Wheat 1/8/2018 Tilled 1,419 5,840 5,186 12,650 10,550
Oats 1/8/2018 Tilled 1,396 9,571 7,395 11,555 11,264
Oats 1/8/2018 Direct drilled 658 5,712 4,580 9,702 7,477
Barley 1/8/2018 Tilled 126 6,289 5,084 10,686 8,240
Barley 18/9/2018 Tilled - 2,468 2,399 8,744 7,472

Catch crop trial 2018.

Full report

Download the full report on the Sheep and Beef monitor farms, including the catch crop results, here.

Last updated: Aug 2023
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