Forages for Reduced Nitrate Leaching, Grant and Jan Early (Canterbury)

Reducing costs through focusing on pasture, reducing imported supplement and establishing plantain in a mixed sward.

The focus for this season was to reduce costs in response to the low milk price, with similar number of cows and amount of N fertiliser as the 2014/15 season. This was achieved by:

• Focusing on pasture, which increased pasture harvested from 15.1 t DM/ha to 16 t DM/ha.
• Reducing imported supplement from 853 kg/cow to 681 kg/cow.

The result was a similar level of production between 2014/15 and 2015/16 (1754 kg MS/ha and 1766 kg MS/ha, respectively) while farm working expenses decreased from $3.25/kg MS to $3.11/kg MS.

There was a reduction in purchased N surplus, and N use efficiency stayed the same. However, N leached per hectare increased by 9%. This is because Overseer assumes:

• A low N feed (barley/wheat) was substituted with a higher N feed (more pasture eaten) resulting in higher urinary N excretion.
• An additional 14 kg N/ha or 17.5% increase in N fixation. This is to account for additional N needed for the greater assumed pasture growth.

During the 2015/16 season, diverse pasture including plantain was established on the farm as part of the re-grassing programme. This totalled 21 ha over three paddocks (5.6% of the milking platform). Kale was grazed on adjacent paddocks in a support block as a supplement to help extend the rotation in autumn.

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

During the 2016/17 season the most significant change was growing fodder beet on the milking platform for autumn feed (April/May) to extend the grazing rotation and start transitioning for wintering on fodder beet.

Plantain continued to be established as part of a mixture, with another two paddocks (16 ha) sown in 2016/17.

Compared to the previous two seasons, the 2016/17 season saw a reduction in N leaching, as estimated by Overseer, as well as a reduction in purchased N surplus.

Fodder beet

• Fodder beet was sown on 14 ha (4%) of the milking platform. Crop yield was 16 t DM/ha, approximately 1 t DM/ha less than budgeted for.
• This created feed pinch points during the year due to higher stocking rate on pasture after the paddocks were taken out of rotation, and cows being fed less than budgeted for in autumn due to the lower fodder beet yield.
• Feeding the fodder beet in autumn presented some practical challenges, with high rainfall in both March (151 mm) and April (164 mm). Cows were moved from 3 in 2 milking to once a day due to the wet and issues with lameness and logistics of grazing the fodder beet.
• Some fodder beet was lifted to create a headland to start grazing, and the break ran lengthwise down the paddock to maximise the face length. However, few cows reached the far end of the break creating allocation issues. Next year a strip will be lifted across the middle of the paddock, with a trough, and then with the break across the paddock, cows will graze in both directions.

Management key messages

• Need to consider feed supply and demand when taking pasture out of rotation to plant a crop.
• Get an accurate crop yield for crop allocation.
• Consider how the paddock will be set up for the first break and following breaks.

Plantain

• Paddocks were sprayed out in December 2016 and January 2017, and a perennial ryegrass, clover and plantain (1 kg) mix was direct drilled.
• By February 2017 the paddocks averaged 53% plantain, decreasing by the end of April 2017 to 18% plantain.
• Paddocks established in 2015/16 averaged 19% in February 2017 and 7% in April 2017.

Plantain establishment trial

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

• Four establishment methods were tested in two paddocks on farm:
  • Graze at 21 days post sowing
  • Pre-graze mow at 21 days post sowing
  • Graze at 30 days post sowing
  • Pre-graze mow at 30 days post sowing
• All trials were broadcast post grazing in the first week of February 2017 at a rate of 8 kg/ha of plantain seed.
• At the end of October 2017 little plantain had established, mostly in low competition areas such as pivot ruts.

Better success was seen with direct drilling in late December on one of the other monitor farms.

In 2017/18 the Earlys will try direct drilling in December at two sowing rates (4 kg/ha and 8 kg/ha).

Support block

A system change was implemented on the support block during 2016/17.

• The Earlys operated a 550 ha dryland support block in 2015/16, with a kale wintering system, growing barley to support the milking platform and grazing young stock.
• In 2016/17 250 ha of leased land was returned and irrigation was installed on the remaining 250 ha. This coincided with the move from kale to fodder beet.
• A new 4-year rotation was established:
  fodder beet → spring barley → short rotation ryegrass → fodder beet.
  The aim is to establish the spring barley as soon as possible after grazing the fodder beet to minimise the fallow period and act as a catch-crop. The short rotation ryegrass is winter-active and in the future may be sown with plantain.

Introducing catch crop, reducing area of fodder beet and continuing to establish plantain as part of a mixed sward.

A catch crop of oats was grown following last autumn’s fodder beet and this was harvested in October. The area of fodder beet established on the platform was reduced to 8.8 ha (one paddock). However, this proved logistically challenging for grazing three herds.

Plantain continued to be established as part of a mixture through regrassing, with another five paddocks (32.3 ha) sown in 2017/18. Establishing plantain into existing pastures was tested using coated and bare seeds. Establishment was the same.

N fertiliser use was increased from 269 kg N/ha to 306 kg N/ha, particularly from February. Fast rotation lengths resulted in more applications and compromised regrowth, which resulted in an increased N fertiliser rate in an attempt to restore growth. This led to an increase in purchased N surplus and N leaching.

Catch crop trial

A catch crop trial was carried out where a catch crop of oats was sown immediately after the fodder beet was finished being grazed (mid-June). Fallow areas were left to allow a soil mineral N comparison with areas where the catch-crop had been sown.

• The oat crop was harvested in mid-October, yielding only 1.7 t DM/ha, at a quality of 12.6 MJ ME/kg DM. The crop was harvested early to get the paddocks back in pasture and minimise the impact of taking the next paddock(s) out for fodder beet.
• Soil under the catch crop had 18% less soil mineral than the fallow, with levels of 55 kg N/ha and 67 kg N/ha, respectively.

Following winter grazing on the support block, spring barley was established. Prior to the cows arriving for winter grazing the Early’s permanently split their 8 ha fodder beet paddocks in half and fed off length wise to give access to water troughs. This resulted in earlier access to eaten fodder beet ground and earlier establishment of catch crops (spring Barley). Barley crops were successfully established in June and July.

On the milking platform last autumn’s fodder beet was followed by a catch crop of Italian ryegrass. Fodder beet for autumn was established in two half paddocks (8 ha total) to overcome last season’s logistical challenges.

Plantain continued to be established as part of a mixture through regrassing, with another three paddocks (21.6 ha) sown in 2018/19.

N fertiliser use was reduced to 248 kg N/ha which resulted in a lower purchased N surplus and N leaching.

1. Continued use of plantain in regrassing programme (10% of platform annually)

2. Focus on increasing grass harvested to reduce purchased supplements

• Use of plate meter to ensure acceptable residuals
• Weekly pasture walks to monitor growth rates to identify surplus/deficits early
• Strategic use of mower to optimise residuals
• 10% Regrassing programme
• Continued cutting/measuring of pre-grazing covers to identify success or otherwise of pasture quality
• Supplements used to support round length only

3. Fodder Beet

• Use of low protein fodder beet as winterfeed for cows and young stock
• Use of fodder beet on the platform as a low protein supplement in autumn and as a transition feed for fodder beet winter grazing
• Surplus beet lifted and fed in spring

4. Catch Crops

• Barley used as catch crop post fodder beet on wintering block. 8ha-paddocks have been split into 4ha-paddocks with breaks fenced lengthwise to give access to water troughs. This has given us the opportunity to establish barley post grazing earlier if conditions allow. Barley is taken through to harvest with grain used as a supplement during the milking season and straw baled as part of the winter diet.
• On the dairy platform we have successfully established short rotation ryegrass after fodder beet in late May /early June. Two mild autumns have helped in this regard.

5. Nitrogen – focus on reducing fertiliser N

• Start the season with an N fertiliser target/budget and monitor to achieve the target (2019/20 target 240 kg N/ha)
• Kg of N behind cows = 90% of round length
• Reduced N use on effluent area
• N not spread around high stock areas i.e. troughs/gateways
• Strategic use of N in February to build covers moving into autumn
• No N applied in May (we already didn’t apply N fertiliser in June and July)

6. Start destocking cull cows in early April