Many farms in Northland (and in also in other coastal locations of the Upper North Island) are kikuyu dominant. Kikuyu grows best over summer and autumn, and on farms with kikuyu dominance its growth suppresses ryegrass and clover.
Kikuyu has many advantages over ryegrass-based pastures in the summer – it is more drought tolerant, resistant to pests such as slugs and crickets, and has low facial eczema and grass staggers risk.
It also has some disadvantages over temperate grasses; it can lose feed quality quickly in autumn and winter unless well controlled, and it is highly susceptible to frost damage, contributing to low pasture cover at calving.
Farms with well-managed kikuyu-based pasture can match the profitability of well-managed ryegrass-based farms.
The key to success hinges on changing kikuyu-dominant pastures to ryegrass-dominant pastures in the autumn and winter through a programme of mulching and drilling Italian ryegrass into the kikuyu. This allows the farm to achieve higher growth rates of ryegrass in the winter and spring, followed by the advantage of kikuyu growth over the summer.
Kikuyu in the farm system
There are three key farm policies which are important for aiding successful kikuyu management.
Policy 1. Set stocking rate
Grazing pressure is important for managing kikuyu quality. Maintain a moderate to high stocking pressure between 2.5 and 3.2 cows/ha, depending on soil type and contour.
Kikuyu has a different seasonal production to ryegrass. Manage rotation length and use cost effective supplement to fill feed deficits and maintain pasture quality.
Kikuyu Characteristics for seasonal growth rates.
Policy 2. Maintain some ryegrass dominant pastures
Maintain 20-40% of the pasture area in ryegrass dominant pastures (or other perennial winter active species such as tall fescue if climate permits). Having a component of perennial pasture on the farm can provide better quality feed in summer and helps to increases stocking pressure on kikuyu paddocks in autumn.
How to establish perennial ryegrass pasture
Use a summer cropping programme to maintain 20-40% of the pasture area in ryegrass dominant pastures. Sow a summer crop on 8-10% of the farm each spring with the aim of establishing perennial ryegrass and clover pastures via a double or triple spray programme as follows:
Double Spray Option
1. Spray glyphosate in spring before sowing crops
2. Spray glyphosate in autumn before sowing in permanent ryegrass and clover
Triple Spray Option (recommended)
1. Spray glyphosate in autumn before sowing annuals
2. Spray glyphosate in spring before sowing crops
3. Spray glyphosate in autumn before sowing in permanent ryegrass and clover
Kikuyu will re-establish in re-grassed pastures. Ryegrass pastures compete best in flat paddocks or south facing paddocks. Kikuyu re-establishes faster (2-3 years) in north facing, rolling or steep paddocks. Spot spraying kikuyu can help slow kikuyu re-establishment.
Policy 3. Have a mulching and oversowing programme
Mulching kikuyu to ground level and selecting paddocks to undersow is important for ensuring winter feed. Kikuyu declines in quality as it accumulates more dry matter and shading prevents ryegrass plants establishing in pasture. The faster it grows the quicker it loses quality. Old kikuyu needs to be mulched to improve feed quality and allow ryegrass to emerge before winter. The kikuyu management through autumn section (below) will explain this bi-annual cycle using oversowing to increase ryegrass numbers every second-year. where good kikuyu management allows.
Kikuyu Management through the Summer
Kikuyu can grow rapidly in summer when conditions are favourable (warm and wet) and must be managed well to optimise pasture quality.
From December to February the aim is to maintain grazing pressure to keep residuals down; this prevents a mat building up, keeps the kikuyu leafy and maintains clover in the pasture. Through summer kikuyu has a high leaf to stem/stolon ratio and with good management the fast-growing green leaf (10-11 MJME) can be achieved.
- Speed up rotation on kikuyu paddocks to 18-30 days if pasture growth is rapid.
- This can be faster during rapid growth
- Prioritise the grazing of your kikuyu paddocks to maintain good residuals. If needed, leave ryegrass paddocks out of the grazing rotation in order to maintain higher stock pressure on kikuyu dominant paddocks
- From December to March target grazing at the 4-leaf stage.
- Grazing at the 4 to 4.5 leaf stage helps prevent a build-up of stem over time. See kikuyu characteristics for more information on leaf stage and grazing interval.
- Manage the residual height to less than 5cm
- Regular grazing to less than 5cm keeps kikuyu leafy.
- Occasionally mow or mulch some paddocks with higher residuals to prevent a kikuyu mat building up in the base of the pasture over the summer. In January, it’s important to start minimising the trash on paddocks you want to undersow in autumn through mowing or hard grazing.
Kikuyu Management through the Autumn
From March to June the aim is to transition from kikuyu dominant pastures over to ryegrass dominant pasture via a mulching and undersowing programme.
Successful autumn mulching will switch the pastures from kikuyu dominance to ryegrass dominance as the cooler months develop, without a disruption to animal production targets. The aim of mulching is to reduce the re-growth of kikuyu and encourage ryegrasses to compete by removing as much of the kikuyu stem/stolon as possible below the growing point in the stem.
This requires the preparation of a mulching plan; aim to mulch all kikuyu dominant paddocks over an 8-week period from mid-March to mid-May
Mulching can be used without the addition of new seed, to promote the growth of ryegrass plants already in the pasture, or through undersowing ryegrass seed to re-establish ryegrass in the pasture. It is recommended that you under-sow at least 50%.
1. Mulching Programme
- Use a mulcher with vertical blades and cut to 0.5cm height so that kikuyu stems and stolons are cut.
Stagger the mulching evenly over the 8-weeks (from mid-March to mid-May) to avoid a feed shortage in late autumn; E.g. 40 pdks = 5 per week, 30 pdks = 4 per week, 80 pdks = 10 per week
- Identify kikuyu dominant paddocks which need undersowing in ryegrass and target these paddocks for mulching and undersowing in April.
- Lengthen rotation out to 30 days in April as the mulching programme slows the regrowth on kikuyu paddocks.
- It is essential that mulching and mowing is carried out every year to encourage emergence of winter active grasses and prevent old stolon shading out white clover and ryegrass.
Paddocks to undersow need to be selected and managed from January to minimise trash at undersowing time. High levels of trash are a recipe for disaster and mowing or hard grazing to a low base avoids the buildup of trash pre-mulching and undersowing.
- In most instances use a hybrid or Italian ryegrass seed. These are winter active and fast establishing to replace Kikuyu in the winter. For multi-year survival, novel endophyte is recommended. For more information on what to sow, including annuals see the FAQ What to sow into mulched kikuyu in autumn? (link)
- The optimal time to start sowing ryegrass into Kikuyu is April, when soil is still warm enough to get good establishment of ryegrass but close enough to the onset of colder weather to restrict competition from Kikuyu. For more information on early or late sowing times see FAQ When to sow into mulched kikuyu? (link)
- Use a disc drill (more reliable than broadcasting) to sow 15-20 kg/ha of seed
- Trials have shown advantages of seed treatment in some years
- Consider using slug bait prior to sowing and cricket bait (crickets love living under kikuyu pasture)
If kikuyu continues to grow rapidly after mulching and undersowing and threatens establishment of the ryegrass, lightly graze the pasture for 2-3 hours /day every 7-10 days after undersowing. Grazing too soon after sowing may reduce seedling ryegrass population by 10-20%, but shading can kill the majority of them. If excessive kikuyu regrowth isn’t a threat, plan to:
- Graze only when the new seedlings survive the “pluck test”
- Apply N on these paddocks after first grazing at 25-30kgN/ha
- It’s important to achieve good residuals in these paddocks through late autumn or early winter – don’t undo the good work with mulching and sowing with poor grazing management.
Kikuyu Management through the Winter and Spring
Through winter and early spring, pastures should be ryegrass dominant, switching back to Kikuyu pastures in the early summer. Kikuyu is not frost tolerant so should not be saved for winter feed.
As a result of the autumn mulching and undersowing programme, ryegrass should be a large proportion of the pasture content by May/June. The mulching required to achieve this switch in pasture species, generally means a well-managed kikuyu farm will have a lower average pasture cover than a pure ryegrass farm on the 1st of June.
- Aim for a pasture cover on 1st of June of 1800 - 2000kgDM/ha of good quality, actively growing pasture
- Use a feed budget through to spring to manage this pasture cover.
- There are a number of options to increase pasture cover quickly for calving e.g. use N to boost pasture growth, grazing animals off farm and have a slow winter rotation
Ryegrass should be the dominant species in early spring (kikuyu growth rate will be very slow and it may not be present in the pasture at all). Follow grazing management principles for ryegrass, use the spring rotation planner to allocate pasture from calving through to balance date. See Early spring management for spring ryegrass management.
As temperatures increase, kikuyu and ryegrass will start to emerge and compete for light and space. The strong growth of ryegrass can supress emergence of kikuyu, however kikuyu will start to become dominant as summer progresses especially during dry weather. Kikuyu responds quickly to warm, moist conditions, expect rapid growth following summer rain.
- Apply grazing management and rotation lengths appropriate for achieving target pre- and post-grazing levels for ryegrass pastures
- Manage timing of nitrogen use
- Make early and light crops of silage.
Sow summer crops in 8-10% of the milking area: this allows for autumn establishment of ryegrass/clover pastures into these paddocks and increases stock pressure on the remaining kikuyu paddocks over summer, making mulching easier in the autumn.