Summer preparation


8 min read

Summer management plan Tactics for a dry summer Decide irrigation priorities Manage pastures Establish summer crops Late sowing options Supplements

Summer dairy farming involves efficiently using spring pasture before summer heat and dryness diminish its quality. You should formulate a summer management plan early to ensure profitable production. Your plan should balance feed supply with demand, incorporate summer crops, and consider the use of nitrogen fertilisers and supplements. Efficient irrigation practices can maximise pasture growth. Understanding and managing pasture residuals and rotation, along with potential applications of nitrogen, can further optimise the yield. Consider summer crops like turnips, chicory, plantain, and fodder beet for added energy and protein during summer. For late sowing, consider green feed maize or sorghum.

Whatever the summer conditions, the first management rule is to fully and efficiently use spring pasture before dry and hot conditions reduce growth and pasture quality over the summer period.

Best practice grazing management in summer builds on good practices applied in spring. Planning your summer strategy in early December can help ensure the herd’s production remains profitable for the rest of the season.

Heading into summer, ensuring feed supply matches demand will mean continuing to meet pre-grazing leaf stage and post-grazing residual targets to encourage as much pasture growth as possible. It may also include the use of summer crops, nitrogen (N) fertiliser and supplements where it makes economic sense.

Have a summer management plan

Restricted pasture growth and milk production occurs in many parts of New Zealand as a result of dry summer conditions and irrigation restrictions. Formulating a summer management plan will prepare you for the conditions that eventuate.

Every farm should have a summer management plan that sets out key decision points concerning stock and feed management. It should include factors such as feed on hand/available, summer crops, BCS and plans to dry off lighter cows, removal of culls etc. Your local DairyNZ extension partner or regional partner can help you with this if required. Alternatively, your farm consultant may be able to help you develop a plan tailored to your own situation.

Tactics for managing your farm during a dry summer

Assess your current position and have a summer management plan.

  • Planning is key to managing a dry summer. A summer management plan will help manage feed in a low payout year, reduce stress in a dry summer, and lighten the impact on production in the following season.
  • It may not be easy to predict summer weather, but a plan provides the framework for what decisions need to be made, and when. Review the plan as conditions change.
  • Assess feed supplies and Body Condition Scores (BCS). Think about how much feed you’ll have vs. how much feed you’ll need during the summer months.
  • Estimate how many cows you can milk in late summer and autumn. Avoid being overly optimistic and consider your options for buying in feed and supplements and for reducing feed demand.
  • Monitor your budget and reforecast as needed if there are further revisions of the milk price. Evaluate how on-farm actions impact your income or expenditure.

Act early to reduce feed demand

  • Monitor the BCS of the herd regularly and make decisions early to address low condition cows.
  • Cull low value stock early to reduce feed demand, rather than keeping them on farm in the hope that it will rain or try to graze them elsewhere. Communicate with your meat processor to book in early cull cows.
  • Book your pregnancy testing as early as possible to identify empty cows and provide culling options.
  • Consider drying off lower-producing animals and younger stock early when they are in good condition as it will reduce the pressure on available resources.
  • Monitor young stock carefully, including animals grazed off-farm. Proactively monitor growth rates and adjust feed where required.
  • Consider once-a-day (OAD) or 3:2 milking. Milking OAD or once every 16 hours are good options to take the pressure off cows and reduce demand before feed is limited.
  • Ensure decisions that are made around reducing feed demand are done in the context of the current milk price, and consider the long-term implications on the farm and business.

Manage your pasture growth

  • Increase rotation length in spring while there is sufficient pasture cover to push out the feed wedge. However, aim to maintain pasture quality as covers increase.
  • Look after your best pastures and remain consistent with residuals. Leaving higher residuals will decrease pasture quality and reduce the amount of feed.
  • Good pasture management throughout spring and summer will result in better recovery in autumn.
  • Avoid overgrazing, particularly new grasses and specific species such as fescue and cocksfoot.
  • Sacrifice poor-performing paddocks or those due for renewal to allow higher-performing paddocks to bounce back when conditions improve.
  • Deferred grazing is a low-cost option to increase grazing pressure and maintain pasture quality at a time of pasture surplus. A paddock, or the backend of several paddocks, can be shut up and left as standing feed for grazing rather than being made into silage or hay.

Use nitrogen tactically to increase available feed

  • Consider a nitrogen application in early summer to stimulate the development and growth of new ryegrass tillers.
  • Further summer nitrogen applications should only be made if soil moisture levels are adequate for good pasture growth and response.
  • Evaluate the cost of nitrogen and response rates and compare this to alternatives such as imported feed or reduced demand.
  • The overall cost of using nitrogen should be well justified and not just an assumption.
  • Consider the cost of applying nitrogen to generate a pasture surplus or silage vs. buying in supplementary feed as needed. In addition to the cost of applying nitrogen currently (21 cents/
    kg DM), harvesting it as silage will add another 12-21 cents/kg DM to get this feed into a stack or bale. Rather than baling surplus pasture, consider deferred grazing as an option to carry surplus pasture forward.

Think about feed availability and supplement use in summer

  • The profitability of feeding supplements depends on the production response of having cows in milk when the drought breaks (the longer the drought, the lower the response) and the cost of supplement relative to milk price.
  • Evaluate the cost of any supplementary feed brought in against the cost of alternative options to meet animal demand, e.g. nitrogen use.
  • Consider the type of supplementary feed, its ME, and when it is purchased. It is likely that the cost of supplementary feed will rise as we move into summer and the probability of drought rises. Make decisions based on cost per unit of ME.
  • Feeding supplements can result in increased stock water drinking rates. Consider providing water in the yards to manage this.

Manage your summer crops

  • Summer cropping is a good tactic to increase feed supply but comes at a financial cost. Think about how this will impact your feed supply and what your alternatives might be.
  • Consider crop establishment with a dry summer in mind:
    • Consider lower planting populations and look at varieties with better drought/insect tolerance.
    • Establish as early as possible and consider direct drilling to maintain soil moisture.
    • Consider the strategic use of effluent on certain crop when establishing.
    • Consider the financial implications of applying chemical, weed control and the potential impact on quality and yield.
  • C4 grasses such as green feed maize and sorghum can be good late-establishment summer cropping options. However, their quality won’t be as high as other crops, such as brassicas.
  • Crops will potentially be under stress due to heat and lack of moisture. This makes them more susceptible to pests, which can then influence yield and quality. Talk to your local cropping and  forage advisor if you have any concerns or need some advice on how to manage the problem.

Don’t be afraid to ask for help, you are not alone this summer

  • As we move into a potentially dry summer, talk to your advisors about your options. Keep in touch with feed suppliers, bankers, and dairy company reps.
  • During the high-stress period of a drought, it is more important than ever to look after your farm team. It can help to talk to others and find out how they are dealing with the situation.
  • Focus on what you can control now. For example, start planning for next season and set short and long-term targets.
  • Participate in local discussion groups or events. Take some of your staff with you and create team-building opportunities.

Decide irrigation priorities

If you depend on irrigation, decide on irrigation priorities, e.g. crops vs pastures, good pastures vs poor pastures, or shallow soils vs deeper soils; and develop a plan to best minimise the impacts of water restrictions.

Saving water in the spring when ET is low (risk to crops is minimal) also means there will be more water left for the peak season. Care must be taken not to let the soil get too dry, as it may be hard to catch up, especially with irrigators that have a long return period, e.g. when it takes longer than ten days to return to a paddock.

What is good irrigation practice?

It is important to know who is responsible for deciding when to start and stop irrigation and how that decision is made. Copying the neighbours is not good practice. The below guide to good irrigation provides information on the best time to irrigate.

Manage pastures

Transitioning from spring into summer (November to December) sees the development of reproductive tillers; where tillers become reproductive the stem elongates and eventually - if the tiller is not grazed - a seed-head is produced. New tillers or daughter tillers are growing in the base of the pasture, replacing their ‘mother’ tillers who have been vernalised over winter, go reproductive and then die.


  • Residual height should be set in spring. Grazing ryegrass pastures to a consistent even height improves summer milk production.
  • Residuals of 1500-1600kg DM/ha will ensure the plant maintains its energy reserves, and will provide some shading of the soil surface.
  • Grazing below the previous spring residual height, indicates underfeeding and is a threat to the growing points of existing and developing tillers.
  • Leaving high residuals in December won’t help fill a feed deficit later; it will simply result in wasted pasture and reduced pasture growth and quality in the months ahead. The way to increase pasture supply in summer is to slow the grazing rotation in late spring.

For more information on residuals see pasture allocation

The below paddock guide provides photos of different post-grazing residuals.

Post grazing residual


  • Slowing down the round in early December by increasing the number of days in the rotation will help achieve maximum growth during summer and help ensure there is adequate feed ahead of your herd for grazing. Increase rotation length towards 30 days while there is still sufficient pasture cover to avoid reductions in production.
  • The recommended 30-day rotation for summer (late December onwards) is determined by the average number of days required for a ryegrass plant to reestablish three leaves after grazing during summer (3 leaves x 10 days per leaf). Ryegrass leaf emergence rates slow as soil moisture reduces and temperatures increase which means the plants need more time between grazings to recover and generate new leaves.
  • Achieving a 30-day rotation helps the plants manage the increased stress of summer and increase pasture growth. Longer rotations also benefit clover growth as clover likes higher temperatures than ryegrass and will help fill in the gaps between ryegrass plants.
  • Increasing rotation length over late spring (Nov-Dec) - For example, changing from a spring rotation of 23 days to 30 days requires a gain of 1 day a week over the next 7 weeks. It’s not done overnight so it helps if:
    • paddocks harvested for silage are returned to the rotation
    • one day per week a single paddock is left to get longer for a few days, then the electric fence is used to provide grazing for an extra 12 hours or 24 hours for the herd
    • crop (or supplement if profitable) is used to help extend rotation
    • some nitrogen fertiliser is applied during November and December
    • grazing of late surplus grass is deferred.

For more information on assessing rotation length see leaf stage.

Early summer nitrogen

  • Consider an N application in early summer to stimulate the development and growth of new ryegrass tillers.
  • Nitrogen applications should only be made if soil moisture levels are adequate for good pasture growth.
  • Mid- to late-summer applications of N fertiliser are not recommended where low soil moisture limits growth. Good responses can occur on irrigated farms or regions with reliable summer rainfall. See soil fertility for pasture for seasonal nitrogen usage.

Deferred grazing

Deferred grazing is a low-cost option to increase grazing pressure and maintain pasture quality at a time of pasture surplus. A paddock or back end of several paddocks can be shut up and left as standing feed for grazing rather than being made into silage or hay.

Deferred paddocks (or end of paddocks) can be grazed off like a crop when there is a feed deficit. Strip graze for part of the day, aiming for 50% utilisation and then return cows to normal pasture. Mowing deferred pasture before grazing may improve utilisation but will not affect milk production, or seedling establishment.

Deferred grazing allows pasture renovation reseeding. This results in significant increases in ryegrass population of up the 15% in the year following deferring. No increase in other grasses, weeds, or clover components of the pasture should occur.

See Deferred Grazing for more information.

Establish summer crops

Summer crops and herbs can provide a good source of energy (and protein) during the summer months in regions where pasture growth rates decline. Summer crop profitability depends on the expected pasture production and expected crop yield.

Summer turnips

Summer turnip varieties need 60-100 days to mature. Research has shown that October sowings consistently give higher yields than November sowings, see turnips.


Chicory establishes best when sown into warm soils (12°C) at less than 10mm depth. Sowing too late runs the risk of dry conditions reducing plant establishment and survival see Chicory.


Plantain grows well in warm, well drained soils when temperatures are above 20 degrees. If moisture and nitrogen are not limiting plantain will grow more than ryegrass/clover pastures. However, plantain is not a high yielding, one graze crop like turnips that can be used to move a large quantity of feed into a feed deficit.  When soil moisture is limiting, plantain growth rates are also limited like ryegrass/clovers pastures.  Therefore, while plantain recovers quickly after a summer dry, it is not a crop that can significantly fill a summer feed deficit, see Plantain.

Fodder beet

Fodder beet is an option for late lactation crop, but yield may be sacrificed where fed as a summer crop. Proper logistics planning for crop growing is important see fodder beet.

Late sowing options

Most summer crops need to be sown before early November. Green Feed maize, sudan, and sorghum provide an exception to this rule and can be established in November and early December which makes them useful when chicory and turnips are no longer an option.

Sorgum x sudan grass hybrid, or sudan x sudan

Sorgum x sudan grass hybrid, e.g. Bettagraze, or Sudan x sudan, e.g. Super Sweet Sudan, can be planted once soil temperatures reach 17+ degrees Celsius and rising at a 5cm depth. Only 35-45 days are required until grazing is possible but must be at least 1.2m at first cut. Regrowth can be grazed when it reaches 0.8m and no higher than 1.2m. Need to plan grazings so that feed quality is kept. Break-feed behind a wire and back-fence to protect regrowth and avoid higher intakes. Must be sprayed out before regrassing as frosted plants are toxic.

  • Be aware of potential animal health issues (nitrate accumulation) and check sulphur levels in the diet are above 0.2%.
  • Supplementation of sulphur is recommended if pasture sulphur is low (less than 0.25%) or more than 50% of the diet is crop.
  • It is recommended that this type of crop is restricted to 30-40% of the diet where possible.
  • Normal yield estimates are 12-15t DM/ha or 3.5-4.5t DM/cut or grazing (but may only get two cuts/grazings in dry years).
  • 9-10MJ ME/kg DM. Protein at 1.2m is 12-14%, and at 0.8m protein is 15-16%.
  • 15% DM is a good average to use. Feed value declines rapidly as crops mature (greater than 1.4m height).

For more information, seek advice from your local seed representative.

Green feed maize

Green feed maize can be planted once soil temperature at a depth of 5cm at 9am is 10oC and rising, and can be green fed from 6-8 weeks after planting - though higher yields can be achieved if crop is left until cob-fill has started. Can be break fed, or harvested with a flail-type harvester or precision chopped.

  • Not suitable for maize silage.
  • Normal yield estimates of 10-18t (8-12t DM/ha when dry.
  • 10.3MJME/kg DM and 9% protein, can be fed as 25-50% of the lactating cow diet.

Green feed maize is 20-30% DM, under "normal” growing conditions, maize silage will accumulate 200-300kg DM/ha/day. Green-feeding reduces the crop's yield and increases the cost/kg DM. As the crop gets closer to harvest, the maize growth slows and the amount of yield you lose decreases.

Talk to your local seed representative for latest seed options and sowing information and see maize for growing tips.


Decision rules around feeding supplements need to be made alongside knowledge of overall expected feed supply and demand.

What to choose? How much to pay?

DairyNZ’s supplement price calculator will help you determine how much you can pay for supplementary feed during a shortage. It provides a more detailed output with regards to different feed types, amounts, and time of the year.

Note the milk response in these resources is determined based on energy being the limiting factor to milk production. While this is typically the case when cows are eating high quality pasture, in summer or early autumn the availability and quality of the pasture declines and the use of low protein supplements, e.g. maize silage and fodder beet, increases. Therefore, in some instances protein may be limiting milk production.

However, protein supplements are usually expensive and even with a milk response, the extra milk revenue does not typically outweigh the cost of feeding a protein supplement.

Another factor to consider if using large amounts of supplements in summer is ensuring cows have adequate effective fibre**.** For example, although PKE is high in neutral detergent fibre (NDF), it contains no effective fibre. From a rumen health perspective, a forage source (pasture, straw, hay) may need to be included in the diet if PKE is being fed. For more information see DairyNZ’s FeedRight booklet.

Body condition score

A pre-Christmas BCS assessment determines if cows have gained BCS since planned start of mating and a management plan for the autumn can be set up.

Plan to assess cows’ gain mid-February to mid-March to determine if the plan is working and to decide if some cows should be dried off early, milked once-a-day (OAD) or preferentially fed.

Last updated: Sep 2023
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