Management notes for April 2019

Date published: 04 April 2019

Management Notes are prepared by staff from the College of Agriculture, Food and Rural Enterprise (CAFRE). CAFRE is a college within the Department of Agriculture, Environment and Rural Affairs (DAERA).

Provide adequate trough capacity and water flow rates to suit demand.


Prepared by: Christopher Breen

Cows at grass

Last month I encouraged you to get your cows out to grass. Now that the time has changed your cows should be going to grass straight after morning milking and grazing for half a day. A ‘crash’ in milk yield is a concern when turning cows out to grass. So how can you maximise daily yield and remain feed efficient on your farm this spring when the yield of individual cows can vary from 15 to 60 litres?

In a spread calving pattern herd batching your cows into yield groups will help. Use milk yield to sort cows into groups for:

  • Grazing full time - lowest yielding/late lactation cows;
  • Grazing by day and housed at night - mid lactation cows;
  • Housed full time - freshly calved/highest yielding cows.

For the full time grazing group the ration M+ depends on grass supply and quality. For the partial grazing or full time housed groups formulate the ration M+ so that the lowest yielding cow in the group is not overfed. The M+ will change as cows are moved from housing, through partial grazing to full time grazing.

Farmers with cows grazing for a few hours after morning milking, are topping them up in the parlour, after their first 10 litres of milk, at a rate of 0.45 kg of concentrate per litre. Once cows are settled on day time grazing, restrict parlour feeding to cows giving more than 15 litres. When full time grazing a cow yielding 40 litres per day requires 7.5 kg of concentrate. Cows yielding more than 40 litres should still have access to a blend in the TMR. Aim to have your grazing rotation fully established by the third week in April. Full time grazing will then provide the nutritional requirement for cows yielding up to 22-25 litres, but this depends on both weather and grazing conditions. The table below shows a practical spring transition. This can be fine-tuned based on daily milk sales and concentrate levels fed.

  Ration Parlour feeding above M+ (litres)
Early April Few hours grazing after morning milking M+ 10
Mid April Quality grass by day and silage by night M+ 15
Late April

Good supply of quality grass full time

M+ 25

Drinking water

As a rule of thumb cows require five litres of water for every litre of milk produced.  As about half of the herd’s daily water requirement is consumed after each milking it is important to provide adequate trough capacity and water flow rates. Have you noticed groups of cows waiting around the water drinkers? Any restriction in water supply will have an impact on milk yield. There should be enough trough space for 10% of the herd to drink at any one time and each drinking cow needs 700 mm of trough space. Position troughs within the grazing area to avoid yield restriction. The lip of the trough should be 850 mm above the ground and the water level 50-100 mm below the lip.

Nitrogen for silage

A splash-plate application of 33 cubic metres per hectare (3,000 gallons per acre) of cow slurry this February or March will have supplied enough phosphate and potash for first cut silage at typical silage field soil indices. It will also have provided some nitrogen for grass growth but there is still a major requirement for nitrogen fertiliser. Apply up to 100 kg of nitrogen per hectare (80 units per acre) now to fields for first cut.

April jobs checklist

  • Prepare for the forthcoming breeding season. How good are your heat detection rates? Can these be improved? Have you selected suitable bulls to achieve your long term breeding goals?
  • Assess condition of young stock, especially maiden heifers. Will they be in the right condition for service?
  • Change your time clocks if not already done.


Prepared by: Nigel Gould


Turning cattle out to grass

Turn cattle out to grass as soon as ground conditions and grass covers allow. The mild winter means that grass availability is higher on many farms compared to other years. Some farmers turned cattle out to grass earlier to graze off these higher covers. Unfortunately the high rainfall in March led to many of these cattle being re-housed. Give priority to lighter stock and target the driest areas of the farm to minimise poaching. Where possible, giving cattle access to an open yard first and turning them out hungry means they are more likely to go out and graze, thus reducing poaching. Where a paddock grazing system is in place, paddocks will ideally be laid out in a square shape as opposed to a very rectangular shape. This minimises time spent walking along the boundary and reduces poaching damage. Where ground is softer and likely to be damaged by heavy suckler cows, older calves can be creep grazed until joined by their dams. Target sheltered paddocks first, especially for calves and ideally turn out early in the morning to allow cattle to adapt their body temperature.

A rotational grazing system is generally best for achieving high grass utilisation rates. For efficient rotational grazing during the peak grazing period follow the rule of three’s - graze at the three leaf stage for three days every three weeks. This requires seven paddocks per field. When the grass plant is grazed it will typically grow a new leaf every week. This fluctuates during the season taking longer in the ‘shoulders’ of the season and a shorter time during high growth periods. Fertiliser application also has an effect. After the third leaf grows the first will die and a new one emerges. This is why it is important to graze the sward on time. Grazing too late means increased quantities of dead material and reduced grass quality. Grazing before the three leaf stage reduces grass growth and total annual yield. It is important for the first grazing that covers are grazed down tight. Failure to do this will have a negative effect on sward quality for the rest of the grazing season as a dead butt of grass is more likely to accumulate. Target pre-grazing grass covers of 2800 kg dry matter per hectare (8-9 cm) and post grazing covers of 1600 kg per hectare (4-5 cm). Cattle can be turned out to lower covers with a lower stocking rate which can be adjusted as the season progresses.


Spread slurry and chemical fertiliser based on soil analysis results if not already carried out. For first cut silage on soil with optimum indices of 2+ and 2- for phosphorus (P) and potassium (K), apply up to 120, 40 and 80 kg per hectare nitrogen (N), P and K respectively (in addition to 35 kg per hectare of sulphur-S). If you are more familiar with units per acre convert to kilogrammes per hectare by multiplying by 0.8. Part of this recommendation is met by slurry application. A rule of thumb is that 2,000 gallons of a typical cattle slurry supplies 8, 11 and 50 kg of N, P and K respectively. However on soils with a low P index (0 or 1) the available P in slurry is halved. In practice nutrient content of slurry is very variable and depends on the feeding level of the animals. Urea fertiliser is the most cost effective form of nitrogen fertiliser, but only when conditions are suitable. Only use where there is some grass cover and damp conditions. Spreading later in the season and in dry weather results in increased quantities of N being lost to the air via volatilisation. An online nutrient management calculator is available via DAERA online services which can be used to calculate fertiliser requirements based on your P and K indices.


Grass tetany (Hypomagnesaemia) can pose a higher risk in early spring when rapidly growing quality grass, with a high passage rate through the rumen, can lead to magnesium deficiency. Lactating cows and ewes are most at risk due to their higher demand. Periods of wet weather can exacerbate the problem. High levels of K in grass also increases the risk as it can interfere with magnesium absorption in the animal. Magnesium cannot be stored by the body so a daily intake is essential. High magnesium lick buckets are the common choice for grass tetany prevention.


Prepared by: Kieran Lavelle

Orchard nutrition

As well as water uptake and light interception orchard nutrition is important in determining performance, yield and fruit quality. Nutrient availability in the soil does not necessarily translate into nutrient uptake by the tree. Often there is also a lack of association in nutrient level between tree canopy and fruit. To increase yield and post-harvest fruit quality it is essential to regularly correct the level of the most limiting nutrient. Regular soil, leaf and fruit analyses are therefore needed.

Before you start applying fertiliser it is important to conduct and interpret your soil analysis. The ideal pH range for optimum nutrient availability is 6.0-6.5. If the pH is low the use of limestone is reasonable as long as the calcium level is below 4000 ppm, otherwise more than one application of potassium carbonate liquid is recommended. Potassium carbonate liquid has no direct impact on calcium level. If pH is within or slightly above the ideal range and calcium level is low use gypsum, which does not impact on pH, at 250 kg per hectare on herbicide strip. Alternatively a moderate application of organic acid mixtures is recommended which may activate soil reactions and stimulate nutrient uptake. If pH is high lower the level by applying sulphur or organic acid mixtures at higher rates.

The compound fertiliser and rate of application depends on the nitrogen, phosphorus and potassium levels in the soil. Some sulphur may also be needed. Usually fertilisers with high nitrogen content are needed. The first application should have been applied at the end of March followed by a second one after petal fall.

Foliar applications are needed during flowering, fruit set and leaf expansion. Ideally boron, molybdenum and zinc are needed from bud burst until the end of flowering. Calcium is usually needed until pre-harvest but is highly important from bud burst to petal fall for fruit tissue calcium levels. Zinc is needed at green cluster stage. Manganese and iron can be applied after petal fall for leaf expansion. Always refer to the product label and/or ask your top fruit adviser. 

Cut flowers

At a NIFFA meeting in February, Lyndon Mason (Project Manager at the AHDB cut flower research centre) reviewed recent AHDB cut flower research and identified a range of promising cut flower varieties. In consultation with NIFFA members, the direction of knowledge technology transfer cut flower work at CAFRE was agreed. The following investigations will be carried out at the Horticulture Centre, Greenmount Campus.

An evaluation of over 20 different sunflower cultivars under glass, an assessment of 10 herbs for use in scented bouquets, a sequential planting of antirrhinum and an autumn crop of chrysanthemum. Work will continue with scented pinks, a range of annual cut flowers for use as fillers (Ammi, Dacus), production of decorative seed heads (Nigella, Scabious) and novel flowers (Lupin, Celosia and Amaranthus) under protection.

The need to carry out more work in open ground cut flower production was identified as a priority. Different cut flowers will be tested for their suitability to be grown in Northern Ireland (sunflower, larkspur, cosmos and zinnia).The same crops will also be grown in a caterpillar tunnel, a low cost structure that minimises damage to flowers by wind and rain. Foliage is another area of great interest and a selection of berried material (Rosa, Symphocarpus and Callicarpa) and foliage material (Ilex, Cotinus) will be demonstrated at Greenmount. A range of willow species, selected on the basis of their attractive catkins and/or stem colour, will also be grown at Greenmount Campus.


Prepared by: Leigh McClean


Most winter cereals are due their second dose of nitrogen at early stem extension (growth stage 30-32), barley reaching this stage before wheat. Aim for between 25 and 40 kg per hectare total of sulphur for all cereals. Lower than normal winter rainfall means less leachable nutrients, such as nitrogen and sulphur, have been washed out of the root zone and in many cases are more readily available to winter crops.

Inspect crops for recently emerged broad leaved weeds applying top-up herbicide as temperatures warm up. As with all pesticides adhere to product labels paying particular attention to latest application timings, sequences with other herbicides and approved tank mixes with other products. Testing tank mixes in a bucket ensures products are physically compatible before adding to the sprayer but does not indicate the crop safety of the mixture.

Disease control

In winter barley foliar diseases Mildew and Rhynchosporium are common. Where infection is severe keep fungicide rates high, particularly where T0 fungicide was not applied or T1 has still to be applied. Apply the follow up T2 fungicide around growth stage 39 when the flag leaf has fully emerged and the first few awns are appearing. This should be no later than four weeks after T1 timing. At both T1 and T2 timings best performance is achieved with a SDHI or prothioconazole in the product mix. Strobilurins and other azoles actives aren’t as strong but still offer useful protection in mixes where crops are clean or disease pressure is lower. With sensitivity shifts to other modes of action Chlorothalonil is now providing the mainstay of Ramularia control and should be reserved for the later spray timings. 

By now some winter wheat will have received a T0 fungicide. Where this has not been applied the T1 will be critical to get on top of Septoria and should be applied around growth stage 32 when leaf three is emerging. For the T1 use robust rates of Triazole, for example Ignite or Proline mixed with a SDHI and multisite protectant to help slow the development of resistant strains. 

Mildew is easily found in most cereals this year and, if present, add a specific mildewicide to the tank mix at the next fungicide timing. Many winter cereals, particularly barley are thick and pose a high lodging risk. If so early stem extension is the most effective timing to shorten straw so include PGR, for example Chlormequat and Moddus with T1 fungicides. For thick early sown winter barley a split application may be necessary, ideally at T0 and T1. However if the T0 timing has been missed products such as Terpal, Canopy or Cerone can be applied after T1. In all cases consult the product label for latest application stage.  


As we move through April gradually increase seed rates up to 400 grains per square metre. Also plan to treat weeds in emerging crops as soon as possible. Using pre-emergence herbicides can help manage resistant broad leaved weeds such as chickweed and also target problem annual meadow grass. 


Sprouting and chitting

Pre-sprouting systems (bag or tray) must provide adequate temperature, ventilation and light to control sprout growth and protect against frost. Seed planted now will be for the main crop. Ensure the pre-sprouting system encourages multiple sprouting to produce many tubers which can increase in size over a longer growing season. 


Both crop diversification, the two and three crop rules, and Ecological Focus Area (EFA) equivalent to at least 5% of arable land remain the same as previous years.  When completing your single application online you will be notified of your greening requirements as part of the process. Completing the application early allows time to make adjustments to crops areas or EFA if necessary to meet greening, which represents approximately 30% of your entitlement value. 

Notes to editors: 

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