Management notes for April 2021

Date published: 31 March 2021

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).

Crops: Apply pre-emergence herbicides as soon as possible after planting.


Prepared by: Richard Gibson

I have recently taken up post as the Dairying Development Adviser for South Antrim, where I will be facilitating Business Development Groups and working with dairy farmers in CAFRE’s Eastern Dairy Team. I previously worked with Aurivo Co-op as farm liason officer for Northern Ireland. I provided daily support to farmers, covering issues like total bacteria counts, somatic cell counts, thermodurics, antibiotics and milk compositional quality. I was also responsible for coordinating all of Aurivo suppliers in the Red Tractor Quality Assurance Scheme. As part of my advisory role I will be writing Dairy Management Notes.

Grazing management for the first rotation

Managing grass at turnout can be critical in dictating the rest of the grazing season, ensuring both surplus and deficit of grass supply does not become a major issue. Regular walking of the grazing platform should already have taken place and should continue throughout April. This will give a picture of grass growth and grazing covers. As ground conditions allow, get as many cows out to grass as possible after morning milking, initially for a few hours. Gradually increase the number of cows going to grass to coincide with improved conditions and grass growth.

Depending on the calving pattern and yield of the herd, cows which are producing less than 30 litres of milk per day and confirmed in calf should be turned out first. This will help ensure maximum milk yield is maintained and to remain feed efficient.

For a spread calving herd, batch cows depending on milk yields:

Management Group
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 maintenance plus (M+) will depend on the grass supply and quality. For the partial grazing or full time housed groups the ration M+ should be formulated 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.

Aim for pre-grazing covers of 2,800-3,000 kg dry matter (DM) per hectare and

post-grazing of 1,500-1,600 kg DM per hectare. Although grass analysis may vary, generally speaking DM intake will be higher than silage, with crude protein and ME also higher than most first cuts. At turnout reduce the protein percentage of the diet accordingly. 

Benefits of spring grazing

Housed cows

Assuming silage ME of 11 MJ/kg DM, protein of 14% and a DM intake of 14 kg per cow per day, a 30 litre cow will need to be fed 7.2 kg of a 19% protein dairy ration to meet her energy and protein needs.

Partially grazed cows

Recent grass analysis indicate excellent quality, with a ME of 12.5 MJ/kg DM and 19.8% protein. Moving to partial grazing on a sward like this, where the cow eats 5 kg DM of grass and is offered silage of the quality above can result in significant savings. To achieve a similar energy and protein intake to support the 30 litre production, 6.5 kg of a 16% protein dairy ration would be fed.

In summary, six hours grazing using the assumptions above will:

  • Save 5 kg DM per cow per day of silage (seven tonnes fresh per week for a group of 50 cows)
  • Save 0.7 kg of meal per cow per day (245 kg per week for a group of 50 cows)
  • Reduce meal protein requirement from 19% to 16% resulting in significant cost savings
  • Increase milk from forage by 1.6 litres per cow per day

Full time grazing

Full time grazing, where possible, will give the opportunity to half concentrate input for a 30 litre cow and further reduce the protein concentration of the feed. This will result in additional savings at a time when the milk:meal price ratio is squeezing margins.

Fertiliser applications for first cut silage

A splash-plate application of 33 cubic metres per hectare (3,000 gallons per acre) of cow slurry in early March will have supplied enough phosphate and potash for first cut silage at soil indices of 2+ for phosphate and potash.

Nitrogen (N) is the key to silage yield and quality. Nutrient requirement for first cut on dairy farms is 120 kg N per hectare (96 units per acre). Given that slurry will have supplied 30 kg per hectare (24 units per acre), this leaves a requirement of 90 kg per hectare (72 units per acre) of nitrogen to be applied using chemical fertiliser. A general guide to nitrogen uptake is 2.5 kg N per hectare (2 units per acre) per day from the date of application. For example, a silage field with 90 kg N per hectare applied on 1st April will be ready for cutting on 7th May without any excess nitrate remaining in the grass.


Prepared by: Nigel Gould

Mineral supplementation for cattle at grass

Consider mineral supplementation at grass as mineral deficiency is a widespread problem in soils across Northern Ireland. Selenium and iodine deficiency are a particular concern for suckler cow fertility. However, it is important to note that while mineral deficiency can affect fertility, if overall nutritional needs aren’t met fertility will still be compromised. Ideally, get a pooled blood sample from a group of untreated animals analysed to identify a deficiency. If a deficiency is identified, minerals can be supplemented using a range of methods. The bolus is often the preferred option for cattle at grass due to the low labour requirement.

Grass tetany

Grass tetany (Hypomagnesaemia) can be a higher risk in early spring as 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 potassium in grass can also increase the risk as it can interfere with magnesium absorption. Magnesium cannot be stored by the body, therefore a daily intake is essential. High magnesium lick buckets are the common choice for grass tetany prevention.

Grazing management

In early spring, opening covers of 2,000-3,000 kg DM per hectare are acceptable. Later in the season, when grass growth is at its peak, follow the rule of threes: aim to graze at the three leaf stage, graze for three days and graze again in three weeks. This means seven paddocks will be required. When the grass plant is grazed, it will typically grow a new leaf each week. This varies depending on growth conditions, taking longer in the shoulders of the season. After the third leaf grows, the first will die. For this reason, grazing at the appropriate time means minimal dead material in the sward, resulting in higher sward quality. It will also serve to increase total utilisable annual dry matter yield.

Closing silage ground

Aim to have silage ground that is being grazed closed by mid-April at the latest. Late closing will push harvest date further into June, at a time when grass will naturally tend to go to seed, rapidly decreasing D-value and overall quality.

Farm safety

The increased workload on farms at this time of year increases the risk of farm accidents occurring. Be aware of the specific risks on your farm and take action to remove or reduce the risks, where appropriate. ‘Stop and Think SAFE’ is a farm safety campaign developed by the Farm Safety Partnership to address the high rate of farm related injuries and fatalities. The word ‘SAFE’ focuses on raising awareness of the four main causes of accidents: Slurry, Animals, Falls (from height) and Equipment. More information on the campaign is available at the HSE website.

Slurry spreading and cows after calving are particularly high risk on beef and dairy farms at this time of year. Assess all slurry equipment and PTO shafts in particular, to ensure they are fitted with secure, sound guards and replace if required. Don’t leave agitation points to slurry tanks open while unattended. Be aware of the risk of hydrogen sulphide gas released from slurry during agitation. Do not agitate on a calm day, wait until there is a breeze which will help dissipate the gas released. Remove all animals from the shed before agitating. The first half hour after the start of agitating is the period when the majority of gas is released, therefore avoid being in the shed during this period. Ideally have another person present or let someone know what you are doing beforehand.

Cows around calving time can be unpredictable and potentially dangerous. Don’t presume a generally quiet cow isn’t capable of an attack, especially where she has a new born calf at foot. Don’t turn your back on a freshly calved cow and have an escape route planned.


Prepared by: Kieran Lavelle

An online presence proving fruitful for horticulture businesses

Ongoing trends see online garden sales increase by 220% in 2020. It is evident that a digital presence is crucial for horticulture businesses to continue to meet customer needs. This trend continues with many businesses reporting an increase in online sales for the first few months of 2021. A 69% increase in online sales for February year on year has been reported.

A year of adaptation was required for many horticulture businesses as lockdowns halted in person sales. As foot traffic was reduced in store many turned to online to purchase and search for their gardening needs. The development of web shops has provided businesses with the opportunity toshow case their stock and reach their customers. This has provided the perfect platform for new customers to experience and access gardening.

An emphasis on delivering attractive content on social media, such as Instagram, Twitter and Facebook is key. Eye catching photos of plants and gardening products, informative advice and special offers are ways of capturing the audience and to increase traffic online. To achieve full benefits from social media an understanding and awareness of the consumer is critical.

For more information check out ‘The Digital Horticulture Consumer’ webinar found on our YouTube Channel, CAFREtv.

Compact herbs

The market for potted herbs has experienced significant growth over the past decade. However, the high seed sowing densities used in many herbs, combined with warm temperatures and low light levels in early spring can result in very ‘leggy’ growth. This can cause the pots to topple over and reduce the attractiveness of the product. Although bedding plant growers can use plant growth regulators to limit ‘stretch’, such products cannot be used in edible crops. To create a stocky, compact growth habit, growers can manipulate their fertiliser regime. For many plants grown under a mild phosphorous (P) deficient feeding regime, shoot growth is restricted. To create this deficiency use a constant feed of a low P compound product with at least an NPK ratio of 3:1:3. However, something closer to a 5:1:5 ratio is preferable to really restrict quantities of P applied (aim to provide about 10-15 ppm P in the final feed). However, research on other crops has shown if the growing media has a substantial amount of P as part of the fertiliser starter charge, this will limit the effectiveness of the low P feeding regime.

Although high levels of nitrogen (N) can produce lush, green crops, it can also lead to excessive growth. Maintain N levels at about 150 ppm to balance the need of crops with excessive shoot growth. Irrigation is important in herbs as overwatering can lead to root disease, but allowing the substrate to dry out will also restrict shoot growth. It takes experience to judge which crops need watered, as some herbs such as rosemary and sage, tolerate much drier substrates than others and the type of substrate will also influence timings.


Prepared by: Leigh McLean 


Most winter cereals are due their second split of nitrogen at early stem extension, Growth Stage (GS) 30-32, barley reaching this stage before wheat. 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 attention to latest application timings, sequences with other herbicides and approved tank mixes with other products. 

Disease control

If mildew and rhynchosporium infection is severe in winter barley keep fungicide rates high, particularly if T0 fungicide was not applied or T1 has yet to go on. The following T2 fungicide should be applied around GS 39 when flag leaf has fully emerged and first awns are appearing. This should be no later than four weeks after T1. At both timings best performance comes with Prothioconazole and an SDHI in the product mix. Without Chlorothalonil, Prothioconazole or new active ingredient mefentrifluconazole (Revysol) have shown useful activity against ramularia in trials.

In winter wheat if T0 fungicide has not been applied the T1 is critical to control septoria. Apply around GS 32 when leaf three is emerging. AHDB fungicide trials have shown a long term gradual decline in SDHI/azole activity on septoria tritici over recent years. New to the market last year, Revystar, containing a new triazole (mefentrifluconazole) and established SDHI (fluxapyroxad), performs well against septoria in trials giving a step up in performance compared with other azole/SDHI products on the market. As T2 timing gives the best return on fungicide investment, Revystar if applied once in the programme is best applied at T2. Where disease pressure is low or on varieties with good septoria resistance, like Extase or Graham, existing SDHI/triazole mixes at strong rates offer cost effective protection. Folpet is considered to be the best replacement for Chlorothalonil. It should be included as a partner in mixes to protect other fungicide groups as it slows the pace of disease resistance developing in both wheat and barley.   


As we move through April gradually increase seed rate up to 400 grains per square metre. Plan to treat weeds in sown crops as soon as possible. Pre-emergence herbicides can help manage resistant broad leaved weeds such as chickweed and also targets problem annual meadow grass. 


Sprouting and chitting

Pre-sprouting systems must ensure adequate temperature, ventilation and light to control sprout growth and protect against frost. As 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 than with early varieties. 

Weed control and desiccation

Diquat got a late emergency approval last season but the same may not happen this year. Therefore, consider alternatives for weed control and desiccation. A range of pre-emergence products offer good weed control, although for best results these need to be applied as soon as possible after planting. If the window for pre-emergence herbicides has passed, contact herbicides such as carfentrazone (Shark) are an option.

Desiccation last year with Spotlight or Gozai was challenging, particularly in seed and salad crops. These products are effective on crops that are starting to senesce, but typically take one to two weeks longer to give the same effect as Diquat. 

Decisions to plant earlier and careful nitrogen management help canopies start senescence earlier and improve the probability of a successful burndown. If planting is delayed a rule of thumb is to reduce nitrogen rate by 1.0 kg per hectare per day after planned planting date and avoid late nitrogen applications which keep the canopy greener for longer. 

Greening requirements gone!

With the greening requirement of the basic payment removed the rules on crop diversification and Ecological Focus Area (EFA) no longer apply.

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