The expansion of Omex in Ireland with the opening of its new liquid fertiliser distribution centre in Co. Cork has focused the spotlight on how to manage what is regarded by many as the most efficient method of adding nitrogen to crops.

There are several advantages to applying N in liquid form and, for the customers of Omex, the first of them usually cited is the accuracy of placement.

Throwing granular fertiliser onto a field has been the standard method of bringing nutrients to crops for many decades now, and it would seem a perfectly natural way of going about the task, but closer examination reveals several shortfalls in the method.

Granular gripes

The biggest problem is ensuring the right amount arrives equally across the spreading width of the spreader.

While the machinery manufacturers go to great lengths to ensure this happens, the flight characteristics of the material and vagaries of the wind do their best to frustrate the result.

Droplets on crop margin — Delivering nutrients to the edge of the crop and no further is often stated as the chief benefit of liquid fertiliser

The alternative method of transporting the nutrients across the spreading width by boom, before releasing them over the intended patch of ground is far less liable to fluctuations in wind speed and direction, while the homogenous nitrogen solution eliminates any fears of granule inconsistency.

This then is the theory, but there are practical considerations to be made when switching from solid to liquid, not least of which is how to handle and store the material before use, and it may not be quite such a challenge as may be feared.

Swapping over

One farm that has made the switch is Howard Farms of Bellewstown, Co. Meath, who started making the switch seven years ago and are now fully convinced of the virtues of nitrogen application in liquid form.

Image of people — L-r: Paul Murry (sprayer operator); Alan McEvoy (Deeside Agri); Ian Howard

The enterprise is run by the father and son partnership of Ian and Podge Howard and it extends to 2,500ac of tillage with some extra ground cultivated in association with a neighbouring potato grower.

Being a large farm, it is no surprise to find that an investment has been made in storage tanks for the product, all of which is supplied directly from Cork through Deeside Agri, the local Omex agents.

Omex will supply the tanks for free, on condition that they are filled twice a year, yet they do need a bunding wall and this needs to be provided by the customer.

Fertiliser tanks — Storage tanks are best sited close to a building to reduce the risk of wind damage

In a grassland situation, this condition can be fulfilled by channelling any spillages into slurry tanks under slats. Although it is, by itself, not a toxic product, it must be kept away from watercourses and aquifers.

Weight of liquid

Tanks come in two different sizes, 30m³ and 50m³, and as a rule of thumb the product weighs 1.3t/m³, a point to be noted when filling larger sprayers.

A 5,000L sprayer tank will be holding 6.5t of liquid fertiliser rather than 5t of spray mix, requiring a little extra pulling power and a sound chassis.

SAM Infinity sprayer — The SAM Infinity Sprayer is the second SAM the Howards have owned

However, Omex and its distributers believe that all modern sprayers, trailed or self propelled, are more than equal to the task and have heard no reports of sprayers failing due to the extra weight.

Sprayer fleet

The majority of the fertiliser at Bellewstown is applied via a 6,000L SAM Infinity self propelled sprayer spanning 24m, backed up by a smaller Landquip trailed sprayer, which, between them, cover around 20,000-25,000ac/yr.

Tractor and sprayer on weighbridge — The SAM self propelled sprayer is backed up with a Landquip trailed unit

This is a large acreage but it points to one further benefit of of liquid fertiliser and that is it can help spread and justify the cost of a new sprayer, allowing farms to update their equipment with TAMS-eligible machinery.

High-volume nozzles

One other cost is that of nozzles that are designed to deliver a high volume of liquid in droplet form, the complete opposite of a chemical spray nozzle, but it is more an incidental expense rather than an investment.

Umbrella Nozzle — There is a wide selection of nozzles available, the Howards choose a version that provides an umbrella shaped cone of liquid

Howard Farms first experimented with a Tee bar type nozzle attachment that dribbled three streams from a single bar, but soon abandoned these for items that gave an ‘umbrella’ shaped cone.

Nozzles being checked — Paul Murry checks the nozzles before treating a field of winter barley

The main reason for the switch was that these gave a more even result with a little bit of overlap and the ability to push the liquid beyond the drop zone of the boom.

They are also less affected by sidewinds and slopes.

Field delivery

With everything going to plan, around 350-400ac can be covered in a day, but this work rate depends on one further link in the chain, and that is a bowser taking the liquid from the main storage tanks out to refill the sprayer in the field.

This task is performed by a stainless steel tank sitting upon a cut down skeletal trailer, both second-hand items repurposed for the job.

Tractor and bowser — The bowser is based on a cut down container trailer with a used bulk tank mounted on to it

Ian Howard noted that cost-wise, there is little, if any, difference between solid and liquid. Sometimes one is more expensive than the other but over the long-term, these balance out.

Less wastage with liquid

The more efficient use of the product helps balance costs, there is no throwing it into the hedgerows and it is generally absorbed into the soil far quicker, and with less wastage of nitrogen than granules sitting on the surface waiting for rain.

Sprayer in field — With normal soil moisture levels, nitrogen delivered in a liquid solution can get to work immediately

A further cost advantage is that it is around half the price of urea to protect, and other micro nutrients can be easily mixed into the tank.

A farming enterprise the size of the Howard farm is not typical of Ireland, and while it may be expected it may be more easily able to adapt to such a change in method, smaller farms are by no means disqualified on terms of cost for there are options available that do not require similar equipment or investment.

Granular gripes

Swapping over

Weight of liquid

Sprayer fleet

High-volume nozzles

Field delivery

Less wastage with liquid

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Managing the switch to liquid N at Howard Farms in Meath