Which fertiliser is right for your farm?
With fertiliser听remaining听one of the largest variable costs on many Scottish arable and grassland farms, growers are increasingly questioning whether traditional granular fertiliser听remains听the best option or whether liquid systems can offer efficiency,听accuracy听and cost advantages. The answer is rarely straightforward, with the decision coming down to more than just the cost of the product.听Both systems can deliver excellent crop performance when managed correctly, and the decision often comes down to farm scale, infrastructure, cropping,听logistics听and management style.听However, as agriculture focuses more heavily on nitrogen use efficiency, carbon reduction and precision farming, the debate between liquid and granular fertiliser has become increasingly relevant听
Scotland听can听present unique challenges for听fertiliser management. Variable weather, short application windows, high rainfall in many regions and听numerous听different听Nitrate听Vulnerable听Zones听(NVZ)听mean nutrient use efficiency听can be challenging.听Optimising nitrogen use requires good soil management,听appropriate timing听and听accurate听application. With fertiliser听representing听a significant proportion听of production costs, improving efficiency听has听a direct impact on profitability.听
One of the biggest arguments in favour of liquid fertiliser is application uniformity.听A boom sprayer applies nutrients evenly across the full working width, removing some of the variability associated with spinning-disc spreaders. For farms already heavily invested in GPS-guidance听and variable-rate technology, liquid fertiliser integrates听easily and听naturally with precision farming systems. Variable-rate nitrogen maps can be applied directly through the sprayer with听high levels听of accuracy.听听
However, granular fertiliser spreaders听have improved听considerably in听recent years. Although wider tramlines can increase the potential for variation on arable farms, modern spreaders can still achieve excellent accuracy when properly calibrated and used with high-quality product. Factors such as wind, slope听and听granule quality can affect performance, but granular fertiliser听remains听a popular choice because large areas can be treated quickly when conditions are favourable.听
Granular fertiliser is easy to store and can be handled using听standard听agricultural machinery.听The product听required听can be听purchased,听delivered to the farm in advance听and stored in existing farm buildings,听ensuring听it听is听available when听required.听Liquid fertiliser requires dedicated storage tanks, bunding,听pumps听and handling systems.听This can free up building space for other uses. Although the听investment听in storage tanks听can be significant. Some suppliers may provide tanks as part of their service.听
Once installed, liquid systems can reduce labour requirements听as there are no bulk bags to听handle and fewer loading operations are听required. Fertiliser听can move directly from storage tanks to听the听sprayer, reducing handling time during busy periods. However,听having tanks in听a single location听can increase travelling time when refilling during application, while granular fertiliser can be carted out to fields on trailers to speed up operations if听required.听In addition, many farms do not have sufficient liquid fertiliser storage capacity to hold their full seasonal requirement, meaning deliveries are often needed throughout the application period, which can occasionally lead to delays.听
In terms of the crop听itself,听plants absorb nutrients in the same chemical forms regardless of whether they originated from liquid or granular products. Yield differences are usually听influenced听more by timing,听placement听and application accuracy than by the physical form of the fertiliser.听
However,听there听are听some differences听between听the two systems.听Liquid fertilisers provide nutrients in听solution听allowing听more rapid听uptake.听This can be useful where crops require a quick response,听e.g.听early spring cereal applications or听when听correcting nutrient deficiencies.听However,听liquid fertiliser can also carry a risk of听scorch to crops that are growing quickly, particularly听when applied in听windy conditions or if there are late frosts.听听
Granular fertiliser听generally requires听moisture,听either soil moisture or rainfall,听after application to dissolve and move nutrients into the soil. Extended dry periods can delay availability,听particularly听with urea-based products.听However, modern granular fertilisers are available in formulations that听can听provide either rapid nutrient release or a slower, more sustained supply. Controlled-release products can continue supplying nutrients over several weeks, reducing the need for multiple applications.听For most听crops, research听generally suggests听that if nutrients are applied at the correct rate and time, there is little yield advantage to either system.听听
Environmental considerations are听becoming increasingly important听as Scotland听seeks听improvements in nitrogen use efficiency as part of climate and water quality听objectives. Inefficient nitrogen use听represents听both an economic loss and an environmental challenge.听Liquid fertiliser can offer advantages through precise placement and integration with variable-rate technologies.听Equally,听well听managed听granular systems can achieve听high levels听of nitrogen efficiency.听It is often the case that the听largest听gains often come from better soil testing, improved听timing听and听accurate听nutrient management rather than simply switching product type.听
Accurately costing the two different systems can be difficult听as听prices听fluctuate听constantly according to nutrient markets, energy听costs听and transport costs.听Traditionally, granular fertilisers have often been cheaper on a per听unit听of听nutrient basis. They also avoid the infrastructure costs associated with liquid storage.听However, liquid fertiliser听supporters听argue that more听accurate听application, reduced overlaps,听increased听compatibility with variable-rate systems,听lower labour听requirements听and听reduced machinery cost听-听most听farms听already require a crop sprayer听-听can offset part of the听additional听expense.听As fertiliser prices听remain听volatile, total system cost rather than product price alone should be considered.听
For most Scottish farms, the key factor is not the form of fertiliser used, but how effectively nutrients are managed. Good soil information,听accurate听application,听timely听delivery, and a clear nutrient strategy will听generally have听a greater impact on profitability and environmental performance than the choice of fertiliser itself.听
Five听top听tips听
- Prioritise nutrient management over type of fertiliser 鈥撎齭oil analysis, timing of application, accuracy etc.听
- Match the fertiliser system to your farm鈥檚听logistics.听
- Use precision technology where possible.听
- Timing of application is more important than whether the fertiliser is liquid or granular.听
- Focus on efficiency.听
Alan Bruce, Senior Consultant听and Area Manager,听Alan.Bruce@sac.co.uk
Posted by SAC Consulting on 17/08/2026
