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