The farming calendar always presents new considerations, opportunities and challenges. At this time of year, one often overlooked yet vital element of soil health always resurfaces: pH management.  

Soil pH significantly influences nutrient availability for plants and soil micro-organism activity, so maintaining the right level is essential for optimal nutrient uptake by crops and to prevent deficiencies.  

Getting the balance right  

Most nutrients are more accessible to plants when soils are within a specific – or optimum - pH range. When levels are too low, nutrients like calcium, magnesium and potassium become more soluble and can be leached away, while higher levels can make it harder for plants to find phosphorus and some micronutrients.  

The ideal range for most arable rotations is between pH 6.0 and 7.0, with the optimum typically at pH 6.5. At this level, most major nutrients - especially nitrogen (N), phosphorus (P) and potassium (K) - are available in forms that plants can easily absorb. 

Crops such as oilseed rape, sugar beet, barley and peas are particularly sensitive to soil acidity. Oilseed rape, for example, can suffer stunted growth, slow root development and poor nutrient uptake in suboptimal pH conditions. Similarly, sugar beet yields considerably less at pH 6.  

Understanding the value of lime 

All limestone products include calcium and magnesium carbonates which are responsible for neutralising acids in soils.  

The calcium carbonate equivalent (CCE) represents the sum of the calcium and magnesium carbonates in a liming material, which means the higher the CCE, the greater the acid-neutralising value (NV) of the lime.   

For lime to work to maximum efficiency, however, the carbonates must come into contact with the acids in the soil to neutralise them. Therefore, lime products with smaller-sized particles react faster because there’s a greater surface area of product exposed to the soil. The maximum particle size should ideally be 2.4mm - anything above this is unlikely to influence soil pH in an effective way. This is why it’s so important to always find out the NV and particle size when ordering product from a supplier - the NV being the relative effectiveness of a liming material compared with that of pure calcium oxide (CaO).  

Lime recommendations are usually given in terms of ground limestone or ground chalk (NV 50–55), but other types can be used as long as an allowance is made for any differences in NV, the fineness of the material and the cost. Due to the properties of more fine lime particles, it is commonly granulated or prilled so it’s easier to spread.  

Different soils have different lime requirements 

Because soils are a living environment, they are vital for providing plants with water, air, anchorage and nutrients. How they are managed can have a direct impact on crop success, so it’s important to consider their condition and structure before making your application decisions. 

This is especially true at harvest when soils become more exposed and vulnerable to lost nutrients following crop removal, making it the ideal time to assess their condition and plan for any remedial action.  This is important when we consider how variable soils can be across individual fields, as well as the whole farm. 

Good soil management requires three 'golden' basics: 

• The provision of adequate drainage to prevent water-logging. 

• The correct level of compaction for root anchorage and movement of air and water. 

• The appropriate pH level to allow plants to grow and mature; helping them make the most of the available soil nutrients. 

Any imbalance of these will reduce a crop’s ability to reach it's potential. Good management is never down to one single action either – it requires ongoing attention as even healthy soils are at risk of pH changes. While good conditions are important for worms and micro-organisms to break down animal and plant residues, over time these processes can lead to more acidity which can eventually cause reduced bacteriological activity. This resulting build up can lower pH levels, create 'stale' soils and put plants under stress. 

Different soil textures respond to liming in distinct ways too. Heavy clay soils retain calcium and magnesium ions longer than lighter sandy soils, whereas clay soils tend to require liming every four-to-five years and are more resistant to pH change, but also are slower to recover if acidic. Lighter sandy soils are typically free-draining and therefore lose lime and nutrients more quickly, so will require more frequent and lower-dose applications. 

All of this variability means it’s important to know what you’re working with so you can make the right decisions for your land - and this is where precision mapping can help. By equipping you with the right insights and tools to support optimised applications, you can make sure your liming plans are targeted to meet the demand across your farm. 

The benefits of a precise approach 

The use of GPS technology to produce soil maps combined with pH soil sampling is a great way to build a more informed picture of your soils. 

As well as targeting applications where they are needed, precision mapping technology also supports greater efficiency; saving time and ensuring inputs are cost-effective and sustainable. 

To help growers with this targeted approach, our precision services team developed a lime application tool; available within the mapping area of our MyFarm platform. 

The tool allows users to create a lime plan in under a minute, with key features including:  

• The ability to see the most recent pH data across multiple fields. 

• Options for crop type, target pH, and type of lime product to ensure plans are tailored. 

• The visibility of tonnage requirements and cost (if price/tonne entered), which can be adjusted for: 

  • Neutralising value  

• Minimum/maximum rates 

• Fixed tonnage or budget constraints 

• Export functions for maps and application files, making it easy to share them with the wider farm team or liming contractors. Having applications plans and spreading files prepared in advance can be invaluable, supporting you with more efficient spreading operations, reducing risks of misapplication and ensuring a faster turnaround should a contractor’s availability suddenly change. 

Overall, the tool provides flexibility and precision, supporting more-informed decisions based on your farm’s soil nutrient data without taking up too much time. 

Support from our precision services team 

Whether you prefer to manage your own pH plans or need support putting them together, our precision applications team can share in the workload so you don’t have to take on all the detail, planning and management yourself.  

By letting us know the relevant field information, your target pH and the lime contractor you’re working with, we can formulate your lime recommendations and application plans – even sending them directly to the contractor where needed.  

If you’d prefer to manage your own plans, we also offer guidance and training for our lime application tool, where we’ll walk you through the process and ensure you have the confidence use the platform independently. 

‘Supply and apply’ – a dedicated service from our contracting team 

For growers based in Norfolk, our local contracting team has recently expanded its fleet with the addition of a new state-of-the-art spreader to support with solid fertiliser and lime applications. 

The KRM Bredal high-capacity trailed spreader is operated by a dedicated driver and further complements our existing wet spray and potato storage services in the region – with applications already underway for this season. 

If you’d like support with your lime applications or have questions about anything mentioned in this blog, please don’t hesitate to get in touch by emailing info@frontierag.co.uk or calling 0800 227445.