With the price of Nitrogen fertiliser at record levels it has never been more important to correct soil pH to ensure maximum uptake of fertiliser both from a financial and environmental perspective. Soil pH is often an afterthought, when it should be the first parameter considered when looking at soil fertility. Having soils at optimum pH (6.5 pH) should be the starting point in nutrient planning. Having the optimum pH increases nutrient cycling with increased microbial and worm activity increasing the availability of nutrients from applied from fertiliser and slurries.
Without regular applications of lime, soils in N. Ireland have a natural pH in the range of 5.5-5.8. Knowing this, what effect from a financial view does a low pH have?
With a soil with a pH 5.5, only 77% of nitrogen, 48% of phosphorus and 77% of potassium is available to the growing plant. Even at pH 6.0 only 89% of nitrogen and 52% of phosphorous is available. The balance is lost to the environment and never available to the growing crop. It is not until pH 6.5 that nutrients become fully available. In terms of financial cost, using current fertiliser prices (£600/t CAN) at soil pH 5.5 for every tonne of CAN Nitrogen purchased 33% is lost which equates to £200 of each tonne never reaching your crop. At pH 6.0 this reduces to 11% but is still a loss of £66. These are avoidable losses which through liming can be avoided. Liming as already stated will increase nutrient cycling from organic matter and soil mineral nitrogen, which can result in an extra 64 units/acre being released naturally from the soil, with a financial value of £70/acre, which is in addition to the financial savings outlined above.
Soil pH is increased by applying liming materials of which the quality and the neutralising value (ability to change pH) vary greatly. The speed and effectiveness of liming materials depends on the material they are sourced from, the solubility and particle size of the source lime is crucial. The most suitable material for liming in Northern Ireland is calcium carbonate due to soils here generally being high in magnesium, calcium carbonate is a very effective material, helping to redress the Calcium/magnesium ratio in soils. The smaller the particle the more effective and faster the product will be at raising the soils pH.
Calciprill is an excellent lime for raising pH, being mined from a pure source of calcium carbonate in Northern Ireland and being ground extremely fine, to under 0.075mm in diameter before being formed into a granule to make it easy to spread and handle. Calciprill is an extremely effective liming material, with trials showing an application of 150kg having the equivalent neutralising value of 1,000kg of bulk agricultural lime.
While very little can be done regarding the cost of Nitrogen fertiliser, pH can very economically be corrected allowing for the savings outlined above to be realised through maximisation of Nitrogen availability. To find out more about soil pH and Calciprill contact Fane Valley Agronomy & Forage office on 028 9261 0485