Importance of lime: By this stage many of you will have, or be thinking about, getting soils analysed before the application of slurry or manures.
This is good practice as fertiliser bills can be reduced by applying only what is needed, according to phosphorus and potassium indices from the analysis. It also answers the question that is often asked “What fertiliser should I use?”
The pH result is often overlooked, but by correcting this perhaps the greatest savings can be made. pH is the measure of acidity or alkalinity and is a major factor contributing to nutrient availability. For example, potash availability for plants at pH 5 is 52% compared to 100% at pH 6.The natural pH of a soil depends on the nature of the material from which it developed and can range from 4 to above 8.Over time the pH of the soil can fall and become acidic for many reasons including heavy rainfall, crop growth, leaching and using large amounts of some nitrogen fertilisers. It is therefore important to analyse soils once every four years.
The recommended pH for optimum grass growth on permanent grassland is 6 to 6.5. Soil analysis provides a liming recommendation to bring the pH up to this level. On peaty soils the optimum pH is lower at 5.3.
What liming material should I use?
Another query that arises regularly is the liming material to use. The liming recommendation provided by the analysis is in tonnes per hectare and is based on using ground limestone. Liming materials are assessed by comparing their neutralising value (NV) or ability to neutralise acid compared to pure calcium oxide which is considered 100%. The table below outlines approximate NV values for typical materials: (see table)
If using materials with a NV that differs from 50 (ground limestone) remember to adjust the application rate. It is also important to compare costs on a cost per unit of NV rather than cost per tonne. Also take account of other nutrients in the liming material. For example, magnesium limestone can be used to improve both pH and correct a soil magnesium deficiency, however when this is applied to soils already high in magnesium it could induce a potash deficiency in the crop.
It is important to follow the application rates (adjusted if required) and a single application of more than 5 tonne per hectare should not be applied. Avoid
over-liming as this may induce deficiencies of trace elements such as selenium, cobalt and copper which could have an adverse effect on livestock performance.
Granular lime: Granular limes are formed from very finely ground particles of calcium or magnesium carbonate. The powders are formed into granules for ease of storage, transportation and more accurate application purposes. They are also advantageous for quick reactivity and spot treatments. As they are manufactured from natural carbonates granules have a similar NV to other natural liming products. The manufacturing process adds cost and consequently their use is generally less than their bulk counterparts. Also they don’t provide a long term pH correction through the whole soil/rooting zone and are not suitable for long term liming rotations.
Accurate records at lambing, whether paper based or electronic, are vital for making informed decisions about replacements/culling at a later stage. What should you record?
Lambing – unassisted, minor intervention or manual delivery
Reasons for lambing difficulty – management, over-sized lambs or malpresentation
Lamb numbers per ewe
Other ewe problems – teat/colostrum problems, prolapse etc.
Before decisions are made it is important to determine if the problem is specific to the ewe or if it was due to pre-lambing management. Using lambing and performance records are key to improving flock performance from one year to another.