Cut costs by going back to basics on soil fertility

Following four simple steps will ensure a good supply of top-quality grass.

Farming has become a very technical profession, and it is very easy for farmers to be blinded by science and often miss the basic principles.

All our livestock ­enterprises are grass based, therefore growing a good quantity of quality grass is an essential ingredient for a profitable enterprise.

Over 90pc of Irish soils are deficient in one of the major nutrients of lime, phosphorus (P) or ­potassium (K).

This represents a huge loss of potential on Irish farms as, very often, farmers end up renting land at high prices or purchasing silage and expensive feed to ensure enough fodder is made when they could produce it from their own land if the soil fertility is corrected.

Frankly, this is very difficult to understand. Farmers need to get back to basics and take the following four steps:

Soil Sample

Every farm should have soil sample analysis completed to show the lime, P&K status of their farm.

Sample the same areas of the farm at least every four years to allow comparisons of previous analysis. Farmers availing of a ­nitrates derogation must soil sample areas of 5ha every four years. This ­practice should really apply to all farmers.

Remember to ensure no slurry, lime or P&K have been applied in the previous three months.

There is no best time to sample once these rules are observed, however, all of the farm together and sampling at the same time of year every time you sample is advisable, if only to better compare to previous results.

When the results are received, get your advisor to prepare a Nutrient Management Plan suitable for your farm and to comply with the nitrates regulations.


Over 70pc of Irish soils are deficient in lime. In the 1970s, there were over two million tonnes of lime spread per annum. This was down to 500,000 tonnes in 2012.

Lime clearly has gone out of fashion, yet it is the most important fertiliser on all farms. Getting lime levels corrected so that the soil pH is in the 6.3-6.5 range will release more P and other nutrients into the soil and significantly boost the growth of grass dry matter.

There is no right time to spread lime. Farmers should take any opportunity available throughout the year to spread, but avoid spreading too close to cutting silage as it will affect silage preservation.

Ground limestone is the simplest and cheapest way to raise lime levels.


Over 50pc of soils are ­deficient in P and there is clear evidence that P levels are falling.

The first source of P&K is slurry or farmyard manure (FYM). Making the most of on-farm slurry/FYM is a cheap way to boost P&K. Spreading early in spring and late into autumn outside the exclusion dates maximises the use of the nitrogen content in slurry/FYM.

The use of a trailing shoe incentivised in GLAS further enhances utilisation of slurry. The balance of P&K required should be applied on a ‘little and often’ basis to minimise loss from run off. Silage removes a lot of K from land, therefore pay particular attention to fields cut twice or more every year.

Application of too much P is the reason many ­farmers get penalties under cross compliance with the ­nitrates regulations, so make sure you know what P you can buy for your farm at the start of the year – and stay under the limit.


Nitrogen (N) is the lifeblood of Irish grassland farms. Good progress is presently being made with ­nitrogen-fixing clover swards at Clonakilty ­Agricultural College but bag N will always be the main driver of grass growth.

Urea is the cheapest source of bag N and it works well in colder non-sunny conditions, but CAN or compounds are the fertiliser of choice of most Irish farmers. In general, Irish farmers use nitrogen well, however some tend to skip a round or two when grass is growing well in May/June. If you are well stocked, this is the time to use it, and when you get the best grass growing response to N. Remember ­silage in the pit is like ­money in the bank.

The above advice has been around since the 1970s, and it is as important today to farm profitability as it has always been, yet many farmers do not follow the advice.

Taking the four steps above will ensure your farm business will have more fertile land, grow more grass and have more money in the bank at the end of every year. Back to basics makes perfect sense when it comes to fertiliser and soil fertility.