This might be a good time for lime

THERE has been a lot of talk in recent years about the benefits of lime application to our soils and of the importance of soil-sampling and monitoring periodically.

The question is though: how many of us are actually using our soil sample results to tailor a nutrient-management plan for our farms?

A nutrient-management plan should be prepared for all farms to ensure the most efficient use of soil nutrients, those primarily being N, P and K, plus lime as a soil conditioner.

Ground conditions at the moment are still generally very good, so it might be a good time to think about applying some lime to ground that has recently been cut for silage or grazed off. As rainfall levels are also increasing slightly, applying lime to heavier covers of grass should be fine, with the increased moisture to wash the lime off the grass. With rotation lengths increasing, animals will not be grazing these fields for a number of weeks again. This will give the fields on the farm requiring lime a head start for next spring and summer.

So what are the many benefits of liming grassland? Soils maintained close to the target pH will have benefits of increased grass yields; more efficient utilisation of applied fertilisers and manures; and better persistence of more productive species in the sward such as perennial ryegrass and clover, as well as being more palatable for livestock.

Limed soils also tend to release more Nitrogen (N) from the soil organic matter. Increases in N release of between 50 and 70 kg/ha/yr of N have been estimated previously. This would be worth approximately €60 to €85/ha at current fertiliser N prices, resulting in more grass and, hopefully, less costs on the farm.

The optimum soil pH for grassland is at or above 6.3. To achieve this, Teagasc advice sets the target pH for grassland at 6.5. This allows for the slow pH changes that occur after liming, and the gradual loss of lime after the target is reached. It assumes that the period between lime applications is not long. The target for peat soils is 5.5.

Lime breaks down the tough sod of old pastures and therefore can, on very heavy wet soils, give rise to a greater risk of poaching. Therefore the ‘ little and often’ approach to liming should be used in cases where land is wetter and more peaty in nature.

Liming of grassland should be done at least every four to five years.

The question of when is the best time to spread Lime is often asked, and the answer is that there is no best time to apply lime. Thus, ground limestone can be spread at any time during the year, provided weather and ground conditions are suitable.

Grass can be grazed as soon as the lime has been washed off the leaves by rain.

Where soil samples have been taken, with results in a high lime requirement of over 7.5ton/ha or 3ton/acre, the advice would be to split the application over two years and apply a maximum of 5ton/ha, or 2ton/acre now and a further 1.5/2ton in two years time.

In summary, you should check your most recent soil sample results identify what fields or paddocks require lime and, if possible, aim to apply 2ton/acre on these fields while conditions are good, to ensure you get the most out of your fields next spring.