Last Wednesday, a Teagasc Heavy Soils Event took place on the farm of John Leahy in Athea, County Limerick.
John has been a farmer in the Teagasc/KerryAgribusiness joint programme and in the Heavy Soils programme for nearly 10 years. The event last week showcased the work from the programme and John’s achievements.
Cow performance on the farm is very impressive with cows producing 495kgms, on 1,017kg ration. The farm grew 12.5 tonne DM/ha of grass last year having started grazing on February 28 and finishing November 5.
Two key things for farming heavy soils are land access and managing water flow.
In the last 10 years, over a kilometre of farm and spur roads have been put in; “nearly every acre has some sort of spur/roadway in it,” said John.
This allows John to maximise days at grass and grass in the diet in early spring through on/off grazing for three to four hours when grazing windows are tight.
Drainage has also allowed John to utilise more of his ground and improve grass production.
Dr Patrick Tuohy from Teagasc spoke on the drainage systems used in a field drained back in 2013.
Shallow drains crossed with grave mole plough were used after test pits were dug to identify the issue.
The first year after drainage, it grew 6t grass, soil fertility issues were identified and its peak growth was in 2019 at 13.5t grass.
Forty-Two per cent of farm is optimal for soil fertility. The plan was to first correct soil pH then focus on building Phosphorus and Potassium.
There’s a huge lime requirement to build lime, however it’s essential to be correct as it unlocks nutrient unavailable in the soil.
To get a soil pH of 5.5 to target, two applications of lime two years apart is required (each application two tonnes/ac).
The maintenance requirement (to replace lime lost through rainfall) is another two tonnes/acre every four years. So total lime requirement for the 5.5 pH soil was six tonnes of lime (pH build up + maintenance).
It takes a lot of lime to build up the foundations for building up Phosphorus and Potassium. The timing of Phosphorus applications during good weather/ground conditions in the April-to-July period is a practice adopted by John and greatly reduces risk of Phosphorus loss to waterways according to Terry O’Mahony, KerryAgribusiness ASSAP Advisor
John has started the next step of the heavy soils programme, introducing clover into his swards. Ensuring optimal establishment and continued management is essential for clover persistence.
Advice from Teagasc Grass 10 Specialist John Maher states “Graze light (800kg-1000kgDM/ha), graze tight!” as getting light into the clover helps promote growth and root development. Clover can produce up to 100kg N/ha when established.
A common questions during the farm walk on Wednesday was ‘What is the right stocking rate for a heavy farm?’
There are a number of different factors that influence a farm’s ability to support and sustain different levels of stocking rate.
If any of these areas are under pressure, they can cause a knock-on effect to cow performance and farm efficiency and a lower potential stocking rate.