One of the main messages highlighted at a recent Teagasc farm walk was that soil compaction will limit the amount of grass that Irish farms will be able to grow.
The walk took place on the farm of John and Brendan Walsh in Ballylooby, Co. Tipperary on Tuesday (October 4).
John and Brendan have continually improved soil fertility and health on their farm, with the farm being soil tested each year.
This has allowed them to achieve a pH of 6.2 on 85% of the farm, index 3 for phosphorus (P) on 85% of the farm, and index 3 for potassium (K) or above on 75% of the farm.
This in turn, has allowed for the successful incorporation of clover and has reduced the farm’s reliance on chemical fertiliser.
Soil compaction
Issues around compaction were discussed at the walk, with Sean McMahon, a regional sales and business development manager with Grassland Agro, stating: “If farmers have been improving soil fertility and a paddock is still not preforming, the sod needs to be turned and soil health investigated.”
Sean noted that soil compaction in fields could be a limiting factor that means paddocks are not reaching their full potential.
“Compaction or some other issue could be limiting on a farm, which means the soil isn’t working,” he said.
“I would advise farmers that have a paddock they are not happy with to turn the sod and do a simple dig with a spade.”
Sean said that on farms with good soil health, the soil should crumble in a hand. If a ball is formed like on the right-hand side of the picture below, then soil health may be an issue.
The sod on the left was taken from the centre of the field, which showed no signs of compaction. The samples on the right of the picture were taken from the entrance to the paddocks and showed signs of compaction.
Sean noted that farmers should not be worried if compaction is seen in areas that have heavy machinery traffic or entrances to paddocks, but that he would be worried if compaction is found in a few random areas of a paddock.
Lime
Commenting on how farmers can solve compaction issues on farms, Sean said: “The first thing we think of is the plough, [however] it wouldn’t be my first port of call.
“I would look at soil pH, [and ask] is lime required. Earth worms will do a lot of aeration for you; they will do the work for you if you create the right environment.
“They won’t be there if there is a pH of 5.5, but if soil pH is corrected, in time they will be there.
“One of the key messages I will say is if you don’t have up-to-date soil samples, take soil samples.
“Assess where the farm is at and put a plan in place; fertility and health is not going to be corrected overnight, it does take a period of time.”
Take-away messages
Take soil samples on your farm to determine the current situation.
Don’t panic if soil fertility is lower than you would like; put a plan in place to correct this and remember it will take time.
The Walsh family has focussed on soil fertility and health, which has allowed them to reduce chemical fertiliser usage to 130kg/nitrogen/year and grow 11t of dry matter/ha.
The target pH for farmers is 6.2-6.5 and P and K indexes of 3 and 4.
Sean noted that proper management of paddocks is important to prevent compaction.
He also advised farmers to vary the direction of travel with machinery, as it is likely the cause of compaction damage on farms.