Differences in rainfall and soil moisture content have led to significant variations in grass growth across NI in the first half of 2017, data from AgriSearch’s GrassCheck programme indicates.

Data recorded on dairy farms located across NI from April to June shows large county by county variations. Dairy farms in Co Antrim have recorded the highest average growth of 7.1t dry matter per hectare (DM/ha) over the three-month period, compared with the lowest average of 4.8t DM/ha in Co Down.

“Variation between counties was particularly evident for the month of May when Down and Armagh yielded 1.8t DM/ha on average over the month, while the remaining four counties yielded 2.9 t DM/ha,” said Dr Debbie McConnell from AFBI.

This was due to rainfall levels falling below average across NI from April, with eastern counties experiencing the driest conditions. Daily growth dipped to around 50kg DM/ha/day on some farms in May as soil moisture reserves were used up, while growth rates of around 100kg DM/ha/day were recorded on farms in the west at the same time.

“High levels of rainfall in June did restore growth rates back to 78kg DM/ha/day across NI with much less variation evident,” McConnell said.

Total growth

Grass growth across NI is on par with previous years with GrassCheck research plots recording total growth of 6.56t DM/ha between March and June this year. This represents a 4% increase on last year, but is in-line with the long-term average (2007 to 2016).

The pattern of grass growth across NI in 2017 has been similar to long term trends, with 1.6t DM produced on GrassCheck plots in March and April and 5t DM produced in May and June.

That compares with 2016, which was characterised by a cold and wet spring, with just 1t DM/ha grown in March and April, and then a large peak in May and June, which yielded 5.3t DM/ha, 1t above the long term average, confirmed McConnell.