The number of hectares of forage maize being grown in NI has been steadily increasing in recent years.
Speaking at an open day last Friday on a farm run by the Dobson family, outside Moy in Co Tyrone, Jonathan Dunn from Fane Valley estimated the area grown this year is around 2,100ha, and this could increase to approximately 2,500ha in 2024. Back in 2018, the maize had dropped to 1,558ha.
Dunn maintained the increase is due to a warming climate and improved crop genetics. From 1960 to 1990 the average July temperature was -14.5°C. Since then, the average stands at 15.5°C and in July 2023 it averaged 16.5°C.
“That small increase is very significant for maize,” he said.
While later maturing maize varieties might have higher yield potential, they are not suited to NI said Dunn, who added it was still very important to carefully choose the site. It should be south facing and low lying – for every 100m increase in altitude, temperature drops 0.5°C.
With the banning of single use plastic, a degradable and compostable product must now be used. It is more expensive than traditional plastic, with costs up to £210 per acre (£520/ha).
“New varieties will get away without it, especially if sown around mid-May when the risk of frost damage is much reduced,” suggested Dunn, although he added it was not simply a trade-off between cost and yield.
Crops sown under plastic will typically have up to 4% higher plant dry matter (DM) and up to 2.5t DM/ha higher yield – probably insufficient to justify using plastic.
However, they will be ready for cutting up to 19 days earlier, which creates a greater window to get the crop off the ground in good conditions and a winter crop sown, avoiding significant nutrient run off when fields are left bare over winter. On the Dobson farm, the crop was established on 14 May with no plastic, and by last Friday it was probably still three weeks off harvest. Other crops in the area, grown under plastic, could be cut in the next week.
Maize has grown well this year, helped by a warm June, with yields expected to be around 19 to 21t fresh weight per acre.
“You want a minimum of 16t fresh weight – it is difficult to justify economically otherwise,” suggested Dunn.