If long-term benefits from the £37m soil nutrient health scheme (SNHS) are to be secured, there must be a continual process of advice and recommendations to farmers, a leading soil scientist has said.
Addressing delegates taking part in a field tour on Tuesday as part of the joint British Society of Soil Science and Soil Science Society of Ireland conference, Dr Rachel Cassidy from AFBI highlighted results from various research programmes in the Upper Bann area.
Since 1990, regular water quality monitoring has taken place across the 220 km2 Upper Bann catchment, while in 2017 there was a large uptake by farmers in the area of free soil sampling offered under an EU scheme.
In addition, two sub-catchments were soil sampled in 2016 and 2017 as part of the process of reporting on the continued operation of a derogation in NI which allows farmers to apply up to 250kg manure nitrogen (N) per hectare (the normal limit is 170kg).
Derogated farms must plan and record fertiliser and manure applications and maintain a phosphorus (P) balance of under 10kg P/ha/year.
Of these two sub-catchments, they are both around 3.5 to 4 km2, with approximately 25 farms in each. In one of the sub-catchments, a significant number of farmers are in the derogation, resulting in nearly half the fields being managed to comply with the 250kg N limit.
Despite having these derogated (intensive) farms, research shows that P is better managed in this sub-catchment, with fewer fields at high indexes and less overall surplus P at risk of being lost to the environment. The results potentially suggest that the rules around derogation have effectively encouraged these farmers to make good decisions when it comes to managing their slurry.
In both catchments, the provision of results to farmers, accompanied by training and advice around nutrient management planning, saw water quality improvements from 2016 to 2020.
However, since then, P levels in soils and concentrations in water are up slightly, especially in the sub-catchment where there are no derogated farms.
“COVID and staff shortages meant we took the foot off the pedal a bit in 2020. It demonstrates to us we need to stay engaged for the long term if we want that behavioural change we would like to see,” said Cassidy. Across the wider Upper Bann catchment, there is also evidence soil P is going in the wrong direction. Analysis of data from Zone 1 of the SNHS suggests that soil P levels have generally increased when compared to results from the scheme in 2017.