Nearly half of the soil samples collected from the Farm Advisory Service Soil and Nutrient Network farms are suffering from low pH levels according to a new report.
A study of 273 soil samples from around the country showed that almost half of the soil samples had a pH below pH 5.8, one third were between 5.8 and 6.2 and 18 per cent were above pH 6.2. This agrees with recent research which highlighted that “many of the UK’s arable and grassland soils were below optimum soil pH levels”. *
Soil acidity is measured by pH and the optimum soil pH range to aim for is 6.0 to 6.2 on mineral soils as recommended by the new FAS Technical Note 714 Liming materials and recommendations (2019). Having a pH in this range will improve nutrient availability and crop yield.
The soil phosphorus (P) results indicated that one third of samples had a soil P Status of Low or Very Low while 60 per cent achieved a Moderate Status. Of the potassium (K) results, only 11 per cent of samples were Low or Very Low while 56 per cent were classed as Moderate.
Finally, the magnesium (Mg) analysis showed that 99 per cent of the soil samples were Moderate Status or greater which is expected in Scottish soils.
Manure and slurry samples were also tested for nutrients and showed high variation between individual samples.
The tests were carried out by SAC Consulting, part of Scotland’s Rural College, on behalf of the Scottish Government’s Farm Advisory Service (FAS). The data was gathered from 20 of the farms making up FAS’s Soil and Nutrient Network (SNN) between 2016 and 2018.
Dr Samantha Dolan, who wrote the report, said that “by combining laboratory analysis with recommendations from the Farm Advisory Service Technical Notes, farmers could improve their nutrient use efficiency while also reducing diffuse pollution risks”.
Chris McDonald, who runs the Crops and Soils theme of FAS and was also involved in writing the report, added: “This report demonstrates how important it is to test soil and organic manures for nutrient content and by using the FAS Fertiliser Technical Notes, farmers can do accurate nutrient management which will make a big difference to the profitability of the business.”
The variation in nutrient levels in soils, manure and slurry reinforces the importance of testing individual samples for nutrient management planning.
The full Report on Soil and Organic Materials Analysis from the Soil and Nutrient Network Farms 2016 – 2018 can be read here.
*Goulding, K.W.T., (2016). Soil acidification and the importance of liming agricultural soils with particular reference to the United Kingdom. Soil Use and Management, 32(3): 390 – 399.