Twenty‐five years of monitoring pH and nutrient status of soils in England and Wales

Abstract

Abstract.The Representative Soil Sampling Scheme of England and Wales was started in 1969. During the 25 year period 1969–1993 mean soil pH values under arable and ley‐arable cropping changed little, but under grassland they fell by 0.3 units. Under arable cropping, mean available phosphorus declined whilst available potassium increased fairly steeply for the first eight years then declined again to near the start value by 1993. No significant changes in soil phosphorus and potassium levels were found under ley‐arable cropping, but the percentage of fields under ley‐arable rotations declined from 33% to 14%. Under grassland, phosphorus and potassium levels both declined, although potassium levels rose initially before falling.For this report England and Wales were also divided into five regions. Wales and the West Country had the lowest pH values; these regions together with the Northern region were also found to have declining pH values. Phosphorus and potassium concentrations have been falling in the Northern region which stands out as having the lowest current potassium status with 20% of all fields deficient at index 0.Changes in pH and nutrients are discussed for soils sampled following the main arable crops. The largest changes found were the reductions in phosphorus and potassium in soils after potatoes. In 1993 almost one in ten sugarbeet crop soils had an excessive phosphorus level (index 5+) giving an increased risk of water pollution by this element.Under arable cropping the proportion of soils with low (< 1.8%) organic matter declined. Average soil organic matter levels for all crops and grass have remained static during the period. It is concluded that agricultural soils in England and Wales have not contributed to an increase in the greenhouse gas carbon dioxide.