Abstract. Plant species￢ﾀﾐrich Calthion meadows on mesotrophic fen peat soil extensively cut for hay are among the endangered semi￢ﾀﾐnatural vegetation types in northwestern Europe. They are often badly affected by lowering the groundwater table (drainage) and fertilization.

In a comparative study of an undrained site with a Calthion meadow and an adjacent drained site, availability of N, P and K was biologically assessed under field conditions (for two years) as well as in a greenhouse (for 18 weeks) by measuring shoot responsiveness. Also, experimental wetting of intact turf samples taken from both sites was applied in order to study the interaction between nutrient supply and anaerobic soil conditions. It was concluded that the above￢ﾀﾐground phytomass yield in the undrained site was restricted by a major shortage of N￢ﾀﾐsupply and a moderate shortage of K￢ﾀﾐsupply by the fen peat soil. The above￢ﾀﾐground phytomass yield of the drained site was only reduced by a strongly limited supply of K by the soil. The extent of K￢ﾀﾐdeficiency was larger for the drained site. No P￢ﾀﾐdeficiency was observed in any of the drained or undrained sites. Rewetting turf samples, taken from the drained site, did not change above￢ﾀﾐground phytomass yields, suggesting that nutrient supplies were not affected by rewetting. Leaching has likely resulted in a strong reduction of K￢ﾀﾐsupply in the drained site. It is assumed that a shortage in K￢ﾀﾐsupply from the peat soil may have become an important environmental constraint for characteristic plant species of Calthion meadows. This may hamper the development of this meadow type on drained peat soils after rewetting by groundwater discharge.

Title	Contributors	Type	Date
Long-Term P And K Fertilisation Strategies And Balances Affect Soil Availability Indices, Crop Yield Depression Risk And N Use		Journal Article	2026/06/26
Nutrient Supply In Undrained And Drained Calthion Meadows	JA Inberg; D. M. Pegtel; I.C. van Duren; Et al.	Journal Article	2026/06/26