The influence of soil potassium status on the productivity of docks (<i>Rumex obtusifolius</i> L.) in intensively managed temperate grassland

Abstract Docks are a widespread problem in grassland, necessitating novel management solutions as pesticides become increasingly regulated. The objective was to investigate the role of soil test Potassium (K) concentrations (Morgan's solution; Na acetate + acetic acid, pH 4.8; STK) on competitiveness docks grassland. experimental site (52°21 N, 7°18 W) reseeded with perennial ryegrass October 2009. A plot experiment laid down randomised complete block design seven rates fertiliser K (0, 50, 100, 150, 200, 250 and 300 kg ha −1 ) eight replicates. Dock numbers were measured over 6 years (2010–2015) herbage production 5 (2012–2016). There poor alignment between STK early study, however this improved time. While had no effect dock numbers, there positive correlations study m −2 throughout study. relatively static 2010 2012 increased substantially 2013 2015. Between 2016 strong inverse relationships ( r &gt; −.765; p &lt; .001) grass production. Towards end lower annual inputs (0 50 resulted .01) root an associated increase .05) It is evident threshold for permanent grassland infested at which more competitive plant‐available than detriment component sward.