Can differences in <i>Cirsium arvense</i> and <i>Rumex obtusifolius</i> densities within pastures be explained by soil parameters

Abstract

Some organic farming literature suggests that the presence of weeds in pastures can be explained by problems with the soil Sixty 1 m2 patches of pasture with different densities of broadleaved dock (Rumex obtusifolius) were identified across six different paddocks on an organic dairy farm Various soil parameters were measured in each patch to determine if any of these correlated well with the differing weed densities Parameters measured included soil pH moisture compaction and concentrations of 12 nutrients in adjacent perennial ryegrass This process was repeated for Californian thistle (Cirsium arvense) using a different series of 60 patches Significant correlations were found between dock density and pH potassium magnesium and manganese and Californian thistle density was significantly correlated to soil pH and sulphur content However these correlations were generally weak and are not considered good indicators of whether these weed species would thrive within this particular farm

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

“…The STK levels in the three‐year study conducted by Strnad et al (2010) were described as optimal for crop growth and hence were probably not sufficiently low for competition between grass and docks for STK to be detrimental to dock biomass production. These results are also broadly in agreement with Harrington et al (2014) who found a significant but relatively weak positive correlation between soil K status and dock population density in grassland.…”

“…At higher STK levels dock herbage production accounted for 47% of combined grass and dock herbage production in 2016. There was evidence to suggest that STK in the earlier years of the study has a positive and persistent influence on dock population densities per plot, which is somewhat in agreement with Harrington et al (2014). There was no evidence that higher fertiliser K input and STK influenced dock numbers via clonal propagation.…”

“…Furthermore, in New Zealand Harrington et al (2014) found a significant but relatively weak positive correlation between soil K status and dock population density in grassland.…”

“…On the other hand, Hrdlickova et al (2011) found a relationship between dock seed germination and the K status of the mother plants. Furthermore, in New Zealand Harrington et al (2014) found a significant but relatively weak positive correlation between soil K status and dock population density in grassland.…”

“…Broad‐leaved dock ( Rumex obtusifolius L.) hereafter described as ‘dock’ or ‘docks’ is an ubiquitous forb of intensively managed temperate grassland in Ireland and elsewhere (Courtney, 1985; Harrington et al, 2014; Hopkins & Peel, 1985). It is widely believed that low levels of docks are relatively harmless in grassland (Hopkins & Johnson, 2002) and may even confer some benefits to grazing ruminants such as reducing the incidence of bloat (Waghorn & Jones, 1989).…”