Weed population dynamics for contrasting organic pasture establishment techniques

Abstract

A trial was conducted on an organic dairy farm in Manawatu New Zealand to determine how well perennial weeds are controlled during pasture renewal Changes in weed populations were monitored following three different nonchemical methods of regrassing Regrassing by planting pasture 4 weeks after ploughing the old pasture (grassto grass) was compared for spring and autumn cultivation The third method involved ploughing in spring growing turnips over summer then regrassing in autumn All three techniques caused significant increases in broadleaved dock (Rumex obtusifolius) and creeping buttercup (Ranunculus repens) populations Although both these species regrew from vegetative organs it was the establishment of new seedlings following cultivation that appeared to increase populations most This buildup of dock seedlings occurred more when using a crop than just grasstograss systems A 2week fallow after ploughing gave better control of perennial weeds than having no fallow but a 4week fallow gave little further improvement