A comparison of the effects of sward improvement on invertebrates, sward establishment and herbage yield

Abstract

SummaryField experiments were done at two widely separated sites in England (Tadcaster, North Yorkshire and North Wyke, Devon). In each case an old permanent sward was re‐seeded after ploughing or by direct drilling, or was left intact and fertilised. The carbamate pesticide aldicarb was applied to half of each experimental plot. The effects of sward improvement and pesticide on various soil invertebrate groups were assessed. Soil‐dwelling macrofauna arthropods were scarce at both sites. Stem‐boring dipterous larvae, however, were numerous at both sites. At Tadcaster, Oscinella vastator was the only species present in the original sward, but 0. frit was by far the most prevalent species in re‐seeded areas. These can only have arisen from direct oviposition of eggs by adults on or near the emerging seedlings and not by migration of larvae from buried turf or the desiccated old pasture.Mites and Collembola were abundant. Their numbers were reduced initially by cultivation and pesticide usage, but the effects of these practices were transient and their numbers recovered to previous levels usually within 10 wk.Earthworms were present at both sites. Deep burrowing species, e.g. Lumbricus terrestris and Allolobophora longa were less affected by the treatments imposed than species such as A. chlorotica and L. rubelius which usually live close to the soil surface. Effects on their numbers were in any case, short‐lived.No improvement method consistently provided the greatest herbage dry matter yield. Pesticide application, however, greatly increased seedling stand and/or herbage yield at both sites and showed the benefits of using crop protectants, especially on direct‐drilled re‐seeds.