Agricultural methods to reduce the risk to birds from cereal seed treatments on fenlands in eastern England. II. Rolling and harrowing as post-sowing cultivations.

摘要

The objective of this study was to assess the usefulness of two common agricultural cultivations to cover exposed seeds after sowing, with the purpose of reducing the risk to birds from pesticide-treated grain. In three experimental trials, both rolling and harrowing buried a large proportion of exposed seeds after drilling or broadcasting, but their relative efficacy was affected by seedbed condition. In a fine seedbed, the proportion of seeds covered by harrowing (84-86%) was substantially higherthan that for rolling (53-58%). In a rough seedbed, rolling gave slightly better results (76-84%) than harrowing (73-77%). In trials simulating seed spills, harrowing proved very effective irrespective of seedbed condition, as it dispersed most spills and buried most of the exposed seeds (85-92%). Rolling was of much less value for spills because seed coverage was lower (25-60%) and most spills remained as clumps of seeds. Estimates are presented of how reductions in surface grain by cultivations wouldaffect an index of risk to two granivorous species of birds from fonofos, a common insecticide seed treatment. The potential of these cultivations for reducing the risk of acute bird poisoning is discussed. A decision scheme summarises recommendations on how to utilize these cultivations in different parts of the field in relation to sowing depth and seedbed condition for agronomic and environmental benefits.