Surface runoff is an important process that affects the local water balance and causes soil erosion and rapid solute transport towards ditches, streams, and rivers. Surface runoff is the fastest route from field to stream and the main transport route for sediment and adsorbed contaminants, such as pesticides. It is the main contributor of pesticides to surface water bodies. The agricultural areas in The Netherlands most vulnerable to surface runoff are peat grasslands, where groundwater levels are kept close to the surface (less than 60 cm below soil surface), riverine heavy clay grasslands with low permeability and drainage by superficial trenches (less than 40 cm below soil surface), and sandy or clay soils with topsoil or subsoil compaction caused by treading, overstress due to large wheel loads of agricultural machinery, and tillage.
Source:
Willemijn M. Appels.Thesis submitted in fulfilment of the requirements for the degree of doctor at Wageningen University (attached)
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A letter from New Zealand
The European Union's failure to suspend the use of neonicotinoid insecticides (Ban on bee-harm insecticide fails, 22 March) will affect more than just bees. Their systemic mode of action makes it impossible to prevent non-target insects being affected. Food sources for insectivorous birds, whose numbers in Europe are reckoned to have declined by half since the mid-1980s, are being decimated and will continue to decline.
The decision also ignores a report by the American Bird Conservancy on the dangers to birds of seeds treated with neonics – eating just one treated seed can kill a song bird and one-tenth of that dose can affect reproduction.
And not only the birds and bees – water-dwelling invertebrates are also disappearing because the solubility of neonics, combined with their toxicity (imidacloprid, has been measured as 7,000 times more toxic than DDT), has made their spread into rivers and lakes inevitable. They are also persistent - laboratory studies give clothianidin a half-life of 158 days in soil.
Breaking one link in the food chain means that all the organisms above that link are threatened.
What we're facing now makes the world described by Rachel Carson seem like a playground.
Pat Baskett
Auckland, New Zealand
Source:
The Guardian, 5 April 2013
http://www.guardian.co.uk/global/2013/apr/02/guardian-weekly-letters-5-…