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Providing evidence to improve practice

Action: Encourage foraging waterfowl Soil Fertility

Key messages

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One controlled, replicated experiment from the USA found increased straw decomposition when ducks were allowed to forage.



Supporting evidence from individual studies


A controlled, replicated experiment in 1995-1996 on a silty clay soil in California, USA (Bird et al, 2000) found that waterfowl foraging activity increased straw decomposition by 78% in untilled plots and 18% in rolled plots (a roller crushes crop remains into the soil) compared to their respective un-foraged plots. Foraging and field tillage reduced nitrogen concentrations in the remaining straw residue at the end of the winter fallow period. Mallards did not incorporate the straw. Individual field plots (25 m2) were subjected to two post-harvest treatments: wet-rolled (field tillage) or untilled, replicated four times. Within these treatments, Mallard Anas platyrhynchos ducks were placed on one half of the plots, equivalent to 33 birds/ha from 1-18 February. Ten soil samples were taken from each plot on five sampling occasions. The study measured levels of residual rice straw and below-ground organic matter (carbon and nitrogen).


Referenced papers

Please cite as:

Key, G., Whitfield, M., Dicks, L.V., Sutherland, W.J. & Bardgett, R.D. (2019) Enhancing Soil Fertility. Pages 627-648 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.