Action: Encourage foraging waterfowl
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One controlled, replicated experiment from the USA found increased straw decomposition when ducks were allowed to forage.
SOIL TYPE COVERED: Silty clay
The primary goal of rice producers after the rice has been harvested is to remove rice straw (crop remains) over the winter fallow period, before preparations for the next growing season begin. In a bid to reduce air pollution in the region, farmers are now required to adopt alternative methods of reducing rice crop remains other than burning the rice straw. Many farmers now flood their land, providing winter habitat for waterfowl (in this case ducks). The ducks crush and tear at the rice crop remains while searching for insects and bits of grain.
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).