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Manure runoff depends on soil texture


March 31, 2011
By American Society of Agronomy

runoffNEWS HIGHLIGHT

Manure runoff depends on soil texture


Research has documented the rise of nutrient runoff from flat agricultural
fields with high rates of precipitation that adds nitrates and phosphates to
waterways.

March 31, 2011, Madison,
WI – Research has documented the rise of nutrient runoff from flat agricultural
fields with high rates of precipitation that adds nitrates and phosphates to
waterways.

These nutrients increase
the amount of phytoplankton in the water, which depletes oxygen and kills fish
and other aquatic creatures. While injecting animal manure slurry into the soil
has been proven to be an effective way of reducing greenhouse gas emissions,
there has been no research on the possibility of nutrients leaching from the
soil and reaching waterways.

runoff  
   

A collaborative study
funded by the Danish Ministry of Food, Agriculture, and Fisheries was carried
out between the University of Copenhagen and the University of Aarhus, Denmark,
to investigate the influence of dairy slurry on leaching of manure nutrient
components.

Loamy sand, a sandy loam,
and loam were the three sub soil textures beneath the plow layer. Bromide was
mixed into the slurry to represent dissolved non-reactive solutes like nitrate.
The experiments were performed under low precipitation intensity and near-saturated
conditions. Researchers analyzed the leaching of the bromide as well as
particulate and dissolved phosphorus.

The results indicated that
the slurry injected into the loam soil reduced leaching; however, there was no
effect on bromide leaching in the sandy loam or loamy sand. The loamy sand also
showed no difference in phosphorus leaching, but a reduction was noted in the
sandy loam and the loam.

“This highlights the
importance of soil texture when evaluating agricultural management strategies
for reducing nutrient losses from agricultural fields,” said Nadia Glæsner, who
conducted the study. “Injection of dairy slurry might reduce leaching of
non-reactive slurry components and phosphorus from fine-textured soils, but the
effect was not seen on coarse-textured soils.”

The full study is
published in the March/April 2011 issue of the Journal of Environmental
Quality
. The abstract can be view at
https://www.agronomy.org/publications/jeq/abstracts/40/2/337.


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