Manure Injection Offers Hope, Challenge for Restoring Chesapeake Water Quality


Research shows the practice is compatible with no-till, doesn't increase sedimentation.

Widespread adoption by dairy farmers of injecting manure into the soil instead of spreading it on the surface could be crucial to restoring Chesapeake Bay water quality, according to researchers who compared phosphorus runoff from fields treated by both methods. However, they predict it will be difficult to persuade farmers to change practices.

In a four-year study, overland and subsurface flows from 12 hydrologically isolated research plots at Penn State's Russell E. Larson Agricultural Research Center were measured and sampled for all phosphorus constituents and total solids during and after precipitation events. During that period, from January 2013 to May 2017, the plots were planted with summer crops of corn and winter cover crops of cereal rye. Half the plots received broadcast manure applications, while the others had manure injected into the soil.

Researchers evaluated loads of total phosphorus, dissolved phosphorus, particulate phosphorus and total solids against flow volumes to learn how phosphorus and sediment losses differed between plots. Shallow-disk injection of manure was found to be more effective than broadcasting manure in promoting dilution of dissolved phosphorus and to a lesser extent, total phosphorus. The broadcast manure plots experienced more runoff of particulate phosphorus than did the injection plots.

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