If the majority of dairy farms in Pennsylvania fully adopt conservation best-management practices, the state may be able to achieve its total maximum daily load water-quality target for the Chesapeake Bay, according to researchers.
That is the conclusion of a novel assessment of the simulated effects of implementing a conservation dairy-farming system on all dairy farms in the Spring Creek watershed, a small drainage in Centre County. In the simulations, the conservation dairy-farming systems — which have been developed and tested by Penn State researchers over the last decade — produce the majority of the feed and forage crops consumed by their cattle, use no-till planting, have continuous diversified plant cover, and have one system to employ manure injection.
Using a variation of the Soil and Water Assessment Tool — known as SWAT — which was customized and calibrated for the karst topography and hydrology in the Spring Creek watershed in earlier Penn State research, researchers modeled nutrient and sediment-loading processes of four dairy-farming scenarios that differed in land area, feed-production and nutrient-input strategies. They compared nonpoint pollution generated by "typical" existing Pennsylvania dairy farms that include some no-till and limited cover cropping, with dairy farms under conservation management.
The customized SWAT simulated the four dairy-cropping scenarios for a 12-year period. All four dairy farms compared had 65 milking cows and young stock, fed the same dairy ration, and were assumed to produce the same amount of manure with the same nutrient composition. But the land needed to produce the crops differed among the four farming scenarios, and the conservation farms had more land over which to grow feed and apply manure.
Read more at Penn State
Image: In the study, the conservation dairy-farming systems -- which have been developed and tested by Penn State researchers over the last decade -- produce the majority of the feed and forage crops consumed by their cattle, use no-till planting, have continuous diversified plant cover, and one system employs manure injection. (Credit: Karsten Research Group, Penn State)