Some states have implemented a phosphorus rule, which means many dairies now need more land for spreading manure.

While that is one strategy, the other is to reduce the amount of phosphorus you feed cows, says Dave Beede, dairy nutritionist at MichiganStateUniversity. Doing so can reduce the amount of phosphorus excreted in manure and, therefore, the acres you need to spread manure.

For example, if a 300-cow dairy producing 21,000 pounds of milk per cow  per year reduced the amount of excess phosphorus fed by 0.1 percent in each ration to National Research Council 2001 recommendations, it would reduce the amount of cropland needed to spread manure by 250 acres, says Beede. 

Percent of phosphorus
in the Ration

High group

Medium group

Low group

Excess

0.44

0.43

0.42

NRC

0.34

0.33

0.32