By focusing on these areas, farmers can maximize efforts to control phosphorus in a way that's practical and economically feasible. What goes in, comes out. What farmers feed their animals affects what nutrients come out in manure. Nitrogen in poultry and swine manure can be reduced by feeding the animals a lower-protein diet. Phosphorus in manure may be reduced by adding an enzyme to feed that helps some animals utilize phosphorus more efficiently.
Field trials find answers.
Penn State scientists continually conduct extensive field trials of different nutrient management methods to find those that can reduce nutrient use without reducing crop yields. One research project demonstrated that 40 percent less nitrogen could be applied to corn crops without reducing the harvest. Researchers also have developed soil and plant tests to determine whether or not plants are adequately supplied with the nitrogen they need. Sometimes the only fix is to move manure to another location where excess nutrients are not already present in the soil. Because manure is expensive to handle, agricultural specialists are exploring ways to make it more manageable.