University of California
Maintenance of Microirrigation Systems
Interactions which can cause precipitation
Interactions which can cause precipitation
The best policy is to not mix fertilizers. However, if mixing is necessary for microirrigation, follow the considerations below. These considerations are based on information contained in a UNOCAL compatibility chart. More detailed information about other reactions can be found in the compatibility chart.
Chemical storage for a microirrigation injection system. Photo: L. Schwankl
- Ammonium nitrate (AN-20). Incompatible fertilizers include ammonium polyphosphate, aqua-sulfur, calcium ammonium nitrate solution (CAN-17), calcium nitrate, diammonium phosphate, monoammonium phosphate, and urea-sulfuric acid. With certain limits, AN-20 is compatible with phosphoric acid, sulfuric acid, and potassium chloride.
- Calcium nitrate. Incompatible fertilizers include ammonium nitrate (AN-20), ammonium phosphate solution, ammonium polyphosphate solution, ammonium polysulfide solution, ammonium sulfate solution, ammonium thiosulfide solution, diammonium phosphate, monoammonium phosphate, urea-sulfuric acid, phosphoric acid, potassium chloride, sulfuric acid, and urea ammonium nitrate solution (UAN-32).
- Calcium ammonium nitrate (17-0-0-8.8 Ca). Incompatible fertilizers include ammonium nitrate (AN-20), ammonium phosphate solution, ammonium polyphosphate solution, ammonium polysulfide solution, ammonium thiosulfide solution, ammonium sulfate solution, diammonium phosphate, monoammonium phosphate, urea-sulfuric acid, phosphoric acid, potassium chloride, sulfuric acid, and urea ammonium nitrate solution (UAN-32).
- Urea-ammonium nitrate solution (UAN-32). Incompatible fertilizers include ammonium nitrate (34-0-0), calcium nitrate, diammonium phosphate, monoammonium phosphate, urea-sulfuric acid, nitric acid, phosphoric acid, potassium chloride, and sulfuric acid. With certain precautions, UAN-32 is compatible with ammonium phosphate, ammonium polysulfide, and aqua-sulfur solution.
For additional information on prevention and mitigation of clogging caused by fertilizer interactions, click here.