The effects of fertilizer applications on runoff loss of phosphorus

The phosphorus index (PI) can be used to effectively identify areas with high risks of phosphorus losses. Manures and fertilizers are important source factors for the establishment of the PI system. An artificial precipitation experiment was performed to evaluate phosphorus losses with the applications of different types of fertilizers and manures. The results showed that the total phosphorus (TP) losses in runoff followed the order of ammonium phosphate monobasic (NH₄H₂PO₄), ammonium hydrogen phosphate ((NH₄)₂HPO₄), monobasic potassium phosphate (KH₂PO₄), chicken manure, and cattle manure with surface application of these fertilizers and manures. The order was slightly changed to NH₄H₂PO₄, KH₂PO₄, (NH₄)₂HPO₄, chicken manure, and cattle manure with incorporation application under the same rainfall condition. Both the methods and the rate of manure application can affect the amounts of phosphorus in water and particles of runoff. More than 90 % of TP in runoff were lost through suspended particles. Manure application had a significant contribution to the P load in runoff.