In-situ comparison of phosphorus losses between organic and inorganic fertilizers

Phosphorus (P) is one of the limiting factors of eutrophication. P added to soil from fertilizer application could pose a threat to water quality. According to agricultural habits, swine manure (SM), oil cake (OC), biogas slurry (BS), commercial organic fertilizer (OF) and compound fertilizer (CF) were selected to compare their P losses on a slope-land under natural rainfall. The results showed that P losses of above fertilizers had significant differences (P < 0.05) compared with control. P losses order arranged by Duncan test showed as total P (TP): SM > OF > OC > CF > BS > CK, total dissolved P (TDP): SM > OF > BS > CF > OC > CK, and particulate P (PP): OC > SM > OF > CF > BS > CK. Concentrations of all the phosphorus forms increased with the increased rainfall. The ratio of TDP to TP gradually decreased after fertilizer application, and PP gradually increased. PP was the dominant form in surface runoff. Organic fertilizers had more P losses than inorganic fertilizers, even though both of them had obvious P losses.