Can periodic phosphorus fertilizer applications reduce the risk of P loss ?

Phosphorus (P) fertilizer should be applied in a way that avoids P accumulation in the topsoil, to limit P losses in surface runoff and leaching through the soil profile. This study compared two P fertilizer regimes (annual application vs. periodic application, once every six years) for their impact on soil P chemistry, P sorption capacity and water-extractable P (WEP) in soil layers to 1 m depth in Inceptisols of northeast China, based on sequential fractionation and P-31 NMR spectroscopy methods. Fertilizer regimes in the continuous corn field were: no N and P fertilizers, 0 kg P ha(-1) (N fertilizer only), 25 kg P ha(-1) annually, 150 kg P ha(-1) every six years, 75 kg P ha(-1) annually, and 450 kg P ha(-1) every six years. Soil inorganic P (Pi) fractions (NaHCO3-, NaOH-, and HCl-Pi) and orthophosphate concentrations were greater with annual or periodic P application than in the control with no P fertilizer (P < 0.05). Nevertheless, annual P application led to greater accumulation (17-48%) of the soil Pi fractions and 4-28% more orthophosphates (P-31 NMR) than periodic P application in the 0-0.8 m soil layers. Still, soils with periodic P application had less water-extractable P (32-124%) and a higher P sorption capacity (12-26%) in the profile. Therefore, while periodic and annual P fertilizer regimes both maintain soil P fertility and sustain crop P uptake, periodic P fertilizer application (i.e., every six years) at agronomic rates should limit P losses from the soil profile.

Automated summary

This study compared the impact of annual and periodic phosphorus fertilizer application on soil phosphorus chemistry, sorption capacity, and water-extractable phosphorus in northeast China. The results showed that periodic phosphorus application can reduce phosphorus losses and maintain soil phosphorus fertility and crop uptake.