Mining of soil legacy phosphorus without jeopardizing crop yield
Vimala D. Nair, Lynn E. Sollenberger, Willie G. Harris, Andrew N. Sharpley, Andressa M. Freitas, José Carlos Batista Dubeux, Amanda N. Rodriguez
Abstract
Abstract Off‐site transport of excess soil P from repeated P fertilizer applications constitutes waste of a vital resource and poses an environmental risk. Excess P can be mined by growing crops without P addition until it is exhausted to the point of P deficiency. This study evaluated the utility of the “soil phosphorus storage capacity” (SPSC) as an indicator of safe P mining for acid soils. The SPSC predicts crop‐available legacy P in absolute terms, (i.e., kg ha −1 ; can be calculated from mg kg −1 if the bulk density and soil depth are known), which is not provided by current soil tests. Results show that mining provides sufficient P for crops when there is adequately negative SPSC. This study provides a “proof‐of‐concept” for SPSC, serving as an indicator of legacy P mining prior to the need for P fertilizer application. However, further study is needed to determine the negative P thresholds more precisely at which P mining would no longer provide adequate P for optimum crop yields.