Phosphorus mining efficiency declines with decreasing soil P concentration and varies across crop species

ABSTRACT

High soil P concentrations hinder ecological restoration of biological communities typical for nutrient-poor soils. Phosphorus mining, i.e., growing crops with fertilization other than P, might reduce soil P concentrations. However, crop species have different P-uptake rates and can affect subsequent P removal in crop rotation, both of which may also vary with soil P concentration. In a pot experiment with three soil-P-levels (High-P: 125–155 mg P_Olsen/kg; Mid-P: 51–70 mg P_Olsen/kg; Low-P: 6–21 mg P_Olsen/kg), we measured how much P was removed by five crop species (buckwheat, maize, sunflower, flax, and triticale). Total P removal decreased with soil-P-level and depended upon crop identity. Buckwheat and maize removed most P from High-P and Mid-P soils and triticale removed less P than buckwheat, maize, and sunflower at every soil-P-level. The difference in P removal between crops was, however, almost absent in Low-P soils. Absolute and relative P removal with seeds depended upon crop species and, for maize and triticale, also upon soil-P-level. None of the previously grown crop species significantly affected P removal by the follow-up crop (perennial ryegrass). We can conclude that for maximizing P removal, buckwheat or maize could be grown.

KEYWORDS:

• Phytoextraction
• P-mining
• sustainable nutrient management
• legacy soil phosphorus
• crop rotation

Disclosure statement

No potential conflict of interest was reported by the authors.

Acknowledgments

We thank Natuurpunt Landschap De Liereman for the collaboration in this study. Also, we thank L. Willems and G. De bruyn for the chemical analysis of soil and biomass samples. We also thank our students E. Decadt, E. Glorieux, and H. Vanheule for assisting with the lab work. During this study, Schelfhout Stephanie was appointed as research assistant and PhD student by Ghent University.