The chemical nature of soil phosphorus in response to long-term fertilization practices: Implications for sustainable phosphorus management
Citation
Liu, J., Han, C., Zhao, Y., Yang, J., Cade-Menun, B.J., Hu, Y., Li, J., Liu, H., Sui, P., Chen, Y., Ma, Y. (2020). The chemical nature of soil phosphorus in response to long-term fertilization practices: Implications for sustainable phosphorus management. Journal of Cleaner Production, [online] 272 http://dx.doi.org/10.1016/j.jclepro.2020.123093
Plain language summary
Phosphorus (P) is an essential element for all plants, and fertilizers must be applied to many soils to sustain crop yields. However, P fertilizer is made from rocks that are mined, as thus are not a renewable resource. In addition, P fertilizer soluble and can lost from fields in runoff, which can cause algal blooms and water quality problems. To maintain adequate soil P for crops while minimizing P losses to water, research is needed to understand P forms and their cycling in soils with different types of fertilizer. This study looked at chemical forms of P in a long-term study from China that received either no fertilizer, chemical fertilizers only or chemical fertilizers plus sheep manure. In soils with chemical fertilizers and manure, total soil P was lower while plant-available P was higher, suggesting combination of chemical fertilizers and manures will increase P availability to crops in these soils while minimizing the need for fertilizers from non-renewable sources.
Abstract
Developing sustainable phosphorus (P) management strategies is a worldwide challenge in the face of growing food demand, dwindling rock phosphate resources, and deteriorating environmental quality. This requires improved knowledge on the effect of current fertilization practices on long-term P accumulation, bioavailability and mobility, which are functions of the chemical nature of soil P. Using state-of-the-art techniques such as solution 31P-NMR and P K-edge XANES spectroscopy, combined with sequential fractionation, this study investigated the chemical speciation and transformation of P in soils under three fertilization treatments (no fertilization, CK; chemical nitrogen (N), P and potassium (K) fertilization, NPK; and partial substitution of chemical fertilizer with sheep manure, NPKM) from a long-term experiment in China initiated in 1990. Compared to the NPK soil, total P and organic P (Po) concentrations were lower in the NPKM soil in the sampling years of 2000 and 2015, suggesting reduced P accumulation under the NPKM treatment. The NaHCO3-extracted P, considered the most readily plant-available P fraction, significantly increased in the NPKM soil relative to the NPK soil in 2000. The P-XANES results revealed the formation of the magnesium (Mg)–P compound newberyite, which probably contributed to soil P availability with NPKM application. Moreover, P-NMR analysis showed higher deoxyribonucleic acid content and ratio of orthophosphate diesters to monoesters in the NPKM soil relative to the NPK soil, which implied the stronger soil Po lability with NPKM fertilization. This study provides new insights on the significant role of NPKM treatment in optimizing soil P fertilization regimes, which benefits sustainable crop production.