A<sup>31</sup> P-NMR spectroscopic study of phosphorus forms in two phosphorus-fertilized grassland soils in Eastern Canada


Abdi, D., Cade-Menun, B.J., Ziadi, N., Shi, Y., Bélanger, G., Lajeunesse, J., Lafond, J. (2019). A31 P-NMR spectroscopic study of phosphorus forms in two phosphorus-fertilized grassland soils in Eastern Canada. Canadian Journal of Soil Science, [online] 99(2), 161-172. http://dx.doi.org/10.1139/cjss-2018-0125

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. In countries throughout the world, including Canada, research is on-going to understand how P cycles in soils when P fertilizer is added and when P fertilization stops, to improve P fertilizer use. This study looked at chemical forms of P in two grassland soils from Quebec with different rates of P fertilizers over a four-year period. The results showed that adding P fertilizers increased inorganic P in the soil, which is the form taken up by plants, while decreasing organic P forms (which is the P associated with carbon).


Phosphorus (P) fertilization can increase grassland production, but will also alter P forms, changing their cycling and potential for loss in runoff. We assessed the effects of mineral P fertilization on soil P forms in timothy swards at two sites in Quebec, Canada. Soil samples (10 cm depth) were collected in autumn 2013 from replicate plots at Lévis on a Kamouraska clay and at Normandin on a Labarre clay loam, each having received three rates of triple superphosphate (0, 20, and 40 kg P ha−1) for 4 yr. These were analyzed for pH, total carbon (TC), total nitrogen (TN), and total phosphorus (TP); Mehlich-3-extractable aluminium (AlM3), iron (FeM3), calcium (CaM3), and P (PM3); and31P nuclear magnetic resonance spectroscopy (31 P-NMR) following sodium hydroxide–ethylenedi-aminetetraacetic acid (NaOH–EDTA) extraction. Phosphorus fertilization had no significant effects on soil TC, TN, AlM3, FeM3, CaM3, and pH, but significantly increased TP, NaOH–EDTA-extractable total P and total inorganic P, PM3, orthophosphate, and glucose 6-phosphate at both sites. In contrast, NaOH–EDTA-extractable total organic P, total orthophosphate diesters, and scyllo-inositol hexaphosphate decreased with P fertilization. Phosphorus fertilization over 4 yr increased soluble inorganic P and decreased organic P at both grassland sites.