Soil phosphorus pools with addition of fertiliser phosphorus in a long-term grazing experiment
Date
2020
Authors
McLaren, T.I.
Smernik, R.J.
McLaughlin, M.J.
McBeath, T.M.
McCaskill, M.R.
Robertson, F.A.
Simpson, R.J.
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Journal Title
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Journal article
Citation
Nutrient Cycling in Agroecosystems, 2020; 116(2):151-164
Statement of Responsibility
Timothy I. McLaren, Ronald J. Smernik, Michael J. McLaughlin, Therese M. McBeath, Malcolm R. McCaskill, Fiona A. Robertson, Richard J. Simpson
Conference Name
Abstract
Grasslands are a globally important use of land for food and fibre production, which often require the addition of phosphorus (P) fertiliser to maximise plant production. However, a large proportion of the added P can accumulate in pools of poorly available inorganic and organic P in the surface soil layer under grasslands. The aim of this study was to identify the chemical nature of the organic P in soils from a long-term fertiliser by grazing permanent pasture experiment that have received varying additions of phosphatic fertiliser (cumulative P input of 27, 169, 311, 513, 745 and 1035 kg P ha⁻¹) over a period of 37 years. The design of the experiment uniquely provides insight into the response of soil organic P to the addition of fertiliser P on the decadal scale. On average, 46% of the added fertiliser P was recovered as total P in the 0–100 mm soil layer after 37 years of phosphate addition. The content of both inorganic and organic forms of soil P increased with the addition of fertiliser P. The accumulation of organic P increased linearly up to a cumulative P input of 745 kg P ha⁻¹ and plateaued thereafter. The majority of organic P in all treatments was detected as a broad signal in the phosphomonoester region of solution ³¹P nuclear magnetic resonance (NMR) spectra; this also accounted for 79% of the accumulated organic P in fertilised soil. Our results indicate that accumulation of P in the organic portion as complex forms eventually reaches a new equilibrium where no net accumulation would be expected with further addition of phosphate.
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Published Online 8 November 2019
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© Springer Nature B.V. 2019