TY - JOUR
T1 - Intensive agricultural management-induced subsurface accumulation of labile phosphorus in Midwestern agricultural soils dominated by tile lines
AU - Xu, Suwei
AU - Gentry, Lowell
AU - Chen, Kai Yue
AU - Arai, Yuji
N1 - Publisher Copyright:
© 2020 The Authors. Soil Science Society of America published by Wiley Periodicals LLC on behalf of Soil Science Society of America
PY - 2020/7/1
Y1 - 2020/7/1
N2 - In addition to surface runoff, subsurface P loss through tile lines in agricultural lands has received attention over the last decade. It is not clearly understood how this strong ligand, phosphate, is distributed in subsoils (≤180 cm), contributing to subsurface P loss. We hypothesized that subsurface accumulation of labile P as a result of long-term intensive agricultural management contributes to subsurface P loss. The depth sequence distribution of P and its speciation and reactivity were investigated in tile-line-dominated Midwestern agricultural fields via chemical extraction and digestion, batch desorption experiments, and X-ray absorption near-edge structure spectroscopy. The results suggest that labile P in subsoils exceeds the eutrophication-inducing level (>0.01 mg L–1). Because of intensive agricultural management, total P was ∼400 mg kg–1 in surface soils and ∼200-300 mg kg–1 in subsoils. The depth sequence distribution of P indicated the translocation of P to subsoils. Although phosphate and phytic acid adsorbed by Al or Fe (oxyhydro)oxides and calcite were found in surface soils, phosphate adsorbed to calcite, hydroxyapatite, or both were the dominant P species in subsoils. Phosphate was highest in surface soils and decreased sharply with increasing depth. Slightly alkaline soil in subsoils suppressed the release of P but the process was continuous after 30 d. Subsurface P loss was influenced by the dissolution and desorption process of inorganic P phases and preferentially transported P from surface soils. Subsurface P loss should be considered in strategies to reduce agricultural P loss in the Gulf of Mexico.
AB - In addition to surface runoff, subsurface P loss through tile lines in agricultural lands has received attention over the last decade. It is not clearly understood how this strong ligand, phosphate, is distributed in subsoils (≤180 cm), contributing to subsurface P loss. We hypothesized that subsurface accumulation of labile P as a result of long-term intensive agricultural management contributes to subsurface P loss. The depth sequence distribution of P and its speciation and reactivity were investigated in tile-line-dominated Midwestern agricultural fields via chemical extraction and digestion, batch desorption experiments, and X-ray absorption near-edge structure spectroscopy. The results suggest that labile P in subsoils exceeds the eutrophication-inducing level (>0.01 mg L–1). Because of intensive agricultural management, total P was ∼400 mg kg–1 in surface soils and ∼200-300 mg kg–1 in subsoils. The depth sequence distribution of P indicated the translocation of P to subsoils. Although phosphate and phytic acid adsorbed by Al or Fe (oxyhydro)oxides and calcite were found in surface soils, phosphate adsorbed to calcite, hydroxyapatite, or both were the dominant P species in subsoils. Phosphate was highest in surface soils and decreased sharply with increasing depth. Slightly alkaline soil in subsoils suppressed the release of P but the process was continuous after 30 d. Subsurface P loss was influenced by the dissolution and desorption process of inorganic P phases and preferentially transported P from surface soils. Subsurface P loss should be considered in strategies to reduce agricultural P loss in the Gulf of Mexico.
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U2 - 10.1002/saj2.20089
DO - 10.1002/saj2.20089
M3 - Article
AN - SCOPUS:85089103091
SN - 0361-5995
VL - 84
SP - 1094
EP - 1109
JO - Soil Science Society of America Journal
JF - Soil Science Society of America Journal
IS - 4
ER -