TY - JOUR
T1 - Dynamics of soil phosphorus measured by ammonium lactate extraction as a function of the soil phosphorus balance and soil properties
AU - Amery, Fien
AU - Vandecasteele, Bart
AU - D'Hose, Tommy
AU - Nawara, Sophie
AU - Elsen, Annemie
AU - Odeurs, Wendy
AU - Vandendriessche, Hilde
AU - Arlotti, Donatienne
AU - McGrath, Steve P.
AU - Cougnon, Mathias
AU - Smolders, Erik
PY - 2021/3/1
Y1 - 2021/3/1
N2 - A sustainable supply of phosphorus (P) to agricultural soils should maintain soil fertility without jeopardizing the environment. This study analyzed the change in the soil P as a function of the net soil P mass balance, i.e. the input minus removal by the harvested crop. The P available for crops was estimated by the P extracted by ammonium lactate at pH 3.75 (P-AL). First, laboratory and pot-trial data showed that the net change in soil P-AL was only 68% of the change in total soil P, either when P had been added to soil or when P had been mined by plants for 1–2 years, indicating removal to or release from the non-extractable pool depending on the balance. Secondly, data were collated from 33 field trials in Europe with a wide range of cumulative soil P balances (−1200 to +2500 kg P ha−1) in time spans ranging from 3 to 51 years. The average change in P-AL across the negative and positive balance was only 27% (95% confidence interval 25–30%) of the net balance. The change in P-AL was larger as the net balance increased and as the initial P-AL decreased. The slope of the change versus the balance was smaller as time increased and initial P-AL decreased. The other soil characteristics did not affect these changes, and the model developed was not different for negative or positive P balances. Our results suggest that a steady state P-AL concentration at optimal P supply for crops is obtained at a net P balance of about 1–10 kg P ha−1. The P mass balance of a 51 year-old trial showed that the aqua regia soluble P of the 0–90 cm layer accounted for only 64% of the net P balances at the surface. This still incomplete P balance could be related to upward P transport by plant uptake from > 90 cm soil layers, lateral P movement in the field, and changes in the soil P fraction that could not be extracted with aqua regia. This study quantified the long-term dynamics of P-AL, which is useful for agronomic and environmental purposes and policy, and pointed out the importance of non-extractable P and vertical P movement.
AB - A sustainable supply of phosphorus (P) to agricultural soils should maintain soil fertility without jeopardizing the environment. This study analyzed the change in the soil P as a function of the net soil P mass balance, i.e. the input minus removal by the harvested crop. The P available for crops was estimated by the P extracted by ammonium lactate at pH 3.75 (P-AL). First, laboratory and pot-trial data showed that the net change in soil P-AL was only 68% of the change in total soil P, either when P had been added to soil or when P had been mined by plants for 1–2 years, indicating removal to or release from the non-extractable pool depending on the balance. Secondly, data were collated from 33 field trials in Europe with a wide range of cumulative soil P balances (−1200 to +2500 kg P ha−1) in time spans ranging from 3 to 51 years. The average change in P-AL across the negative and positive balance was only 27% (95% confidence interval 25–30%) of the net balance. The change in P-AL was larger as the net balance increased and as the initial P-AL decreased. The slope of the change versus the balance was smaller as time increased and initial P-AL decreased. The other soil characteristics did not affect these changes, and the model developed was not different for negative or positive P balances. Our results suggest that a steady state P-AL concentration at optimal P supply for crops is obtained at a net P balance of about 1–10 kg P ha−1. The P mass balance of a 51 year-old trial showed that the aqua regia soluble P of the 0–90 cm layer accounted for only 64% of the net P balances at the surface. This still incomplete P balance could be related to upward P transport by plant uptake from > 90 cm soil layers, lateral P movement in the field, and changes in the soil P fraction that could not be extracted with aqua regia. This study quantified the long-term dynamics of P-AL, which is useful for agronomic and environmental purposes and policy, and pointed out the importance of non-extractable P and vertical P movement.
KW - Mass balance
KW - Phosphorus dynamics
KW - Phosphorus release
KW - Soil phosphorus fractions
UR - https://www.mendeley.com/catalogue/5ef843aa-76ed-32dd-857b-e2a3396f2d03/
U2 - 10.1016/j.geoderma.2020.114855
DO - 10.1016/j.geoderma.2020.114855
M3 - A1: Web of Science-article
VL - 385
JO - Geoderma
JF - Geoderma
SN - 0016-7061
ER -