Dynamics of soil phosphorus measured by ammonium lactate extraction as a function of the soil phosphorus balance and soil properties

A - Papers appearing in refereed journals

Amery, F., Vandecasteele, B., D'Hose, T., Nawara, S., Elsen, A., Odeurs, W., Vandendriessche, H., Arlotti, D., McGrath, S. P., Cougnon, M. and Smolders, E. 2021. Dynamics of soil phosphorus measured by ammonium lactate extraction as a function of the soil phosphorus balance and soil properties. Geoderma. 385, p. 114855. https://doi.org/10.1016/j.geoderma.2020.114855

AuthorsAmery, F., Vandecasteele, B., D'Hose, T., Nawara, S., Elsen, A., Odeurs, W., Vandendriessche, H., Arlotti, D., McGrath, S. P., Cougnon, M. and Smolders, E.
Abstract

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.

KeywordsSoil phosphorus fractions ; Mass balance ; Phosphorus dynamics; Phosphorus release
Year of Publication2021
JournalGeoderma
Journal citation385, p. 114855
Digital Object Identifier (DOI)https://doi.org/10.1016/j.geoderma.2020.114855
Open accessPublished as non-open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeThe Rothamsted Long Term Experiments [2017-2022]
S2N - Soil to Nutrition - Work package 1 (WP1) - Optimising nutrient flows and pools in the soil-plant-biota system
BBS/EC/00005197
Output statusPublished
Publication dates
Online16 Dec 2020
Publication process dates
Accepted15 Nov 2020
PublisherElsevier Science Bv
ISSN0016-7061

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