Decrease in soil test phosphorus levels under omitted phosphorus fertilizer application

Autor: Steinfurth, K.; Börjesson, G.; Denoroy, P.; Eichler-Löbermann, B.; Gans, W.; Heyn, J.; Hirte, J.; Jansen, F.; Koch, D.; Merbach, I.; Mollier, A.; Morel, C.; Panten, K.; Peiter, E.; Poulton, P.R.; Reitz, T.; Rubæk, G.H.; Spiegel, H.; van Laak, M.; ...
In:

Soil Use and Management
Volume 40 Issue 3
DOI: 10.1111/sum.13088
Jahr: 2024

Einordung:
Institut: Professur Pflanzenbau

Abstract:
Many European cropped soils have high soil test P (STP) values in the top soil
because of P accumulation over many years of fertilizer application. This should
allow to save P fertilizer applications for some years without STP values decreas-
ing to a level that might negatively impact crop yield. However, the way STP de-
velops under omitted P fertilizer application is not well understood. We examined
STP development under omitted P fertilizer application for timeframes between
7 and 46 years on 96 unfertilized treatments (P0 treatments) of 43 European long-
term P field experiments, using five different STP methods. For comparability,
values obtained by different STP methods were converted to Olsen-P concentra-
tions. We fitted exponential decay curves to Olsen-P data of each P0 treatment
defined by initial Olsen-P values (Olsen- Pi), rates of decrease (k) and asymptotes
(A), reflecting minimum obtainable STP. Subsequently, we analysed whether the
variables most commonly recorded in experiments, are sufficient to explain the
variation in model parameters, these variables being P export, clay content, C org
and pH as well as average annual temperature and precipitation. We found that
out of our predictor variables, soil clay content, precipitation and temperature
were showing the most prominent effects on the parameters Olsen- Pi, A or k.
However, the amount of variation explained by the considered variables was too
low to potentially facilitate a prediction of STP decrease, and various P0 treat-
ments showed no clear Olsen-P decrease or unexpectedly high asymptotes. This
hints at a strong influence of the P sorption capacity of the soil with often high
potential for replenishment from less available P pools. In connection with P in-
troduction from the subsoil or possibly from surrounding plots, the extension of timeframes of omitted P fertilizer application without reaching critical STP val-
ues for crop production, might be explainable. Corresponding effects could not be
analysed because of lack of data for most P0 treatments, calling for the additional
determination of, for example, the maximum P sorption capacity, total P and sub-
soil P in future experiments.

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