Can grain P concentration be used as an indicator of fertilizer requirements in winter wheat?

A - Papers appearing in refereed journals

Haefele, S. M., Gregory, A. S., Poulton, P. R., Hernandez, J. M. B., White, R. P. and McGrath, S. P. 2024. Can grain P concentration be used as an indicator of fertilizer requirements in winter wheat? Field Crops Research. 322 (1 March), p. 109691. https://doi.org/10.1016/j.fcr.2024.109691

AuthorsHaefele, S. M., Gregory, A. S., Poulton, P. R., Hernandez, J. M. B., White, R. P. and McGrath, S. P.
Abstract

Context or problem: Available phosphorus (P) management is a continuous task in wheat-based systems of the UK, primarily to balance applying enough P to support high yields while avoiding unnecessary costs and damaging losses to the environment by applying too much.
Objective or research question: Grain P concentration with a corresponding threshold value of 0.32 % has been
proposed as a new method for P management, supporting or replacing soil test-based evaluations. The objective
of this study was to investigate if this approach was a reliable option.
Methods: We used data from the long-term “Exhaustion Land” experiment on the Rothamsted Farm in southeast
England, to investigate the relations between winter wheat grain yield, grain P concentration, and Olsen P values
in winter wheat over the last 32 years.
Results: Our results show that maximum grain P concentrations in high yielding years are much lower than in low
yielding years, indicating a dilution effect through high assimilate transfer to grains. We could not confirm a
lower threshold of 0.32 % grain P as an indicator of crop P deficiency at high yields, in our trial the value was
closer to 0.24 % grain P. The Olsen P test at our site was a good indicator of P response, and the Olsen P threshold
value of 20 mg P kg–1 was sufficient to support the highest yields of winter wheat.
Implications or significance: We conclude that P recommendations for cereals should continue to be based on soil Olsen P values, possibly supported by better estimations of P exports using grain analysis. Evaluation of the
suitability of grain P concentration as a tool for P fertilizer management in cereal based systems would require
more research. In the future, the existing Olsen P Index classes in the current UK Nutrient Management Guide
(‘RB209’) should be reviewed to possibly increase P fertilizer use efficiency and reduce P losses to the envi
ronment whilst maintaining current production levels.

KeywordsP management; Olsen P; Wheat grain P concentration; Nutrient Management Guide RB209; P pollution
Year of Publication2024
JournalField Crops Research
Journal citation322 (1 March), p. 109691
Digital Object Identifier (DOI)https://doi.org/10.1016/j.fcr.2024.109691
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeGrowing Health (WP2) - bio-inspired solutions for healthier agroecosystems: Understanding soil environments
Publisher's version
Accepted author manuscript
Output statusPublished
Publication dates
Online07 Dec 2024
Publication process dates
Accepted27 Nov 2024
PublisherElsevier
ISSN0378-4290

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