Artefacts in Field Trial Research—Lateral Ammonia Fluxes Confound Fertiliser Plot Experiments

Karin S. Levin (), Felizitas Winkhart, Kurt-Jürgen Hülsbergen, Hans Jürgen Reents and Karl Auerswald
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Karin S. Levin: Chair of Organic Agriculture and Agronomy, Technical University of Munich, Liesel-Beckmann-Str. 2, 85354 Freising, Germany
Felizitas Winkhart: Chair of Organic Agriculture and Agronomy, Technical University of Munich, Liesel-Beckmann-Str. 2, 85354 Freising, Germany
Kurt-Jürgen Hülsbergen: Chair of Organic Agriculture and Agronomy, Technical University of Munich, Liesel-Beckmann-Str. 2, 85354 Freising, Germany
Hans Jürgen Reents: Chair of Organic Agriculture and Agronomy, Technical University of Munich, Liesel-Beckmann-Str. 2, 85354 Freising, Germany
Karl Auerswald: Aquatic Systems Biology Unit, Technical University of Munich, Mühlenweg 22, 85354 Freising, Germany

Agriculture, 2023, vol. 13, issue 8, 1-21

Abstract: Agricultural ammonia (NH 3 ) emissions can have serious environmental impacts, lower fertiliser nitrogen-use efficiencies, and cause economic losses. NH 3 losses may not only occur directly from organic fertilisers such as biogas digestates when applied to crops, the crops themselves may also be a source of ammonia emissions. Wheat yields from 14 years of an organic small plot fertiliser trial fertilised with biogas digestate were analysed to determine if there was significant lateral N transfer between plots. A simple NH 3 loss/gain model was developed to calculate possible N gains and losses via NH 3 volatilisation from the applied digestate. This model was tested using NH 3 volatilisation measurements. In addition, 15 N isotope measurements of crop biomass were used to analyse plant N uptake. While digestate fertilisation increased wheat yields, yield patterns indicated that NH 3 emissions from plots fertilised with biogas digestate affected yields in neighbouring unfertilised plots. Measurements of ammonia losses and gains in the field validated our modelling results, showing that 55% of digestate NH 4 + -N was volatilised. 15 N isotope analysis indicated that crops took up as much as 30 kg ha −1 NH 3 -N volatilised from digestate, and that plots closer to fertilised plots took up more of this NH 3 -N than crops further away from fertilised plots. Our results imply that neither the results from the fertilised plots nor from the unfertilised plots are without bias. To avoid inadvertently introducing artefacts into fertiliser field trials, plot sizes need to be increased and treatments situated further apart.

Keywords: experimental design; ammonia fluxes; isotope; biogas; digestate; organic agriculture (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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