Document Type : Research Paper
Chair of Plant Nutrition, Department of Plant Sciences, Technische Universität München, Emil-Ramann-Str. 2, D-85350 Freising-Weihenstephan, Germany.
Nitrification inhibitors (NIs) delay the oxidation of ammonium by soil
microorganisms, maintaining a higher proportion of applied nitrogen (N) in the soil
by preventing nitrate-N loss from leaching and gaseous N losses from nitrification
and denitrification. Thus, a large number of studies have shown N fertilizers with
NIs are more environmentally friendly. In contrast, there are only a limited number
of studies about effects of the N fertilizers added with NIs on arable crop yields
and the conclusions are also divergent. This study presents a meta-analysis of
recent research in Germany investigating the effects of NIs on the yields of
different agricultural crops (winter wheat, winter barley, winter rapeseed, potato,
grain and silage maize) compared to conventional N fertilization without NIs at a
given N rate. Crop yields with and without NIs at a reduced number of N fertilizer
applications were also compared. Nitrogen fertilizers with NIs did not significantly
influence the yields of all investigated crops. For a given N application rate, the
number of fertilizer applications could be reduced by at least one without any
significant effect on yield when fertilizers with NIs were used. By contrast, the
crude protein content of winter wheat was decreased significantly when the number
of applications of NI fertilizers was less than that of non-NI-containing fertilizers.
These findings may suggest that the key advantages to using N fertilizers with NIs
are helping to protect the environment due to reduced N losses and reducing labor
costs due to saving at least one fertilizer application, all while maintaining the
yields of the investigated crops.
Keywords: Field crops; Nitrification inhibitor (NI); Nitrogen (N); N fertilizers;