Nitrogen acquisition by two U. humidicola genotypes differing in biological nitrification inhibition (BNI) capacity and associated microorganisms

Abstract

Biological nitrification inhibition (BNI) has been considered a plant strategy to increase N use efficiency by reducing N losses via N2O emissions or nitrate leaching. However, recent studies have revealed no difference in gross nitrate production among Urochloa humidicola genotypes with previously described high- and low-BNI capacity and pointed towards a crucial role for microbial N immobilization. In the current greenhouse study, we compared the (15) N acquisition by two U. humidicola genotypes (with high- and low-BNI capacity) and their soil-associated microorganisms at four points in time after fertilization (50 kg N ha(-1)). Soil microorganisms slightly out-competed both genotypes during the first 24 h after fertilization, and microorganisms associated with high-BNI genotype immobilized more N than microbes associated with low-BNI plants. Nevertheless, by the end of the experiment, low-BNI plant genotype had acquired more (15) N, despite higher to N2O emissions. Furthermore, higher (15) N root-to-shoot transfer was observed in low-BNI plants, potentially indicating higher contribution of nitrate to plant N uptake. In conclusion, our results confirm higher importance of microbial N immobilization in high-BNI genotypes, at least in the short-term. However, this did not result in higher N uptake by the high BNI genotype during the first 3 weeks after fertilization as could be expected. Long-term field studies are required to better understand the implications of direct (BNI sensu stricto) and indirect mechanisms (including differences in rhizosphere microbial biomass, activity and composition between high- and low-BNI genotypes), processes on plant N use efficiency, N storage in soil, and N losses to the environment.

Keywords

Plant-microbe competition; (15) N tracing; Tropical grasses; N acquisition

Published in

Biology and Fertility of Soils
2022, Volume: 58, number: 3, pages: 355-364 Publisher: SPRINGER

SLU Authors

• Vazquez Garcia, Eduardo

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Soil Science


Publication identifier

DOI: https://doi.org/10.1007/s00374-022-01635-y

Permanent link to this page (URI)

https://res.slu.se/id/publ/116548