|Title||Strategic timing of nitrogen fertilization to increase root biomass and nitrogen-use efficiency of Lolium perenne L.|
|Author(s)||Boer, H.C. de; Deru, J.G.C.; Hoekstra, N.J.; Eekeren, N. van|
|Source||Plant and Soil (2016). - ISSN 0032-079X - 10 p.|
LR - Animal Nutrition
Chair Soil Biology and Biological Soil Quality
|Publication type||Refereed Article in a scientific journal|
|Keyword(s)||Delayed N application - Lolium perenne L. - N fertilization - N-use efficiency - Root biomass - Timing|
Aims: During the first days after harvest of Lolium perenne L., N remobilized from roots and stubble forms the main N source for regrowth. Low N uptake from the soil during this period may lead to N loss if N fertilizer is applied too soon. Furthermore, temporary N deprivation has been found to stimulate root growth. We therefore hypothesized that a strategic delay in N application after harvest may improve N-use efficiency of L. perenne grassland by increasing root biomass and reducing N loss. Methods: In a laboratory and field experiment with L. perenne, we delayed N fertilizer application after harvest for 0, 3, 6, 9 and 12 days, repeated this for up to six harvest cycles, and determined effects on herbage yield, herbage N uptake and root biomass. Results: In both experiments, delaying N application for up to 12 days had no significant effect on root biomass or total herbage N uptake, but it significantly reduced total herbage yield in the laboratory experiment. Total yield tended to be highest when N application was delayed for 3 days. Two growth periods in the field experiment showed significantly higher N uptake when N application was delayed, possibly due to rainfall-induced N losses in the treatments with shorter delay. Conclusions: Our results do not provide evidence that delaying N application improves N-use efficiency of L. perenne grassland by increasing root biomass. However, strategic timing of N fertilizer application based on rainfall forecasts could contribute to improve N-use efficiency by reducing N losses from leaching and denitrification.