Abstract

The aim of this study was to evaluate a number of methods for estimating nitrogen fertilization demand and the contribution of plant available nitrogen from the soil. This was done by analysing data from 36 field trials (three years, 12 field trials per year) in the south of Sweden. Large variations were observed between the 36 field trials in both economical optimum nitrogen fertilization (optimum N fertilization) and the contribution of nitrogen from the soil (measured as nitrogen yield in unfertilized plots).Only taking into account the expected yield was not enough for predicting optimum N fertilization. However, including nitrogen delivery from the soil improved the predictions (r2 = 0.60). Clay and soil organic matter content could not predict the nitrogen yield in unfertilized plots in this study. Neither could accumulated mineral nitrogen in the soil down to 60 cm depth in spring or after harvest. Best predictions of the nitrogen yield in unfertilized plots were obtained using measurements of crop reflectance in unfertilized plots by a handheld Yara N-sensor at GS37, with cross validated r2-values for all years as well as individual years between 0.54 and 0.79. However, results from estimations on single years not included in the calibrations (r2-values between 0.20 and 0.69) indicate a need for larger data-sets to establish more reliable calibration models. Establishing unfertilized plots within the fields has large potentials as a tool for estimating optimum N fertilization. Besides the information on the contribution of plant available nitrogen from the soil at that place during that particular year, reflectance measurements using a handheld N-sensor at GS37 could act as guidance for a late nitrogen application

Keywords

Optimal N-gödsling; växttillgängligt kväve; kväveskörd

Published in

Rapport (Sveriges lantbruksuniversitet, Institutionen för mark och miljö)
2010, number: 4
ISBN: 978-91-86197-75-9
Publisher: Institutionen för mark och miljö, Sveriges lantbruksuniversitet

SLU Authors

• Wetterlind, Johanna

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

UKÄ Subject classification

Agricultural Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/29264