Variable-rate nitrogen fertilization of winter wheat under high spatial resolution

S. Stamatiadis, J. S. Schepers, E. Evangelou, C. Tsadilas, A. Glampedakis, M. Glampedakis, N. Dercas, N. Spyropoulos, N. R. Dalezios, K. Eskridge

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Variable-rate application (VRA) addresses in-field variation in soil nitrogen (N) availability and crop response, and as such is a tool for more effective site-specific management. This study assessed the performance of a VRA system for on-the-go delivery of granular fertilizer in 7-m wide and 200-m long strips of a 2.4-ha wheat field. A randomized complete block design consisted of three treatment strips (a preplant uniform application of 100 kg N/ha, a preplant + in-season uniform farmer rate of 212 kg N/ha and a preplant + in-season VRA) within four blocks. The VRA prototype consisted of Crop Circle ACS-430 active canopy sensors, a GeoScout X data logger that processed the geospatial data to convey a real-time N rate signal (1 Hz) to a Gandy Orbit Air 66FSC spreader through a Raven SCS 660 controller. Crop monitoring included analysis of in-season soil and plant samples, water balance and grain yield. VRA delivered an economic optimum N rate using 72% less in-season N or 38% less total N (131 kg N/ha) than that applied by the farmer (212 kg N/ha). The reduction of total N inputs came about without any yield losses and translated to 58% N-use efficiency in comparison to 44% of the farmer practice and 52% of the preplant control. VRA also provided a much higher revenue over fertilizer costs, €68/ha and €118/ha higher than the preplant control and the farmer practice, respectively. The return of VRA per unit of N was equal to that of the large preplant application due to low leaching losses. Overall, the high-resolution VRA was superior in terms of environmental benefits and profitability with the least uncertainty to the farmer.

Original languageEnglish (US)
Pages (from-to)570-587
Number of pages18
JournalPrecision Agriculture
Issue number3
StatePublished - Jun 1 2018


  • Crop nutrients
  • Economic optimum N rate
  • Environmental impact
  • Ground canopy sensors
  • N-use efficiency
  • Precision agriculture
  • Profitability
  • Soil properties
  • Stable isotopes
  • Water balance

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)


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