Evaluation of variable-rate nitrogen recommendation of winter wheat based on SPAD chlorophyll meter measurement

To develop a time-Specific and timecritical spatial variable rate nitrogen application (VRN) method and to overcome the limitations of traditional field sampling methods, this study focused on the relationship between SPAD chlorophyll meter readings and nitrogen content in leaves in order to determine the amount of nitrogen fertilisation required for agricultural objectives. Field experiments were conducted in three wheat growth duration stages from 2003 to 2006. Grain yields and soil N03-N contents were measured in all plots. Our results indicated that VRN technology reduced wheat yield spatial variability. The benefits of VRN included low soil residual NO,-N content and N03-N leaching potential, suggesting that VRN technology based on SPAD readings can potentially reduce groundwater pollution and therefore protect our limited environmental resources.