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AUTOMATED CALIBRATION STAMP TECHNOLOGY FOR IMPROVED IN-SEASON NITROGEN FERTILIZATION

^a Dep. of Plant and Soil Sciences, Oklahoma State Univ., Stillwater, OK 74078
^b Dep. of Biosystems and Agricultural Engineering, Oklahoma State Univ., Stillwater, OK 74078

View larger version (155K): [in a new window]   Fig. 1. Continuous calibration stamps (9 m2) at Perkins, OK, in winter wheat at Feekes Growth Stage 4, and superimposed schematic of actual N rates in kg N ha–1 using urea ammonium nitrate applied as a foliar spray.

View larger version (110K): [in a new window]   Fig. 2. Automated controller, 8-L pressured delivery tank, and on-board pressurized air tank.

View larger version (69K): [in a new window]   Fig. 3. Calibration stamps applied soon after planting (left) and visual stamp differences midseason (right) that are used to prescribe accurate midseason N fertilizer rates.

View larger version (113K): [in a new window]   Fig. 4. Side view of the calibration stamp showing the outside nozzle and center three nozzles, and delivery of dyed urea ammonium nitrate via fan nozzles.

View larger version (19K): [in a new window]   Fig. 5. Schematic diagram of the calibration stamp applicator retrofitted for assembly on a conventional four-wheeler including the air tank, fertilizer tank, electronics, and applicator boom.