The Hand-held GreenSeeker sensors were recently modified to include ground-based N fertilizer rate recommendations based on NDVI readings taken from the N-Rich Strip and the Farmer Check.  This EXCEL program is now available on the IPAQ that accompanies the GreenSeeker sensor.

The program developed primarily for Crop Consultants is available in both English and Spanish and is currently being tested in Mexico, Ecuador, and Oklahoma.

STEP 1:

Once you have established preplant N Rich Strips in your farmer fields, you can return 45 to 60 days later (winter wheat) and collect NDVI (normalized difference vegetative index readings) readings.

The N Rich Strips (NRS) are determined by the farmer in cooperation with the fertilizer dealer.  In general, winter wheat NRS rates will range between 80 and 120 lb N/ac applied preplant or soon thereafter.  These strips serve as indicators of whether or not added N is going to be needed and how much.

NDVI readings are normally collected between January 30 and March 30, but will vary depending on the season (planting date, rainfall, etc.).  The first reading, 100 to 200 feet in length is collected from the NRS established preplant and this number is recorded (see example on left).  The second reading is taken from the Farmer Practice where either no N was applied preplant or a small amount was applied to avoid severe N stress. 

Once these 2 values have been recorded, proceed to STEP 2.

STEP 2:

The average NDVI value from the NRS and the Farmer Practice (from STEP 1) are entered on the right (EXCEL Program). 

In addition, the Max yield for the region (determined by the Crop Consultant along with the farmer), planting date, and sensing date are entered in the fields listed.