Regional Project

Objectives  To evaluate the performance of sensor-based N recommendation algorithms across a wide range of soil and climate conditions.  To develop a database that will allow for development of improved algorithms.  Foster cooperation across research programs (i.e., the end product will be better if we collaborate).

Elements of the Study  2005: Algorithm recommendations imposed as treatments.  2006: N rate response trials with sensor readings taken at time of in- season N application. At the end of the season, EONR is calculated and algorithms are evaluated to determine which ones best predict EONR.

2006 Sites  Kansas  Nebraska  Missouri: 6 sites  Illinois  Ohio: 5 sites  Virginia  Quebec Total of 16 sites

Analysis Steps 1.Calculate EONR  Relative to in-season N applications only  Quadratic-plateau model  By site 2.Average sensor measurements 3.Relate EONR to sensor measurements (SI or RI) 4.Using the proposed algorithms, calculate from sensor data N recommendations 5.Compare EONR to N recommendations

Findings  7/16 sites were sensed pre-V8.  10/16 sites were sensed at pre-V9.  7/16 sites had a side-dress EONR < 50 lbs N/A (total < 90 lbs N/A).  40 lbs/A at planting may be too much… masking the soil N supply.  In some cases, starter with N and/or N in P fertilizer has also been applied, further masking soil N supply.  Should the experimental design be altered?

Questions  How do we account for: Maturity group or hybrid? N source/placement? Other N applications (e.g., MAP)? Irrigation? Weather information?  Differences related to sensor types: GS and CC?  Should the analysis include a comparison to the existing state N recommendation, and if yes then this will need to be added to the spreadsheet by the individual researchers before compiling?

Other Issues  Submission of new algorithms to be tested.  Sharing of SAS code and compiled regional data base.  Publication recognition: Data and writing (at least “eyes on the manuscript” before submission)

2007 Regional Sites?  Missouri: 3 sites  Ohio: 6 sites

 NDVI, V6, V8, V10, V12  SPAD, V6, V8, V10, V12  Daily Temperature (min and max), entire season  Precipitation, entire season  Issues for ALL TRIALS  Replications: 3-4  Plot size: 4 rows wide x ft long  Row Spacing: As per equipment used (30" or 36")  P and K applied preplant to local sufficiency levels  Nitrogen to be applied between V8 and V12  Nitrogen Sources:  1. Pre-Plant: Urea or UAN  2. Topdress: UAN  Sensor/Chlorophyll Meter Readings  Active Sensor readings taken weekly, Greenseeker RED  Chlorophyll meter readings (SPAD) taken weekly  Pre Plant Soil Tests (0-12, and 12-24")  NO3-N, and NH4-N  Total N  Organic C  pH   Regional Trial 2006  Treatment  Pre-plant N  Top-dress  Comments   lb/ac   1  0  Check   2  N Rich Strip  0  N Rich Strip (160 to 200 depending on preplant soil test)   3  40  0   4  40  30   5  40  60   6  40  90   7  40  120   8  40  150    10  40   Sufficiency (30lbs applied when SI<95%) 