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April 2012 N-STaR Update
Author: Trenton Roberts, Associate Professor, Crop, Soil & Environmental Sciences


N-STaR Lab Will not accept samples for analysis after April 30th, 2012. Samples that are received into the lab following the cutoff date will not be analyzed.

The purpose of this strict cutoff date is to ensure that samples can be analyzed and returned in a timely manner so that producers can consider the N-STaR recommendations prior to pre-flood N application. Due to the exceptional weather over the past few months the sample load has exceeded our lab capacity and has delayed the return of results to producers. The current turn-around time for samples is 15-20 business days. Please be advised of the current turn-around time if you plan to submit samples. If you have 2-3 leaf rice and try to pull a sample and get an N-STaR recommendation prior to flooding it may not get analyzed before you need to apply your pre-flood N.

As of April 16th, 2012 the N-STaR lab has processed ~2500 soil samples from Arkansas, Louisiana and Missouri. The majority of the samples that have been analyzed are from Arkansas, Lonoke, Cross, and Poinsett Counties. Following the completion of this year’s sample analysis we will compile data related to the number of samples submitted from each county, average field size, average days to flood, varieties planted and a comparison of the N-STaR recommendation to both the current University of Arkansas Division of Agriculture recommendation as well as the producer’s planned N application rate. These data will be presented and several meetings will be scheduled with faculty and Ag County Agents to determine the best way to proceed with N-STaR for the 2013 growing season. Producer and Agent input will be requested as we try to expand the N-STaR Lab and accommodate the demand for this new N fertilizer recommendation tool. With current urea prices near $750.00 per ton, that equates to roughly $0.82 per unit of N a significant increase from January, 2012 where urea was selling for $400.00 per ton ($0.43 per unit of N). Based on current N-STaR recommendations that have been processed by the lab, roughly 50% of the samples resulted in a N rate recommendation that was equal to or higher than what the producer had intended to apply. For the other 50% of the samples, where N-STaR recommended a lower N rate, it was generally 25 units lower than what the producer had intended to apply. At the current urea prices that is roughly a $20.00 per acre savings for implementing the N-STaR recommendation.  Please keep in mind that the purpose of the N-STaR program is to identify the correct N rate required to optimize rice yield. In some cases that will result in a lower N recommendation, it may result in a higher N recommendation and in some cases there will be no change in the N rate recommendation.

As we move through the 2012 growing season please look for updates and news concerning N-STaR research, field days and lab upgrades.

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