North Texas Panhandle Dumas Texas | In our Corn in-season nitrogen sampling program we sample 4 times in the growing season.
1. Before planting when we have a 10 day 6" soil temperature of 60 degrees (0-10' NO3 & NH4, 10-20" NH4)
2. 4-leaf collar stage, same soil sample as first sampling and tissue sampling (NO3 ppm, N%,P%,K%,S%)
3. Pollination 10" soil sample (NO3 & NH4), ear leaf sample same test as 4-leaf stage.
4. After black layer 10" soil sample (NO3 only) and a stalk segment (NO3 ppm). This is a "post mortem" test run as a followup to see how well we did.
All of our corn here is irrigated and most of my customers put out most of there N thru the pivot even after pollination. Growers applying most of thier N thru the pivot have been average about .82 lbs. of N per bushel compared to 1.16 for growers appling pre-plant. I know most corn in the midwest is not irrigated and those growers don't have those application options we have here, but we have learned a lot about how and when corn uses N and how to cut N losses that could be used elsewhere.
Turnaround time from our lab is about 2 days(4 days if over a weekend). Sometimes it may take a little longer for the tissue tests results. Our recs our based mostly on the soil tests.
When I started doing this type of sampling 19 years ago I realized right off that tissue sampling alone would not work.
We usually sample between 150 to 200 fields a year and collect field data as well as the test data and have built up a large database that we started in 1998.
Our biggest problem with the time from sampling to results is shipping time to the lab, but we now have a lab 60 miles away and usually have samples at the lab the same day our the next day.
Most of our sampling is done on the weekend and samples are in the lab on monday morning. I have tried an in-field testing equipment and not had good results. I would rather use a good lab and the right procedures and feel more confident in the results.
|
Pre side dress N test
