Stalk N test a no-brainer?
A Late Season Stalk Nitrate Test is a reliable end-of-season indicator of crop N status, affirms Beegle. The LSSNT is very useful for fine-tuning future N and manure management decisions. But stalk sampling instructions must be followed carefully.
Samples should be taken between ¼-milk line and up to three weeks after black-layer. If you're taking samples after silage harvest, be sure to do it within 24 hours of harvest.
Collect 8-inch long stalk sections starting 6 inches above ground. Collect from at least 10 representative plants in a field. Then cut the sample pieces into shorter pieces to promote drying and sent to a lab for analysis.
Corn must be chopped at least 14 inches high where the sample is to be taken to get the correct sample, reminds Beegle. Some farmers will raise the chopper head occasionally to leave some taller stubble to facilitate sampling later.
If test results fall between 700 and 2,000 parts per million, your N management was optimum, he adds. Below that range, the crop likely ran out of N and didn't achieve full yield potential. Results above that range indicate that the crop had more than enough N.
If N amendments were used, the LSSNT could help indicate how well they worked under this year's conditions. This would be especially helpful for check plot comparisons.
See Agronomy Factsheet #70: Late Season Cornstalk Nitrate Test for all of the details.