The following is copied from an email sent to extension agents from Debbie Joines, Plant and Soil Testing lab in Nashville concerning nitrate testing in forages including drought stressed corn that may end up being used for forage.
We are experiencing increased calls and concerns related to high nitrates in forages, particularly corn. Many fields are on the edge of failure or beyond with no rain in sight. Forage nitrate testing has revealed some increased levels however not as high as we saw when fertilizer prices were lower. Keep in mind nitrates will dissipate during ensiling however when forage is cut as hay, there is no reduction. Nitrates are also a concern in summer annuals such as Sudex or Sudan grasses and even Bermudagrass. We have seen one elevated fescue however not critically high. Nitrate screen is good for checking these situations.
I took some time yesterday to visit with Dr. Gary Bates, Professor and Director, UT Beef and Forage Center and get a good idea on our recommendations.
- Sampling for nitrates–
- We do not have the capability to process whole plants (corn) for nitrates at the Soil, Plant and Pest Center. Samples must be chopped.
- If corn is rolled, it needs to be sampled using a core tube for best results. Sample at least 10-20 bales.
- Bermudagrass or summer annual hays- Core sample is best in baled situations.
- If fresh (for summer annual or corn pasture situations), sample across field in X pattern, then chop with hatchet or machete knife before sending.
- Amount to send for quantitative nitrate (ppm) testing-
- A quart sized Ziploc bag is perfect for silage
- About 5 – 10 representative cores for hay
- When to sample
- Dr. Bates suggested pulling a silage sample during loading of bunk/silo then at some period of time before feeding.
- Hay can be sampled any time and certainly within 2 weeks of feeding.
- What to do
- We supply guidelines with each nitrate report. All is not lost if nitrates are elevated as silage or hay can still be fed at reduced levels in total ration.
- Moisture is critical for proper ensiling. At least 60% moisture is suggested. We are seeing samples with much lower moisture and the hot weather is making matters worse.
Nitrate screen solution is available by contacting me and arranging for pickup or delivery. Solution cannot be shipped. I am working to get screens transported to region offices and have them here at the Center. Remember that screen reaction has no indication of nitrate concentration but only shows if nitrates are present.
To run the quantitative nitrate analysis through the UT Plant and Soil Lab will cost $6.00 however if the Basic Forage test is requested, there is a $2.00 discount.
Turnaround time on nitrates (provided we do not get overwhelmed), is next day. Time constraint is usually related to drying the sample for processing therefore silage samples or fresh sudex might take longer to dry. If levels are critically high, we will call. Otherwise, reports will be e-mailed.
Please let me know if we can help in any way. Let’s pray for rain.
Regards,
Debbie
Debbie Joines
Manager – Soil, Plant and Pest Center
5201 Marchant Drive
Nashville, TN 37211-5112
615.832.5850 office 615.832.4936 fax
http://www.facebook.com/SoilPlantPestCenter
