With all of the wet weather that we have had this spring and summer, there has been a lot of talk about nitrogen losses. In our sandy soils, leaching is the main culprit. In our heavy clay soils, denitrification is our enemy. It is very important to be thinking about how much nitrogen was available to your crop and how much is needed to make your yield goal. The wet weather that we have had definitely has impacted the available nitrogen for our nitrogen using crops.
Here are a few items that you should think about, the more of these items that you can say, “yes this has happened on my farm this year,” the more likely you will have nitrogen deficiencies. To remedy the situation, you should probably add some supplemental nitrogen.
1. Did you fall or spring apply your nitrogen, fall applications are subject to more losses due to the amount of time that nitrogen was in soils above 50 degrees.
2. Did you fertilize for the bare minimum or over fertilize? If you fertilized for 120 bushel corn, but typically get 150+ bushel corn, you don’t have any cushion.
3. Is your corn on high residue ground such as old corn stalks or wheat straw? High residues of high carbon to nitrogen ratio crops, such as corn or wheat, typically can tie up nitrogen as those residues are being broken down.
4. Have your soils been wet or waterlogged, while temperatures have been above 70-75 degrees? If so, microbes have been very busy devouring your nitrate nitrogen, using it as an oxygen source.
These are just a few major causes of nitrogen losses, it is important that you keep an eye on you fields, yellow leaves, especially lower leaves as the plant matures are a sign that nitrogen is deficient.
If you need to add nitrogen to you crops, here are a few options. We’ll start with corn. Side-dressing corn is a very common practice, either with anhydrous or with 28%. Other options are to use drop nozzles and dribble 28% between the rows, or to broadcast urea over the top. Do not use stream bars or stream nozzles with 28% on corn, there is too much leaf burn. In the case of urea, don’t broadcast urea over the corn after it is 4-6″ tall. There is too much risk for urea to get into the whorl and burn the corn.
With wheat, broadcasting urea up to 5-6 leaf wheat works great, the other options are to use stream nozzles or stream bars to apply nitrogen to the wheat. Do not use fan type nozzles as they will burn the wheat. If you want to apply nitrogen to increase protein, that should be done after flowering has finished. Post anthesis nitrogen should be 10 gallons of water and 10 gallons of 28% applied with a flat fan nozzle. That is the only time you should foliar apply 28% to a crop with a flat fan nozzle.
Depending on how much nitrogen you need, here are a few examples:
Anhydrous Ammonia: 82-0-0 50 lbs/acre would give you 41 lbs of nitrogen
Urea: 46-0-0 90 lbs/acre would give you 40 lbs of nitrogen
28% N: 28-0-0 13 gallons/acre would give you 40 lbs of nitrogen
If you are not injecting the nitrogen directly into the ground and there is not rain coming within one day, it is important to use a nitrogen stabilizer to protect against volatilization. There are many products on the market: Arborite, Instinct, Nutrisphere-N, and Agrotain are just a few. Be sure to use a nitrogen stabilizer and protect your investment.
2011 is going to be a year where we look back and say, “we lost a lot of nitrogen that year, I wish I would have added some in-season.” Be sure that you are monitoring your crops and take care of them as you see fit.
