Nitrogen Confusion

As the spring season starts off and you are planning your fertility programs a question may arise as to what is the best way to handle nitrogen? When we used to talk about nitrogen management it was largely based on your method of application, were you going to put the nitrogen in the ground or apply it on top. After that we would recommend different fertilizers due to their properties to minimize loss. These approaches still work, however the focus has now been turned to nitrogen stabilization products to help keep nitrogen in the field and crop available.

Before we get too deep into these products we first need a basic understanding nitrogen and the major ways we can lose it. For plants there are two forms of nitrogen they can utilize, ammonium and nitrate. Each of these have their own losses associated with them. It is also important to note that these forms are not static in the soil, for instance ammonium can change forms to nitrate.

The most common form of loss is volatilization. This occurs when ammonium (NH₄⁺) looses a hydrogen ion to form ammonia (NH₃). The ammonia ion is what we associate with some of the manure smell on broadcast applications. This ammonia is a gas and it is lost to the atmosphere. This only happens in our soils with products containing urea such as UAN and manures. The 'old' way to control this loss was to incorporate these products into the soil by either injection or tillage.

The other loss mechanism is leaching. If we think back to basic soils we may remember that our soil has a negative charge. This allows it to hold positively charged ions such as ammonium, potassium, calcium and others. However the negative to this is that our other plant available form of nitrogen, nitrate, is negatively charged. As we all know like charges repel. This means that the nitrate molecules are not held to the soil and can be washed out of the root zone during wet conditions.

Now how do you choose between the products on the market such as Agrotain, Agrotain Plus, N-Serve, Twin N, Instinct; just to name a few. Although there are a many products the answer still lies in what you are applying and how you will be applying it. It is very important to ask your sales representative what form(s) of nitrogen loss their product inhibits. For instance, if you are applying UAN (an ammonium product) with a sprayer or broadcasting dry urea your largest worry is volatilization. This means you want a product that inhibits volatilization. These products are broadly known as urease inhibitors. This actually stops the reaction that changes ammonium to ammonia. So if you are broadcasting nitrogen that is subject to volatilization (UAN, Urea, etc.) you want to use a urease inhibitor. Agrotain is an example of a urease inhibitor.

If you are injecting your nitrogen you are already limiting the losses due to volatilization so you are more likely to be worried about losing nitrate nitrogen. For this situation you will need to use the product broadly called a nitrification inhibitor. It is important to note that these products to not stop the leaching of nitrate already in the soil they simply do not allow the ammonium ion to convert to nitrate. Products such as N-Serve , Instinct, and Guardian are nitrification inhibitors. Nitrification inhibitors have the most value when N is applied long before expected crop uptake and especially on soils at the extreme of soil drainage ie. excessively well drained or very poorly drained soils. For example, a lot of N is fall applied in the midwest and a nitrification inhibitor is essential but that is not a common practice in our area. The last class of nitrogen stabilization products are nothing new but actually a mix of the two previous. Products such as Agrotain Plus and Twin N are actually a mixture that will mitigate volatilization and nitrate leaching.

The important point on all of this is pay for what you need, not what you don't need. For instance, if you are injecting it makes little sense to use a urease inhibitor, but a nitrification inhibitor may be a good option depending on your soil conditions and timing of N application. For those who are broadcasting you have the choice of using just a urease inhibitor to stop volatilization or both urease and nitrification inhibitors. This will largely depend on your rate of application and how long you are depending on that nitrogen. If you are putting everything on up front well before crop uptake you may want to use both inhibitors, if not maybe only a urease inhibitor.

A final note is that the products mentioned are only a few of the total products out there. For products not listed, simply ask what the specific mode of action is for the product. If you have any other questions please contact me or your local extension agent.

Additives	Mode of Action	Example Products
Urease Inhibitors	Inhibit volatilization from surface applied urea containing fertilizers	Agrotain
Nitrification Inhibitors	Inhibits conversion of ammonium N (NH4+) to nitrate N (NO3-). Can reduce loss of N by leaching in well drained soils or denitrification in poorly drained soils	N Serve Instinct Guardian
Combination Products	Both urease inhibitor and nitrification inhibitor	Agrotain Plus

IPM Bulletin

Penn State Extension in Franklin County has established a grid of eight trapping sites across the county to attempt to survey populations of black cutworm and true armyworm moths. Both species have now been found in the county; however, black cutworm moths have not been found at threshold levels. True armyworm moths have been found at most sites with the most in the St. Thomas area, which had 10 moths last week. Other sites had two or less. These findings suggest that populations may be heavy in the greater St. Thomas area for true armyworms and special attention should be given when scouting and making recommendations in this area.

One of the most important management considerations when dealing with true armyworm is to make sure in areas where you have cover crops or heavy weed cover that you allow a 2 week period after the plants are dead until you plant. This would lead producers trying to get a timely planting of corn who have yet to spray to use a quick killing herbicide such as gramoxone instead of glyphosate.

Once corn is established scout fields closely, especially where heavy cover was. If you find more than 10 percent of your corn in a given field has an infestation of armyworms treatment is encouraged. Armyworms typically are found hiding in the whorl of corn during the day and their feeding creates a ragged looking leaf. In bad cases the leaves will be fed on until nothing but the mid-rib is left.

More information on this pest can be found online at http://ento.psu.edu/extension/factsheets/armyworm, or by visiting the local extension office. Please share this information with others who may be interested in it. Again it appears that the pressure at this point is limited to the greater St. Thomas area. I will continue to keep you up to date if populations build elsewhere.

The ‘Corn Guys’ have left the county!

Penn State has established two plots in Franklin County to help you make better decisions when buying next year's corn for grain and/or silage. In cooperation with Professional Dairy Managers of Pennsylvania (PDMP) Penn State established a corn silage hybrid test plot. This plot will include both full season and short season varieties and will be taken to harvest where quality samples will also be analyzed from each hybrid. In addition to the research going on we will also have a field day held at Burk-Lea Farms in association with this plot on August 12^th.

The other plot established in the county is a corn grain hybrid trial. This trial will be similar to the PDMP trial; however it will be taken to yield for grain. Measurements from this plot will include yield and grain quality.

All of this data is then compiled into the 2010 Pennsylvania Commercial Grain and Silage Hybrid Corn Test Report. These reports come out over the winter and are typically available during our winter meetings. The reports give you a way to see local data as well as the other sites around the state. Hopefully this will help you in your future decisions for what varieties may suit you the best.

Wheat Fungicide Trials

As some may know Penn State Extension is continuing a wheat fungicide trial and we have a site in Franklin County. This trial is looking at early applied (Feekes 5-6) fungicide with a follow up at emergence to the typical fungicide application at boot to emergence. So far there are no notable differences among treatments but it is interesting to note that powdery mildew is present in all treatments. The severity of the infection is quite minimal so little can be said about performance among treatments, however it is present. Dr. Collins of our SE Research station, a pathologist by training, has stated that this fungus likes 50-70 degree weather the best so if it warms up significantly it could slow the infection. Looking ahead at the forecast it appears in the near future we will likely keep conditions favorable for infection. If you are scouting for this pathogen look for lesions as noted on the bottom leaf in the photo. These lesions will have a small amount of white 'fuz' in and around them. This may be visible with the human eye but you can definitely see it with a 10x hand lens. I will keep you up to date as this study continues to unfold.

Cutworm Moth Trapping Update

So the first moth has been caught. My colleague Jeff Graybill in Lancaster County got a moth this week. When I check the Franklin County traps this week I did not have any moths but it appears we may start finding them. Just a reminder that this does not mean we are at a threshold of moths just simply that they appear to be starting their yearly trek northwards. I will keep you up to date on the progress of these as well as what it means as far as treatment etc. If you want to check out the data yourself as we progress remember to check out PA PIPE. This website has a plethora of information for pest management.

Spring pastures can bring bloat

Spring time is here and pastures are growing quickly. With this new lush growth also comes an increased concern for bloat. Bloat typically occurs on young fast growing pastures that have more than 50 percent legumes (clover, alfalfa, etc.). Bloat is simply a condition brought on due to excess protein in the rumen which creates foam that will not allow gasses to escape the rumen. This condition leads to excess pressure in the cattle's rumen and in worst cases can lead to death. Bloat can be a major problem on lush spring pastures, however it can be managed.

The first step in managing bloat is to identify your pastures containing more than 50 percent legumes. These pastures will contain high protein levels especially in the spring when all of the growth is new and lush. Identify your pastures that are most likely to be a problem and use extra caution when animals are on those pastures. If all of your pastures contain high portions of legumes you want to take special care to give animals time to get used to the pastures early in the spring.

Management strategies such as feeding grass hay prior to the grazing period and not allowing access to pastures when excess moisture is present due to rain or heavy dew will help minimize the occurrence of bloat. Over eating frequently occurs when hungry cattle are turned onto fresh pastures with high percentage of legumes. Bloat is probable if these animals have not been accustomed to the legume mixture. Feeding grass hay prior to grazing allows the cattle to fill the rumen with a lower protein feed and will decrease the occurrence of over eating and thus minimizes the risk of bloat. Continue to feed hay prior to grazing for 5-6 days. During this time decrease the amount of hay fed until they are dependent totally on the pasture.

Poloxalene is another management option for those dealing with high percentage legume pastures. This chemical reacts in the rumen and decreases the instance of foam and allows excess gasses to escape naturally. This chemical is most easily fed in a molasses, salt, and poloxalene block mix. Allow one block for every 5-6 cattle and keep them in places where cattle typically gather. You may also be able to add poloxalene into any grain mixes you may be feeding. You should feed half a pound of poloxalene per animal.

Finally, the best management strategy will be to check your cattle frequently, about twice a day. This will allow you to observe any problems that may exist. The first visual sign of bloat is a notable increase in the fullness of the left side of the animal. If a cow is struggling with bloat you may be able to alleviate the symptoms by inserting a hose into the rumen to allow gasses to escape. Additionally there are oral products on the market that can be fed to aid in recovery. Consult your veterinarian about these products. If neither of these options work, you may want to attempt to use a trocar or cantula to relieve the pressure in the rumen; however, these should be the last resorts and should be observed by a veterinarian.

Using these steps you should be able to effectively manage bloat in your cattle without instances of emergency management. If questions or concerns still exist call myself or your local extension agent to assist you in your specific situation.

Weather, IPM, Soil and more…

As spring is kicking off a lot is starting up in the Agronomy program too. I have installed a new weather station at the office and hopefully it will be up online soon to get real-time local data to you. This is especially important with the calculation of degree days for some of our IPM efforts. The station also tracts soil temperature and moisture at 3 inches and 1 foot as well as leaf wetness. I believe this will be a great asset to our local farmers as well as research efforts to have good, consistent, local data.
We have also started our IPM network that has 8 sites throughout the county trapping for cutworm moths and armyworm moths. So far we have had no activity in the traps, which is to be expected, but as we continue to warm we should start some catches. I'll keep you up to date on where the catches are and if we reach the economic threshold. I'll also be posting information on how to react to the levels of pressure I'm seeing.
As soils continue to warm we know planting season is near. Soil temperatures at the office are averaging about 51 degrees at 3 inches. What I have observed so far in the field has been anywhere from 49 to 52 degrees (the field temperatures were taken in the afternoon).
Overall everything seems to be coming together nicely for us. Hopefully we will stay away from extremely wet soil conditions so we can start this growing season of with a timely corn planting. This week looks like lots of sunny weather to catch up on alfalfa planting and get manure hauled if need be.