Nitrogen in Starter Fertilizers

(Dave) I’m Dave Mengel from the Agronomy Department K-State. And this morning we talked a little bit about nutrient management and being more efficient here in 2016, how to get the most bang for our fertilizer dollar. There were three basic areas that we focused on. One is the whole idea of soil testing, how to go about soil testing and the importance of soil testing, focused on the nutrients that we really ought to be testing for here in Kansas. We’re talking primarily about phosphorus, potassium, nitrogen, sulfur, chloride and also then the importance of soil pH. That’s really something that’s not taken as seriously as it should. Then we focused on the use of starter fertilizer a little bit. But generally we talked about starter fertilizer for phosphorus, but what we were focusing on or talking about today was the use of nitrogen in starter fertilizers. And how that really needs to be looked at in corn production today. Something that’s often overlooked but can pay some really big dividends. Then the majority of the time we really talked about the whole concept of nitrogen management and the four R’s of nitrogen management. The right rate, what is the right rate? How much nitrogen does corn need? What percentage of the nitrogen that a corn plant takes up is actually from fertilizer as compared to the soil itself? Things of that nature. Then we talked about the sources that are available and how we can utilize them more efficiently. And the whole idea was to really build a management system looking at source and rate and time and placement to get the most efficiency out of that product. In Kansas in general, we’ve generally figured we get about a 50 percent utilization of nitrogen fertilizer. About half that we apply goes into the plant, about a quarter of it goes into the soil and about a quarter of it is lost. So how can we change that around so that a higher percentage goes into the plant and a smaller percentage is lost in the system? That’s the whole idea. And if we can do that successfully then we can ensure that we get high yields. We can stabilize those yields by reducing loss in some of the bad years and we can also be more efficient in terms of the cost of product and such. Nitrogen loss, there’s four basic mechanisms that we can lose nitrogen fertilizers and they’re all different and they all occur in Kansas but in different places. Leaching is a process that has evolved in sandy soils. So if we have lots of nitrate nitrogen out there in the soil and it rains, a lot of it’s going to move through the soil and be lost out the bottom. Denitrification is a similar process in heavy soils, only here it’s a gaseous loss. If we get a heavy rain, we have nitrate present. Some of the organisms in the soil are adapted to utilize that nitrate as an oxygen source and so “poof” we’ll lost the nitrogen off into gas. Denitrification is that process. Another process is immobilization and basically what happens is if we have a lot of residue present and it is wide carbon seed… carbon to nitrogen ratio, in other words, has lots of carbon and little nitrogen- cornstalks, grain sorghum stubble, wheat stubble, and we put nitrogen fertilizer on top of that then a significant amount of that nitrogen fertilizer will be used by the bugs in that residue trying to decompose it. That’s immobilization. And then the last one is volitilization. It’s a urea problem. You put urea on top of that residue or on top of a high pH soil, as it converts to ammonium, a portion of it will go off into the atmosphere as ammonia gas. So, you assess the situation you’re dealing with, how much rainfall do you get? What’s the drainage of your soil? How are you applying that nitrogen? The placement? Can you put a fertilizer below that residue and reduce volatilization and immobilization process? You can. There’s ways to do it fairly inexpensively so these are the kinds of things that we want guys to talk about, think about.

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