Episode 13 - Midseason N and Beyond Arkansas Row Crops Radio, providing up to date information and timely recommendations on row crop production in Arkansas. Jarrod Hardke: Welcome to Arkansas Row Crops Radio. My name is Jarrod Hardke, Rice Extension Agronomist for the University of Arkansas System Division of Agriculture. Today we're gonna talk a little bit about mid-season nitrogen and beyond. We're reaching that point where a lot of the crop is hitting a mid-season timing or the reproductive growth stages most often sit off of what we refer to as Beginning Internodal Elongation (BIE) or green ring and from this point forward, were passed focusing on the early season nitrogen management and were seeing what additional good that we can do from top dressing or again mid-season nitrogen application standpoint. So, for just a moment we want to focus exclusively on variety. So, I’m talking Diamond or Jupiter something like that, non-hybrid so strictly varieties. So, what we’ve seen over the past about 10 years now, not quite that, but pretty close, mid-season nitrogen work is that going too early might be our biggest enemy in mid-season nitrogen fertilization in rice. And, that might explain some inconsistent responses to mid-season fertilization that some do see at times. Now, I will say that some of the other inconsistency is that we’ve seen time and again that a lot of times that pre-flood nitrogen will have been taken up extremely well and may include additional uptake of native soil nitrogen and there just may not be a tremendous response from mid-season fertilization. It does happen from time to time. But, when we are planning to perform mid-season nitrogen fertilization a few key things to keep in mind, we absolutely do not want to make that application prior to green ring or Beginning Internodal Elongation, that’s our first minimum that we wanna meet. But our second minimum is really that we wanna wait at least four weeks since we incorporated the pre-flood nitrogen with the flood. So, you can sort of say that once your field has a flood established you can set your calendar for about four weeks from then and we probably don’t want to apply that mid-season nitrogen any earlier than that. That could mean by the time that rolls around we’re way past Beginning Internodal Elongation, maybe we're already at a half-inch, maybe we're already past a half-inch Internodal Elongation. That's fine, basically, it takes at least 21 days for a plant to take up the pre-flood nitrogen under certain conditions, cooler, milder for plant growth may take as long as 28 days. So again, pointing to that window allowing plants to take up every bit of that pre-flood nitrogen so they're ready to take up that mid-season nitrogen. What our work has shown us that the window of optimum response from mid-season nitrogen fertilization is about 4 to 5 weeks after again, the pre-flood nitrogen was incorporated with the flood. If you get out even a little bit longer than that there’s really not much of a decline in response it just does start to ease down just a little. So, we always wanna get that application out before we get the late boot and late boot being when the flag leaf is fully exerted its all the way out, you can see the collar. We definitely want to make the application before then, so just keeping that in mind if you do get pushed really far back seemingly or say miss the earlier application, something happens. We do wanna get it out there, so that's kind of the timing were shooting for so we wanna hit some minimum growth stage timing being reproductive growth but beyond that, we have a very wide window and can go pretty late and still get a tremendous optimal response to mid-season nitrogen fertilization that way. Shifting gears just a little bit since we’re talking about again mid-season nitrogen again and beyond, moving to hybrids. Generally speaking, we do not recommend a mid-season nitrogen application to hybrids. We don’t really want any nitrogen out during that phase of growth. A lot of negatives can happen there from excessive height increase to general rank growth, it's usually not a great benefit and we fertilize pre-flood with pretty high rates on the hybrid anyways, so all we're really timing for the hybrids other than the pre-flood application, we really just want that late boot application and that again is mentioned before on the late boot flag leaf all the way out fully exerted you can see the collar. And, even if a field has the first few panicles, few heads staring to pop out that’s perfect. That’s great timing, you’ve essentially reached terminal height for those plants. You make the application then you’re not gonna get any stretch or increase in height. Not too much extra tillering or rain growth and usually what we see out of that application is a few bushels yield increase and improvement in milling and then, of course, an increase in standability but even without the standability part and resistance to lodging typically we see a pretty good economic return, net return over the cost of that late boot application compared to not making it. So, definitely want to encourage continuing to make that application again that’s 65 lbs. of urea, 30 units, 30 lbs. of nitrogen per acre with that late boot application in hybrid. With that, that’s gonna sort of wrap things up. Again, I guess while mentioning rates on going back to varieties and mid-season nitrogen timing and its 45 lbs. of nitrogen per acre or 1000 lbs. of urea in a single application. Really, have never seen any benefit to splitting up mid-season nitrogen timing in varieties. If you see some benefit from splitting up and trying to do like 2 smaller applications at mid-season on a variety, you might see an increase benefits, it's mostly because the 1st applications going out too early and you’re not getting any benefit from mid-it’s that later applications that’s giving the kick. So, something there to keep in mind. Both of these applications whether we're talking varieties or hybrids and they're mid-season or boot applications respectively we see a very nice positive net return from these applications meaning that you’re going to make more money off of them then what it costs to apply them. So, again, try to shoot for those timings to get the best benefit on both varieties and hybrid from mid-season and later nitrogen applications and certainly if you have any problems or questions please feel free to reach out to your local county agent or myself, also Dr. Trent Roberts soil fertility specialist and we’ll try to get things squared away for you and help you along the way. Thank you for joining us once again on Arkansas Row Crops Radio, see you next time. Arkansas Row Crops Radio is a production of the University of Arkansas System Division of Agriculture. For more information please contact your local county extension agent or visit uaex.edu