Nitrogen Management
Last year we had nearly 75% of our corn acres in Corn on Corn and our nitrogen management plan was to have about 60 units of N between my fall dry AMS and MAP, starter and 0x2 placement of UAN and ATS and then follow with the remaining 100-120 units with side dressed UAN and ATS. The thought behind this plan was that we would limit the early spring losses and apply the heavy load of N right when the corn plant was taking off on its exponential growth curve between V5 and V8. It sounded good last winter when we were making our plans. Then after planting we received about a foot of rain with cold temperatures which made timely side dressing nearly impossible with the exception of our pattern tiled ground. The farms that we couldn't side dress because of the wet and cold conditions likely lost some of the surface applied N to excess runoff and looked nitrogen deficient. The farms that we had pattern tiled we were able to side dress around V4 and received a rain immediately after which helped move the nitrogen to the root zone and we raised very good corn on corn on those farms.
The farms that remained wet we had to wait til nearly V8 before they were dry enough to get across. To complicate things further, once we were able to side dress, we didn't receive another rain to move the nitrogen to the roots for about 2 weeks. The corn stood still with a crappy yellow color until that next rain came along. It was too late as the yield potential had been set in a nitrogen deficient status and those farms were significantly less in yield than the farms we had applied nitrogen at the critical time. We knew this specifically as one farm we had pulled in and tried to side dress through the mud in about 3 different rounds in various spots of the field to try to find a dry spot to work. You could see the difference in those 3 strips in the field the rest of the year as they were greener and taller. When we combined it, we could tell to the row where those strips were as the weight on the grain cart and yield monitor shot up about 20 bu/A. It was all about timing and availability in 2013.
So how do I fix it? Well my thought is that I'm going to increase my at planting nitrogen application by 2X and consider options to apply it into the soil rather than dribble it on to the surface. Benefits to this would be to limit nitrogen losses due to volatilization and surface runoff in the event of a heavy rain like I had last year. Disadvantages include that I am still subject to leaching losses with a more significant portion applied up front however this could be overcome by using nitrification inhibitors like Instinct.
The problem with injecting fertilizer with a coulter on the planter has always been the risk of compacting the seed trench in wet conditions. My Dad has warned me about issues he used to have in the 80's trying to do 2x2 placements with his dry starter in front of the disc openers. For that reason, I want the coulter injection system to be behind my gauge wheels to limit the risk of pulling up wet sticky soil that would potentially build up on the gauge wheels. I found a system online here that I'm inquiring about that I think will do what I'm looking for. The system is a double coulter split injection about 3" away from the middle of the seed furrow. It was invented by a farmer out in Illinois named Jeff Garman. Here's a pic of it of what it looks like.
There will still be a risk of sidewall smearing but that could be mitigated by utilizing spaded closing wheels as shown in the photo in wet conditions which is something that I've been wanting to add to the planter as well.
Hopefully if I can can implement these changes I can safe guard the nitrogen shortfalls I had last season early from cold wet soils in my corn on corn strip till. I'll follow up this application with a side dressed application to finish out my nitrogen program hopefully again during that V4-V8 window with less pressure of getting the N on at that point. My end game is to try to get to a point where I have a nitrogen management system that limits and balances both environmental and economic losses of this key input within my cropping system.
More to come next week of things I'm considering changing as the snow melts and planting season draws near. Cheers.
PS-I wanted to share a Ted Talk I watched this week that discussed the value of carbon retention within soils and how that plays into the discussion around controlling global CO2 with smarter agriculture systems. Really enjoyed it.
