I am writing this because after 41 crop seasons it feels as if number 42 is like I’m back at maybe number 2. The first crop is special because, well, it’s the first. I get to make the decision to buy inputs, prep the ground, plant the crop, watch it grow, and harvest it. Then market that crop profitably. So at the end of the crop cycle my report card tells the tale. In my generation I was graded A (excellent) thru F (failure). I strove to get that A, got mostly B’s and C’s. I won’t mention that last letter as that usually wasn’t a pleasant experience.
Why do I feel as if I’m starting over?
Mainly it’s the issues with nitrogen runoff and dissolved reactive Phosphorous that has gained headlines recently.
What could I do better?
I was 100% no till with some cover crops. I was variable rate surface applying my P and K according to grid sampled soil test. I was split applying my nitrogen for corn.
AND THE ANSWER IS
Start injecting fertilizer under the soil surface. Start applying nitrogen to the corn crop in 3 different applications. That sounds easy but involves extra trips across the field with specialized equipment. How could I make these changes and not get an F on my report card?
First, I had to rethink my approach to soil fertility or how to manage it differently. I wanted to still put P and K on the fall before planting the next corn crop. Then, to get the most out of that application banding was the answer, made possible with RTK auto steer. My next planted crop would be directly over that fertilizer band. This would allow me to remove the liquid 10-34-0 starter fertilizer applied with the planter and cut expenses. The dry band would act as my starter band of fertilizer. I will still apply 28-0-0, zinc, and KTS at planting.
Then the next question was how much to apply in the fall and whether or not to variable rate this application. The equipment pictured above was purchased used to help keep costs affordable for the amount of acres used yearly. The Montag is a single commodity hopper. I am limited to just one product or a blended product.
Total phosphorous removed in grain harvested for a 2 year cycle of corn and beans based on 50 bushel beans and 170 bushel corn (be totally honest) would be about 103 pounds of actual phosphorous. Total potash removal in grain would be about 115 pounds of actual potash. Using an 11-52-0 product and 0-0-60 product that would equal 200 pounds of material for each product or a total of 400 pounds applied together. Then you want consider soil test levels for both. For potash CEC is a factor also. The lowest critical level for P=30 and K=200. Sounds complicated but the basics should be explained and understood. Since most of my fields are at critical levels or better I apply nutrients according to grain removal. In doing grid samples for the small areas that need extra I plan to take the spinner buggy using the GPS and apply build up amounts to that area for now.
After considering all these variables and with the ability of a single product applicator I’ve settled on doing a straight rate blended product. There are efficiencies to be gained by putting the fertilizer in a band right next to or under the planted row. I settled on a blend of 78 pounds of actual phosphorous and 90 pounds of actual potash per acre for a corn and bean cycle.
The reasons for wanting to apply this in the fall and not in the spring are the weight of the equipment, the depth of the coulter at 5 inches would cause to much compaction in the seed zone, and the fact that this tool bar has the configuration for row middle openers. Wheel tracks in the row in the spring would be a disaster. Wheel tracks on the planted row in the fall while not the best should freeze and thaw enough to alleviate negative effects. This configuration also allows me to use this tool for side dressing nitrogen after corn is up and growing. This was another cost benefit for a specialized piece of equipment.
This is my approach to fertility for now based on chemical nutrients and university data. Adding continuous cover crops, more crop rotation, or a more biological approach are also good alternatives. Cover crop seeding is the next operation that I want to do along with fertilizer application in the fall, or maybe at side dressing time with this equipment. That will be a work in progress. I will write later about the continuous cover crop and biological approach. As the heading (STARTING OVER) suggests! The learning stops when living stops!
Nitrogen management for the corn crop is the other nutrient that needed some tweaking. After several years of participation in OFN (On Farm Network) with nitrogen rate trials I am comfortable with the amount of total nitrogen applied to the crop. That method involved 39 pounds of actual nitrogen applied with the planter. Than at side dressing time the balance of nitrogen as NH3 is applied for a total of 160 to 165 pounds of actual nitrogen per acre. This is pretty close to one pound of nitrogen per bushel of corn. The latest trend is to put a third application of nitrogen on at about V10 just prior to tassel.
This would involve the use of a higher clearance self-propelled sprayer equipped with Y drops or a similar setup that can place nitrogen right at the base of the plant. Practicality of this application depends on whether a person already has a bigger sprayer or custom application is done.
As far as nitrogen rates and timing my approach based on 165 to 170 pounds of total nitrogen applied would be, 39 pounds at planting, 100 to 110 pounds at side dress time about four weeks after planting. The final application of 20 to 30 pounds of actual nitrogen could be timed at about V10. This application could be weather dependent based on rain fall received prior and also what the two week forecast might look like. The theory is to apply nitrogen closer to the time that the corn plant actually uses it.
THE REAL ANSWER IS
My report card will tell the truth. I strive for an A, probably get a B or C, and avoid that F.