Some final thoughts regarding fertilizer on the planter. Last time, we covered in-seed furrow liquid fertilizer applications.
Remember, the seed provides the nutrition for the corn plant through V1. From V1 to V2, plant nutrition is obtained from the seed-furrow area, so having a source of plant-available nutrients is important, especially in the cool soil environment encountered in no-till during the early growing season.
At V3 to V4, the corn plant is determining the potential number of kernels that the ear will develop. This number will never go higher (kernel counts only fall after this stage) than what is determined during early growth, so we do not want to stress the plant by not having enough plant-available nutrients at this stage of growth. The idea is to use plant-available nutrients and/or plant growth regulators to make the plant sense that growing conditions are better than they actually are in cool soils.
There are many fertilizer materials to use as in-furrow nutrient sources. A common starter in our area is based on 10-34-0 at 5 to 7.5 gallons per acre with potassium thiosulfate fertilizer at 1 to 3 quarts per acre and liquid zinc at 1 to 2 quarts per acre. Some growers add a plant-growth regulator type of material, such as Stoller BioForge, at 4 to 16 ounces per acre in the mix.
*Caution* — In high-fertility fields where only nitrogen is needed, our growers are using a stabilized and diluted UAN-solution-based starter in-furrow. Done right, this starter will provide a great starter effect.
*Caution* — You must stabilize the UAN with a product Agrotain or Agrotain Plus to prevent seed and/or seedling injury (ammonia burn) and the UAN must be diluted to a 50:50 UAN:water mix so you can apply enough material for a continuous string (6 gallons per acre). Dilution provides a measure of protection from ammonia injury as well. Do both or do not try it!
You can add liquid zinc if needed and a plant growth regular type of material to provide additional early growth stimulation. If the soil is dry or becomes dry at planting time, add water for a 33:67 UAN/water ratio. Limit nitrogen in-furrow to recommended limits set by your state extension. We do not exceed 10 pounds nitrogen (or nitrogen plus potassium) per acre in-furrow in our area and we reduce this limit in dry soils.
Starter fertilizer that is banded beside or over the row can be liquid or dry granular. The liquid materials listed for in-furrow application work well as long as the 70-pound limit of nitrogen plus potassium is adhered to and the band is at least 2 inches from the row or seed. If using UAN, stabilizing it with a product like Agrotain Plus adds a safety margin and will help protect the supply of nitrogen until the crop needs it.
One of our recommended dry granular starters is a 50:50 blend of SuperU (Agrotain’s stabilized urea) and Sulf-N-45 (Honeywell’s ammonium sulfate) at 100 to 210 pounds of fertilizer per acre when applied 2 to 3 inches from the seed. This is a great high-fertility nitrogen (or nitrogen plus sulfur) starter program with lots of nitrogen stretch into the growing season.
A quick note or two about no-till coulters. First, use a coulter designed for no-till, such as a 13-wave (preferred) or turbo coulter (distant second choice). Bubble coulters are not designed to be used in no-till planting. They are a carry-over from minimum-till days. Because bubble coulters usually cause seed-furrow sidewall compaction, the spike closing wheel came on the scene to correct a problem that in most cases should not have existed.
Type and setting are critically important. Never set the no-till coulter deeper than the double-disc, seed-furrow opener. Standard setting is 1/8 inch shallower than the double-disc opener. *Never set the coulter deeper than the double-disc opener.*
The 13-wave coulter is designed to provide some loosened soil to work with and offer some row cleaning action.
No-till coulter depth control is critical in establishing a stand with high yield potential. It’s very difficult to set and/or maintain the relationship of no-till coulter setting to the double-disc opener setting if the no-till coulter is mounted to the planter frame. Our recommendation is unit-mounted, 13-wave no-till coulters almost without exception. The exception would require a spring-loaded mounting system and depth gauge wheels or other depth-limiting system on a frame-mounted no-till coulter.
Next time, I’ll share my thoughts on row cleaners, planting unit opener discs and depth gauge wheels, and row-closing systems.
Send your questions to Darrell Bruggink at firstname.lastname@example.org or leave your comments below the blog. You can also view our planter setup video on the Penn State Crop Management Extension Group Web site.