December 15, 2006

Q & A: Using pop-up fertilizer in no-till corn

For more information on this topic, be sure to check the UNL NebGuide, Using Starter Fertilizers for Corn, Grain Sorghum and Soybeans, G361

A: I've not seen any data that shows a difference between the Keeton Seed Firmers and the Schaffert Rebounders. Both get the seeds to the bottom of the seed-vee for a more uniform planting depth, leading to a more uniform emergence. Both have options for putting on the pop-up fertilizer. The Keeton does firm the seed into the soil, an advantage in dry soils. The Schaffert doesn't directly contact the seed-vee, an advantage in wet soils to avoid soil build-up or dragging the seed. We've run them both and haven't seen differences in performance for the average no-till planting conditions in Nebraska. I'm to the point where I won't plant corn without using a device that makes sure the seed is at the bottom of the seed-vee. Achieving a more uniform planting depth leads to better yields.

Also, I wouldn't plant no-till corn without the pop-up fertilizer. It helps provide good early growth, especially in cooler soils or under heavy residue. We use 5 gallons per acre of 10-34-0 and have no problems with germination problems. For some of my research, I've used 10 gallons per acre of 10-34-0 and not seen any injury in moist no-till soils. The five gallon rate will give you the pop-up effect at a reasonable cost; however, depending on the soil test level, the pop-up may not give you increased yields, just better early growth. Continue dry broadcasting to build low phosphorus soils, even in no-till, as the broadcast phosphorus is a surface "band" of fertilizer that works it's way down slowly. With residue on the soil surface in no-till conserving soil moisture, there are plenty of feeder roots right at the soil surface to pick up the phosphorus. Also, sulfur and zinc can be broadcasted to build the low testing soils.

Don't put too much "salt" in the seed furrow. The salt equivalent of the total fertilizer in the furrow for no-till shouldn't exceed 7 pounds on lighter soils or 10 pounds on heavy soils. The salt comes from the total pounds of nitrogen (N), potassium (K), and sulfur (S) in the starter fertilizer. The phosphorus doesn't add salt, that's why we use 10-34-0 as it has the most phosphorus with less salt. Ammonium thiosulfate shouldn't be used in the furrow because of the high salt content and ammonium toxicity on the germinating seed. The "low salt" products like 9-18-9 must be kept below 5 gpa, giving you only about 10 pounds phosphorus (and 10 pounds of salt equivalent). Five gallons of 10-34-0 gives you about 18 pounds of P for less cost (and only 5 pounds of salt equivalent). The "low salt" products are not really low salt — they are low corrosion because they don't contain chlorine. Even though they cost more per unit of nutrient, some producers want the low corrosion aspect to reduce bearing problems. We just make sure our 10-34-0 is placed in the bottom of the furrow with no splash and we haven't had corrosion problems.

Paul Jasa
Extension Engineer

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