What is in this article?:
- Extra phosphorus, sulfur, zinc can boost corn yield
- Nutrient uptake timing is key
- Subsurface banded below row
With transgenic corn rootworm hybrids’ widespread adoption, it may be time to rethink high-yield corn fertility, says Fred Below, University of Illinois plant physiologist.
Research conducted by Below and grad student Ross Bender shows that rootworm hybrids’ roots are active longer after flowering than conventional corn’s roots. This increases nutrient uptake, especially of nitrogen, phosphorus, potassium and zinc.
“We would argue that soil-fertility recommendations might be out of date for the yield goals that are achievable with today’s hybrids,” Bender says.
With the increased uptake, phosphorus is of special concern, given current fertility practices, says Below. Surveys show that on average, Illinois farmers apply just over 90 pounds per acre phosphorus in a corn and soybean rotation. Since corn and soybean harvest removes about 80% of phosphorus, Illinois soils are being depleted of phosphorus at the rate of 30 pounds of P2O5 per acre every two years, he estimates.
“This suggests a looming phosphorus-soil fertility crisis if adequate phosphorus-application-rate adjustments aren’t made as productivity increases,” Below says.
Fully filled corn ears indicate that the supply of soil nutrients — including P, S and Zn — was adequate to meet crop demand.
Subsurface banded below row
The phosphorus, sulfur and zinc boost in the University of Illinois research was supplied by 250 pounds/acre of a 12-40-0-10S-1zinc fertilizer. The fertilizer used in the test, MicroEssentials SZ, from Mosaic, was banded 4-6 inches below the row at planting.
Subsurface banding may help improve nutrient uptake, says Below. The fertilizer formulation, which fuses a blend of nutrients in each granule, may also contribute to improved uptake and season-long sulfur availability, according to the manufacturer.
“Our approach is to feed the plant, not the soil,” says Below. “Feeding the soil is probably not going to get you to 300-bushel corn. Fertilizer sources that supply nutrients at the rate and time that match corn nutritional needs are critical for optimizing nutrient use and yield.”
Below says the “booster” fertilizer application rate used in the research trials, which supplies 100 pounds/acre of P2O5, 25 pounds/acre of sulfur and 2.5 pounds per acre of zinc, would be sufficient for corn with a yield goal of 230 bushels per acre. For a 300 bushels per acre yield, he recommends bumping rates 25% to 30%.