The latest findings in Fred Below's 25-year research quest to achieve a consistent 300-bu. corn crop focus on a combo of precision fertility and racehorse hybrids."We also have developed a way to identify these so-called racehorse hybrids that respond to high-yield management," says the University of Illinois plant physiologist. How to move your corn yields towards 300 bu., according to Below.
Leave no plants behind
RTK guidance brings more precise fertility needed to position specific nutrients in cornrows. Below bands the whole supply of P, sulfur (S), zinc (Zn) and some N 4-6 in. deep. He then plants corn directly over top the banded nutrients.
"Banded fertility gives corn plants nutrients they need for high yields right from the start. Roots do not have to travel to find phosphorus and micronutrients, which are immobile in the soil," he says. "I believe you must feed the plant, not the soil. You have to focus on nutrients that are highly allocated to the grain – including N, P, S and Zn – since grain makes corn yield."
Below's trials in 2011 showed a 14-17 bu./acre increase in yield (versus standard practice – see table) with placed fertility, even in soils with medium to high levels of P. Soil tests have worked well to determine plant nutrient needs for the last 50 years, but he speculates whether soil tests are calibrated high enough to feed the higher plant density and grain requirements for 300-bu. corn. Below believes you have to supplement soil tests with application and fertilizer technologies that supply those nutrients in the right amount at the right time to reach 300 bu.
"We have confirmed that with higher plant densities, placed fertility is more effective, sustainable and cost-efficient," he says. "We believe in the concept of 'no plant left behind,' and we see fewer early stragglers with better placed fertility, since yield potential begins as soon as the seed is planted. All plants must grow rapidly right from the start to achieve high yields."
Choose high-density hybrids
Below stresses that banded fertility must go hand-in-hand with choosing the right racehorse hybrids that can handle higher plant populations, perhaps up to 45,000/acre. to reach 300 bu.
He screens an array of commercial hybrids for two factors – tolerance to high plant density and N use. He grows each hybrid at 32,000 and 45,000/acre and feeds them 0, 60 and 240 lbs. N. In general, he says racehorse hybrids are the ones that can handle higher densities and that thrive on extra N.
"Hybrids change over quickly, and as soon as we determine the best hybrids, they may leave a company's lineup. Related hybrids from the same families under high management systems tend to perform similarly," he says. "We are working with seed companies to access hybrids sooner or even before commercial release so we can identify them quickly."
Some examples of racehorse hybrids that have been successful in Below's trials include DKC62-97VT3P, DKC63-84VT3, N68A-3000GT, P1184XR and Croplan7505VT3.
Below also evaluates different row configurations and spacings in his high-density trials. While the results from his twin-row research have been disappointing, he is still testing 20-in. rows.
"Twin rows do not work as well with higher populations, especially where summers are very warm. You would need to use heat-tolerant hybrids, or only plant in more moderate climates," he says. "If you only change row configuration or spacing and do not adjust for hybrid or fertility, you will be disappointed. You can't just change one management factor," Below says.
He encourages farmers to try their own banded fertility and high-density racehorse plantings. "Take advantage of synergies. You may not get 300-bu. corn, but 250 bu. are possible," he says. "Gaining the last 50 bu. will require you to also reduce plant stresses. You must plan for high yields and commit to the system to make it work."