Striving for 300 Bushel Corn

freshly picked bushel of corn on the field under a sunny day

At the 2024 National No-till Conference, Dr. Fred Below, University of Illinois talked about “Striving for 300-bushel Corn.” Almost all of his research was done on conventional tillage corn plots, however; he made important points that apply to all farmers striving for higher yields. With the world population currently 8 billion and reaching 9 billion by 2037, higher yields will be needed to feed the growing world population.

Dr. Below emphasized three pre-requisite conditions that all farms need to follow to achieve optimal yields. First, good soil drainage and good soil structure. Without good drainage, roots can not grow to reach soil nutrients. Without good soil structure, both the soil microbes and root development is limited. Second, control all pests including weeds, insects, and diseases. Pests reduce yields by about 30% world-wide. Healthy plants can reduce the harmful effects of almost all agricultural pests. Third, soil test to get adequate fertility (pH, macro-, and micro-nutrients). Current soil tests are not calibrated for 300-bushel corn, so stay in the mid to slightly higher range to have adequate plant nutrition for optimal yields.

Dr. Below revised and updated his 7 wonders (tips) for 300-bushel corn. The order is still the same, just updated from 200 to 250 to now 300-bushel corn. Dr. Below list 7 factors needed for 300-bushel corn followed by what his research shows to be the bushel advantage (disadvantage). Good (Bad) Weather accounted for a 90-bushel change, Fertility (90 bushel), Corn Hybrid selection (50 bu.), Corn Population (25 bu.), Type of Tillage/No-till (15 bu.), Biologicals (10 bu.). Again, this was research on conventional tilled plots.

Dr. Below emphasized that planting date is determined by weather. Most years, May 15th seems to be the cutoff date, but one year he still got 310 bu./A on corn planted May 30th. Weather influences nitrogen (N) losses and all 7 factors have interactions with each other. The 4 R’s (right placement, right rate, right source, right time) are all important; but Dr. Below emphasized right placement. Get it close to the roots! Putting N on in the middle of the row may not allow the corn roots to get access, especially in conventional soils with compaction and poor soil structure. On conventional tilled soils 30-inch rows apart, most roots only reach out 6-8 inches into the middle of the row. Most long-term no-till fields roots with good soil structure can reach the middle of a 30-inch row.

For fertilizer, starter fertilizer on the seed (low salt) and 2-inch by 2-inch placement is needed. You never want your corn to turn yellow or light green. Corn determines yield from V2 (two true leaves) to V6 (six true leaves). Spoon feeding corn throughout the corn season is beneficial, and Y drops, putting the N fertilizer right at the base of the corn plant are beneficial.

Over the last 4 years, Dr. Below said corn hybrids had a 38 to 62-bushel swing, averaging 50 bushel. Get hybrids that are adapted to your soil type and environmental conditions. For No-till (NT) farmers, get varieties that do well in those conditions. Most corn hybrids are tested under conventional tillage, corn hybrids need to be tested for NT conditions. According to Dr. Peter Thomison, retired OSU corn specialist, moisture at pollination is a big factor in determining final yield, more so than crop maturity (e.g. 100-day corn versus 115-day corn).

On corn population, the average increase in corn yield is 2 bu./Acre/year due to a linear increase in corn population of about 400 seeds/year. More plants equal more grain with adequate moisture. Yield is based on the formula Number of Plants/Acre * Kernels/corn cob * grain weight/kernel. The only factor farmers can really control is the corn population. In 30-inch rows, 38,000 (38K) seeds/acre is about maximum while 20-inch rows can intercept more sunlight and max out at 44K. Average yield increase is 25 bu./A in 20-inch rows versus 30-inch. As farmers increase population in a row, roots get smaller (2.5% decrease in root mass/1K seeds) but root size increases in 20-inch rows due to better distribution and sunlight interception. Dr. Below says, on root mass, 38K on 30-inch rows equal the root mass on 44K on 20-inch rows except the yields are higher in 20-inch rows.

A good crop rotation (Corn-Soybeans-Wheat) may add 20 bushel per acre by decreasing pests. Tillage or long-term NT may add 15 bu./A and good biological activity may add another 10 bu./A. Biologicals and NT is of higher importance in long-term NT plus a cover, but less of a factor in conventional tilled soils where corn is more dependent on commercial fertilizer. More info to come!