b'Research planter used to establish comparative plots of corn in 30- and 20-inch rows.Belows team has found another advantage of growing cornpopulation versus wider rows, but with increased planting popu-in narrower rows in research thats about to be published.lations in narrow rows, we did see more light interception and As you increase density, each individual plant has a smallerfaster canopy closure. root system, so its more exposed to water, nutrient and stand- Ill go one step further and say that in our soils, at our lati-ability issues, he explains. Plants in 20-inch rows have roottudes, the only way to get a yield increase in 15-inch rows (a 5 to systems that are larger by 20 to 25% than those in 30-inch rows,10% increase) is with 50,000 or 55,000 plants per acre. In this at every density from 38,000 to 56,000. region, that requires irrigation. So wherever growers are, they However, Below believes the greatest advantage of narrowhave to look at their latitude, their soils, their typical planting and rows is seen when farmers employ a systems approach thatgrowing conditions, look at the research done there and make combines more and better-placed fertilizers, higher plantingtheir decisions on row spacing in corn accordingly. populations and fungicide spraying because of less airflow.Similarly in its row-spacing work, Bayer Crop Science has Six years ago, he says, we almost never saw 300 bushelsgenerally seen that many factors influence yield response. per acre in our research trials, and now its routine with placingEchoing the thoughts of Below and Lee, Bayer U.S. Product fertilizer in the row at planting with proper crop management. Communications Lead Brian Leake notes that one of the con-siderations in going to narrower rows is for in-season access for Narrow Rows with Irrigation nutrient management as well as the upfront capital investment In Kentucky, Chad Lee and his team have found 15-inch rowsneeded to shift an operation from 30-inch to narrow rows. provide a yield advantage compared to 30-inch rows with highFarmers will need to do the math, he says, to determine if the plant populations, but thats with irrigation in place. The directoryield and agronomic benefits pencil out for their operation.at the Grain and Forage Center of Excellence at the UniversityLeake believes that over the long term in corn, narrower rows of Kentucky and his team have studied irrigation with 15-inchdo provide the opportunity to consistently increase density as rows and in-furrow fertilizing. That resulted in yields of 300 towell as gain benefits from earlier canopy closure, resulting in 325 bushels per acre, both with and without the in-furrow treat- better weed suppression and improved moisture preservation. ments, but he says more research is needed. However, like Below, Leake notes that even with advancements To get a sense of the bigger picture, Lee did a review ofin new technologies and plant breeding that will support the shift published narrow-row corn studies. He says that in looking atto narrower rows, it may not be a mainstream practice within these trials, there seems to be a yield advantage of 3 to 5% norththe next 10 years. of the Iowa-Minnesota state line, but to the south of that, its hitThe question that Below is most often asked by seed compa-or miss. Drought, he notes, can be a significant factor in morenies is whether response to planting density in corn is the same southern latitudes, and that it isnt much of an issue where Belowas it is to narrow rows. does research in Illinois. Lee adds that although corn roots mayIf thats the case, he explains, they can make their hybrid be larger with narrower row spacing, in a drought situation thebreeding program selections accordingly, and not have to try plants may fight for water against each other, and he would notand evaluate hybrids across different row spacings, which is a recommend narrower rows as a drought-resistance strategy. huge amount of effort. In the latitude and soil types of Kentucky, the only reason toBelows answer to this persistent question? While he and his go to narrow rows is to push plant population, he explains. Weteam have found a relationship existsplants that like higher know from our research that narrower rows do not provide anydensities do ok in narrow rowshe says that in the end, the light interception advantage for the crop at the same plantingrelationship isnt as strong as companies would like.SW66/ SEEDWORLD.COMDECEMBER 2019'