Are Current Corn Plant Populations High Enough to Maximize Yield and Profit?.

Corn yields have increased dramatically in Arkansas over the last 30 years with state average corn yields nearly doubling during this time.  There are many reasons for increased yields such as irrigation, higher yielding hybrids, better management practices, and technology to control weeds, insects, and diseases.  Increasing plant populations have also contributed to increasing yields.   Increasing corn plant populations are viewed by producers as an easy way to increase yields, but increasing plant populations does have some negative aspects such as increased seed costs and risk of late season lodging.   To further investigate the optimum plant population for maximum yield and economic returns, field trials were conducted in 2015 and 2016 in the Mississippi Delta region of Eastern Arkansas evaluating corn plant populations from 25,000 to 45,000 plants/acre of several widely grown hybrids.  Trials were conducted under irrigated conditions following current production recommendations and row spacing’s of 30 and 38 inches.    Corn yields were never maximized in any trial by populations less than 30,000 plants/acre regardless of hybrid, yield level, or row spacing.  Depending on hybrid, plant populations greater than 40,000 did not maximize yields under high yield potential.  The most economical plant population varied by location and depended on yield level, but plant populations needed to maximize yield and profit were higher for most hybrids than what is currently recommended.  Current recommendations of 32,000 to 34,000 plants/acre for irrigated fields with high yield potential may be too low for maximum yields and profits.  However increasing plant populations to higher levels does increase the risk of lodging, especially in production systems that utilize 38 inch wide rows that are common in Arkansas.