Corn grain yield response to crop rotation during odd growing seasons
Earlier this week we looked at corn grain yield response to crop rotation in extreme growing seasons when both Growing Degree Unit (GDU) accumulation and precipitation were abnormal.
In extreme growing seasons, crop rotation was the best treatment while continuous corn was impacted more than during average growing seasons.
I was asked a follow-up question about the crop rotation effect on grain yield when growing seasons were "off" for GDU accumulation or precipitation. Again, data from the 35-yr corn-soybean rotation experiment conducted during 1987 to 2021 at Arlington, WI was used for the analysis.
Odd GDU accumulation years were selected when a growing season was + one standard deviation from the average (Figure 1). Cooler seasons included: 1992, 1993, 1997, 2004, 2008, 2009, 2013 and 2014. Warmer growing seasons included: 1987, 1988, 1991, 1995, 2005, and 2021. Grain yield during an average GDU growing season was 195 bu/A. Warm seasons averaged 170 bu/A, and cool seasons averaged 171 bu/A.
Likewise, odd precipitation years were identified when a growing season was + one standard deviation from the average (Figure 2). Drier growing seasons included: 1988, 1989, 2003, 2005, 2011, 2012, and 2021. Wetter growing seasons included: 1993, 2006, 2008, 2010, 2018, and 2019. Grain yield during an average precipitation growing season was 188 bu/A. Grain yield during dry seasons averaged 166 bu/A, and during wet seasons averaged 178 bu/A.
The key point is that crop rotation maximizes corn grain yield consistently regardless of the kind of growing season. As a cropping sequence becomes more continuous, corn grain yield is more affected by odd growing seasons compared to an "average" growing season whether cool/warm or dry/wet. Grain yield in the second corn year following five years of soybean (2C) is more affected in a warm growing seasons than 2C in cool or dry/wet growing seasons. By 3C, the rotation effect is gone and grain yield are similar to 35+ years of continuous corn.
Joe Lauer is an agronomy professor at UW-Madison