Identifying Factors Controlling the Continuous Corn Yield Penalty

Abstract

It is widely accepted that yields decline when corn (Zea mays L.) is grown continuously vs. in rotation with soybean [Glycine max (L.) Merr.], although causes for the yield reduction are unclear. The primary objective of this study was to elucidate the source(s) of the continuous corn yield penalty (CCYP). The experiment was conducted from 2005 to 2010 in east‐central Illinois beginning with third‐year continuous corn (CC) or a soybean–corn (SC) rotation at six N fertilizer rates. Averaged across all years, yield at the agronomic optimum N rate for CC was 8.84 Mg ha−1 and for SC was 10.20 Mg ha−1, resulting in a CCYP of 1.36 Mg ha−1; values ranged yearly from 0.47 to 2.23 Mg ha−1. Using a regression model, three significant and independent predictors explained >99% of the variability in the CCYP: unfertilized CC yield (0NCCYD), years in CC (CCYRS), and the difference between CC and SC delta yields (maximum yield – unfertilized yield) (DELTADIFF). The strongest predictor, 0NCCYD, reflects net soil N mineralization and demonstrates that it decreases in CC systems. The CCYRS was strongly and positively correlated with CCYP, indicating that the CCYP increased through Year 7. We believe that CCYRS measures the effects of accumulated corn residue in CC systems. Finally, we consider DELTADIFF to be a measure of the interaction between yearly weather patterns and crop rotation, which results in more negative yield responses for CC than SC under hot or dry conditions. This study concluded that the primary causative agents of the CCYP are N availability, corn residue accumulation, and weather.

Continuous Corn and Soybean Yield Penalties across Hundreds of Thousands of Fields

“…The decrease in the CCYP with higher early and late-season minimum temperatures is also supportive of this, as higher soil temperatures increase soil N mineralization. Contradicting Gentry et al (2013), however, we do not find an increasing CCYP with the number of years continuously cropped. This may be due to differing corn residue management practices used in that study as compared with many commercial farms.…”

“…This result was consistent with findings by Crookston et al(1991), but not with Gentry et al (2013) who found that CCYP increased with the number of years of continuous cropping. For soybean, the penalty increased with duration of continuous cropping, with differences between 1-and 3-yr, 1-yr and 4-plus yr, and 2-yr and 4-plus yr all being significant, a finding that is also consistent with Crookston et al (1991).…”

“…If we are to assume that less N is typically used in dryland corn in the western Corn Belt given lower yield potentials and higher risks (Shapiro et al, 2001), then our results would support the Gentry et al (2013) observation that N availability influences the CCYP more than any other variable. The decrease in the CCYP with higher early and late-season minimum temperatures is also supportive of this, as higher soil temperatures increase soil N mineralization.…”

“…Th e yield benefi t of rotation may derive from improved soil structure (Barber, 1972), decreased disease pressure (Meese et al, 1991), decreased allelopathy between corn residue and growing plants (Martin et al, 1990) and increased N availability for corn in rotated systems (Stanger and Lauer, 2008). Nitrogen availability, however, is thought to be the primary driver behind this benefi t (Gentry et al, 2013). Benefi ts for soybean also have a wide range, reported as 8 to 17% by Crookston et al (1991), an average of 25% by Edwards et al (1988), approximately 4% by Nafzinger (2007), and for no-till fi rst-year soybean, 13% by Pedersen and Lauer (2002), with pest pressure from soybean cyst nematode historically cited as a major reason for this benefi t (Dabney et al, 1988).…”

Limited Irrigation of Corn‐Based No‐Till Crop Rotations in West Central Great Plains

“…The main reason why corn yield was less in CC than in the other rotations is confounded among the 254 mm of irrigation water applied to corn in CC while corn in the other rotations received 381 mm of irrigation, the obvious differences in the rotations (different crops and sequences), and interaction of the two. A relatively lower corn grain yield in CC vs. other rotations (C-Sb, W-C-Sb, C-Gs-Sb, …) was reported by many other researchers (Schneekloth et al, 1991;Porter et al, 1997;Erickson, 2008;Gentry et al, 2013). However, the 20% less yield that we have reported here for CC is probably mostly due to the difference in irrigation amount.…”