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Pioneer: Yield-Limiting Factors in Continuous Corn Production

18 April 2014

Pioneer

Numerous studies have documented yield reductions when corn follows corn rather than soybeans, even when all yield-limiting factors appear to have been adequately addressed. Better understanding of factors that limit continuous corn (CC) yield can help improve management of this production system.

A recent study in east-central Illinois compared CC and corn following soybean (CS) yields over a 6-year period (Gentry et al., 2013). With the exception of nitrogen (N) fertilizer rates, which were varied as part of the study, high-yield management practices were applied uniformly to both CC and CS systems - this included the use of soil-applied insecticides for rootworm control. In general agreement with previous research (Erickson, 2008), the Illinois study reported a significant yield penalty and generally higher N fertilizer requirement for CC compared to CS (Table 1). On average over 6 years, CC yielded 25 bu/acre less than CS and required 10 lbs/acre more N fertilizer to achieve optimum (but lower than CS) yields.

The authors of the study used their field data to develop a regression model that identified the most important combination of factors contributing to reduced yields in the CC system. Of 11 potential yield-limiting factors that were evaluated, 2 factors were identified that, when taken together, explained more than 97% of the difference between CC and CS yields: soil N supply and CC history of the field (Table 2).

Nitrogen Supply

N supply was by far the most important factor explaining the difference between CC and CS yields. Overall, the ability of soil to supply N explained 85% of the CC yield penalty (Table 2). Soils with higher N mineralization capacity supported higher CC yields, as was evidenced by a negative relationship between unfertilized (0-N) corn yield and the CC yield penalty (Figure 1). Soil N mineralization is reduced in CC systems due to the slower rate at which corn residues break down and release N relative to soybean residues. Soils also tend to warm more slowly in the spring when the previous crop was corn, which reduces activity of soil bacteria responsible for N mineralization. The fact that the CC yield penalty was smallest where relatively high corn yields were achieved, even in the absence of N fertilizer, shows that soils with high intrinsic N supply capacity are generally best suited for CC.


Figure 1. Relationship between unfertilized Continuous Corn yield and the Continuous Corn yield penalty. Adapted from Gentry et al., 2013.

Continuous Corn History

CC history was identified as the second most critical component of the CC yield penalty. Soil N supply and CC history together explained 97% of the difference between CC and CS yields. While many growers report that their CC yields approach CS yields over time, this study found that the CC yield penalty increased with years in CC (Figure 2). While producers typically alter management as they gain experience with CC, management remained relatively constant over time in the Illinois study. Therefore, CC history in this study likely reflects the underlying effects of excessive corn residues accumulating in and on the soil over time in the CC system. Corn residues exert negative effects on nutrient cycling, early season soil temperature and moisture, and increased disease pressure for subsequent corn crops.


Figure 2. Relationship between years in Continuous Corn and the Continuous Corn yield penalty. Adapted from Gentry et al., 2013.

Managing Factors that Limit Continuous Corn Yield

There are numerous management factors that must be taken into consideration in order to maximize CC yields, including hybrid selection, tillage, soil fertility, and weed and insect control practices (Butzen, 2012). The following review focuses on just those factors that relate directly to the findings of Gentry et al. (2013) described in this article.

Field Selection - University research and grower experience both indicate that CC yield losses are minimized in highly productive and low stress environments (Porter et al., 1997). This understanding is consistent with Gentry et al.'s (2013) findings that soil N supply capacity was the most important factor explaining the CC yield penalty. The ability of soil to serve as a source of N for crop growth is directly related to its organic matter content. Soils with high organic matter, in turn, generally have high water-holding capacity. Positioning CC on these soils (or having access to irrigation) is critical for maximizing yields in this system.

Hybrid selection is a critical decision in any production system, but is particularly important for CC where high residue levels often cause additional management challenges. To assist in selecting hybrids for CC, Pioneer sales professionals can provide hybrid ratings for high residue suitability, disease resistance, and stalk and root strength. They can also recommend products with appropriate insect resistance traits and refuge options, as well as the best seed treatments.

Residue Management - Interference from past years’ corn residues was a key factor identified by Gentry et al. (2013) as contributing to the CC yield penalty. Growers can take several actions to manage residues for improved CC performance.

Partial residue removal can be very effective in managing excessive residue in high-yield CC environments. DuPont Pioneer on-farm research in Iowa indicated that removing half the previous year’s corn stover improved CC yield by an average of 6 bu/acre. Removing excess residue was found to increase CC yields through improved stand establishment and reduced N immobilization. Removing excess corn residues can provide many of the benefits associated with rotation with soybean. Additional details are available on the potential agronomic benefits of residue removal in CC systems (see Heggenstaller, 2012a). Residue removal is particularly advantageous in no-till CC systems, where residues are not incorporated into the soil (Heggenstaller, 2012b).

Tillage is a key residue management practice in most CC systems. Sizing and incorporating residues into soil are the first steps in getting them to begin to break down in advance of establishing the next crop. Full-width chisel plowing and strip-tillage in the fall are generally the best suited tillage practices for CC systems.

Fall N applications can help to accelerate the rate at which residues break down in environments where temperature and moisture are not limiting.

Limited rotation with soybean can be an effective way to maintain high yields in systems where corn is frequently grown consecutively for 2 or more years. Research conducted by DuPont Pioneer and the University of Illinois found a 5% yield penalty for second-year corn in a corn-corn-soybean rotation vs. corn grown the first year after soybean. This compared to a 17% penalty for corn grown continuously (Doerge, 2007).

References

Butzen, S. 2012. Best management practices for corn-after-corn production. Crop Insights. Vol. 22, no. 6. DuPont Pioneer, Johnston, Iowa.

Doerge, T. 2007. A new look at corn and soybean rotation options. Crop Insights Vol. 17. No. 2. DuPont Pioneer, Johnston, Iowa.

Erickson, B. 2008. Corn-soybean rotation literature summary. Department of Agricultural Economics. Purdue University. West Lafayette, Ind.

Heggenstaller, A. 2012a. Corn production following partial stover harvest. Research Update. DuPont Pioneer Agronomy Sciences, Johnston, Iowa.

Heggenstaller, A. 2012b. Residue management: partial stover harvest increases no-till continuous corn yield. Crop Insights Vol. 22, no. 6. DuPont Pioneer, Johnston, Iowa.

Gentry, F., M.L. Ruffo, and F.E. Below. 2013. Identifying factors controlling the continuous corn yield penalty. Agron J 105:295-303.

Porter, P.M., J.G. Lauer, W.E. Lueschen, J.H. Ford, T.R. Hoverstad, E.S. Oplinger, and R.K. Crookston. 1997. Environment affects the corn and soybean rotation effect. Agron J 89:441-448.

April 2014

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