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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #304825
Title: Yield and yield gaps in central U.S. corn production systems

Author
item EGLI, DENNIS - University Of Kentucky
item Hatfield, Jerry

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2013
Publication Date: 3/6/2014
Citation: Egli, D.B., Hatfield, J.L. 2014. Yield and yield gaps in central U.S. corn production systems. Agronomy Journal. 106:2248-2254.

Interpretive Summary: Demand for increased production from agricultural lands in order to meet the increasing demand for food, feed, and fiber; does not consider the limitations to yield and the reasons for the yield variation. A study was conducted to evaluate different methods of evaluating the yield gap as defined as the difference between the potential yield and the actual yield. We used an analysis of the county level yields for corn from Iowa, Kentucky, and Nebraska (irrigated lands only) to define the attainable potential yield. We found the yield gap varied across years and decreased as the county level yields increased. The ability to attain the yield potential was related to the quality of the soil as defined by a productivity index which is used by NRCS to evaluate different soils. Results from Iowa and Kentucky showed a strong relationship to soil quality; however, this was not true in Nebraska because the addition of irrigation water overcame the impact of the natural soil conditions on soybean yield. This research will be of interest to researchers, consultants, and producers as they strive to increase crop yields.

Technical Abstract: The magnitude of yield gaps (YG) (potential yield – farmer yield) provides some indication of the prospects for increasing crop yield. Quantile regression analysis was applied to county maize (Zea mays L.) yields (1972 – 2011) from Kentucky, Iowa and Nebraska (irrigated) (total of 115 counties) to estimate the attainable potential yield (APY) (yield in the most favorable environments in the 40-yr record). The YG for each year was the difference between the APY and the county yield. There was substantial variation in potential productivity (40-yr mean county yield) within and among states (579 to 1001 g m-2). The mean county APY within each state increased linearly (p < 0.0001) in conjunction with mean county yields. The mean relative YG (RYG) varied from 9 to 24% of APY and decreased linearly (p< 0.0001) as the mean county yield increased for each state. Large YGs were partially related to very low yields that occurred in some years during the 40-yr period and may reflect the ability of the soil to supply water to the crop. Other soil or management factors may be involved because irrigation did not reduce the RYG in Nebraska to zero. A second YG was defined by the difference between the maximum mean APY in each state and each county mean APY. The maximum APY varied from 10 (Nebraska) to 26% (Kentucky) of the minimum APY. Reducing the first YG in Kentucky and Iowa will probably require irrigation. Reducing the second YG may be more difficult if it is related to intractable soil characteristics. These results suggest that soil conditions may play an important role in determining the size of YGs.