Effects of Nitrogen Application Strategy on Corn

Trial Overview

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  • Farmers are constantly looking for information on how to be more efficient with farm inputs.
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  • Nitrogen (N) is an input that provides many options relating to application strategy that can affect the efficient use of the material.
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  • The use of irrigation systems to apply N can be a very cost effective application method, because it allows for a delay in N investment.
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Research Objective

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  • The research was set up to determine what effects the N application strategy had on corn. 
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  • Specifically, whether higher yields result from putting N on before planting, with split applications between planting and irrigation, or applying all of the N through irrigation. 
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Location
Soil Type
Previous Crop
Tillage Type
Planting Date
Harvest Date
Potential Yield
Planting Rate
Gothenburg, NE
Silt Loam
Corn
Strip-till
05/25/2016
10/10/2016
240
36,000
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Site Notes:

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The trial was set up as a randomized complete block with 3 replications of 4 treatments.All treatments had a strip-till base application of 40 lbs/acre of phosphorus (P) as 10-34-0 which also supplied 12 lbs/acre nitrogen (N) on April 14, 2016.At this time the 60 and 120 lb/acre of preplant N treatments were also applied with the strip-tiller.The site was irrigated with subsurface drip irrigation and in-season fertilizer was applied through drip irrigation. Nitrogen application through irrigation started 6 to 10 days before the corn required irrigation for water purposes.Soil test results determined nitrate level was 101 lbs/acre, organic matter was 4%, and soil pH 6.7 with a cation exchange capacity of 18.2.
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Understanding the Results

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Figure 1. Corn Yields Based on Nitrogen Application Across Treatments.  No treatments were significantly different at the P=0.10 level. 
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  • The corn had improved stalk diameter because it had more vigorous early-season growth when the majority of N was applied at the beginning of the growing season. The growth effect did not significantly influence yield even in treatments when all the N applications were delayed to growing season applications (Figures 1 and 2).
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  • Treatments with N applications after planting had less vigorous early-season growth.
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What Does This Mean for Your Farm

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  • Nitrogen applications through irrigation are an effective tool to manage N. ­These N applications did not lead to greater yields in this study, but they did provide yields that were similar to applying all of the fertilizer at planting.
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  • Applying all of the N at or near planting can be risky because excessive rainfall could result in leaching.  ­Nitrogen losses result in costly reapplication and rescue treatments required to meet corn needs later in the growing season.
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  • If corn is N stressed early in the growing season continue to monitor the field and consider management with sidedress or rescue treatments. 
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  • In this study, corn reached yield potential similar to the greatest-yielding treatment.  This was true even for the first N applications in the late vegetative stage of corn development.
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