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Establishing Nitrogen Credits Following a Sweet Corn Crop on Non-Irrigated Soils

Start Date: 2017
Principal Investigator: Carl Rosen
Organization: University of Minnesota, Department of Agronomy and Plant Genetics
Status: Ongoing

Background Info

The objective of this study is to assess the effect of soil-incorporated sweet corn stover, relative to field corn and soybean stover (which have C:N ratios of >50:1 and 30-50:1, respectively), on the N response of field corn grown the following season. We hypothesize that sweet corn, unlike field corn, will provide an N credit for field corn grown the following year, that this N credit will be smaller than that of soybeans, and that a rye cover crop will conserve some N from sweet corn stover that would otherwise be lost. In this report, we report on the amount of N and the C:N of the stover of field corn, soybean, sweet corn, and sweet corn followed by rye grown in two fields, one in 2017 (hereafter, “Field 1”) and one in 2018 (“Field 2”), as well as the N response of field corn in 2018 following each of these crops in Field 1.

Objectives

The objective of this study is to assess the effect of soil-incorporated sweet corn stover, relative to field corn and soybean stover (which have C:N ratios of >50:1 and 30-50:1, respectively), on the N response of field corn grown the following season. We hypothesize that sweet corn, unlike field corn, will provide an N credit for field corn grown the following year, that this N credit will be smaller than that of soybeans, and that a rye cover crop will conserve some N from sweet corn stover that would otherwise be lost. In this report, we report on the amount of N and the C:N of the stover of field corn, soybean, sweet corn, and sweet corn followed by rye grown in two fields, one in 2017 (hereafter, “Field 1”) and one in 2018 (“Field 2”), as well as the N response of field corn in 2018 following each of these crops in Field 1.

Key Findings

Based on our results for Field 1, which was planted in rotation crops in 2017 and in field corn fertilized at a range of N rates in 2018:

Sweet corn stover clearly provides an N credit to a subsequent field corn crop

Sweet corn provides a similar N credit to soybeans, and the rye cover crop has little effect

It is likely that rye served to both sequester and release N for the 2018 field corn crop and reduce N losses to leaching between sweet corn harvest and field corn establishment

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