Managing nitrogen availability for increased yield of corn and soybean

Schwartz, Stephen Arnold

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https://hdl.handle.net/2142/115484 Copy

Description

Title

Managing nitrogen availability for increased yield of corn and soybean

Author(s)

Schwartz, Stephen Arnold

Issue Date

2022-04-26

Director of Research (if dissertation) or Advisor (if thesis)

Below, Frederick

Committee Member(s)

• Mulvaney, Richard
• Lee, DoKyoung

Department of Study

Crop Sciences

Discipline

Crop Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Nitrogen
• Corn
• Soybean
• Fungicide
• Placement
• Banding
• Fertilizer Source
• Y-drop

Abstract

Over time, the productivity of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] has been influenced by many factors that have contributed to the United States, in 2021, accounting for 32% and 31%, respectively, of the total world production for these crops. Improved cultivars have played a significant role in the increased productivity of both corn and soybean with breeding methods and genetic selection rapidly advancing the overall yield potential of these crops. With better genetic yield potential, the total amount of nutrients demanded by corn and soybean has also increased which has highlighted the importance of crop management practices that improve crop fertility. Research into better fertilizer placement, new times for nutrient applications, enhanced fertilizer sources, and the synergy between these and other management practices is key to optimizing corn and soybean yield and quality. Nitrogen (N) is one of the most important nutrients for corn and soybean because it is required in large quantities for the growth and development of both crops which elevates the importance of proper N management. Therefore, the objective of this research was to understand how N fertilizer management practices can be better deployed to improve the productivity of both corn and soybean. Yield Level Determines Corn Yield Response to Enhanced Nitrogen Management Practices Nitrogen management practices can improve corn productivity, but their effectiveness can vary widely based on environmental factors. Alternative application timings and placement combinations of N fertilizer are used to manage N availability for various environments, but polymer-coated N fertilizer offers a different approach to season-long N availability and creates new N management opportunities. The objective of this study was to compare the effectiveness of conventional and enhanced N sources across fertilizer timing and placement combinations to optimize corn productivity. Nitrogen timings included supplying 180 lbs N acre-1 pre-plant or divided equally across pre-plant and side-dress applications. Pre-plant fertilizer placement was either broadcast on the soil surface or sub-surface banded 6 inches directly below the future crop row, while side-dress provided urea ammonium nitrate (UAN; 32-0-0) applied at V6 along the crop row (Y-drop). Nitrogen fertilizers applied pre-plant consisted of one standard source, urea (46-0-0), and two polymer-coated sources, Environmentally Smart Nitrogen (ESN; polymer-coated urea 44-0-0) and a 1:1 mixture of urea and ESN referred to as the Blend. To evaluate these management combinations, field trials were conducted at three locations in Illinois in 2019, 2020, and 2021 resulting in eight site years of data. Based on the average yield across all treatments, the eight site years of data were divided into three groups, and ranked according to final yield, i.e., low yielding, (<200 bushel acre-1), average yielding, (200-249 bushel acre-1), and high yielding, (>250 bushel acre 1). In the high yield group, applying the Blend increased grain yield by 5 bushel acre-1 over urea and 4 bushel acre-1 over ESN. There was no difference in the yield response to the various N sources in either the low or average groups. Banded placement of N fertilizer induced greater yields than when the fertilizer was broadcast, averaging a 13 bushel acre-1 increase in the low group and 4 bushel acre-1 more in the high yield group. Fertilizer placement, however, did not significantly affect yield in the average group. Using a split application of N fertilizer in the low group increased yield by 4 bushel acre 1 compared to only applying N fertilizer pre-plant, while in the average and high groups yield was not impacted by split applications. Regardless of the yield group, the Blend was the best N source when using Broadcast applications, increasing yields compared to urea and ESN fertilization, respectively, by 5 and 6 bushel acre-1 in the low, 4 and 3 bushel acre-1 in the average, and 9 and 4 bushel acre-1 in the high group. The Blend and ESN fertilizer affected corn yield similarly, on average across placements in the high yield group, but banding the urea increased yield by 10 bushel acre-1 compared to when it was supplied by Broadcast. The variation in yield response to the source, placement, and timing combinations across multiple yield levels makes it difficult to confidently select and recommend practices for corn production and explains why variation in the response to N management practices is often observed. Foliar Protection to Increase the Yield Response of Soybean to Nitrogen Management The high N requirement for soybean growth and yield implies that N fertilizer applications may be needed to supplement biological N2 fixation. Historically, however, soybean yield responses to added N have been inconsistent, suggesting that environmental or management factors may temper the response to N. One important management factor that may affect the N fertilizer response is foliar protection (fungicides for leaf diseases and insecticides for insect feeding), which would prolong leaf area duration and allow for N-induced maintenance of leaf photosynthesis. The objective of this study was to determine if foliar protection enhances the yield response of soybean to N fertilization. Two soybean varieties were fertilized at Champaign, IL in 2020 and 2021 with 75 lbs N acre-1 as urea ammonium nitrate (UAN; 32-0-0) using five distinct placements and timings and compared to an untreated control. Fertilizer treatments included: 1) pre-plant broadcast sprayed on the soil surface; 2) pre-plant banded 2 inches beside and 2 inches below the seed; 3) R3 side-dress placed at the base of the plant using Y-drops; 4) R3 side-dress banded 6 inches deep between crop rows using a coulter; and 5) fertigation during seed development (R1-R5) in five 12.5 lbs N acre-1 increments using subsurface irrigation to place the N directly in the soybean root zone. All treatments were compared to an unfertilized control treatment, which received no nitrogen. Foliar protection applications, consisting of both an insecticide and a fungicide, were made at the R3 growth stage in both years and compared to experimental units that did not receive any foliar protection applications. In both 2020 and 2021, banded placement of pre-plant N significantly reduced nodulation at the V6 growth stage but broadcast placement had no negative impact on nodulation. All pre-plant N applications, regardless of placement, increased canopy coverage by V6 and plant biomass at V6 and R3. When averaged across all other factors, root zone placement in multiple small increments between the R1 and R5.5 reproductive stages was the only nitrogen application that increased yield. However, without a foliar protection application, no nitrogen application increased yield compared to the unfertilized control. When foliar protection was included, both the pre-plant broadcast and R1-R5.5 root zone placement treatments increased soybean grain yield. Soybean plants responded to supplemental N with greater growth, but these applications needed to have minimal impact on nodulation and required additional foliar protection for increased yields.

Graduation Semester

2022-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Stephen Schwartz

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