Optimization of Starter Nitrogen Fertilizer Application for Corn Planted into a Cereal Rye Cover Crop

Progress report for LNE18-366

Project Type: Research and Education
Funds awarded in 2018: $199,790.00
Projected End Date: 10/31/2021
Grant Recipient: University of Maryland
Region: Northeast
State: Maryland
Project Leader:
Dr. Katherine Tully
University of Maryland
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Project Information

Summary:

Cover crops convey benefits that are typically maximized by maximizing the amount of time the cover crop is in the field. For example, delaying termination of cereal rye gives the cover crop a chance to potentially produce almost double the amount of biomass and thus scavenge more N that might otherwise be lost to the environment. However, delaying rye termination may require different fertilizer application strategies to account for the effect of large rye biomass on soil N dynamics in a following corn crop (i.e. it may be beneficial to apply more fertilizer as a starter and less at corn side-dress). We tested varying ratios of starter to side-dress N fertilizer in corn to fine-tune the fertilizer strategy following delayed (i.e. late) rye termination. The educational approach in this project, which was put into action in workshops and through demos, featured a curriculum involving topics such as a) benefits of cover crop use, b) benefits of maximizing time the cover crop grows in a field, c) cover crop planting and termination methods and timings, and d) corn fertility programs following late-terminated rye.

Performance Target:

A total of 60 farmers in DE, MA, MD, NY, and PA will terminate cereal rye 2-4 weeks later than they usually would (April vs. early March) on 2,400 acres, doubling the average amount of cereal rye biomass produced and preventing the leaching of 45,000 lbs N into local watersheds.

Introduction:

Cover crops convey benefits that are typically maximized by maximizing the amount of time the cover crop is in the field. For example, delaying termination of cereal rye gives the cover crop a chance to potentially produce almost double the amount of biomass and thus scavenge more N that might otherwise be lost to the environment. However, it is speculated that delaying rye termination may require different fertilizer application strategies to account for the effect of large rye biomass on soil N dynamics in a following corn crop. For example, it may be beneficial to apply more fertilizer as a starter and less at corn side-dress. The research approach in this project was to test varying ratios of starter to side-dress N fertilizer in corn to fine-tune the fertilizer strategy following delayed (i.e. late) rye termination. The educational approach in this project featured a curriculum involving topics such as a) benefits of cover crop use, b) benefits of maximizing time the cover crop grows in a field, c) cover crop planting and termination methods and timings, and d) corn fertility programs following late-terminated rye. This curriculum was delivered at workshops and demonstrations.

Cooperators

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Research

Hypothesis:

1) If split-N applications are used, the amount of starter N applied at corn planting must increase proportionally with increasing cereal rye biomass.

2) Total N requirement for optimal corn yield is not influenced by the quantity of cover crop biomass at planting.

3) Larger amounts of cereal rye biomass will have a net positive effect on corn yield and reduce N loss.

Materials and methods:

We implemented field trials at five sites in the region (MA, NY, PA, two in MD, DE) in 2018 and 2019. Treatments were arranged in a split-plot design with cover crop treatments as main plots and all fertility treatments (0, 150, and 210 lb ac-1) fully randomized as the split-plot. Four starter and side-dress combinations resulted in application of 150 lb ac-1 (0:150, 25:125, 50:100, 75:75) or 210 lb ac-1 (0:210, 25:185, 50:160, 75:135). This generated a total of nine fertility treatments for each cover crop. The no cover crop treatments served as a control in this experiment and did not receive the full factorial of N application rates. The no cover crop treatment had two rates: no N fertilizer (0:0) and 210 lb ac-1 (50:160). Therefore, there were a total of 29 cover crop x fertilizer plots per rep. Each site had a minimum of four replicates.

Cereal rye and corn variety selection varied by site to accommodate climatic differences. Cereal rye was established in the fall of 2018 and 2019 at 90 lb ac-1 using a grain drill. Sites normalized conditions by planting cereal rye after a soybean cash crop on fields without a history of frequent manure applications to ensure moderate to low base soil N levels. No cover crop treatments were established by killing the cereal rye with glyphosate within 2-3 weeks of emergence. Sub-plots were 10 ft (4 corn rows) by 50 ft in length. No cover crop plots were maintained weed-free using glyphosate and 2,4-D, as needed, until corn was planted. Cover crops were terminated with glyphosate plus 2,4-D at appropriate times in the spring to meet treatment objectives.

Corn was planted in all plots the same day, but allowed to vary by site. Standard herbicide programs were used that reflect state recommendations. Corn was planted using a no-till planter on 30-inch row spacing at a population of 28,000 seeds ac-1. Nitrogen source for both starter and side-dress N applications was made with urea-ammonium nitrate treated with a urease inhibitor to minimize ammonia volatilization losses. Starter N application was spread on soil surface 3 inches from the corn row and side-dress applications were placed 15 inches from the corn row. All other nutrient limitations were remedied based on soil test recommendations. 

 

Research results and discussion:

We measured corn yield as influenced by cereal rye biomass, proportion of N applied as starter vs side-dress, and total N. Contrary to hypothesis 1, the proportion of N applied as starter vs at side-dress did not affect corn yield (Fig. 1). Contrary to hypothesis 2, total N applied did affect corn yield dependent on cereal rye biomass (Fig. 1). However, this effect was only detected in the 0 kg ha N (control) treatment, which was to be expected. Contrary to hypothesis 3, we did not detect differences in corn yield based on rye biomass, even with large quantities of rye (Fig. 1). While the effect was not statistically significant, there was a general positive trend – as cereal rye biomass went up, so did corn yield. This may be due to increased weed suppression and/or water retention at higher rye mulch levels. We also investigated the effect of sulfur application and rye termination timing on corn yield at sites in PA, DE, and MD; we detected no differences in corn yield (p = 0.31) (Fig. 2).

 

 

Figure 1. Corn yield as affected by cereal rye biomass and starter N rate. Starter N rate had no detected effect on yield (p = 0.31).

 

Figure 2. Effect of sulfur application and rye termination timing on corn yield at sites in PA, DE, and MD. We detected no differences.

Participation Summary

Education

Educational approach:

The educational approach used in this project was a curriculum featuring topics such as a) the value of including cereal rye in a corn/soybean rotation, b) rye planting timing and methods, c) rye termination timing and methods, d) value of delayed rye termination in the spring, e) management of late-terminated rye, and f) costs/benefits of altering corn starter/side-dress fertilizer ratios after late-terminated rye. The curriculum was presented at grower conferences and field demonstration days.

Milestones

Milestone #1 (click to expand/collapse)
What beneficiaries do and learn:

1. We contact 2,000 farmers via e-mail with an invitation to participate in project activities (May 2018).

Proposed number of farmer beneficiaries who will participate:
2000
Actual number of farmer beneficiaries who participated:
3015
Proposed Completion Date:
May 31, 2018
Status:
Completed
Date Completed:
October 31, 2019
Accomplishments:

The number listed above represents the number of people reached via listservs, newsletters, and events.

Milestone #2 (click to expand/collapse)
What beneficiaries do and learn:

2. An anticipated 600 farmers sign up to the project listserv to receive updates about research results and educational events in their state (June 2018).

Proposed number of farmer beneficiaries who will participate:
600
Actual number of farmer beneficiaries who participated:
3015
Proposed Completion Date:
June 30, 2018
Status:
Completed
Date Completed:
October 31, 2019
Accomplishments:

The number listed above represents the number of people reached via listservs, newsletters, and events.

Milestone #3 (click to expand/collapse)
What beneficiaries do and learn:

3. Approximately 400 farmers attend workshops held across the collaborating states and increase their knowledge of the benefits of delaying cereal rye termination to increase biomass, the risk of N immobilization that cereal rye poses when grown before corn, and strategies for adjusting N fertilizer applications in corn based on cereal rye quality and quantity at the time of termination (March 2019).

Proposed number of farmer beneficiaries who will participate:
400
Actual number of farmer beneficiaries who participated:
818
Actual number of agriculture service provider beneficiaries who participated:
125
Proposed Completion Date:
March 31, 2019
Status:
Completed
Date Completed:
October 31, 2019
Accomplishments:

Events included the 2019 Agronomy Day in Maryland and the Sussex Conservation District field day in Delaware; this project was featured at five events in Pennsylvania. The corona virus pandemic precluded in-person meetings and demos in 2020, but 76 farmers attended a webinar on November 19 hosted by Penn State Extension on “Nitrogen Management with Cover Crops” that presented results from the experiment. 125 ag service providers attended a webinar hosted by the Pennsylvania 4R Alliance on “Nitrogen Management with Cover Crops” where results from the Pennsylvania experiments were reported.

Milestone #4 (click to expand/collapse)
What beneficiaries do and learn:

4. Approximately 200 farmers attend a field day at on-farm demonstration sites and increase their knowledge of the benefits of delaying cereal rye termination to increase biomass, the risk of N immobilization that cereal rye poses when grown before corn, and strategies for adjusting N fertilizer applications in corn based on cereal rye quality and quantity at the time of termination (September 2019).

Proposed number of farmer beneficiaries who will participate:
200
Actual number of farmer beneficiaries who participated:
373
Proposed Completion Date:
October 31, 2019
Status:
Completed
Date Completed:
October 31, 2019
Accomplishments:

Among others in 2019 there were 165 farmers total who participated in an annual field day or one of two twilight dairy meetings in Massachusetts; 145 who attended either a weed day, the Sussex Conservation District field day, REC field day, or New Castle County Twilight tour in Delaware; and 63 who participated in demos in Maryland.

Milestone #5 (click to expand/collapse)
What beneficiaries do and learn:

5. Approximately 100 farmers contact project personnel to receive assistance with managing delayed termination of cereal rye cover crops (April 2020).

Proposed number of farmer beneficiaries who will participate:
100
Actual number of farmer beneficiaries who participated:
150
Proposed Completion Date:
April 30, 2020
Status:
Completed
Date Completed:
October 30, 2020
Milestone #6 (click to expand/collapse)
What beneficiaries do and learn:

6. Approximately 60 farmers agree to keep records of field activities and receive personalized assistance from project personnel (via email and phone consultations) to achieve the project performance target (May 2020).

Proposed number of farmer beneficiaries who will participate:
60
Actual number of farmer beneficiaries who participated:
73
Proposed Completion Date:
May 31, 2020
Status:
Completed
Date Completed:
October 30, 2020

Milestone Activities and Participation Summary

15 Consultations
1 Curricula, factsheets or educational tools
2 Published press articles, newsletters
5 Tours
11 Webinars / talks / presentations
8 Workshop field days
3 Two articles in the Delaware Weekly Crop Update (reaching 850 subscribers).
One ASA-CSSA-SSSA 2020 Poster attended by 20 professionals.

Participation Summary

818 Farmers
510 Number of agricultural educator or service providers reached through education and outreach activities

Performance Target Outcomes

Target #1

Additional Project Outcomes

2 Grants applied for that built upon this project
2 Grants received that built upon this project
$10,013,000.00 Dollar amount of grants received that built upon this project
7 New working collaborations
Assessment of Project Approach and Areas of Further Study:

Dr. Hashemi, the Massachusetts co-PI, notes in 2019 that this project raised some good research ideas. He has a graduate student determined to investigate one of these ideas in her upcoming SARE Graduate Student grant.

Overall, he believes corn growers have two options to deal with their winter rye cover crops. The first option is harvesting the cover crop as emergency forage. In this case, time of planting in fall would be crucial.

The second option is the topic of the current project where the interactive effect of time of termination and N application is crucial.

As a supplement to this project, Dr. Hashemi feels the following ideas should be pursued:

  • Use of roller crimper instead of disking residues into soil and if the best fertility scenario will change with type of termination.
  • Focusing on root residues and their decomposition trend.
  • Manure application in fall and its impact on the best fertility scenario.
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.