Source: UNIVERSITY OF NEBRASKA submitted to NRP
EVALUATION AND DEMONSTRATION OF BROADCAST INTERSEEDED COVER CROPS TO REDUCE NITROGEN LOSS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
ACTIVE
Funding Source
AFRI COMPETITIVE GRANT
Reporting Frequency
Annual
Accession No.
1030255
Grant No.
2023-68008-39446
Cumulative Award Amt.
$300,000.00
Proposal No.
2022-10053
Multistate No.
(N/A)
Project Start Date
Apr 1, 2023
Project End Date
Mar 31, 2026
Grant Year
2023
Program Code
[A1701]- Critical Agricultural Research and Extension: CARE
Recipient Organization
UNIVERSITY OF NEBRASKA
(N/A)
LINCOLN,NE 68583
Performing Department
(N/A)
Non Technical Summary
The long-term goal of this project is to provide farmers knowledge and technology from adopting cover crops into their cropping systems, which will strengthen cover crop adoption while improving cash crop efficiency for nitrogen uptake, crop productivity, soil resilience and environmental quality. The short-term goal of this project is to leverage an existing cover crop interseeding technology demonstration project (covering 30 fields and over 3000 acres) as a framework to conduct on-farm research trials to expand our understanding of cover crop practices and improve adoption by local farmers. Understanding cover crops impact on nitrogen dynamics are very important to strengthen Extension recommendations for farmers to adopt innovative practices. Given the short window to grow cover crops in Nebraska after cash crop harvest, the demonstration and on-farm testing of interseeding technology will help improve farmer awareness and adoption of these practices. There is a critical need to address the high nitrate level in Nebraska groundwater and research into cover crops and their influence on Nitrogen dynamics are critical to develop recommendations and increase adoption of these practices. To this end, we will investigate interseeding cover crops impact on nitrogen dynamics and nitrogen cycling in two different cropping rotations, continuous corn and corn-soybean-corn, with at least two nitrogen rates applied, all under irrigation system, compared with cropping systems that do not receive cover crops and remain fallow in the off-season from October to May. Previous research has investigated nitrogen cycling by adding cover cropping and different planting time but there still need demonstration and on-farm testing of these practices to strengthen recommendations. The novelty of our proposal is the focus on investigating nitrogen dynamics and cycling by adopting cover cropping in eight locations in Nebraska which will result on better recommendations for farmers by giving more details of how cash crop can improve nutrient efficiency and decreasing nitrogen losses. To accomplish this, our research and extension objectives include:Research Objective: To evaluate interseeded cover crops for decreasing nitrogen loss and to assess the impact of cover crops on nitrogen dynamics over the season.Extension Objective: To demonstrate cover crop interseeding technology and encourage farmers and stakeholder adoption of cover crop practices that improve nitrogen capture to limit losses.?This proposal addresses several priorities for the 2022 NIFA-AFRI Foundational and Applied Science Program, in the Critical Agriculture Research and Extension (CARE), which seeks projects that Focus on a clear, time-sensitive, stakeholder-identified need, Describe a meaningful approach for blending research and extension expertise... and implementation approaches throughout the project to address principal objectives, State expected solutions or improvements and how these will be assessed and measured and Explain how the project will strengthen agricultural and food-production systems and how results will be adopted or applied at a local, regional, or national level. This project addresses the need for improving environmental quality by strengthening knowledge on cover cropping and its impact on nitrogen dynamics which leads for improving cash crop nitrogen using efficiency and reducing nitrogen losses.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
0%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
11201991060100%
Knowledge Area
112 - Watershed Protection and Management;

Subject Of Investigation
0199 - Soil and land, general;

Field Of Science
1060 - Biology (whole systems);
Goals / Objectives
The overall goal of this proposed work is to encourage and motivate farmers by demonstrating cover crop interseeding technology and improving their knowledge of cover crops that will lead to improved nitrogen uptake efficiency and reducing losses, which will improve sustainable food production and water quality. To accomplish these goals, we propose the following objectives.Research Objective: To evaluate interseeded cover crops for decreasing nitrogen loss and to assess the impact of cover crops on nitrogen dynamics over the season. This objective will be accomplished via on-farm trials and in plots at research station which we will conduct over a three-year period, in both continuous corn and corn-soybean-corn rotation under irrigation system. Cover crop, corn and soybean plant biomass will be sampled, and soil sampling will be performed to assess nitrogen cycling and loss.Extension Objective: To demonstrate cover crop interseeding technology and encourage farmers and stakeholder adoption of cover crop practices that improve nitrogen capture to limit losses. This objective will be accomplished through cooperation with farmers, Nebraska Extension, Nebraska Natural Resource Districts, and USDA Natural Resources Conservation Service (NRCS) in hosting six local field day demonstrations each year to better understand the value of using of cover crops to reduce nitrogen losses.
Project Methods
Methods:Small plot research will be conducted at research stations to investigate the interaction of cover crops withdifferent nitrogen rates and evaluate crop efficiency while evaluating Nitrogen cycling anddynamics across the season. On-farm research and demonstration plantings will be conducted onsix farms across Nebraska adopting cover crops into continuous corn and corn-soybean-cornsystems.Research task 1.1: Conduct On-Farm DemonstrationsSix fields under irrigation will be selected for on-farm cover crop demonstrations. Three fields will be in a continuous corn system and three fields will be in a corn-soybean-corn rotation. These fields will be integrated into the Clean Water Act Section 319 funded demonstration project led by the PI.Cover crops will be interseeded at crop stage R5, using a high clearance broadcast interseeder. Seeding rate will be determined according to the cover crop seeding species mix and following USDA-NRCS seeding rates recommendations. The experimental design will be randomized complete block with five replications, two treatments. Proposed treatments for on-farm demonstrations are shown below.Figure 1. Treatment design for on-farm demonstrations and small plot research at research stationsResearch task 1.2: Conduct Small Plot Trials at UNL Research StationsWe will conduct small plot trial at two UNL research stations, which will be one trial located at West Central Research, Extension and Education Center (WCREEC - UNL) in North Platte, NE and at the Eastern Nebraska Research and Extension Center (ENREC - UNL) located near Mead, NE. The small plot trials will be conducted in continuous corn and corn-soybean-corn systems, all under irrigation management. The experimental design will be randomized complete block with five replications, with at least four treatments. Figure 1 above shows proposed treatments for small plots trial.1.2.ACover crop factor: The treatments that will receive cover crops will be Fall interseeded using the high clearance interseeder when corn and is at the R5 stage. The seeding rate will be defined according to method of planting and following recommendation from USDA for species selected.1.2.B Nitrogen rate factor: The treatments will receive at least two nitrogen rates.Research task 1.3: Data collection for soil organic and inorganic nitrogen and cover crop biomass sampling The following data will be collected to assess the impact of cover crops in a corn or corn-bean rotation cropping system impact nitrogen dynamics.1.3.ASoil sampling: Soil sampling will be performed on the six on-farm demonstration sites and at small plots located at UNL's research station, over three years, following the schedule below for a single year. Total N, nitrate, and ammonium will be assessed using Extraction method (Sparks et. al 1996), with the Nitrogen dynamics Soil Health Assessment.Continuous corn system: Spring sampling: one deep soil sampling before cash crop planting and fertilization will be performed on each foot, reaching four feet depth.Mid-season sampling: three soil sampling will be performed, being one soil sampling on each specific crop stage. Deep soil sampling will be performed on each foot reaching four feet depth.Fall sampling: one deep soil sampling after cash crop harvested will be performed on each foot reaching four feet depth.Corn-soybean-corn system: Spring sampling: one deep soil sampling before cash crop planting and fertilization will be performed on each foot, reaching four feet depth.Mid-season sampling: three soil sampling will be performed, being one soil sampling on each specific crop stage. Deep soil sampling will be performed on each foot reaching four feet depth. In the soybean rotation year, four soil sampling will performed on each specific crop stage. Fall sampling: one deep soil sampling after cash crop harvested will be performed on each foot reaching four feet depth.1.3.B Cover crop biomass: Aboveground biomass will be taken from cover crops to assess nitrogen content, biomass production and C:N ratio.Mid-season sampling:Above ground biomass by sensor to estimate cover crop production.Above ground cover crop sampling prior first frost killing to assess N content and C:N ratio.Prior to cover crop termination sampling(before cash crop planting):Above ground biomass by sensor to estimate cover crop production.Above ground cover crop sampling to assess N content and C:N ratio.Above ground biomass will be collected using scissors and one square feet frame to delineate area of sampling on each plot, for each treatment, five replications. Samples will be sent to commercial lab for analysis of weight, nitrogen content and C:N ratio.1.3.C Corn biomass: In the corn rotation year, above ground biomass will be taken from corn plants to assess nitrogen content and C:N ratio. This task will be performed together with soil sampling described above. Four plants will be collected from each plot, all treatments, five replications.Mid-season sampling: three corn sampling will be performed, being one sampling on each specific crop stage. In the reproductive stages, ear will be separated from the plant, and both will be analyzed apart, to get nitrogen content from both parts.Fall sampling:one corn residue sampling after cash crop harvested will be performed.Samples will be sent to commercial lab for analysis of weight, nitrogen content and C:N ratio.1.3.D Soybean biomass: On soybean rotation year, above ground biomass will be taken from soybean plants to assess nitrogen content and C:N ratio. This task will be performed together with soil sampling described above. Six plants will be collected from each plot, all treatments, five replications.Mid-season sampling: four soybean sampling will be performed, being one sampling oneach specific crop stage.Fall sampling: one soybean residue sampling after cash crop harvested will be performed.Samples will be sent to commercial lab for analysis of weight, nitrogen content and C:N ratio.1.3.E Data analysis: We will perform regression analysis on R-studio using the packages "dplyr", "broom", "ggpubr" and "ggplot2" to evaluate impact and estimate the relationships of cover crops on nitrogen cycling (soil nitrate, residual soil nitrate and ammonium) and crop yield throughout cash crop season between treatments, over three years study.

Progress 04/01/23 to 03/31/24

Outputs
Target Audience:Nebraska producers (farmers) interested in conservation management practices, especially cover crops were reached during the reporting period. Other stakeholders interested in the impact of cover crops on nitrogen and groundwater were also reached, including Nebraska Natural Resource Districts, Natural Resources Conservation Service, The Nature Conservancy, Rainwater Basin Joint Venture, and Nebraska Department of Environment and Energy. Changes/Problems: Ideally, this project would evaluate the nitrogen dynamics on continuous corn systems, however we were unable to find willing producers with this system to participate in the on-farm research and do not have this system available for researchat the research centers. The R5 interseeding of cover crops at one of the research station sites (ENREEC) came under significant grasshopper pressure during the fall of 2023. This resulted in a total cover crop failure at this site and no spring cover crop biomass for evaluation. What opportunities for training and professional development has the project provided? Six new Extension Educators have been engaged in this project. It has provided opportunities for mentorship, building relationships with local farmers, and training for on-farm research processes such as protocol development, data collection, and analysis. NRD staff has been trained through field days on use of the technology, planning, on-farm research data collection, and collaboration training with the University. NRCS, NRD, and TNC staff have been trained through field days on the use of the highboy cover crop interseeding technology. Undergraduate and graduate students have been trained on developing protocols and collecting data in partnership with farmers. How have the results been disseminated to communities of interest?Interim results have been disseminated to farmers, natural resources agency staff (NRCS, NRD, and TNC), students, and Extension Educators through field days. What do you plan to do during the next reporting period to accomplish the goals? Twelve field days will be conducted during the 2025 and 2026 seasons. Extension articles will be published in 2025 and 2026. Articles are intended to provide growers and interested stakeholders with and mid-project overview and an analysis of the success of interseeding cover crops late season. On-farm: data collection and analysis will be conducted in 2024, 2025 and 2026. All biomass samples will be analyzed for C:N. Deep soil samples will be collected to 6 feet before planting in spring 2024. Research: Spring biomass samples will be taken in April of 2024. Samples will be compared to fall sample results and future biomass results of the project. Additional research activities include: Conduct data analysis for soil and biomass sample data. Analyze all biomass samples will for C:N. Analyze water sampling data. Collect and analyze deep soil samples will be collected to 6 feet prior to planting. Data will be complied and presented at the American Society of Agronomy annual meeting and written for publication in a peer reviewed journal. This NIFA-sponsored study has provided the framework for additional student training. We expect that the on-farm trial farmers participating in the study will work with students and Extension Educators to conduct additional on-farm research and support student research.?

Impacts
What was accomplished under these goals? ?Extension Objective:To demonstrate cover crop interseeding technology and encourage farmers and stakeholder adoption of cover crop practices that improve nitrogen capture to limit losses.This objective will be accomplished through cooperation with farmers, Nebraska Extension, Nebraska Natural Resource Districts, and USDA Natural Resources Conservation Service (NRCS) in hosting six local field day demonstrations each year to better understand the value of using of cover crops to reduce nitrogen losses. Extension Objective Accomplishments Six field days were conducted during seeding of the on-farm trials. Forty-nine natural resources agencies representatives (NRCS, NRD, NDEE, TNC), 32 farmers, 15 ag retailers, and 22 high school students participants attended the six field days. Highboy cover crop interseeding demonstrations were completed on approximately 800 acres. Research Objective:To evaluate interseeded cover crops for decreasing nitrogen loss and to assess the impact of cover crops on nitrogen dynamics over the season.This objective will be accomplished via on-farm trials and in plots at research station which we will conduct over a three-year period, in both continuous corn and corn-soybean-corn rotation under irrigation system. Cover crop, corn and soybean plant biomass will be sampled, and soil sampling will be performed to assess nitrogen cycling and loss. Research Objective Accomplishments On-farm trials Six producers and fields were identified for partnership in on-farm trials. Fields were planted and managed per the farmer's standard operating procedures. Cover crops were interseeded with one of two different seeding mixtures: cereal rye or a cereal rye, turnip, rapeseed mix. Each of the on-farm trials were established to compare high clearance interseeding of cover crops with one or more alternative systems. This includes cover crops drilled after harvest, no cover crop, and variable seeding rates with the high clearance machine.Baseline soil samples were collected at the time of interseeding.Soil samples were collected.Cover Crop biomass samples were collected and stand counts were taken before harvest.Corn biomass was collected before harvest.Deep soil samples were collected to 6 feet after harvest in fall 2023. Preliminary data entry and analysis of the on-farm sites has begun. Field Plots Field plots were established at two research stations: the Eastern Nebraska Research, Extension and Education Center (ENREEC) at Mead, Nebraska at the West Central Research, Extension and Education Center (WCREEC) at Brule, Nebraska. Cover crop planting timings were compared at each research site to evaluate nitrogen loss and nitrogen dynamics over the season. The following actions were taken at each of the research stations. Corn was planted. Four nitrogen treatments were applied. Lysimeters were installed. Baseline soil samples were takin in the spring of 2023. Soil was sampled three times during the 2023 corn growing season (2 foot depth) and after harvest, in fall 2023 (6 foot depth). Corn biomass samples were taken twice during the 2023 corn growing season and at harvest, in fall 2023. Cover crop biomass samples were taken in fall 2023. The data collected from soil and biomass sampling has been entered into a spreadsheet. Preliminary analysis of data has begun. Water samples were collected from the lysimeters at each site following irrigation and rain events. Samples were analyzed at an external laboratory. Soil moisture sensors were installed and monitored during the growing season.

Publications