Progress report for LS20-335

Cover Crops and Cropping System Sustainability in a Changing Global Climate

Project Type: Research and Education
Funds awarded in 2020: $299,995.00
Projected End Date: 03/31/2023
Grant Recipients: Middle Tennessee State University; University of Kentucky; Auburn University
Region: Southern
State: Tennessee
Principal Investigator:
Dr. Samuel Haruna
Middle Tennessee State University
Co-Investigators:
Dr. Song Cui
Middle Tennessee State University
Dr. Audrey Gamble
Auburn University
Dr. Seockmo Ku
Middle Tennessee State University
Dr. Chaney Mosley
Middle Tennessee State University
Dr. Edwin Ritchey
University of Kentucky
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Project Information

Abstract:

Improving crop productivity and cropping systems resilience in a changing global climate is a big challenge for governments, scientists and producers around the world. The challenge is exacerbated, due to the predicted 17% human population increase and 0.7 – 1.8°C temperature increase by 2050. Rising temperatures may affect the soil ecosystem services, crop productivity and agricultural and environmental sustainability. Therefore, it is important to identify soil and crop management practices that are more adaptive to a changing climate. The adoption of cover crops has been encouraged, through various agricultural policies, due to their benefits in enhancing soil quality and health, crop productivity and environmental sustainability. The goal of this project is to evaluate the influence of cover crops on in situ soil thermal properties and how these may influence crop productivity and agricultural resilience in a changing climate. Both the TP01 soil thermal properties sensors and HFP01 heat flux plates were installed in plots planted to cover crops and plots with no cover crops on two farmer fields in Middle Tennessee for in situ measurement of thermal conductivity and heat capacity. Soil temperature and water content sensors were also installed on these fields after cover crops were planted. Soil samples were collected from each plot (in both fields) right after cover crops were planted for the baseline analysis of soil bulk density, water retention, saturated hydraulic conductivity, pore size distribution, soil nitrate, organic carbon, soil pH and microbial biomass. A week before the termination of cover crops, soil samples will be collected and analyzed for the aforementioned properties. Corn will be planted during May on both cover crop and no cover crop plots. Plant growth parameters and soil samples will be measured and collected during the growing season. The various samples will be analyzed to understand the impact of cover crops on soil ecosystem, crop yield and soil resilience in a changing climate. Results will be published in peer-reviewed scientific journals. Due to the COVID-19 pandemic and public health regulations, outreach activities were suspended during this first year. However, the farmer cooperators have been involved in site selection, soil sampling and agronomic advice. Further, several students are gaining hands-on research experience at the research sites.

Project Objectives:
  1. Investigate the interaction between cover crops and soil health indicators (bulk density, soil pH, soil organic carbon, soil water content, soil water infiltration) on in situ measured soil thermal properties (thermal conductivity, volume-specific heat capacity, thermal diffusivity) (farmers will be involved with sensor installation and soil sample collection). Learning Outcome: participating farmers learn the philosophies behind soil sample collection for scientific and agronomic purposes and the mechanisms through which cover crops may help buffer against extreme soil temperature change. Action Outcome: Growers increase cover crop use to improve soil health and buffer against extreme soil temperature change,
  2. Assess the role of cover crops and in situ measured soil thermal properties on microbial (gram (+) bacteria, gram (-) bacteria, arbuscular mycorrhizae, actinomycetes, rhizobia, and protozoa) population and activity and on greenhouse gas (CO2, CH4, N2O) emissions with the help of farmers. Learning Outcome: 7 researchers, farmers and educators learn to optimize microbial activity and reduce greenhouse gas emissions through cover crop usage. Action Outcome: Researchers and educators develop guidelines on incorporating cover crops for reduced greenhouse gas emissions,
  3. Evaluate the interaction between cover crops, soil thermal properties, microbial activity and crop yield (farmers will be trained on the use of UAS for yield monitoring). Learning Outcome: 20 farmers learn to use UAS for crop yield monitoring. Action Outcome: 10 farmers integrate technology for yield monitoring.
  4. Educate local producers on benefits of using cover crops to improve productivity and enhance cropping systems resilience. Disseminate research findings, with farmer input, through training and extension services. Learning outcome: 60 farmers in 3 states (Tennessee, Alabama, and Kentucky) learn to improve crop productivity through proper management of cover crops. Action Outcome: Educators organize farmer-led field days and distribute recommendations on climate-conscious cover cropping for improved productivity and environmental resilience.

Cooperators

Click linked name(s) to expand
  • Adam Daugherty - Technical Advisor (Educator)
  • Adam Daugherty - Technical Advisor (Educator)
  • Chris Hancock - Technical Advisor (Educator)
  • Chris Hancock - Technical Advisor (Educator)
  • Will Hutchinson - Producer
  • Sammy Morton - Producer
  • Jackie Reed - Technical Advisor (Educator)
  • Jackie Reed - Technical Advisor (Educator)
  • Jamie Weaver - Producer

Research

Materials and methods:

The research fields are located in Rutherford County and Coffee County, both in Tennessee. The fields are laid out in a randomized complete block design with two treatments (cover crop vs. no cover crop) and three replicates of each. 

The soils at both fields are classified as Fragiudults with particle size analysis currently underway to determine the exact soil texture on both fields. During November-December 2020, soil samples were collected from each plot at 6 cm depth increments from the soil surface down to a depth of 30 cm to determine baseline soil physical and hydraulic properties. These properties include soil bulk density (core method), saturated hydraulic conductivity (constant and falling head methods), water retention (at 0, -0.4, -1.0, -2.5, -5.0, -10.0, -20.0, -33.0, -100.0, -300.0, and -1500.0 kPa soil water matric potentials using pressure plate apparatus), thermal properties (thermal conductivity, heat capacity, and thermal diffusivity using a KD2 Pro in the laboratory) at the various soil water potentials, and pore size distributions (using the capillary rise equation from soil water retention data). Additional soil samples were collected from the aforementioned soil depths for the determination of baseline microbial community structure using the phospholipids fatty acid analysis. These various analyses are currently on-going. In addition, just before the cover crops are terminated, soil samples will be collected again and these soil properties will be analyzed. This will enable researchers, farmer collaborators, and students assess the influence of cover crops on these properties.

Further, during November and December 2020, The TP01 thermal properties sensors and HFP01 heat flux sensors were buried in each field at 5 cm depth and connected to data loggers. The sensors are able to take measurements every 6 hours and the dataloggers average these measurements over a 24-hour period to generate an average daily in situ soil thermal property measurement. In addition, three watermark sensors were buried in each plot at 0-10, 10-20, and 20-30 cm depths. Soil temperature sensors were also buried at these depths. Both sensor types take water energy and temperature measurements every hour. These sensors are linked in a mesh at each location and connected to the internet through cellular gateways. The watermark sensor measures soil water energy (rather than soil water content) and the choice of these sensors adds uniqueness to the data being generated (most literature report on water content). However, if needed, soil water content can be calculated from these measurements using the van Genuchten equation and soil water characteristics curve.

Other measurements that will be collected in the future include cash crop yield data. Yield data will be collected after the cover crops have been terminated and the cash crops planted. They will be collected throughout the growing season. Crop yield and vigor, at various stages of crop growth will be measured using a vegetation index derived from UAS imagery. This will also provide a learning opportunity for collaborating farmers. We are also currently calibrating the Gasmet DX4040 portable gas analyzer for field measurement of greenhouse gases.

Research results and discussion:

Currently, none of the results are conclusive (since the cover crops are still growing during this first year). However, analysis of the baseline properties shows, as expected, no significant differences in the soil physical and hydraulic properties measured between cover crops and no cover crop management. On the average, current water energy measurement shows that soil matric potential tends to be slightly lower in cover crop plots compared with no cover crop plots probably due to reduced evaporation. As the soils warm up in the coming weeks and months, it will be interesting to see soil water energy dynamic between these management practices. We will continue to analyze our results and we hope to have some manuscripts ready for peer-review in the coming months.

Participation Summary
3 Farmers participating in research

Educational & Outreach Activities

2 Curricula, factsheets or educational tools
2 Currently, four undergraduate students are working on various parts of the project for their independent/capstone project. These students have been involved in soil sample collection and are able to analyze some of the preliminary data and are writing a report based on this analysis.

Participation Summary

2 Ag professionals participated
Education/outreach description:

During the first year of this project, 2 classes have been modified to include activities in this project these classes include Soil Physical Properties (PLSO 4730) and Soil Fertility and Fertilizers (PLSO 3350), both at Middle Tennessee State University. Preliminary results have been used as teaching examples and field sites have been used for hands-on experience in these classes. Due to the COVID-19 pandemic and the public health requirements, we did not engage in any outreach activity during this first year. During the second and third years of this grant, we will conduct seminars and field demonstration for farmers, students and citizens in the collaborating states (Tennessee, Kentucky, and Alabama).

Learning Outcomes

3 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation

Project Outcomes

1 New working collaboration
Project outcomes:

Currently, working collaboration is being developed with researchers at the University of Missouri to enhance the capacity of researchers in analyzing soil microbial activity. Another collaboration has been developed with an extension educator at the University of Tennessee on ways to improve farmer participation in scientific research. These new collaborations will be beneficial to producers in Tennessee and Missouri

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.