Cover Crops and Cropping System Sustainability in a Changing Global Climate

This Research and Education Grant project was awarded a 2022 James Harrison Hill, Sr. Young Scholar Enhancement Grant award in the amount of $3,872. The award provides high school and undergraduate college students the opportunity to conduct sustainable agriculture research, as part of an existing Research and Education Grant project.

View the project final report

Commodities

Practices

• Crop Production: cover crops, cropping systems
• Soil Management: soil quality/health

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 thermal 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 field 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 were also collected and analyzed for the aforementioned properties. Results showed that volumetric heat capacity was 13% higher under cover crop, compared with no cover crop management. As a result of higher bulk density, no cover crop management had 21% higher thermal conductivity, and 35% higher thermal diffusivity compared with cover crop management. This suggests that cover crops may be able to resist extreme soil temperature changes and this could lead to improved soil health and crop productivity under this cropping system. Water infiltration measurements were also made just prior to cover crop termination (during April) and again two months after termination (during June). Results showed that cumulative infiltration after 2 hrs was 52% higher in April and 68% higher in June under cover crop compared with no cover crop management. Further, in situ measured saturated hydraulic conductivity was numerically higher under cover crop compared with no cover crop management. These results show that cover crops can reduce surface runoff and soil loss while increasing water infiltration and storage, and this can improve crop productivity. Research efforts have resulted in 2 published manuscripts, and 1 manuscript in production. Nine undergraduate students were involved during the second year as undergraduate research assistants. Seven of those students are also co-authors on one of the manuscripts that resulted from this research. Outreach activities were carried out in Tennessee and Kentucky during the second year. In Tennessee, over 500 high school students participated in a day-long activity which introduced them to the various aspects of this research, including the benefits of cover crops. In Kentucky, several education efforts were included in several extension publications that have been made available to over 200 recipients. During the third year, we plan to hold several outreach activities in Tennessee, Kentucky, and Alabama. We will also conduct further research on crop yield, in situ water content under cover crop management, and soil hydraulic properties. Results will be published in scientific journals.

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.