Effect of Climate-Smart Practices on Soil CO2 Emissions from Grain Sorghum Cropping Systems in South
Board Location: #145
Discipline: Ecology Environmental and Earth Sciences
Subcategory: environmental science
Session: 1
Malani Clark - Cooperative Agricultural Research Center Prairie View A&M University
Co-Author(s): Ali Fares, Ripendra Awal, Anoop Valiya Veettil, and Atikur Rahman
Agriculture contributes significantly to global warming, accounting for approximately 10–12% of global anthropogenic greenhouse gas (GHG) emissions. Effective management practices, such as organic amendment applications (e.g., dairy manure, chicken manure, biochar), are critical components of Climate Smart Agriculture (CSA) strategies that can alter GHG emissions while maintaining adequate crop yields. However, the nexus between organic amendment applications and reductions in soil GHG emissions remains poorly established and is influenced by pedo-climatic conditions, substrate composition, and management practices. This study hypothesizes that organic amendment type and rate significantly impact soil CO2 emissions, with higher manure rates expected to emit more CO2 than biochar due to differences in organic carbon content and decomposition rates. Biochar is hypothesized to mitigate CO2 emissions at higher rates because it stabilizes soil organic carbon.
To test this hypothesis, a randomized block field experiment was conducted at the Prairie View A&M University Research Farm. Treatments consisted of two rates of biochar (2.5 and 5 t ha⁻¹), two types of organic manure (chicken and dairy manure), and three nitrogen application rates (0, 180, and 360 kg total N ha⁻¹) under the sorghum cropping system. Soil CO2 emissions were measured using an automated CO2 measuring device, and the data were analyzed using Analysis of Variance (ANOVA) and Tukey Mean Separation tests.
The results revealed that higher manure rates significantly increased soil CO2 emissions, with chicken manure emitting more CO2 than dairy manure at equivalent rates. Biochar amendments, particularly at the higher rate of 5 t ha⁻¹, were found to reduce CO2 emissions relative to manure treatments, supporting its potential as a climate-smart amendment. These findings highlight the importance of amendment selection and application rate in mitigating GHG emissions in agricultural systems. This study underscores the potential of biochar as a mitigation strategy to reduce soil CO2 emissions while maintaining crop productivity. Future research should explore the long-term impacts of these amendments on soil carbon sequestration and their scalability under diverse pedo-climatic conditions.
Funder Acknowledgement(s): The National Science Foundation (NSF) Award # 1828974 and USDA (Evans-Allen project 1021753)
Faculty Advisor: Ali Fares, alfares@pvamu.edu
Role: I collected soil CO2 emissions from each organically amended plot during the growing seasons. The data was collected two times a week using an LI-8100A (LI-COR Biosciences, Lincoln, NE) survey system. In addition, I was also engaged in plot design, seeding, irrigation, and organic amendment management. I collected soil samples before sowing and after harvesting the biomass. The soil chemical analysis was performed using CHNS and ICP machines at the departmental core lab. Finally, I completed data extraction from the Li-COR machine and performed soil CO2 data analysis, including ANOVA and Tukey test, using RStudio statistical software.