Health & Environment

A ‘Gold Standard’ Assessment Of Greenhouse Gas Emissions In Sorghum Fields

A U.S. Department of Energy-funded collaborative project will allow Texas A&M AgriLife researchers to measure greenhouse gas emissions from agricultural fields in the Southern Great Plains.
By Kay Ledbetter, Texas A&M AgriLife Communications June 22, 2020

a man standing in a field with equipment used to take measurements
Walker Crane, a member of Nithya Rajan’s team, measures nitrous oxide measurements from a young sorghum field.

Texas A&M AgriLife


Greenhouse gas emissions from sorghum fields in the Texas High Plains will be the focus of a Texas A&M AgriLife Research study funded by a U.S. Department of Energy grant through the Advanced Research Projects Agency-Energy, ARPA-E.

This $3.1 million collaborative project led by Oklahoma State University is funded through ARPA-E’s Systems for Monitoring and Analytics for Renewable Transportation Fuels from Agricultural Resources and Management, or SMARTFARM, program. About one-third of the grant will be used in Texas by Nithya Rajan, crop physiology and agroecology associate professor, who is the lead investigator for AgriLife Research on this project.

Rajan will be joined by Ronnie Schnell, Texas A&M AgriLife Extension Service cropping systems specialist for sorghum. Both are in Texas A&M University’s Department of Soil and Crop Sciences in College Station.

“We are excited about this multi-state SMARTFARM project,” said David Baltensperger, head of the Department of Soil and Crop Sciences. “This project strengthens our ties with Texas sorghum producers and supports the goal of sorghum production in an environmentally friendly manner.”

Goals of measuring greenhouse gas emissions

The SMARTFARM program’s objective is to bridge the data gap in the biofuel supply chain by funding technologies that can quantify feedstock-related emissions at the field level and enable new market incentives for efficiency.

Rajan said the ARPA-E project will use current technology and sensor networks to continuously quantify field-level emissions for major greenhouse gases. This is expected to provide a “gold standard” assessment of emissions from bioenergy feedstocks in the Southern Great Plains.

graph with plotted points showing relationship between fertilzier application and nitrous oxide
Associate professor Nithya Rajan has plotted the relationship between nitrous oxide emissions and fertilizer application.

Texas A&M AgriLife


“With any agriculture production field, greenhouse gas emission is inevitable — typically carbon dioxide and nitrous oxide — and that increases with the application of fertilizer, manure and other management practices,” she said. “Nitrous oxide is a powerful greenhouse gas that can stay in the atmosphere for several decades and can cause environmental issues.”

Rajan’s current research shows that there is a daily pattern associated with nitrous oxide emissions in agricultural fields. Emissions usually happen after fertilizer application and rainfall, but such frequent measurements are rarely made by scientists in production conditions due to the cost of equipment needed for continuous monitoring.

Carbon source or sink

Agricultural fields also sequester carbon. Tracking both carbon sequestration and greenhouse gas emissions simultaneously is necessary to understand if the field is a carbon source or a sink, as greenhouse gas emissions are usually expressed in carbon dioxide equivalents.

Schnell said sorghum production systems in the Southern Great Plains have an opportunity to contribute sustainable energy production in the U.S. Production environments, and water use and common management practices have the potential to lower greenhouse gas emissions.

Rajan said the team is concentrating on grain sorghum initially, because Texas, Kansas and Oklahoma are three of the nation’s main sorghum-producing states. According to the U.S. Department of Agriculture’s National Agricultural Statistics Service, about 5 million acres of grain sorghum were planted nationwide.

Grain sorghum acreage is beginning to replace some corn acreage in the Texas Panhandle because of its water efficiency, she said. The Texas portion of the project is designed to take measurements of greenhouse gases, especially carbon dioxide and nitrous oxide, at an 85-acre commercial production field, continuously using the state-of-the-art instrumentation and methodologies. Schnell will assist with spatial measurements of soil water, nutrient, and crop growth at the site.

Gold standard greenhouse gas emissions data set

“This is the first time anyone is trying to do it at this scale,” Rajan said. “We are using a farmer’s field in the Panhandle area. We will be setting up a lot of equipment to make these measurements.”

She said the equipment will allow researchers to take greenhouse gas measurements continuously from the sorghum field. Additionally, soil temperature and moisture sensors will be installed on each sub-acre of the 85-acre field. Soil and plant samples will also be collected from each acre.

The end goal is to build a ‘gold standard’ data set. The data set then will be available for all researchers studying the life cycle analysis and modeling of greenhouse gas emissions.

The project will begin in October and continue for three years. While the data gathering will be automated and managed through the internet, Rajan said project participants will make frequent visits to the site for installation, equipment maintenance, and plant and soil sample collection. This is only one of Rajan’s projects with sorghum.

Gopal Kakani from Oklahoma State University is the lead principal investigator of this three-state project. Other team members are: Oklahoma State University researchers Jason Warren, Saleh Taghvaeian, Paul Weckler and Ning Wang; and Kansas State University researchers Peter Tomlinson, Eduardo Alvarez Santos and Lucas Haag.

This article by Kay Ledbetter originally appeared on AgriLife Today.

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