Student Research: Monitoring Agricultural Greenhouse Gas Emissions

Update on Agricultural Season Extension with High Tunnels: a Greenhouse Gas Source or Sink?

Tessa's research evaluating the differences between greenhouse gas emission in high tunnels and agricultural fields is continuing into the fall and winter seasons. The tomato crops have been pulled out of the ground and the soil has been plowed. Even without crops, it's still important to know what's happening below-ground by measuring the carbon dioxide (CO₂) and nitrous oxide (N₂O) emissions that result.

Because the soil has been disturbed and the rows of crops removed, she's trying a new approach to measuring these trace gas emissions:

Sampling trace gas emissions using a "portable flux chamber" (an upside down cooking pot) as an alternative to semi-permanent plastic collars that were used during the growing season. This method may allow for an improved snapshot of greenhouse gasses emitted from agricultural soils, especially because it is more adaptable for sampling around typical agricultural management practices.  

The portable flux chamber in the traditional high tunnel. UNH's new moveable high tunnel and several low tunnels are in the background. 

Student Research: Monitoring Agricultural Greenhouse Gas Emissions

Agricultural Season Extension with High Tunnels: a Greenhouse Gas Source or Sink?

New England is undergoing dramatic agricultural changes - we are expanding and intensifying production to meet increasing food demands. These changes have important consequences for our agricultural ecosystems, and Tessa's research aims to describe the potential atmospheric effects of agricultural intensification through high tunnels. 

A high tunnel planted with tomatoes at UNH's Woodman Farm.

Many farmers in the Northeast are growing crops under high tunnels as a means to extend their growing season and protect their crops from inclement weather (see NRCS's High Tunnel Initiative).  By growing crops under these plastic covered metal structures, farmers can grow high-value specialty crops, and protect their crops from frost, temperature fluctuations, excess precipitation, pests and disease. While this form of plasticulture is widely used, little is known about the environmental impacts of such practices. 

To address this question, Tessa is measuring carbon dioxide (CO₂) and nitrous oxide (N₂O) emissions (trace gasses) from soils under high tunnel management and comparing these data to trace gas emissions from the same crop planted in an adjacent field. These data will provide insight into the effects of increased high tunnel production on climate change and strategies for mitigating these effects.

Gas samples are taken simultaneously from tomato interrows and rows in the field. 

Tessa, extracting and storing a gas sample. 

Research Assistant Matt Morris measuring soil moisture.
Soil moisture is an important driver of trace gas production and is sampled each week.