Non Technical Summary
Measurement of greenhouse gas (GHG) fluxes is essential for verifying the effectiveness of "climate-smart" farming practices intended to reduce GHG emissions or promote long-term storage of carbon in soils. Comprehensive measurement of GHG fluxes from fields is not currently possible. There is an opportunity to market a low-cost, automated device for monitoring GHG fluxes across fields by collecting gas samples for off-field analysis. The overall project goal is to increase the technical readiness of a prototype robotic chamber for monitoring GHG fluxes from soil surfaces between rows of a crop like corn. The supporting objectives are: (a) redesign the autosampler and chamber; (b) develop a more robust solution for automatically opening and closing the chamber periodically; (c) test performance compared to existing research flux chambers; (d) test performance over 24-hr periods of operation. Testing will be carried out on a nitrogen fertilizer experiment at a research site near St. Paul, MN. A final round of prototyping will be conducted to develop an improved design that would be used in a Phase II project. The proposed Phase I project is directly relevant to USDA's strategic goal of combatting climate change, because actions cannot be taken to alter GHG fluxes without first measuring them.

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
141	0110	2020	100%

Knowledge Area
141 - Air Resource Protection and Management;

Subject Of Investigation
0110 - Soil;

Field Of Science
2020 - Engineering;

Goals / Objectives
Major Goal of Project: Develop and test a low-cost, automated system (FluxBot) for measuring fluxes of greenhouse gases (GHGs) on crop fields.Technical Objective 1: Redesign Autosampler. The novel design of the FluxBot leverages an autosampling system contained within a rigid chamber installed over a patch of soil in a crop field. Prior to the start of the project, a V2 design of the autosampler (syringe pump) system will be completed and tested. Over the first two months of the project, a final V3 design will be completed based on testing of V2. The final design will be used in Technical Objective 5.Technical Objective 2: Redesign Chamber Movement. It is necessary for the FluxBot chamber to be periodically opened such that the soil surface can be exposed to the atmosphere. This opening and subsequent closing for sampling needs to be automated and carried out such that interference from the crop does not occur. A V2 concept for chamber movement will be developed prior to the start of the project and a V3 concept will be developed and tested over the first two months of the project. The final design will be used in Technical Objective 5.Technical Objective 3: Redesign Chamber Base. Conventional chambers rely on bases that are installed semi-permanently in the soil and on which the chamber seals. The bases need to be lighter weight than the V1 design while also providing rigidity and a flat mating surface for the chamber. A V2 design will be completed prior to the start of the project and a V3 design will be refined and tested during the first two months of the project. The final design will be used in Technical Objective 5.Technical Objective 4: Redesign Chamber. The V1 chamber proved to be unnecessarily tall, which led to a large inside chamber volume. This may create stratification of trace gasses inside the chamber; it also makes for a cumbersome chamber to move. Pending advancement of Technical Objective 1, a new chamber (V2) will be designed prior to the start of the project and refined (V3) during the first two months of the project. The redesign will include attention to the packaging of electronics in a manner that is durable and capable of withstanding exposure to moisture. The final design will be used in Technical Objective 5.Technical Objective 5: Produce Updated Full System. Over the first two months of the project five V3 complete systems will be produced, with preliminary "shake out" testing extending into the third month. There will be ongoing software improvements made over the course of the first six months of the project. As shortcomings of the V3 design are revealed, a V4 design will be completed primarily during months three and four in preparation for a Phase II project.Technical Objective 6: Develop Automation Features. There are several features that will facilitate deployments of the FluxBot system in the future. It is necessary to estimate the volume of air contained within the bases that are semi-permanently installed in the soil. Over the first four months of the project methods for estimating this volume using smartphone images will be tested. Longer-term deployments would benefit from solar charging of the FluxBot's onboard battery, and sizing of such a system will be carried out during months four to seven in parallel with the V4 design for Phase II.Technical Objective 7: Test FluxBot v. Conventional Chambers. Testing and evaluation of the FluxBot automated chamber compared to conventional chambers will be performed weekly on a test field at the Rosemount Research and Outreach Center (RROC) that is part of the University of Minnesota. The test field will be prepared with low, medium, and high nitrogen fertilizer application zones during months one and two of the project. Testing is expected to be conducted twice weekly over months three to seven.Technical Objective 8: Evaluate Impact of Circulation in Chamber. Depending on the volume of the final V3 chamber resulting from Technical Objective 4, there may be a benefit to using a fan to gently mix air in the chamber prior to sampling events. Testing over months one and two will be carried out so that circulation, if necessary, can be implemented for most of the testing described in Technical Objective 7.Technical Objective 9: Test FluxBot Movement Automation. Apart from testing the automated chamber function compared to conventional chambers (Technical Objective 7), testing of the automated opening and closing design (Technical Objective 2) will be carried out during months three through five. This testing will inform the V4 design (Technical Objective 5) for a Phase II project.Technical Objective 10: Test FluxBot 24-hr Sample Collection. A virtue of the FluxBot design is that fully-automated sampling can be carried out over extended periods of time. During months three through five, side-by-side testing will be carried out comparing a FluxBot that is manually opened and closed to one that has automated movement (opening and closing).

Project Methods
The methods of the project fall into two broad categories: protype development and validation of prototype operation during field studies.Typical engineering design methods will be used for prototype development. Three-dimensional design software (SolidWorks) will be used by the mechatronics engineer to develop and prepare concepts for fabrication. Periodic design reviews with the project PI and an outside consultant employed by partner Carnegie Robotics will be used to help guide design outcomes based on in-depth experience in mechanical design and operating robotic equipment on crop fields. Fabrication will be carried out using a 3D printer and by a collaborating company (Agri-Fab Inc.) that specializes in metal fabrication. Assembly of FluxBot systems will occur in the company facilities.Field trials will be established using typical methods used by agronomists and crop scientists. Replicated strip trials will be established on a research field providing a range of amounts of applied nitrogen fertilizer--a key nutrient tied to the emissions of nitrous oxide, a potent greenhouse gas (GHG). FluxBot chambers will be installed at various locations across the test field in order to provide a range of expected GHG fluxes. Trace gasses will be collected using established methods utilized by the cooperating USDA Agricultural Research Service (ARS) lab in Saint Paul, MN. Further, gas vials will be prepared under contract with the ARS lab , and they will be analyzed using a research-grade gas chromatograph in the ARS lab.Evaluation of FluxBot chamber performance will be carried out by comparing estimated GHG fluxes to those of conventional chambers. In other cases, GHG fluxes captured in chambers utilizing an automated opening and closing system will be compared to other chambers manually opened and closed by a field technician.