Development of a soil gas analysis device using IR for a profile method

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K05888
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 41030:Rural environmental engineering and planning-related
• Research Institution: University of the Ryukyus
• Principal Investigator: SAKAI KAZUHITO 琉球大学, 農学部, 教授 (10253949)
• Co-Investigator(Kenkyū-buntansha): 平良 英三 琉球大学, 農学部, 教授 (20433097) ; 仲村渠 将 琉球大学, 農学部, 准教授 (70537555)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 亜酸化窒素 / 土壌ガス / NDIR / 透過性チューブ

Outline of Final Research Achievements

In this study, we developed a device to measure N2O concentration using NDIR. Then, we measured the N2O concentration in soil gas using the device. Moreover, we tried to estimate the amount of N2O flux from the soil. As a result, (1) The N2O concentration in the soil gas was about 1,000 times of it of the atmosphere. Therefore, it was confirmed that the device can be used to measure the N2O cinsentration in the soil gas. (2) We measured N2O flux from the soil using a closed chamber method, and at the same time, we measured the N2O concentration in the soil gas. By solving the one-dimensional diffusion equation using the observed N2O concentration in the soil gas, the N2O flux could be estimated. Though an outburst of N2O soon after irrigation could not be simulated, it was confirmed that the N2O flux in the normal time could be simulated using the device and the analysis method in this study.

Free Research Field

農業土木学

Academic Significance and Societal Importance of the Research Achievements

パリ協定では先進国だけでなく発展途上国でも温室効果ガス(GHG)削減が義務付けられている。発展途上国における農業からのGHG排出量は30%程度と言われているが、地域によって違うGHG排出係数が特定されていないため明確ではない。その原因として農地から排出される主なGHGであるN2Oは大気中での濃度が低く測定コストがかかるため実測例が少ないことが挙げられる。本研究で試作したNDIRガス分析装置およびそれを用いた測定手法を用いれば低コストでN2O排出量の測定が可能であり、今後発展途上国を含む様々な国での農地からのN2O排出量のモニタリングが可能となる。