Relationship between greenhouse gas emissions and changes in soil gas diffusivity in a field experiment with biochar and lime

Sammanfattning

Reducing greenhouse gas emissions from arable soil while maintaining productivity is a major challenge for agriculture. Biochar is known to reduce N2O emissions from soil, but the underlying mechanisms are unclear. This study examined the impact of green waste biochar (20 Mg ha(-1)) and lime (CaCO3; 2 Mg ha(-1)) application on soil gas transport properties and related changes in these to soil N2O and CO2 emissions measured using automated chambers in a field experiment cropped with maize. In situ soil water content monitoring was combined with laboratory measurements of relative soil gas diffusion coefficient (D-p/D-0) at different matric potentials, to determine changes in D-p/D-0 over time. Cumulative N2O emissions were similar in the control and lime treatment, but much lower in the biochar treatment. Cumulative CO2 emissions decreased in the order: lime treatment > biochar treatment > control soil. When N2O emissions were not driven by excess N supply shortly after fertilisation, they were associated with D-p/D-0 changes, whereby decreases in D-p/D-0 corresponded to N2O emissions peaks. No distinct pattern was observed between CO2 emissions and D-p/D-0. Cumulative N2O emissions were positively related to number of days with D-p/D-0 < 0.02, a critical limit for soil aeration. These results indicate that improved soil gas diffusivity, and hence improved soil aeration, may explain the effect of biochar in reducing N2O emissions. They also suggest that knowledge of D-p/D-0 changes may be key to explaining N2O emissions.

Nyckelord

soil aeration; soil gas emissions; soil gas transport; soil structure; soil water content

Publicerad i

Journal of Plant Nutrition and Soil Science
2019, volym: 182, nummer: 4, sidor: 667-675
Utgivare: WILEY-V C H VERLAG GMBH

SLU författare

• Keller, Thomas

  • Institutionen för mark och miljö, Sveriges lantbruksuniversitet
    
  • Agroscope

Globala målen (SDG)

SDG15 Ekosystem och biologisk mångfald

UKÄ forskningsämne

Folkhälsovetenskap, global hälsa, socialmedicin och epidemiologi

Publikationens identifierare

• DOI: https://doi.org/10.1002/jpln.201800538

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/101259