World Soil Day

05 December 2019

5 December 2019

The condition of the world’s soils is an important consideration if the needs of a growing population are to be met. According to the Food and Agriculture Organisation of the United Nations; one third of our global soils are already degraded. In addition soils have a role to play in helping manage climate change. Today is World Soil Day; here we look as some of the research being done to help us better understand this important resource.

Muriel Cozier

Irrigation is an important factor in regulating the emission of CO2 from soil. Winter wheat is one of China’s main crops, accounting for about 30% of the total planted area of grains.  Studies of soil CO2 emissions from this crop are therefore of national and global significance for estimating greenhouse gas emissions.  The main process for soil CO2 emissions are recognised as crop root respiration and soil microbial respiration.

Research published in the Journal of Science Food and Agriculture, indicates that deficit irrigation, water saving irrigation technology, reduces the CO2 flux by 10.2-25.5% when compared with fully irrigated wheat fields in China. Researchers found that the greater the degree of water deficit, the greater the reduction on soil CO2 emissions. However deficit irrigation could decrease winter wheat yields.

Researchers concluded that their work laid preliminary theoretical foundations for formulating water saving, emission-reducing and high yield winter wheat irrigation system.

Further research, also published in the Journal of Science Food and Agriculture, indicated that plant residues from pruning, which were subsequently left in the field as a potential source of organic matter, led to increased CO2 emissions from the soil to the atmosphere. Researchers looking at the cultivation of tea bushes found that pruning the green canopy stopped the flux of CO2 from the atmosphere to the tea plantation, recording negative values. The negative flux was attributed to the emission of CO2 due to microbial respiration in the soil. Researchers determined the reduction in CO2 flux from the atmosphere to the tea ecosystem to be approximately 22%. The extent of the decrease was dependent on the canopy size of the tea bush and the amount of pruning litter incorporated into the soil.


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