Biochar can mitigate the environmental impacts of agriculture

A new study carried out at the University of Helsinki shows biochar can be a promising tool in mitigating the environmental impacts of agriculture also in Finland, as written by the university in a press release.

In his doctoral study,  Subin Kalu found that biochar addition to soil can reduce nitrogen leaching from agricultural soils to waterways, and reduce the emissions of N₂O – a potent greenhouse gas. 

Biochar boosts nutrients retention

The high specific surface area and porous structure of biochar can improve the retention of soil water and nutrients in the soil, and thus their availability to crops. Biochar can also alter the physical, chemical, and biological properties of soils which could eventually reduce greenhouse gas emissions and nutrient leaching. Whether these beneficial effects after a single application of biochar persist for the long-term, especially in boreal climates, has remained unknown so far.

“It is also essential to find out the long-term effects of biochar before its widespread application to soils, to detect if biochar would have any detrimental effects because it is not possible to remove it once it has been applied to the soil,” says Kalu.  

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Enhancing soil carbon storage

Kalu studied the long-term effects of biochars in four different agricultural field experiments in southern Finland where biochars had been applied two to eight years ago. Kalu says, “Although the effects of biochars were not consistent throughout these years, some improvements in plant growth were observed when the previous growing seasons were planted with legumes. This special biochar and pre-crop effect warrant further study”.

“In some cases, biochars showed tendencies to improve agricultural benefits such as increases in crop yield, soil nitrate retention, and plant nitrogen uptake while reducing the negative environmental effects such as decreases in soil N₂O emissions and nitrate leaching”.

Even if the observed positive agricultural and environmental effects were not consistent in all fields in the long term, researchers detected no negative effects of biochar over the study periods. This indicates that the application of biochar in agricultural soils is a safe way of enhancing soil carbon storage.