4 May 2023

Biochar provides relief for saline soils in Bangladesh


Biochar promotes tomato crop yields in salt-affected soils, a research conducted in Bangladesh has found. Effects on carbon sequestration are also positive

by Matteo Cavallito


Biochar use represents an important resource in saline soils by leading to better agricultural yields and positively affecting soil properties. These are the conclusions of a study conducted by researchers at the Agricultural University in Khulna, Bangladesh. The investigation was carried out in a neighboring area and measured the effects of the product in combination with the recommended dose of fertilizer.

“Using biochar in saline soil significantly influenced tomato growth and yield character,” the study states. “Days after planting, plant height was dramatically impacted by various biochar treatment levels.”

Salt threatens soil

Created by thermochemical conversion of biomass through so-called slow pyrolysis, biochar “has been found to have beneficial effects on the soil’s microbiota, microbial community, and nutrient status,” the authors say. “However, there is scant literature on how biochar alters soil properties and the stress caused by salinity.” Investigation of the substance’s effectiveness in this context assumes extremely important significance given the scale of the problem on a global level.

Indeed, according to the FAO, excess salt affects 20 to 50 percent of all agricultural land on the Planet, “meaning over 1.5 billion people worldwide face significant challenges in growing food due to soil degradation.”

The effects of salinity are most evident in coastal areas and could worsen due to climate change, according to researchers. This is no small problem for Bangladesh, which is managing more than 30 percent of its agricultural land in these environments with the risk of experiencing declining productivity.

Biochar is good for crops

Conducted between July 2021 and June 2022, the experiment compared yields in soils treated with biochar with those found in soils to which only fertilizer had been applied or which had not been treated. “The application of varying concentrations of biochar in conjunction with the recommended amount of fertilizer significantly influenced the overall height of tomato plants,” the authors write. “This resulted in a significant increase.” With obvious positive effects on total yield.

The use of biochar also reduced the salinity of treated soils. The substance, the researchers explain, works by immobilizing sodium ions, limiting their uptake by plants. This research, in particular, “showed that increasing the amount of biochar to 2 tons per hectare effectively reverses the fruit-yield loss caused by salinity and decreases the amount of sodium accumulated in the roots and fruit.”

Carbon content increases

Also important are the effects on soil properties. “Organic matter in the soil influences soil health, microbial activity, nutrient cycling, and water retention (SOM),” the researchers write. “Soil biochar has been shown to increase its C content, its ability to retain water, and the strength of aggregates.”

Application of the substance, in fact, improves and preserves the physical and chemical properties of saline soils by increasing the element’s sequestration potential. This phenomenon was particularly evident in soils characterized by an alkaline pH, treated with a higher amount of bio-based fertilizer and subject to larger tomato crops.