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Biochar magic

It is screened to investigate how the use of biochar affects the soil. The mesh of the sieve measures 2 mm. Credit: Damian Gorczany

In many parts of Africa, ensuring a stable food supply is a problem, and a significant increase in population will only exacerbate it in the future. Still, the agricultural sector can definitely produce more crops. Experts estimate that current yields are 20 to 60 percent less than they really are.


One of the reasons is poor soil quality. Isaac Asirifi, a PhD student in the Faculty of Soil Science and Soil Ecology at RUB, led by Professor Bernd Marschner, is exploring how this can be improved. Already working as a master’s student in a previous project, Urban Food plus, completed in 2018, he is now devoted to the biological aspects of soil quality in various vegetation zones in Ghana.

Too many and not enough

“Many vegetable farmers in urban areas of Ghana not only are contaminated with heavy metals and other substances, but also water dry soil with highly nutritious wastewater for feces,” explains Asirifi. To do. “But they also use mineral fertilizers. It’s too much to meet real needs.” Soil management, How German Academic Exchange Service scholarship holders know it when doing research in Germany.

To find ways to improve soil quality, Isaac Asirifi focused on three vegetation zones in Ghana, Soil sample There: It rains only once a year in the coastal savanna in the southeastern part of the country, the mixed deciduous forests in the center, and the Guinean savanna in the north. Studies have shown that one particular problem is hindering high-yielding harvests. That is, the pH level is too low. “Soil is too acidic to be a good habitat for microorganisms that contribute to soil fertility in many ways,” he explains. “They eat, breathe, consume energy, and return much to the soil where plants need to grow, such as phosphorus and nitrogen.”

Biochar magic

Preincubation of ash and calcium carbonate (CaCO2) treated soil for calcification experiments Credits: Damian Gorczany

Possibility of unharvested residue

There is a way to make it easier for them: Biochar.. “In Ghana, plant residues that cannot be eaten or fed to livestock are not used after harvest, but simply burned,” says Asirifi. This also causes the problem that large amounts of carbon dioxide are released into the atmosphere, promoting climate change. However, crop residues have great potential. Combustion in a container in the absence of oxygen produces biochar. It can be made from what is left over from the harvest and does not require complicated and expensive techniques. “When it’s introduced 15 to 25 centimeters above the soil, it works its magic,” explains Asirifi. This means that once applied, the quality of the soil will improve over the next few years.

Biochar magic

Analytical Methods for Determining Nitrogen and Phosphorus Available to Plants in Soil and Biochar Credits: Damian Gorczany

“Biochar itself does not add much nutrients to the soil, as it does when adding compost,” continues Asirifi. Rather, charcoal ensures that microorganisms such as bacteria and fungi can settle and propagate more easily. “It reduces acidity and many small cavities in biochar provide protection from predators.” Also, they are not washed away. As a result, when biochar is introduced, Positive effect on Soil quality For years to come, compost will have to be reapplied almost every year. A welcome side effect is that the carbon contained in the biochar remains bound to the soil and is not released into the atmosphere as in the case of open burning.

Studies of soil samples showed that the carbon content of the top 10 centimeters of soil, which was 0.8% without biochar, increased by 60-70% after biochar was incorporated.

Biochar magic

Ultrasonic vortex credit for extracting extracellular enzymes from biochar: Damian Gorczany

Yield increases by a quarter

Isaac Asirifi believes there is a problem with the amount of biochar needed for soil improvement. According to calculations, 20 tonnes per hectare of cultivated land is required to significantly improve quality. “It’s almost impossible for the locals to achieve that,” says Asirifi, who also knows how to solve the problem, by replenishing biochar with ash. About 80% of all Ghanaian families cook on firewood or coal, so that’s not a shortage. By mixing 0.5-1% ash with biochar and spreading the mixture in the field, 10-15 tonnes per hectare of land is sufficient. This is an amount that Asirifi estimates is feasible. Agricultural land treated in this way is about a quarter more than untreated agricultural land.

Biochar magic

The structure of biochar can be seen under a microscope. It provides a lot of space for microorganisms. Credit: Isaac Asirifi

He is currently studying while in Germany soil Use advanced analytical techniques to gain a deeper understanding of biology. Returning to Ghana, he wants to help ensure that the findings actually apply. Application notes, target group discussions, and workshops with stakeholders such as ministerial staff are planned.


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Quote: Biochar Magic (September 28, 2021) was obtained from https://phys.org/news/2021-09-magic-biochar.html on September 28, 2021.

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