Increasing urbanisation, industrialisation, pollution, extensive destruction of forests and unplanned cultivation have been leading to soil erosion.
The rise of salinity because of climate change and the lack of nutritious elements have also put soil health under threat.
All these factors contribute to a four percent drop in crop production every year.
The observation came from a seminar at the AKM Giasuddin Milky Auditorium in the capital's Khamarbari area on Thursday, marking World Soil Day.
Dr SM Imamul Haque, president of the Soil Science Society of Bangladesh, presented a keynote paper at the event.
The extent of soil erosion in hilly areas is 12 percent, the highest in the country.
The rising number of brick kilns is one of the reasons for the decay of top soil. As a result, the extent of cultivable land is shrinking, said Dr SM Imamul.
One decimal of cultivable land is decreasing every year because of urbanisation and various activities of non-agriculture sectors.
Villages and upazila towns are now facing the impending threat of urbanisation. New housing and non-agricultural activities have occupied some 30 percent of village land, according to the keynote paper.
Agriculture Minister Dr Md Abdur Razzaque said both nature and humans are responsible for the destruction of top soil.
"If we cannot retain liveable land for our children, our cash and properties will be of no use. Crop cultivation will fall because of soil erosion," he added.
World Soil Day is observed across the globe every year on December 5 as a means of keeping attention on the importance of healthy soil, and to advocate for the sustainable management of soil resources.
The theme of this year's day is "Stop Soil Erosion, Save Our Future".
The Soil Resource Development Institute organised a daylong fair at Khamarbari to mark the day.
People can get advice on the use of different types of fertiliser based on soil quality, and also on soil management at the fair.
Three people in three categories got the Soil Care Award-2019. They were Md Sultan Hossain from Barishal, Dr Md Nurul Islam Bhuiyan from Narshingdi and Md Abdul Ahad Shahin from Sylhet.