Nearly 40 percent of Bangladesh’s agricultural land has been found to contain severe levels of acidity, while more than 58 percent has a low presence of organic matter. Soil Resource Development Institute (SRDI) revealed the findings in the annual report. The report was published on the agency’s website on Saturday. The state-run institution tested soil samples from 28,912 locations across 50 upazilas using a sampling method.
Soil scientists say that an increase in soil acidity directly affects agricultural production. In acidic soil, normal root growth is hindered, and plants cannot properly absorb essential nutrients. Crop growth and yield consequently decline significantly.
The unit used to measure the acidic and alkaline conditions of soil or a solution is “pH.” Soil with a pH level below 4.5 is considered “very strongly acidic.” A pH value between 4.6 and 5.5 is categorised as strongly acidic, while 5.6 to 6.5 is regarded as slightly acidic. Soil with a pH between 6.6 and 7.3 is considered neutral or acid-free. A pH level from 7.4 to 8.4 is classified as slightly alkaline, while 8.5 to 9 is regarded as strongly alkaline.
According to the SRDI report, 6.89 percent of farmland falls under the category of “very strongly acidic.” Another 32.11 percent is “strongly acidic,” while 24.11 percent is “slightly acidic.” But only 15.92 percent of soil is neutral or acid-free. The report further states that 20.16 percent of agricultural land is slightly alkaline, while 0.75 percent is strongly alkaline and 0.02 percent is extremely strongly alkaline.
The highest concentration of extremely and strongly acidic soil was found in the Sylhet Division, according to the state agency’s findings. In the division, 19.17 percent of the land is very strongly acidic, while 57.62 percent was strongly acidic.
The second-highest level of soil acidity was recorded in the Rangpur Division, where 52.91 percent of land was strongly acidic, and 14.58 percent was very strongly acidic. In the Dhaka Division, 9.71 percent of the land was very strongly acidic and 46.75 percent strongly acidic. In the Rajshahi Division, 1.49 percent of the land was very strongly acidic and 19.83 percent strongly acidic.
But researchers did not find any very strongly acidic soil in the Barisal Division and Khulna Division. While no strongly acidic soil was found in Khulna Division, the rate in Barisal Division stood at 11.78 percent. At the same time, 61.92 percent of the soil in Khulna Division was slightly alkaline, while the rate of slightly alkaline soil in Barisal Division was 32.23 percent. But the report did not include data for the Mymensingh Division.
Researchers believe that both natural and human-induced factors are responsible for increasing soil acidity. Amir Muhammad Zahid, chief scientific officer at SRDI’s Dhaka Divisional Office, told Bonik Barta, “Excessive rainfall washes away important alkaline elements from the soil, such as calcium, magnesium and potassium. The excessive use of urea and sulphur fertilisers also increases soil acidity. Once acidity develops, proper soil management becomes very important. If management isn’t done properly, it affects crop production. When the pH level falls to 5.5 or below, we advise the use of lime.”
Soil researchers say that increased soil acidity hampers root growth and nutrient absorption in crops, leading to lower yields. Elements such as aluminium and iron may also become toxic. This disrupts the activity of beneficial microorganisms and the biological balance of the soil. In the long run, it also raises farmers’ production costs.
The SRDI report also found that, alongside rising acidity, the presence of organic matter in the soil has declined. 15.40 percent of soils contain a “very low” level of organic matter, while 42.69 percent contain a “low” level, according to the report. The level is considered moderate in 35.48 percent of soils. Only 2.39 percent recorded a “high” level of organic matter, while 1.27 percent showed a “very high” presence.
The report further noted that nitrogen levels are “very low” in 34.81 percent of agricultural land and “low” in 38.83 percent. Phosphorus levels are “low” or “very low” in 21.24 percent of land. Potassium levels are “low” in 30.35 percent of the land and “very low” in 14.5 percent. Sulphur deficiency is also significant, with 43.33 percent of land recording low or very low sulphur levels. Nearly 34 percent of the land, meanwhile, falls into the low or very low category for zinc content.
Dr Md Anwarul Abedin, professor at the Department of Soil Science of Bangladesh Agricultural University, told Bonik Barta that the excessive use of urea is the main reason behind rising soil acidity. “Farmers are cultivating as many as three to four crops a year on the same land. To increase production, excessive chemical fertilisers are being used, which is accelerating acidity. To protect farmland, one tonne of lime should be applied per hectare every three years. This is a proven treatment,” he said.
He further added that the amount of organic matter in the soil is steadily declining, which is reducing yields and increasing production costs. “To address the problem, soil testing should be carried out, and organic materials should be applied according to need. The use of cow dung, poultry litter, vermicompost, or leaving part of rice plants in the field after harvest to decompose can help increase organic matter in the soil. Although organic materials do not work as quickly as chemical inputs, they provide long-term benefits,” he noted.