Bangladesh farmland hit by rising acidity and falling soil fertility

A new SRDI report warns that rising soil acidity and declining organic matter are degrading Bangladesh’s farmland, threatening crop yields, increasing farming costs and raising concerns over long-term food security.

Bangladesh is facing a growing threat to agricultural productivity as soil acidity spreads across large parts of the country and organic matter levels continue to decline, according to a new government report.

The Soil Resource Development Institute (SRDI) said nearly 40 percent of the country’s agricultural land now suffers from severe acidity, while more than 58 percent contains low levels of organic matter, a key indicator of soil fertility.

The findings were published in the agency’s annual report released on Saturday on its website. Researchers analysed soil samples collected from 28,912 locations in 50 upazilas using a nationwide sampling method.

Soil scientists warned that rising acidity directly affects crop production by disrupting root growth and limiting plants’ ability to absorb essential nutrients. They said the problem could significantly reduce crop yields if left untreated.

The pH scale is used to measure soil acidity and alkalinity. Soil with a pH below 4.5 is classified as “very strongly acidic”, while levels between 4.6 and 5.5 are considered strongly acidic. A pH of 5.6 to 6.5 is regarded as slightly acidic and 6.6 to 7.3 is considered neutral. Soil with a pH between 7.4 and 8.4 is slightly alkaline while levels from 8.5 to 9 are strongly alkaline.

According to the report, 6.89 percent of farmland falls into the “very strongly acidic” category and another 32.11 percent is “strongly acidic”. A further 24.11 percent is slightly acidic. Only 15.92 percent of the country’s soil was found to be neutral or free from acidity.

The report also showed that 20.16 percent of agricultural land is slightly alkaline, while 0.75 percent is strongly alkaline and 0.02 percent extremely strongly alkaline.

The highest concentration of acidic soil was recorded in the Sylhet Division, where 19.17 percent of land was categorised as very strongly acidic and 57.62 percent strongly acidic.

Rangpur Division had the second-highest acidity levels, with 52.91 percent of land strongly acidic and 14.58 percent very strongly acidic.

In Dhaka Division, 9.71 percent of land was very strongly acidic and 46.75 percent strongly acidic. Rajshahi Division recorded 1.49 percent very strongly acidic land and 19.83 percent strongly acidic land.

Researchers found no very strongly acidic soil in Barisal or Khulna divisions. Khulna also recorded no strongly acidic soil, while the rate in Barisal stood at 11.78 percent.

At the same time, 61.92 percent of soil in Khulna Division was slightly alkaline, compared with 32.23 percent in Barisal Division.

The report did not include data for Mymensingh Division.

Scientists said both natural and human activities are contributing to worsening soil acidity.

“Excessive rainfall washes away important alkaline elements from the soil such as calcium, magnesium and potassium,” Amir Muhammad Zahid, chief scientific officer at SRDI’s Dhaka Divisional Office, told reporters.

“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,” he added.

Researchers said higher acidity levels can also increase the toxicity of elements such as aluminium and iron, disrupt beneficial microorganisms and damage the soil’s biological balance. They warned that the long-term impact would raise production costs for farmers.

The SRDI report also highlighted a sharp decline in soil organic matter.

It found that 15.40 percent of soils contain a “very low” level of organic matter while 42.69 percent contain a “low” level. Organic matter levels were moderate in 35.48 percent of soils.

Only 2.39 percent of soils recorded a “high” level of organic matter and just 1.27 percent showed a “very high” presence.

The report further said nitrogen levels were “very low” in 34.81 percent of agricultural land and “low” in 38.83 percent.

Phosphorus levels were found to be low or very low in 21.24 percent of land, while potassium levels were low in 30.35 percent and very low in 14.5 percent.

Sulphur deficiency was also widespread, with 43.33 percent of land showing low or very low sulphur levels. Nearly 34 percent of land also fell into the low or very low category for zinc content.

Dr Md Anwarul Abedin, a professor at the Department of Soil Science at Bangladesh Agricultural University, said excessive use of urea fertiliser was the main reason behind the rise in 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,” he said.

“To protect farmland, one tonne of lime should be applied per hectare every three years. This is a proven treatment.”

He also warned that the continued decline in soil organic matter was reducing crop yields and increasing farming costs.

“To address the problem, soil testing should be carried out and organic materials should be applied according to need,” he said.

“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.”

This post is republished from Daily Bonik Barta.