A distinct lack of recovery compared to higher cropping intensity has been causing a severe nutrient deficiency in soil in Bangladesh.
Speakers at a World Soil Day seminar said nearly 78 per cent of the total arable land suffers a shortage of necessary organic matters.
For such deficiency, they said, farmers hardly could produce healthy safe food.
A 2.8 times higher production since the 1980s, a vast rise in grain, potato, vegetable and other crop production, also took its heavy toll as soil lacks a shortage of seven key nutrients.
The findings were disclosed at a discussion at KIB Auditorium, hosted by agriculture ministry in collaboration with Soil Resources Development Institute, and Food and Agriculture Organization, marking World Soil Day.
The day was observed laying highest emphasis on soil health for safe food production with the theme 'Soil: Where Food Begins'.
Agriculture minister Dr Muhammad Abdur Razzaqe called for a close linkage between academia and farmers through appropriating practical curriculum for the students of the agricultural universities.
Students should also visit different companies to get the know-how of an agro-based industry's mechanism.
Both public and private sectors should work jointly to make agriculture safer and more vibrant to ensure healthy food for all, added Mr Razzaqe.
Additional agriculture secretary Md Ruhul Amin chaired the event where land secretary Md Mostafizur Rahman, DAE director general Benazir Alam, SRDI director general Dr Kamaruzzaman, FAO Bangladesh representative Robert D Simpson also spoke.
Sheikh Md Bakhtiar, Bangladesh Agricultural Research Council executive chairman presented a keynote styled 'Soils: Where Food Begins'.
It said crop production increased by 2.8 times since the 1980s, thanks to heavy reliance on chemical fertilisers and other chemical inputs, use of high-yielding crop varieties, improved irrigation systems.
Arable land decreases from 65.05 per cent of Bangladesh in 2010 to 58.19 per cent in 2020 at an average annual loss of about 0.69 per cent.
The area under homestead, rivers, urban area increases from 30.1 per cent to 36.93 per cent over the years, said the paper.
Thanks to heavy reliance on chemical fertilisers and other chemical inputs, use of high-yielding crop varieties, improved irrigation systems etc, crop production has increased by 2.8 times since 1980.
"The more we're raising our production, the more we're losing soil nutrients," said the keynote, adding that land has a deficiency of nitrogen (N), potassium (K), sulphur (S), phosphorus (P), boron (B), zink (Z), magnesium (Mg) and others.
Seventy-four per cent of the arable land lacks those seven nutrients while 78 per cent have shortage of organic matters, according to the paper.
Such nutrient shortages are even reflected in human food intake as hidden hunger for shortages of nutrients like Z, K, P and N Br are being found among a vast global population.
The paper suggested that the nitrogen rate for T-Aman rice could be reduced by 25-30 kg per hectare if 10-12 tonnes of green biomass be incorporated.
As uptake is 15-25 per cent of applied fertiliser, the phosphorus rate for the second and third crops could be reduced by 40-50 per cent for rice and jute and by 30-40 per cent for vegetables, it said.
It also said potassium or K could be reduced by 30-40 per cent for next crops after potato, sugarcane and vegetables while K dose could be reduced by 20-40 per cent for subsequent crops if 2.0-4.0 tonnes of crop residue could be applied.
After Rabi crops, sulphur dose could be reduced by 50 per cent for rice crops, according to the paper. Six actions should be taken for preventing and reversing nutrient imbalance, said the paper.
"Judicious use and management of fertiliser, crop diversification, adequate use of micronutrients, enhancement of technical support for farmers, soil nutrient measurement and mapping, adoption of long-term sustainable soil management were the key to achieve the goal," reads the paper.