According to sources in the state agriculture department, while some districts have widespread sulphur deficiency, some have deficiencies in zinc, manganese and copper. This has led the state agriculture department to carry out soil testing in several districts.
So far we have collected 75,000 soil samples from different districts. We are collecting samples from the land at every one km, said Naren De, state agriculture minister.
According to the Agriculture Commission report, productivity has come down over the years. While 11.78 lakh tonne of NPK fertilizer was used in 2001-02 to get a yield of 201.5 tonne per hectare, 13.65 lakh tonne NPK fertilizer had an yield of 196.7 tonne per hectare productivity in 2006-07.
Sources in the department pointed out that deficiency of secondary nutrients or microelements act as limiting factors in increasing agricultural productivity in the state. Nine districts of the state including Murshidabad, Nadia, Birbhum, Hooghly , 24 Paragans (N), Burdwan, Jalpaiguri, Midnapur (W) and Malda have widespread sulphur deficiency.
Moreover, a major portion of rice and wheat growing areas in the state has also shown deficiency in zinc, boron, manganese and copper. Most of these areas have been avoiding organic manures with the spread of green revolution technology, said an agriculture department official.
Use of chemical fertilisers has increased by 5.6% over last three years from 13.65 lakh tonne in 2006-07 to an estimated 14.42 lakh tonne in 2008-09.
We have to stress more on organic manure, De told reporters on the sidelines of Agro Protech 2009 organised by Indian Chamber of Commerce. Organic fertiliser usage in the state has increased by 42.9% from 87.47 lakh tonne in 2006-07 to 125 lakh tonne in 2008-09.
Indicating that there is a need to build up soil organic matter (SOM) and restore soil fertility, De said: Productivity of the soil might come down with errant use of chemical fertilizer.
The state government would concentrate on site specific nutrient management after the soil map is ready, he said.