Saturday, 15 July 2006

Direct Application of Phosphate Rock in Bangladesh Agriculture.

S. A. Haque, Bangladesh Agricultural Univ, Dept of Soil Science, Mymensingh, Bangladesh

Phosphorus is the second most important nutrient (next to nitrogen) that has been found limiting crop production in Bangladesh. Deficiency of phosphorus is widespread in Bangladesh soils. It covers roughly an area of 5.6 million hectares with soils having pH acidic to saline. In most cases soils are around neutral. Management of phosphorus fertilization should be considered as a means of improving soil P in crop production in the cropping system.

Phosphate rock has so far not been used in crop production in Bangladesh. As such, field trials with phosphate rock, first of its kind in Bangladesh will go a long way in catering the need for P fertilizer for crop production. Since, phosphate rock is quite cheap and has long term effect on availability of P, its uses will be very good as a P fertilizer and also expected to bring socio-economic benefit to the farmers. Thus the use of rock phosphate may open up new horizon of improved and commercially beneficial fertilizer for the farmers in Bangladesh agriculture. Six experimental sites were selected for the study under different agro-ecological zones of Bangladesh with different cropping patterns having rice, wheat, oil crop and pulses with rice as the dominant crop using four treatments such as (1) Control (-P), (2) PR - 35 kg P ha-1 (3) TSP - 35 kg P ha-1  and (4) PR - 210 kg P ha-1.  Treatment 4 was designed for assessing residual effects of 6 succeeding crops.


The investigation was designed to determine the extent of agronomic efficiency and economic benefit that the farmers would get on use of rock phosphate for high yielding varieties of rice, wheat, oil crop (mustard) and pulses (Mungbean and Black gram) under different agro-ecological zones in six different sites of Bangladesh. 

In Bangladesh, phosphorus plays a very important role in crop production sector.  Its deficiency is also quite high in crop growing areas. Phosphorus is part and parcel of the total fertilizer system in crop production in Bangladesh. The main P supplying fertilizer being used in Bangladesh till to-day is TSP. DAP was tried off and on but without success. Cost, apart from P utilization from the fertilizer appears important factors to succeed in farmers' acceptance for use of the fertilizer. Our farmers are now quite conscious about the need of fertilizers as well as kind of fertilizer to be used by them in order to maximize crop production.

Phosphate rock being used on trial basis in crop production in Bangladesh will be a new fertilizer as a source of P.  Its low price and residual effect of cropping system could be an added factor for easy acceptance of P fertilizer compared to other phosphatic fertilizers.  Present work in different sites with Transplanted rice as the first crop in the trial with rock phosphate, although in general indicates TSP has better performance over PR, economic consideration might prove otherwise. Further more, treatment No. 4 with higher rate of P has shown the best results in all the sites.  It is yet premature to make any comment on effectiveness of PR fertilizer for crop production and its socio-economic impact on farmers' acceptability.

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