P K Saha
Soil Science Division, BRRI,Gazipur-1701
S Islam
Soil Science Division, BRRI,Gazipur-1701
M N Islam
Soil Science Division, BRRI,Gazipur-1701
J C Biswas
Soil Science Division, BRRI,Gazipur-1701
Md Mozammel Haque
Soil Science Division, BRRI,Gazipur-1701
Unfavorable ecosystems, Soil fertility, Rice production
Crop-Soil-Water Management
Cropping System
Description of the study siteFive locations were selected from unfavorable ecosystems, such as AEZ-18 (Char and saline area of Sonagazi); AEZ-21(Haor area of Habiganj); AEZ-3 (Submergence and cold area of Rangpur); AEZ-13 (Tidal flood ecosystem of Barisal) and AEZ-26 (Drought prone and cold areaof Rajshahi). In collecting soil samples, global positioning system (GPS) datawere recorded. The GPS data were: 22.69412-22.81959oN latitudes and 91.38613-91.38967oE longitudes for Londonipara, Feni (AEZ-18); 24.41719-24.41889oN latitudes and 91.42238-91.42539oE longitudes for Nagura, Habiganj (AEZ-21); 25.86088-25.88511oN latitudes and 89.23211-9.23856oE longitudes for Gunnarpar, Rangpur (AEZ-3); 22.75666-22.75991oN latitudes and 90.29867-90.30708oE longitudesfor Gozalia, Barisal (AEZ-13) and 24.5417-24.54442 N latitudes and 88.55575-88.55886oE longitudes for Raitanboso, Rajshahi (AEZ-26). In Bangladesh, coastal area covers about 2.5 million hectares, which is about 25% oftotal cropland (S A Haque, 2006; Rasel., 2013). About onemillion hectares are affected by varying intensities of salinity (Karim et al., 1990). Crop production in this area is dominated by traditional T. Aman rice with yield of 2 t ha-1. Flood-prone rice ecosystem of Bangladesh coversabout 2.6 million hectares (Karim, 1997). The average yield of rice under such ecosystem is very low (2.5 t ha-1). Nearly 2.5 million hectares are affected by drought in the north-west parts of Bangladesh (Karim, 1997) where yield of BRRI dhan39 can vary from 0.61 to 2.8 t ha-1 (Mazid et al., 2004). The non-saline tidal floodecosystem of Bangladesh covers about 1.9 million hectares and average yield of rice isnot more than 3.0 t ha-1 due to lack of appropriate fertilizer management packages, etc. Haor is the wet land ecosystem in north-eastern part of Bangladesh. Total area in this ecosystem is 80,000 square kilometers. Most of this area remains under water for seven months of the year. During dry season, most of the water drains out, leaving small shallow lakes or completely dried out by the end of winter season. This exposes rich alluvialsoil, extensively suitable for rice cultivation. Sampling and laboratory analysesA total of 125 composite soil samples (10 samples/spot) were collected from the surface layer (0-20 cm depth) from five AEZs (3, 13, 18, 21 and 26). Soil samples were collected from 25 farmers’ fields at each location. The GPS reading and some basic information like village, union, upazila, land type, soil series and land usewere also collected. Soil samples were air-dried, ground and passed through a 2-mm sieve and prepared for routine analyses of texture, pH, EC, OC, total N, exchangeable Ca, Mg and K, available P, S and Zn.Texture was determined by hydrometer method. Soil pH was measured using glass electrode method with a soil-to-water ratio of 1:2.5 (McLean, 1982; Jackson, 1962). The EC was measured by EC meter with a soil-to-water ratio of 1:5. Soil organic carbon (SOC) was determined by wet oxidation method (Walkley and Black, 1935; Nelson and Sommers, 1982). Soil totalN was determined by micro-Kjeldahl method (Bremner and Mulvaney, 1982). The available soil P from acid soil was extracted using the Bray 2 method (Bray and Kurtz, 1945) and from neutral and calcareous soils by modified Olsen’s method (Olsen and Sommers, 1982). Available soil S was extracted using calcium di-hydrogen phosphate (500 ppm of P) and determined by turbidity method. Available soil Zn was extracted using the DTPA and determined by using an atomic absorption spectrophotometer. Exchangeable Ca, Mg and K were extracted with 1 M NH4 OAc pH 7.0. Exchangeable Ca and Mg were determined by an atomic absorption spectrophotometer. Exchangeable K was determined by flame photometer (Barker and Surh, 1982).
International Journal of Biological & Pharmaceutical Science Volume-2 | Issue-2 | February, 2016 | Paper-1 ISSN: 2208-2166
Journal