SOIL PLANT NUTRIENT STATUS UNDER INTENSIVE RICE-FARMING SYSTEMS IN UNFAVORABLE ECO-SYSTEMS OF BANGLADESH

Soil fertility and crop production varies depending on ecological factors and soil parent materials. A baseline study was conducted to delineate soil nutrient status of unfavorable ecosystems under different agro-ecological zones (AEZ) of Bangladesh (Char and saline, AEZ-18; submergence and cold, AEZ-3; tidal flood ecosystem, AEZ-13; drought and cold prone, AEZ-26 and haor area, AEZ-21). A total of 125 composite soil samples (10 samples/spot) were collected at 0-20 cm depth, maintained geographical positions and data on village, union, upazila, land type, soil series and land use patterns. Soil samples were analyzed for texture, pH, electrical conductivity (EC), organic matter (OM), total nitrogen (N), available phosphorus (P), exchangeable potassium (K), calcium (Ca), magnesium (Mg), available sulfur (S) and zinc (Zn). Soil pH was slightly acidic to neutral in AEZ-18, 3 and 13. In AEZ-21, soil was strongly acidic but neutral to slightly alkaline AEZ-26. In most locations, soil OM was below critical level (1.72%) in 80 to 96% samples. Soil N was below critical level (0.12%) in almost all samples except in AEZ-21. In AEZ-21, 100% samples showed P deficiency and in AEZ-26 it was 24%. In AEZ-3, 60% samples were K deficient and in AEZ-26 it was 40%. Thirty-two and 24% samples were S deficient in AEZ-3 and 26, respectively. The highest 84% samples were Zn deficient in AEZ-18 followed by AEZ-21 (48%). About 52% samples were Ca deficient in AEZ-3 followed by AEZ-21 (4%).  Nutrient status of soils was mostly low and varied among locations.