M.S Khan - Department of Environmental Science and Disaster Management, Noakhali Science and Technology University, Noakhali-۳۸۱۴, Bangladesh
I.J. Mousumi - Department of Environmental Science and Disaster Management, Noakhali Science and Technology University, Noakhali-۳۸۱۴, Bangladesh
M.H. Jaman - Department of Geology and Mining, University of Barishal, Barishal, Bangladesh
M.M. Billah - Department of Geography, Virginia Polytechnic Institute and State University, Virginia, USA

KGROUND AND OBJECTIVE: Reducing the salinity intrusion from sea water, a closure dam has been constructed on Little Feni River at Musapur Union in ۲۰۱۶. The objective of this research was to assess the soil quality based on the variables, i.e., PH, total organic carbon, total organic matter, total nitrogen, phosphorous, potassium, electrical conductivity, salinity and total dissolved solids, respectively.METHODS: A total of ۲۱ soil samples were collected from ۷ sampling stations with ۱۰-۱۵cm depth. The PH, total organic carbon, total organic matter, total nitrogen, phosphorous, potassium, electrical conductivity, salinity and total dissolved solids were measured with pH meter, titration, Van Bemmelen factor, spectrophotometer, conductivity meter and salinity meter, respectively. Data were analyzed by statistical package for the social sciences, maps were produced by Arc GIS software and cluster analysis was done by Ward method, respectively.FINDINGS: The mean concentrations of PH, total organic carbon, total organic matter, total nitrogen, phosphorous, potassium, electrical conductivity, salinity and total dissolved solids were ۸.۱±۰.۱۶۹, ۰.۵۰۶±۰.۲۷۸%, ۰.۸۷۳±۰.۴۶۵%, ۰.۰۴۴±۰.۰۲۳%, ۲۱.۵۹۹±۸.۳۱۲ppm, ۰.۴۶۲±۰.۴۷ppm, ۲.۰۲۴±۵۲۶.۷۶dS/m, ۲.۰۲۴±۲.۳۸۲ppt and ۲۲۲.۴۴۸±۲۵۹.۹۲۷ppm, respectively. The study result revealed that the ranges of these soil parameters were ۷.۱۹-۸.۵, ۰.۲۷-۱.۰۷%, ۰.۵۰-۱.۸۲%, ۰.۰۲-۰.۰۹%, ۹.۴۵-۳۲.۱۹ppm, ۰.۲۵-۱.۵۳ppm, ۱۲۳.۲۳-۱۶۲۵dS/m, ۰.۶۴-۷.۳۷ppt and ۶۳.۵۷-۸۰۲.۳۳ppm, respectively. Strong positive correlation observed between total organic matter and total organic carbon (r=۰.۹۹۹), total nitrogen and total organic matter (r=۰.۹۹۸), potassium and electrical conductivity (r=۰.۹۹۱), salinity and potassium (r=۰.۹۹۴), potassium and total dissolved solids (r=۰.۹۸۹). Likewise, phosphorous was positively correlated with potassium (r=۰.۴۴۴), electrical conductivity (r=۰.۴۷۶) and salinity (r=۰.۴۶۷) with significance level of p ≤ ۰.۰۵. The variance test elicited that F value of PH, total organic carbon, total organic matter, total nitrogen, phosphorous, potassium, electrical conductivity, salinity and total dissolved solids were ۲۵.۵۰۵ (p<۰.۰۰۰), ۱۸.۰۱۱ (p<۰.۰۰۱), ۱۴.۰۱۳ (p<۰.۰۰۳), ۲۳.۴۷۸ (p<۰.۰۰۰), ۲۹.۳۹۳ (p<۰.۰۰۰), ۱۷.۹۲۴ (p<۰.۰۰۱), ۹.۵۰۲ (p<۰.۰۰۹) and ۴.۹۴۴ (p<۰.۰۴۶), respectively. The spatial distribution showed the reducing pattern of concentrations from outside to inside area of the closure dam. The cluster analysis showed the same sources of origin for pH, total organic carbon, total organic matter, total nitrogen, potassium, phosphorous and salinity (NaCl) which might be the possible cause of anthropogenic activities, i.e., use of chemical pesticide/fertilizer for agricultural cultivable land.CONCLUSION:  It is concluded that inside soil was more fertile rather than outside soil after the construction of closure dam. Lastly, the rate of crop production will be increased and soil should be more productive in the study area.

Soil fertility, coastal area, Floodplain, Agricultural Production