A study was conducted to explore the spatial variability of major soil nutrients of Agricultural fields in South-western region of Bangladesh. From the study area, 40 surface soil samples were collected by a random sampling strategy using GPS. Then soil physico-chemical properties i.e., pH, electrical conductivity (EC), organic matter (OM), total nitrogen (TN) N, soil available nutrients (P, K and S) were measured in laboratory. After data normalization, classical and geo-statistical analyses were used to describe soil properties and spatial correlation of soil characteristics. Spatial variability of soil physico-chemical properties was quantified through semi-variogram analysis and the respective surface maps were prepared through ordinary Kriging. Spherical model fits well with experimental semi-variogram of pH, EC, OM, TN, available P, K and S. Soil pH, available phosphorus (Av P), potassium (Av K) and sulfur (Av S) have the moderate spatial dependence, with nugget/sill ratios of 41.13% to 72.21%. The others have the strong dependence with nugget/sill ratios of less than 25%. The spatial variability of estimating soil properties varies within range of 0.0142 for Av P to 0.0383 for Av S and this model can calculate the un-sampled within neighboring distance of about 12.65 m for Av S to 150.82 m for TN, respectively. Cross validation of kriged map shows that spatial prediction of soil nutrients using semi-variogram parameters is better than assuming mean of observed value for any un-sampled location. Therefore, it is a suitable alternative method for accurate estimation of chemical properties of soil in un-sampled positions as compared to direct measurement which has time and costs concerned. Bangladesh J. Sci. Ind. Res.54(1), 55-66, 2019

A long term (1990-2000) soil and water salinity monitoring programme was undertaken to address the salinization problem in paddy cum brackish water shrimp cultivation area . The information generated during this period has been presented in this paper. In monsoon season, particularly from August to October soil salinity had increased from 1.4 dS/m to 10.3 dS/m. In between November and February depth of ground water table remained within 0.12 m to 0.33 m and rest of the year it remained at or close to the surface. So, due to presence of ground water table at shallow depth and slower permeability downward movement of soluble salts from the top is very limited. Under Pashur river system average submerged water salinity was found to be 13.8 dS/m to 17.5 dS/m in between March and- May. In Shibsha river system it was found to be 13.2 dS/m to 24.2 dS/m in between February and June. More soluble salts have been accumulated in the topsoil over long period brackish water shrimp cultivation. Increasing tendency of soil pH from 7.5 to 8.2 may be due to high amount of cations like Ca, Mg, and K. High amount of S may be one of the possible reasons for P deficiency in brackish water submerged condition. Soils are rich in B. Cu, Fe except Zn. Late transplantation, without or very little fertilization, without insecticides, use of aged seedlings, wider spacing, relatively high flooding at the time of aman transplantation, minimum tillage and little opportunity of flushing and leaching of fresh water are the common constraints of paddy cultivation in paddy cum brackish water shrimp cultivation area.

The results of the experiments conducted on a high land belonging to Salna Series under Madhupur Tract (Shallow Red Brown Terrace Soil) with different rates of N, P, K, S, B and Mo with cow dung and organic compost evince that the application of N120 P120 K100 S20 B1 Mo0.20OC0.5 (T16) had the best effect on the growth and yield of cauliflower followed N120 P180 K100 S20 B1 Mo0 2CD10 (T7).

The coastal area of Bangladesh lying in the sou thern deltaic zones of the country covers about 3.2 million hectares. About 0.833 million hectares of land in the coast is affected by varying degrees of salinity. Major limitations of saline soils are high salinity of soil, river and ground water; ionic and osmotic imbalance; low to very low soil fertility and scarcity of quality irrigation water during drought season. A field experiment was conducted in the coastal saline soil of the Khulna district. The area is mostly under monocropped local T. aman practices having cropping sequence of Fallow-Fallow-T. aman. Topsoil, river, pond and ground water salinity in this area ranges from 3.8-13.8, 1.35-14.9, 2.6-6.7 and 3.5-8.3 dS/m respectively during January to May. At the advent of summer, the topsoil initiates the cracking and extends to a few cm during the peak period both horizontally and vertically. Soil is incapable of retaining irrigation or rainwater as per crop demand at the beginning of the season. Frequent irrigation with pond water increases the germination (>20%) of exotic BINA Mung-2. BINA Mung-2 can exist at soil salinity (ECe ) of 6.5-9.8 dS/m and with irrigated water (ECw) of 3.0-4.8 dS/m up to 45 days after sowing during drought period. Soil test based fertilizer dose responded better growth and yield than other recommended doses.