Experimental site and design:
The experiment was conducted at the Agricultural Research Station (ARS), BARI, Benarpota, Satkhira during the rabi season of 2017-2018 to know the effect of different tillage practices on soil properties and
crop productivity. The crop varieties were BARI Gom 25, BARI Mung-6 and BRRI dhan49.There were four treatment combinations viz. T1 = Zero tillage (ZT), T2 = Minimum tillage (4-6 cm) (MT), T3 = Conventional tillage (10-12 cm) (CT) and T4 = Deep tillage (20-22 cm) (DT). In zero tillage, seeds were placed just by making furrow with a hand rake. The conventional tillage was conducted by a power tiller, whereas the deep tillage was maintained by a chisel plough.
The soil belonged to the AEZ-11 and AEZ -13. The land topography was medium low. The soil of the experimental field is clay loam in texture with pH 6.79. Experiment was conducted in a randomized complete block design with three replications. Wheat Seeds were sown on 07 December, 2017 at ARS, Benarpota, Satkhira with a row to row distance of 25 cm. Seeds of mugbean and rice were sown on 20 March, 2017 and 07 August, 2017 respectively. Unit plot size was 4m X 4m. At every 15 days interval soil salinity (dS m-1) was measured by EC meter (HANNA: HI 9835).
Seed sowing & crop management:
Wheat Seeds were sown on 07 December, 2017 at ARS, Benarpota, Satkhira with a row to row distance of 25 cm. Seeds of mugbean and rice were sown on 20 March, 2017 and 07 August, 2017 respectively. In case of wheat, the experimental plot was fertilized with Urea (220 kg ha-1), TSP (180 kg ha-1), MoP (50 kg ha-1), Gypsum 120 kg ha-1 and Cowdung (10 t ha-1) ha). All required fertilizers except urea were applied at the end of final land preparation and incorporated into the soil. The Urea was applied in 3 equal splits at 7-10, 25-30 and 50-55 DAS after matching with critical growth stages. In case of mungbean, seeds were sown in line with a spacing of 30 cm × 5 cm. Fertilizers and 50-85-35 kg ha-1 Urea, TSP and MP were applied as basal during final land preparation. Three irrigations were applied during the growing period for wheat as well as mungbean. All the intercultural operations were done when necessary. Disease and insect pests were always well controlled using suggested applies (BARI, 2014). The wheat was harvested in the last week of March. Mungbean pod picking was started in the first week of May whereas rice was harvested in the second week of November 2017 at full maturity. After pod picking, remaining biomass of mungbean was incorporated in the soil as brown manure.
Data collection and analysis:
Data on yield and yield contributing character were recorded and analyzed statistically using MSTAT-C program. After following the standard methods, soil samples were analyzed for pH, OM, N, P, K, S, Zn, B, Cu, Fe, Mn, Ca, Mg and Na. Soil pH was measured using a glass electrode pH meter (WTWpH 5.22) at a soil-water ratio of 1:2.5 as described by Ghosh, soil organic C was measured by Walkley and Black’swet oxidation method as described by Jackson et. al, and total N was measured by micro-Kjeldahlmethod; available P was determined following the Bray and Kurtz method, exchangeable K was determined using NH4OAC extraction method, S was determined by turbidimetric method with the help of a spectrophotometer using a wavelength of 420 nm, Ca was determined by complexometric method of titration using Na2-TA as a complexing agent, Mg was determined by using NH4OAC extraction method, available Zn, Cu, Fe, and Mn were determined by using diethylenetriaminepentaacetic acid (DTPA) extraction method, B was determined by spectrophotometry method and Na was determined by flame photometry method. CEC (Cation Exchange Capacity) was measured as the summation of the K, Ca, Mg and Na content. Particle size distribution was done by hydrometer method and the textural class was determine dusing the USDA textural triangle. Bulk density and particle density of the soil samples were determined by core sampler method and Pycnometer method, respectively. The soil porosity was computed from the relationship between bulk density and particle density using equation.