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 evaluate the best tillage practice for wheat in saline area and observed the effects of permanent soil cover on wheat. The crop variety was BARI gom-25. There were six treatments combinations considering three replications. The treatment T1 was Farmers practice in where land was prepared by Power Tiller (2-Wheel Tractor) at optimum “Zoe” (appropriate moisture level) condition. T2 was relay of wheat with previous crop residue. In relay cropping treatment (i.e., T2), the wheat seeds were broadcasted carefully in line at the standing rice field before ten days of harvesting and after rice harvesting almost 25cm of rice straw was kept in the wheat field.
The treatment T3 was relay of wheat without residue. In case of T3, all methods were followed as same as T2 but after rice harvesting no more rice straw was kept in the wheat field. The treatment T4 was the strip-tillage of wheat with residue. The treatments T5 was strip-tillage of wheat without residue and the final treatment of T6 was PTOS of wheat in where land was prepared by Power tiller operated seeder (PTOS) along with seeding. PTOS performs three functions i.e., ploughing, seeding in rows and laddering simultaneously. Power tiller-operated seeder (PTOS) has 48 numbers of rotating blades for pulverizing soil at shallow depth with very high-speed rotating blades. The seeding part attached with power tiller replacing the rotavator part of the power tiller. In strip till system, rotating blades were reduced to 24 numbers. Only four blades in face to face configuration remains in the gang at the front position of seed furrow opener for tilling in strip 4-6 cm and creating tilt soil just in front of furrow openers and between the two furrow openers the soil remained untilled. The English J type blades of the seeder were rotating at the speed of 450 rpm. Concurrently, the seed and fertilizer placement was done in a single operation.
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 7.3. The experiment was conducted in a randomized complete block design with three replications. Seeds were sown in T2, T3 on 10 December, 2017 & T1, T4, T5, T6 on 18 December, 2017 at ARS, Benarpota, Satkhira. Unit plot size was 5m × 4m.
Field measurement of soil salinity:
Soil salinity at different dates was recorded at 09:00-10:30 a.m. every 15 days interval, starting from sowing until harvest. The salinity was measured by EC meter (HANNA: HI 9835). Data were taken at the middle of the plot. Collected data were analysed using ANOVA procedure. Once a week, a calibration for the meter was made by comparing with laboratory data.
Seed sowing & crop management:
The experimental plot of T2, T3, T4, T5 and T6 were 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). The Urea was applied in two equal splits at 23 and 53 days after sowing (DAS) after matching with critical growth stages. All required fertilizers except urea were applied at the end of final land preparation and incorporated into the soil. Two irrigations were applied during the crop growing period. All the intercultural operations were done as and when necessary. Diseases and insect pests were always well controlled using suggested applies (BARI, 2014). In case of farmer’s practice, TSP, MoP, Gypsum were applied @ 130, 80 and 90 kg ha-1 respectively as a basal dose during the final land preparation. Urea was applied in 3 equal splits at 26, 44 and 58 DAS after irrigation. The wheat was harvested in the last week of March in all treatments.