The field experiments were conducted during the growing season of T. Aman season, 2016 at the farmers' field of the village of Pankhali and Sikandorkhali under the ACIAR-KGF project sites Dacope, Khulna and Amtali, Barguna which are situated in the coastal region of Bangladesh. The project site of Dacope, Khulna is situated in the latitudes and longitudes of 22o34/19.92//N and 88o30/39.96//E, and Amtali, Barguna is situated in the latitudes and longitudes of 22o07/45.842//N and 90o13/44.04//E, respectively, as shown in Fig.1. The study site of the project is located 35 km south of the Khulna and 40 km from the Barguna.
The experimental plots were selected through extensive field visits of research personnel of BARI, BRRI, KU, and foreign experts which included the physical condition of the existing canal, salinity conditions, cropping patterns and systems, soil health, and socio-economic condition of the farmers. Farmers mainly cultivate T. Aman only in a year. Researchers are trying to introduce new varieties and technologies for increasing cropping intensity in the project area. Therefore, field experiments were laid out with RCB design with research management and farmer’s management under each farmer each having three replications. Two irrigation practices (Optional) were considered for all experiments. The treatments were IR1 (Research management): one or two supplemental irrigations given each at booting and grain filling stage (if needed), and IR2: Rainfed / Farmers’ practices. Three farmers were randomly selected under each site. Most of the data were collected by field experiments and having interviews with farmers. The cropping pattern is based on water management for different crops in the saline-prone area of Bangladesh. The cropping pattern (CP) is as follows for Amtali.
CP1 : Watermelon -T. Aus (Optional) -T. Aman
CP2 : Sunflower -T. Aus (Optional) -T. Aman
CP3 : Maize -T. Aus (Optional) -T. Aman
CP4 : Wheat – Mungbean/Sesame (Optional) –T. Aman
CP5 : Fallow - Fallow -T. Aman (Farmers’ practice).
T. Aman crop was also used under the other two experiments which were (i) conjunctive use of fresh and saline water for irrigation to maize in coastal areas of Bangladesh, and (ii) conjunctive use of fresh and saline water for irrigation to sunflower in coastal areas of Bangladesh. The total plot size was 1348 m2 (33.33 decimal). The experimental plots for T. aman were prepared about two days before the seedling was transplanted. The fields were usually flooded. The puddling was done mechanically by a two-wheeled tractor-operated power tiller. After ploughing, the leveling was done. 28 days old seedlings of BRRI Dhan-62 were planted in the experimental plots through research management (IR1). The genetic characteristics of BRRI Dhan 62 are short duration, high yielding, and zinc content. The seedlings were transplanted after land preparation on 28 July at Sikandorkhali, Amtali and 7 August 2016 at Pankhali, Dacope. The ages of seedlings were 32 days at Sikandorkhali and 28 days at Pankhali. Only healthy seedlings were transplanted in straight rows with 20 cm and 15 cm plant to plant as proper spacing and two or three seedlings were transplanted per hill. Weeding was done as necessary throughout the growing season. To some extent, herbicide was applied as a preventive measure of weed infestation. The yield contributing characters, such as plant height, number of hills/m2, number of panicle/m2, panicle length were taken from each plot within 1 m2. Plants were harvested manually at the ground level from the corner avoiding the border effect. After manually threshed, cleaned, dried filled grain per panicle and grain yield was recorded at desired moisture content. The profitability analysis was done based on seasonal variable costs. The variable cost was estimated based on the operating cost of land preparation using machinery, chemicals, fertilizers and human labors for all cultural practices. In this study, the fixed cost was not considered. Gross return was calculated by simply multiplying the total grain yield and its unit price in the harvesting period. The gross margin was calculated by the subtraction of variable cost from the gross return. The output-input ratio was calculated as the gross return divided by the total seasonal variable input cost of T. Aman rice production.