Effect of Sowing Dates on Yield of Wheat Grown in Excess Water and Salt Affected Soils in Southwestern Coastal Bangladesh

Abstract

Transplanted aman rice (T. aman) is the only crop in a year during the monsoon season and no crop is grown during the rest of year in the southwestern (SW) coastal region of Bangladesh. The fallow results from the prolonged post-monsoon (kharif 2) soil saturation, soil and water salinity, as well as the low risk-bearing and investment capacity of resource-poor farmers. In response, we investigated the potential of a rabi season crop, wheat, by establishing the crop in excessive wet soil within the optimum sowing window during 2016-17 and 2017-18. To cultivate wheat, we planned from the kharif 2: cultivation of short duration rice, drainage of land and irrigation with less saline water (electrical conductivity (EC) <3 dS m^-1). By early vacating the land, sowing of wheat seed was possible within the optimum sowing window in excess soil water than that of field capacity. As wheat is a new crop in typical SW region, it was necessary to investigate how wheat responds to early and late sowing in this constraint cropping environment. In 2016-17 season, there were eight sowing dates started from early (November) to late (January). Sowing in relatively wet soil wheat was established in both years. By sowing wheat after 15 December, the grain yield was lower than those of before 15 December. In 2017-18 season, the sowing was very late (four sowing dates) started from after 15 December to early January. The grain yield was poor ranging from 2.72 to 1.34 t ha^-1 which was lower than those of the last four sowings of 2016-17. The cause of poor yield in all sowings in 2017-18 season was mainly delayed sowing as well as some plant and soil factors. With proper crop planning and management of field, wheat could be a potential crop during rabi season for increasing cropping intensity and food security of the country.