Rice straw incorporation: its impact on potassium supply and soil fertility in rice-rice cropping pattern in saline areas of Bangladesh

This study carried out to investigate the bestowed of potassium (K) from rice straw and its higher use in rice production at southern coastal saline region of Bangladesh during July-October, 2018 and January May, 2019. The different dose of potassium fertilizers were the treatments with rice straw. Saline tolerant rice variety Binadhan-8 used as test crop and six treatments designed for the study. The different treatments expressed significant difference among the treatments due to the different K fertilization along with the rice straw incorporation. The rice straw incorporation recovered the reduced K fertilizer in which higher amount of rice straw added. Treatments T-4 and T-6 receive same amount of K fertilizer but amount of rice straw addition different. The highest grain yield produced from treatment T-6, which was 75% K fertilizer with 2.5 t ha(-1) rice straw incorporation revealed higher amount of K was available from rice straw mineralization. In fact, there were positive trend changes occurs in soil pH, Om, N, P S contents and K content has very noticeable change observed due to the rice straw addition although some portion of chemical fertilizer was reduced as well as one year cultivation. Rice straw can supply K that can reduce chemical fertilizer as well as increase organic matter and reduce adverse effect of salinity to some extent.