Rainfall analysis for crop planning for paddy grown in North Bank Plain Zone of Assam

This study was undertaken to analyse the rainfall data for crop planning in three districts (Lakhimpur, Biswanath, and Sonitpur) of the North Bank Plain Zone (NBPZ) of Assam using long-term rainfall data (1991-2020). During the study period, the mean annual rainfall of 3209, 1811, and 1828 mm was observed in Lakhimpur, Biswanath, and Sonitpur, respectively. A non-significant decreasing trend of annual rainfall was observed in Lakhimpur (2.75 mm year-1) and Sonitpur (8.62 mm year-1), while an increasing trend was observed in Biswanath (8.98 mm year-1). In all districts, regardless of probability levels, the maximum and minimum expected rainfall was found between the 26th to 30th and 49th to 2nd SMW, respectively. The expected weekly rainfall during the monsoon season was lower in Biswanath and Sonitpur at all probability levels compared to the Lakhimpur district. Based on the understanding of existing patterns, variability of rainfall, probability of occurrence of rainfall in a period, observed rainfall trends, etc. the contingency crop planning for Sali, Ahu and Boro rice grown in the zone were suggested for the concern districts.