Estimation of evaporation and soil moisture index based length of growing period for enhanced agricultural production in Bihar

Estimation of length of growing period for a region is an important aspect in understanding agroclimatic potential and avoiding moisture stress during growing season for sustainable crop production. Keeping this in view, an agroclimatic study was carried out for all 38 districts of Bihar to evaluate drought free growing period (DFGP) by following the concept of AE> 0.5 PE and length of growing period (LGP) on the basis of potential soil moisture and soil moisture index (SMI). Historical rainfall data (30 to 55 years) of 110 rain-gauge stations, normal weekly potential evapo-transpiration (PE) and available water holding capacity (AWC) of different soil textural classes were utilized in this study. The onset, cessation and LGP in coarse, medium and fine textured soils for each district of the state were worked out based on SMI > 0.4 and potential soil moisture (SMI >0.7). Thematic maps of onset, cessation and LGP were generated to identify areas having similar crop production potential. The highest LGP was found to prevail in Zone II and the lowest in Zone IIIB. The information generated with respect to DFGP and LGP could prove to be an important guideline in framing district level crop planning under changing climatic condition.