Contents & Foreword, Characterizing And ... - IRRI books

Appendix. Agroclimatic zones of BiharThe state of Bihar is divided into six agroclimatic zones based on rainfall and temperature, soiltype, and physiographic features: (I) northwest alluvial plains, (2) northeast alluvial plains, (3)south Bihar alluvial plains, (4) central and northeastern plateau, (5) western plateau, and (6)southeastern plateau. Of these, the first three form the segment of the middle Gangetic plains.The climate is dry to moist subhumid and the soil type is heavy-textured sandy loam to clayey,medium acidic. This subzone receives more than 1,200 mm of rainfall annually. The last threeform part of the eastern plateau and hills. The climate of this subzone is moist subhumid tosubhumid and the soil is red sandy, loamy, red, and yellow. It receives a higher rainfall ofaround 1,300–1,400 mm but irrigation development is very poor as only 8% to 10% of thecultivated area is irrigated.The Rajendra Agricultural University, Pusa, however, classified Bihar into four comprehensiveagroclimatic zones: (1) northwest alluvial plain, (2) east alluvial plain, (3) southwestalluvial plain, and (4) plateau region.The selected districts, Samastipur and Patna, come under the northwest alluvial plainand southwest alluvial plain, respectively. The southwest alluvial plain has about 33% of thestate’s total production of rice with around 24% area. The northwest plains contribute about26% to rice production in the state. The east plains contribute about 18%. The rest is contributedby the plateau region. Across different zones, the southwest zone displayed higher yield(1.58 t ha –1 ) than the northwest plains (1.08 t ha –1 ).322 Kumar and Jha