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Rice based cropping systems are the most predominantly grown systems in India contributing a major share to India's food grain production. However, systems i.e., rice-rice and rice-wheat brought us second generation sustainability issues over long run. Cowpea being a multi-role legume crop can be considered for the intensification of rice-based system with limited resources and its residue having lower C:N ratio can easily decompose in soil and enhance soil fertility. Following experiment was conducted at Institutional Research Farm, ICAR-National Rice Research Institute, Cuttack, Odisha during kharif, rabi and summer season during 2017-18 and 2018-19. The treatments were laid out in split plot design and consisted of three replications. The main plot consisted of two rice-based cropping systems i.e., rice-maize-cowpea (R-M-C) and rice-groundnut-cowpea (R-G-C), sub-plots consisted of five nutrient and residue management practices i.e., C-C-C, R-R-R, RI+R75-R-R, RI+R75-SM+R-R and RI+R75-SM+R-R50. The pooled value for the season 2017-18 and 2018-19 revealed that, RI+R75-SM+R-R and RI+R75-SM+R-R50 resulted higher yield i.e., pod yield, seed yield, stover yield, HI, nutrient content, nutrient uptake, economic return i.e., gross return, net return and B:C ratio, higher CH4 flux and lower N2O flux than R-R-R. Between two cropping systems, R-M-C cropping system recorded highest yield and is more feasible to take over R-G-C. Among nutrient management, RI+R75-SM+R-R recorded higher growth and yield but due to consistent residue retention and incorporation, even if using 50% of recommended dose of fertilizer in cowpea i.e., RI+R75-SM+R-R50 recorded similar growth, yield, economic return, and even higher B:C ratio than RI+R75-SM+R-R and recommended. Cowpea residue incorporation and 25% reduced dose of chemical fertilizer application in rice crop, rice straw mulch in rabi maize and 50% reduction in chemical fertilizer application in summer cowpea (RI+R75-SM+R-R50) received highest cowpea yield, and economic return and this system-based nutrient management should be recommended in R-M-C cropping system. [ABSTRACT FROM AUTHOR]

Abstract The performance of the solar air collector is experimentally investigated at the climate of North Eastern India. Various governing parameters considered for the present investigation are collector tilt angles (30⁰, 45⁰, and 60°), single and double glazing, mass flow rate (0.0039–0.0118 kg/s) and two different absorber plates (plain and corrugated). Results reveal that double glazing absorber plate always gives better performance both energy and exergy point of view, because of reduction of top loses. Increase in mass flow rate of air enhances the energy efficiency. An overall increment of the efficiency with the increase of mass flow rate and number of glazing is as high as 10.35–17.42%. Use of corrugated plate enhances the energy efficiency by 14%, because of improved turbulence effect and increment of the heat transfer area. The maximum enhancement of exergy efficiency for double glazing collector is 6.867% for mass flow rate 0.0118 kg/s compared to single glazing collector. Corrugated absorber plate show 30Pa higher pressure drop than plain absorber plate. Thermo-hydraulic efficiency is found to deviate by almost 6.35% from the corresponding thermal efficiency. Mass flow rate of air in the range of 0.0078–0.0094 kg/s is found to yield qualitative heat transfer. Highlights • Comparison of flat and corrugated plate solar air collector is presented. • Double glazing reduces losses and increase the thermal efficiency by 6.87%. • Increase in mass flow rate by 3 times results in 6%increase of efficiency. • Corrugated plate provides 14% higher efficiency than flat plate collector. • Mass flow rate of air enhances energy efficiency and reduce exergetic efficiency. [ABSTRACT FROM AUTHOR]