Assessing the performance of irrigation and nitrogen fertigation on yield, water use efficiency, nitrogen use efficiency and benefit-cost ratio of onion

The amount of water allotted for agriculture is gradually declining due to rising demands in the industrial and municipal sectors. Reduced water availability affects irrigation, which is the primary necessity for agriculture. As the increasing population and climate change pose new challenges, there is a growing need to boost food production while conserving water resources in agriculture. Drip irrigation is one proposed method that enables to maintenance or even improvement of crop yields by utilizing less amount of water and nutrients. Therefore, the present field study was carried out during the two winter seasons of 2016-17 and 2017-18 in a split-plot design having drip irrigation treatments (60, 80, 100, and 120% CPE) as main plot and nitrogen fertigation treatment (75, 100, 125 and 150 kg/ha) as sub-main plot for onion cultivation. The highest fresh and dry weight of bulb (63.18 and 73.20 g/bulb; 10.90 and 11.04 g/bulb, respectively) as well as marketable bulb yield (285.60 and 301.17 q/ha) were achieved when irrigation water was applied at 100% CPE in combination with nitrogen application @ 125 kg/ha through fertigation, while, the lowest fresh and dry weight of bulb (42.00 and 45.34 g/bulb) along with marketable bulb yield (137.15 and 142.15 q/ha) were observed where the irrigation was given at 60% CPE in combination with 75 kg/ha nitrogen application through fertigation during 2016-17 and 2017-18. However, the highest water use efficiency (59.20 and 60.60 kg/ha/mm) was recorded where the irrigation water was given at 60% CPE through drip. In contrast, the highest nitrogen use efficiency was recorded with the application of 75 kg nitrogen through fertigation (263.53 and 259.80 kg/ha), surpassing the results of other treatments. In conclusion, farmers can get better yields and profitability by adopting drip irrigation at 100% cumulative pan evaporation and 125 kg/ha nitrogen fertigation levels. This study would shed light on the impact of drip irrigation system among the researchers, which could be utilized for further strengthening the drip irrigation system in onion farming.