Optimising drip irrigation and fertigation schedules for higher crop and water productivity of oilseed rape (Brassica napus L.)

Abstract

Drip irrigation and fertigation, being advocated for higher crop and water productivity require optimization of irrigation and fertilization schedules. Field experiments were conducted during 2016–2018 to evaluate water and energy-efficient drip irrigation and fertigation schedules for higher productivity and profitability from oilseed rape. The treatments comprised of a combination of three levels of drip irrigation {60, 80 and 100% of cumulative pan-evaporation (CPE)} and three levels of fertigation {60, 80 and 100% recommended dose of fertilizers (RDF)} along with one absolute control (flood irrigation and soil application of RDF). The yields of crop under drip irrigation at 100 and 80% of CPE were statistically similar but significantly higher than irrigation at 60% of CPE. The irrigation use efficiency (IUE) and water use efficiency (WUE) were maximum at 80% of CPE followed by 100 and 60% of CPE. Drip irrigation at 80% of CPE resulted in 18% higher yield along with a water-saving of 35.4% than absolute control. Energy use efficiency (EUE) was higher at 100% of CPE followed by 80 and 60% of CPE. Whereas, energy productivity at 100 and 80% of CPE being statistically similar but significantly higher than 60% of CPE. Highest benefit: cost (B:C) ratio and net returns were obtained with drip irrigation at 100% of CPE and lowest at 60% of CPE. Fertigation at 100 and 80% RDF recorded significantly higher seed yield than 60% RDF and absolute control.