Simulating the effect of different transplanting dates on rice water footprints for different irrigation practices by APSIM-Oryza under changing climate

Abstract:

The changing climatic conditions have already started showing their negative effects on rice water footprints. Therefore, a study of consumptive water footprints of rice under different irrigation methods (i.e. water limited and saturated) with climate change adaptation strategies (i.e. shifting transplanting dates) was conducted to identify the most favourable irrigation method with the most suitable transplanting time during dry season. Kharagpur (eastern India) region was selected as a study area. In this study, historical (1990-2019) and future (2020-2100) climate data were collected from HadGEM3-RA based on RCP8.5 scenario. APSIM 7.10, a water-driven crop model (calibrated and validated with the experimental data) was used for the development of future scenarios under different transplanting dates (i.e. 15^th December, 30^th December, 15^th January, 30^th January and 14^th February). The water-deficit irrigation with early transplanting (i.e. 15^th December) was projected to be capable of reducing consumptive water footprints significantly (p < 0.01) by 38%, 41% and 44% in 2030s, 2060s and 2090s respectively as compared to historical value of saturated practice (1226 m³ t^-1) with existing planting date (i.e. 15^th January). Hence, the study recommended the water-deficit irrigation with early transplanting as the best adaptive measure during dry season under future climatic conditions.

Keywords: APSIM-Oryza, Climate change adaptation, Consumptive water footprint, Transplanting date.