Comparative study on annual yield, water consumption, irrigation water use efficiency and economic benefits of different rice-oilseed rape rotation systems in Central China

Abstract

Direct seeded planting pattern is considered as a practicable substitute to transplanting planting pattern because it has the advantages of saving labor, low input cost, high water use efficiency, and easy to manage. However, the comparison between different direct seeded rice-oilseed rape rotation systems and traditional transplanting rice-transplanting oilseed rape rotation system (TTR-TPO) has rarely been studied. In this study, the annual yield, water consumption, water use efficiency and economic benefits of different rice-oilseed rotation systems were compared during the rice and oilseed rape growing seasons from 2018 to 2020. Our results show that the average annual yield and water consumption of wet direct seeded rice-direct seeded oilseed rape rotation system (WDSR-DSO) and wet direct seeded rice-transplanting oilseed rape rotation system (WDSR-TPO) were significant higher than that of TTR-TPO and TTR-DSO. Annual yield of dry direct seeded rice-direct seeded oilseed rape rotation system (DDSR-DSO) and TTR-TPO was similar, but the water consumption of DDSR-DSO was reduced by 22.6% on an average than that of TTR-TPO. Irrigation water use efficiency (WUEi) and net economic return of DDSR-DSO were the highest, which were 72.3% and 15.2% higher than TTR-TPO, respectively. On the contrary, WUEi and net economic return was similar between WDSR-DSO, WDSR-TPO and TTR-TPO, traditional transplanting rice-direct seeded oilseed rape rotation system (TTR-DSO). Here, we show that DDSR-DSO is an alternative to TTR-TPO in central China due to higher WUEi and net economic return, less water consumption and similar annual yield. In addition, WDSR-DSO and WDSR-TPO may be suitable for regions where water levels are high for soil puddling during land preparation and rainfall is sufficient in the rice growth season.