Calculating Water Footprint of Rice Production Based on Experimental Data

WU Nan; ZHENG Yalian; LUAN Yajun; GONG Yan; WANG Ziyang; WU Mengyang

doi:10.13522/j.cnki.ggps.2017.11.004

Abstract：Traditional methods for calculating water footprint (WF) of crop production areusually based on esti-mation, giving rise to uncertainties. This paper proposed a direct methodto calculate WF based on the data mea-sured from rice growing in lysimeters in attempts to improve its accuracy. The blue-green water footprint (BG-WF) of the rice was first calculated from water balance and the gray water footprint (GWF) was calculated using the nitrogen and phosphorus concentrationsmeasured fromall drains. We then applied the methods to four scenari-os: frequent and shallow irrigation (FSI), wet irrigation (WI), controlled irrigation (CK) and rain-catching and controlled irrigation (RCCI). The results showed that the BGWF of the paddy field varied with time in increase-decrease-increase-decrease, peaking at jointing-booting stage (J).The BGWF appeared predominantly in the re-turning green stage (R) and the earlytillering stage (Te) due to fertigation and precipitation. The overallwater foot-prints changed with time in increase-decrease-increase-decrease over the growth season, higher at early tillering stage. BGWF was higher than GWF during R and Te stages, while the opposite was true during other stages. Overall, the BGWF and GWF were457.3~548.3 mm and 214.3~511.9 mm respectively, affected significantly by how the rice was irrigated (P<0.05). The proposed method for calculating water footprints based on the data measured from the experiment is more accurate and reliable than other methods.