Evaluation of grey water footprint of grain production in Hetao Irrigation District, Inner Moreongolia

Abstract: As non-point source pollution and salinization being the important environmental pollution source that affects food security, the evaluation and quantification of such negative effects on agricultural production become the urgent eco-environment issues need to be solved. It is possible to quantify the negative effects of agricultural production because of the foundation of Water Footprint Theory. Water footprint contains blue water footprint, green water footprint and grey water footprint. Grey water footprint(GWF) can represents the value of different types of negative effects, of which the GWF of grain production represents the negative effect of per unit grain production. In the study, water footprint theory is used and Hetao irrigation district in Inner Mongolia was employed as the study area. The calculation method of the grain production GWF were given and the parameters of maximum environmental allowable concentration(Cmax) and background concentration(Cnat) were selected. Each kind of GWF was calculated Item by item, and the total GWF was computed using the Cask Theory, so the GWF of grain production was calculated and analyzed. The results showed that the GWF of non-point source pollution was 0.55-0.58×108m3 during the period of 2005-2008. The GWF of salification was 4.570×108m3 in 2005 and decreased to 1.825×108m3 in 2008. The total GWF was declined from 5.872×108m3 in 2006 to 1.825×108m3 in 2008. In year of 2005-2008, the total GWF was less than 10% of total water footprint, and showed a slightly decline tend along the years. The GWF of grain production from year of 2005 to 2008 was 0.129 m3/kg, 0.159 m3/kg, 0.062 m3/kg and 0.043 m3/kg, respectively. In general, the GWF of grain production showed declining tend, which in 2008 was only equivalent to 27.04% of that in 2006. The extension of new agricultural technologies such as water-saving irrigation was the main reason, water-saving irrigation significantly reduce GWF of grain production by decreasing ineffective irrigation and invalid moisture evaporation. Based on these, the measures, including water saving, cropping structure adjustment, reasonably determination of ground water level and reasonable utilization of fertilizers and pesticides, are recommended for reducing the GWF of grain production. The negative effects of environmental issues on food production and GWF of grain production in large-scale irrigation area are quantified preferably. The results can offer a valuable reference for the agricultural sustainable development and formulating agricultural industry policy for other similar grain- producing regions.