Assessing potential water savings in agriculture on the Hai Basin plain, China

The Hai Basin in China exemplifies problems that are observed in many arid environments: excessive water consumption, depletion of aquifers, and damage to eco-systems. Progressively since the 1970s water resources in Hai Basin have been over-exploited, primarily for irrigation, while the water requirements of other sectors have increased. Water tables are falling and outflows to the sea are sporadic and heavily polluted. Current consumption of water in the basin is estimated to exceed the renewable supply from rainfall by 6.25×109m3yr−1. Traditional approaches—improving irrigation efficiency through structural works and on-farm technologies such as drip and sprinkler—have failed to restore a balance. Researchers have investigated various on-farm techniques to reduce consumption, including mulching, zero tillage, deficit irrigation, revised cropping patterns, and improved cultivars. We project the results of such experiments for winter wheat (Triticum aestivum L.), maize (Zea mays L.), and cotton (Gossypium spp.) to basin scale to assess their potential in restoring sustainable water consumption. Widespread adoption of mulching, which is the most promising option for farmers, would reduce the over-consumption by 25% (1.6×109m3yr−1). If water quotas are introduced, forcing a reduction in consumption, current production could be maintained while saving 4.1×109m3yr−1. Ending the remaining over-consumption of 2.15×109m3yr−1 would require reducing grain production by 4–7.8Mtyr−1.