North China's groundwater overexploitation areas launch a battle for agricultural water conservation

In recent years, the groundwater overexploitation situation in North China's groundwater depression areas has become increasingly severe. It is necessary to make good use of rainwater and focus on water conservation, working on planting structure, drought-resistant varieties, and water-saving technologies, to achieve the transformation of agriculture from confrontational agriculture to adaptive agriculture, from passive drought resistance to proactive disaster avoidance

The Agriculture Department of Hebei Province announced recently that Hebei will appropriately reduce the winter wheat planting area relying on groundwater irrigation in areas with severe groundwater overexploitation, changing the winter wheat and summer corn double-cropping system to a single-cropping system, achieving "one season of fallow, one season of rain-fed farming," and tapping the yield-increasing potential of autumn grain when rain and heat occur in the same period. Hebei also stipulates that farmers in project areas who reduce wheat planting will be subsidized at a standard of 500 yuan per mu.

In early September, Beijing also issued a plan designating areas with severe groundwater overexploitation as key control areas, within which high-water-consumption crop planting will be gradually and orderly phased out, and water source conservation functions will be restored by planting trees where suitable, grass where suitable, fruit trees where suitable, and fallowing where suitable; where withdrawal is not yet possible, dryland farming or ecological crops will be developed. According to the policy of "determining industry by water," the water use structure will be adjusted and reduced.

Why did the two provinces and municipalities introduce similar measures in unison? Gao Xiangzhao, Director of the Water Conservation Division of the National Agricultural Technology Extension Center, said that China uses 580 billion cubic meters of water annually, of which agricultural water accounts for 62%. The annual agricultural water shortage exceeds 30 billion cubic meters, and the average water consumption for producing 1 kilogram of grain is as high as 800 kilograms, while the world's advanced level of water consumption is only 500 kilograms. On the one hand, water is unavailable; on the other hand, there is flood irrigation. Under these circumstances, adjusting planting structure by region at the appropriate time and promoting efficient water-saving irrigation actions is an inevitable choice.

"Groundwater overexploitation areas must establish a long-term mechanism for sustainable agricultural development, allowing the land to rest and recuperate, and reducing agricultural groundwater irrigation volume. This reflects the new national strategy for food security, which, while emphasizing grain quantity, pays more attention to agricultural environmental governance and sustainable development." Cheng Guoqiang, a researcher at the Development Research Center of the State Council, said in an interview with an Economic Daily reporter that the plans of Hebei and other places are good measures. This year's Central Document No. 1 proposed for the first time to carry out pilot projects for the recuperation of agricultural resources, and the comprehensive treatment of North China's groundwater overexploitation depression areas was included among them, and it proposed that through comprehensive measures such as fiscal rewards and subsidies and structural adjustment, the overall income level of farmers in restoration areas should be ensured not to decline.

Wheat is the major water user for agricultural irrigation in the north, and it is also the focus of this planting structure adjustment in the two provinces and municipalities. Considering wheat water demand and natural precipitation together: the Jianghuai region is basically balanced in supply and demand; north of the Huai River there is a water shortage of more than 100 millimeters; north of the Yellow River, precipitation can only meet one-third of wheat water demand, and the gap needs to be supplemented by irrigation; the arid region of the northwest mainly relies on irrigation.

Will planting structure adjustment affect food security in the project areas? Before the plan was issued, Hebei had already conducted relevant pilot research. Wang Huijun, President of the Hebei Academy of Agriculture and Forestry Sciences, introduced that from this year's 5,000 mu of wheat fields using micro-irrigation and water-fertilizer integration technology in Wuqiang County, under the premise of stable and increased yields, 70 to 80 tons of water can be saved per mu. If promoted throughout the province, even calculated at 50 tons of water saved per mu, the water saved from the province's 35 million mu of wheat would be equivalent to the water volume that the South-to-North Water Diversion Plan allocates to Hebei.

Beijing, on the basis of clarifying a water use standard of 200 cubic meters per mu of field per year, also uses measures such as installing facilities and increasing agronomic practices to tap the potential of water-saving agriculture and ensure the stable supply of "vegetable basket" products. Beijing has built supporting high-efficiency water-saving irrigation facilities, with different facilities used for different planting structures. For grain fields, advanced water-saving equipment such as mobile sprinkler irrigation and center-pivot sprinkler irrigation and water-fertilizer integration technology are promoted; for vegetable fields, film-mulched irrigation and water-fertilizer integration are the two core water-saving technologies.

In recent years, the scope and degree of drought in China have shown an increasing trend, and the groundwater overexploitation situation in North China's groundwater depression areas has become increasingly severe. Experts believe that it is necessary to conform to the timing of nature and the laws of crop growth, not simply increasing irrigation volume, but striving to synchronize precipitation with crop water demand periods. This requires making good use of rainwater and focusing on water conservation, working on planting structure, drought-resistant varieties, and water-saving technologies, to achieve the transformation of agriculture from confrontational agriculture to adaptive agriculture, from passive drought resistance to proactive disaster avoidance. In addition, good technical measures such as deep plowing, rational fertilization, and intertillage management can effectively increase the soil's water storage and moisture conservation capacity and improve water use efficiency.