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 cone 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 realize the transformation of agriculture from confrontational agriculture to adaptive agriculture, and from passive drought relief to proactive disaster avoidance

The Agriculture Department of Hebei Province announced recently that Hebei will appropriately reduce the winter wheat planting area that relies on groundwater irrigation in areas of severe groundwater overexploitation, changing the winter wheat and summer corn double-cropping system to a single-cropping system, realizing “one season of fallow, one season of rain-fed farming”, and tapping the yield-increasing potential of autumn grain with its concurrent rain and heat. Hebei also stipulates that farmers in the 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 of severe groundwater overexploitation as key control areas, in which high-water-consumption crop planting will be gradually and orderly phased out, and the water conservation function will be restored by planting trees where suitable, grass where suitable, fruit trees where suitable, and leaving land fallow where suitable; where withdrawal is not yet possible, dryland farming or ecological crops will be developed. According to the policy of “determining production by water”, the water-use structure will be adjusted downward.

Why did the two provinces and municipalities launch 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 each year, of which agricultural water accounts for 62%. The annual shortfall in agricultural water exceeds 300 billion cubic meters, and producing 1 kg of grain consumes as much as 800 kg of water on average, while the world's advanced level of consumption is only 500 kg. On the one hand, there is not enough water to use; on the other hand, there is flood irrigation. Under these circumstances, adjusting the planting structure by region at the appropriate time and advancing efficient water-saving irrigation actions is an inevitable choice.

“Areas of groundwater overexploitation must establish a long-term mechanism for sustainable agricultural development, let the land rest and recuperate, and reduce the amount of groundwater irrigation for agriculture. 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 a good measure. This year's No. 1 Central Document proposed for the first time to carry out pilot projects for the recuperation of agricultural resources, among which comprehensive governance of the North China groundwater overexploitation depression cone areas is included, and proposed that through comprehensive measures such as fiscal rewards and subsidies and structural adjustment, the overall income level of farmers in the restoration areas should be ensured not to decline.

Wheat is the largest water user in northern agricultural irrigation and 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 in balance between supply and demand; north of the Huai River there is a water shortage of more than 100 mm; 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 the adjustment of planting structure affect food security in the project areas? Before the plan was issued, Hebei had already carried out relevant pilot surveys. Wang Huijun, president of the Hebei Academy of Agriculture and Forestry Sciences, introduced that from this year's 5,000 mu of wheat fields in Wuqiang County using micro-irrigation and water-fertilizer integration technology, on the premise of stable or increased yields, 70 to 80 tons of water can be saved per mu. If promoted across the province, even calculating 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 open field each year, also uses measures such as installing facilities and enhancing agronomy to tap the potential of water-saving agriculture and ensure the stable supply of “vegetable basket” products. Beijing is building supporting efficient water-saving irrigation facilities, with different facilities used for different planting structures. In grain fields, advanced water-saving equipment such as mobile sprinkler irrigation and center-pivot sprinkler irrigation and water-fertilizer integration technology are promoted; in vegetable fields, the two water-saving technologies of mulched irrigation and water-fertilizer integration are the core.

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 cone areas has become increasingly severe. Experts believe that it is necessary to comply with the timing of nature and the growth patterns of crops, not simply increasing the amount of irrigation, but striving to synchronize precipitation with the crop water demand period. This requires making good use of rainwater and focusing on water conservation, working on planting structure, drought-resistant varieties and water-saving technologies, to realize the transformation of agriculture from confrontational agriculture to adaptive agriculture, and from passive drought relief to proactive disaster avoidance. In addition, good technical measures such as deep plowing, rational fertilization and intertillage management can effectively increase the soil's capacity to store water and preserve moisture, and improve water use efficiency.