Huang Fenghong of the Chinese Academy of Agricultural Sciences inspects combined soybean and corn planted on saline-alkaline land at the Agricultural High-tech Industry Demonstration Area of the Yellow River Delta in Dongying, Shandong province. ZHAO YIMENG/CHINA DAILY

The greater use of previously nonproductive land will help raise production levels and ensure the nation's food security. Zhao Yimeng reports from Dongying, Shandong.

In mid-July, soybean and corn that had been planted together were growing well on farmland at a demonstration area in Dongying, Shandong province. Meanwhile, a large number of freshly harvested potatoes were spread out on the porous, fast-draining soil.

Those results were not easy to achieve because 80 percent of the soil in the Agricultural High-tech Industry Demonstration Area of the Yellow River Delta in Dongying has high levels of salinity and alkalinity as a result of coastal erosion and high saltwater saturation. Those conditions inhibit crop growth and result in lower plant biomass.

In recent years, a wide variety of high-yield saline－and alkaline-tolerant crops have been grown on such soil through environmentally friendly land use and innovations in the seed industry.

From managing the soil to make it suitable for plant cultivation to breeding crop varieties that can tolerate saline-alkaline soils, the demonstration area is adapting its strategy to increase farmland yields in a more environmentally friendly way.

Experts inspect tobacco planted on saline-alkaline land in the demonstration area in Dongying. ZHAO YIMENG/CHINA DAILY

In the same month, the area's soybean yield reached 3.5 metric tons per hectare, a record high on the "white land"－as it was dubbed by local people because of the high salt content that left a distinctive "frost" on the top layer of the soil－that once produced no more than 2.2 tons per hectare.

The soybean variety will soon be promoted in the provinces of Hebei, Henan and Anhui, covering 2,333 hectares of farmland.

The No 1 Central Document for 2022－the first policy statement released by the central authorities every year as an indicator of policy tools for work in rural areas－underscored the rising production capacities of soybeans and oil crops and ordered that the demonstration planting of soybeans should be launched on saline-alkaline soils.

Wang Jingshan, a professor at Qingdao Agricultural University, said her team has created 10 new saline-tolerant varieties of peanuts in Dongying, including one with high oil content, at the same time.

Sixty-eight percent of the edible oils used in China are imported. "So, when promoting new peanut varieties on saline-alkaline soils it is very important to use salty land and raise the production capacity of peanut oil. This is important for ensuring the national security of edible oils," Wang said.

Meanwhile, the Ministry of Agriculture and Rural Affairs said one-third of China's 100 million hectares of saline-alkaline land has the potential to enable increased grain production and ensure national food security.

A soybean-corn combined planting belt is seen in the area. ZHAO YIMENG/CHINA DAILY

Production potential

Li Yuyi, chief scientist of saline-alkaline soil improvement at the Chinese Academy of Agricultural Sciences, said that although the area of salty land is included in calculations of the country's total arable land, its production capacity is only about half that of more-productive farmland.

"These soils have great potential to increase the level of grain production," Li said.

He added that the traditional way of managing the soil through water conservation projects poses environmental challenges because it wastes large amounts of water.

Saving water, controlling the salt content and ensuring adequate fertilization are the keys to using the soil in an environmentally friendly way. Instead of disturbing the ecosystem by saturating salty soil, the precise irrigation and water-saving facilities can control salt levels while saving water, he added.

"Now, we are working on qualified use of the soils and studying suitable crop varieties planted on saline-alkaline land," Li said.

Researchers pack seeds at the quinoa germplasm resource bank in the demonstration zone in Dongying. ZHAO YIMENG/CHINA DAILY

The research team has learned how to raise the yields of grain and oil crops planted on mildly saline soil. In such conditions, salt-tolerant forage crops, such as alfalfa, can be planted to aid animal husbandry processes.

"There is no need to grow grain on severely saline soil at high cost. Instead, we can grow some local plants, such as sword-leaf dogbane, which can be used as a source of medicines," Li said, adding that the active ingredients in the plants can be applied to cosmetics and health products.

Li Yiqiang, an official with the Tobacco Research Institute at CAAS, said their marine agriculture center has discovered tobacco plants with outstanding tolerance of saline.

Since the center was established in 2015 to study special plants' adaptation to saline-alkaline soils and the comprehensive use and improvement of such land, it has assessed the saline tolerance of nearly 100 plant species, including tobacco.

"It turns out that tobacco is one of the few plant species that can be cultivated in severely saline soil," Li Yiqiang said, adding that most varieties can tolerate soil with a salt content of about nine parts per 1,000.

This year, the center tried for the first time to conduct large-scale experiments of planting different varieties of tobacco on saline-alkaline land and also explored multiple uses of the crop.

People plant sea rice seedlings at the Chengyang Saline-Alkaline Land Rice Improvement Demonstration Base in Qingdao, Shandong. ZHANG JINGANG/FOR CHINA DAILY

Though the crops planted in the area so far have mainly been used for experiments rather than as materials for cigarettes, regular cultivation of tobacco has contributed to poverty alleviation in remote areas, Li Yiqiang said.

Tobacco cultivation on saline-alkaline land will not only use the land efficiently, but also produce tobacco without occupying arable land used for grain production. Pests are the biggest enemy of tobacco leaves growing on the soil, so prevention and control is one of the biggest challenges faced by agronomists.

"Profusely growing weeds on saline-alkaline soil provide pests with a good habitat and may trigger outbreaks. We have to check the tobacco leaves frequently and treat the pest bites and other wounds in time," Li Yiqiang said. He added that a regular task is to ensure that the lure lamps used to control pests are not blown away by strong winds on the saline-alkaline land.

"Currently, the multifunctional tobaccos we have tested on the saline-alkaline soil in the demonstration area are growing well, so they will be harvested and cured. Evaluations of different tobacco leaves will follow," he noted.