Post-disaster soil salinization recovery production technology achieves results in Hainan

Soil salinization has plagued farmers in Hainan's coastal areas for many years, forcing tracts of land to be abandoned. In 2014, seawater intrusion caused by the super typhoon "Rammasun" turned 16,000 mu of fertile farmland in Luodou Farm and Puqian Town, Wenchang City, Hainan Province into saline-alkali land.

In order to help villagers restore agricultural production as soon as possible, in early 2015, the Hainan Provincial Department of Science and Technology and the Department of Agriculture invested 20 million yuan and jointly launched the "Hainan Cultivated Land Improvement Key Technology Research and Demonstration Science and Technology" project with major research institutions and universities in the province. "Research and Demonstration Promotion of Post-Disaster Recovery Production Technology for Farmland Soil Salinization Caused by Seawater Intrusion" is an important part of it.

Recently, in a field less than 50 meters from the seaside in Tanlan Village, Puqian Town, the reporter saw a vegetable growing vigorously on this saline-alkali land, its emerald green leaves reflecting light under the sun like ice crystals.

"This vegetable is called ice plant, and it can be irrigated with 100% seawater. The ice-crystal-like bubbles are actually salt bubbles," said Duan Ruijun, associate researcher at the Institute of Bioscience of the Chinese Academy of Tropical Agricultural Sciences. Ice plant can be served as a cold dish, stir-fried, or used in soup. Because it contains salt itself, no salt needs to be added during cooking.

Duan Ruijun believes that China's tropical tidal flat land and saline wasteland are vast in area and have many islands, and the cultivation of salt-tolerant vegetables in tropical areas has strong economic and social benefits. By effectively utilizing tropical tidal flat land and saline wasteland, it saves grain fields and freshwater resources, protects the coastal ecological environment of tropical areas, and at the same time supports the agricultural construction and development of South China Sea islands.

In another piece of saline-alkali land in Puqian Town, Professor Jiang Xingyu of the College of Agriculture at Hainan University and his research team successfully grew sweet waxy corn with a yield of more than 800 kg per mu for two consecutive years in farmland intruded by seawater with a salinity of nearly 1%.

"Our salt-resistant technology is easy to learn and use, and the cost is not high, making it suitable for promotion in rural areas," Jiang Xingyu said. Farmers only need to choose sweet waxy corn seeds with relatively strong salt tolerance and soak them in the crop salt-tolerant growth regulator developed by his team, so that during the critical seedling stage the corn can both ensure that it does not lose its own water and absorb water from the soil. The treated salt-tolerant corn emerges uniformly, with thick stems and broad, full leaves. According to estimates, the yield reaches more than 3,000 ears per mu. Calculated at two yuan per kg, farmers can obtain more than 2,000 yuan per mu, with lower costs and higher benefits compared with growing rice.

After two years of effort, researchers from the Institute of Biotechnology of the Chinese Academy of Tropical Agricultural Sciences and the College of Agriculture at Hainan University selected a batch of tropical salt-tolerant crops and successfully trial-planted them in fields, mainly including sea blite, seepweed, ice plant, New Zealand spinach, Gynura divaricata, and New Zealand spinach, and some varieties have already been marketed and sold.

"These salt-tolerant crops can both help desalinate the soil and have economic value," Jiang Xingyu said. Salt-tolerant crops can rapidly increase vegetation coverage in farmland intruded by seawater, reduce soil moisture evaporation, prevent soil salinization from returning, and lower the salt content of the soil surface. At the same time, because they themselves can absorb large amounts of salt from the soil, planting salt-tolerant plants can gradually help desalinate the soil. Reporter Deng Weizhe