Irrigation with seawater
The new system will enable people without access to fresh water to irrigate their crops
A new system which allows food crops to be irrigated with seawater will solve global problems of food production, according to researchers at the University of Surrey, UK. “97.5% of the world’s water is salty and not usable for the great majority of agriculture,” says Professor Adel Sharif, team leader. “With this approach, there is no need for investment in genetically modified crops or ongoing treatments for the soil. The technology will be accessible and will genuinely solve the problem for people without access to fresh water for agriculture.”
The low-cost solution, which makes seawater irrigation on a large scale a realistic and sustainable solution to food supply problems, does not require high pressure pumps or expensive distillation units. Instead, the new approach makes use of the natural process of evaporation alongside a membrane designed to retain the impurities in the water, including the salts, allowing only pure water to reach the plants.
The project has built on Professor Sharif’s work on Manipulated Osmosis Desalination (MOD), which is used in Gibraltar and Oman to produce drinking water for human consumption. MOD is currently the leading technology for desalination, reducing energy use by up to 30 per cent compared to conventional desalination plants, chemical consumption and the carbon footprint.
From water rights and desalination treatment processes to community-scale sustainable technology, the University team is continuing to work alongside governments and disaster relief NGOs worldwide to improve water for drinking, sanitation and agriculture.
Date published: January 2012
http://www.new-ag.info/en/news/newsitem.php?a=2403
[NOTE: The Israelis have been working on saltwater irrigation for more than 20 years. bl]
China Experiments Seawater-irrigated Agriculture
Chinese scientists are experimenting on irrigating crops with seawater in vast areas of coastal provinces, in an effort to help feed its huge population bothered by land and a fresh water shortages.
Since early 1990s, almost 300,000 hectares of alkaline land and mudflat stretching along the country’s coastline, covering Shangdong, Hebei, Guangdong and Hainan provinces, have been planting either wheat, rice or oil crops, which is unprecedented around the world.
Like killing two birds with one stone, developing seawater-irrigated agriculture is believed to be a way to create more farmland and lower irrigation cost.
China’s population accounts for one-fifth of the world’s total, but it only has 7 percent of the world’s arable land.
Professor Xia Guangmin with Shandong University estimated that another 40 million hectares of cultivated land, approximately one-third of the total of the land that can be cultivated in China, could be gained if all the alkaline land and beaches across the country can accommodate crops.
If all that extra land can be used for planting crops, 150 million tons of agricultural products could be yielded, about 30 percent of China’s yearly output.
In another aspect, seawater irrigation can mean a lot for China whose per capital possession of fresh water equals only about one-fourth of the world’s average.
Water consumption for agricultural use in China accounts for 70 percent of the nation’s total, and 60 percent of the cultivable land were desperately short of water supply.
According to Professor Xu Zhibin with the Zhanjiang Oceanic University, as much as 300 billion tons of fresh water could be saved, if seawater is used directly to irrigate crops on alkaline land and beaches.
Compared with the technique to turn seawater into fresh water, it would cost only one-thirtieth of the price to bring seawater directly through canals or to plant crops directly in saline soil, suggested Xu.
Since ancient times, almost all agricultural plants have to be irrigated with fresh water. However, with crossbreeding and gene techniques, Chinese scientists have cultivated a group of halophytes capable of living in a saline environment.
A special species of wheat developed by Professor Xia, for example, reported nearly 400 kilograms of yield per mu (1 hectare equals 15 mu) and tastes exactly the same as wheat grown using fresh water.
Employing special techniques like cloning or “pollen canal technique,” scientists in the Chinese Academy of Sciences successfully induced an hereditary element of halophytes into eggplants and pepper and produced special species that can grow in a mudflat.
So far, the experiment is moving forward smoothly from the Yellow River Delta in east China to the Pearl River Delta in south China, where wheat and rice are growing in abundance.
Dongying and Binzhou counties, where seawater was first introduced for irrigation, reported an annual increase of millions of kilograms in agricultural output.
The sterile alkaline land in Guangrao County was no longer a nightmare for local farmers like Li Jianbin, who netted 100,000 yuan per year by planting rice and wheat that was resistant against salt.
A halophyte garden, cultivating some 80 species has been recently set up in Shandong Province. However, scientists predicted that the number of plants capable of using seawater can topple 400.
During the past five years, Chinese agriculture has witnessed marked progress, but the Chinese government still regards it as a major priority to restructure the agricultural structure, increasing farmer’s income and insure food safety.
Science and technology, the Chinese government believed, will be the keystone for progress in the national economy including agriculture.
Now that the technical bottleneck has been conquered, China is very likely to use land irrigated with seawater on a vast scale early next century, said Xu confidently.
http://english.people.com.cn/200012/22/eng20001222_58549.html