With its arid desert landscape burnt by bright sunshine, the UAE is not the easiest place to grow crops. But scientists in Dubai believe that they can transform barren areas into green fields, and are beginning trials that could be a major step towards that goal. After several years of detailed analysis at the International Centre for Biosaline Agriculture and in small-scale farm experiments, work is starting to show how various types of pearl millet, sorghum and buffel grass perform in the UAE.
They are being looked at as potential "forage crops" to feed to the country's 10,000-strong herd of dairy cattle. The researchers aim to find which types of each plant can best cope with the country's highly saline water. "The grasses grown here require a lot of water," said Dr Nanduri Rao, a plant genetic resources scientist at the centre. "Since there's a scarcity of fresh water, we are looking into alternative forage crops that are salt-tolerant. We want to be sure they perform well in fields, so we're doing a number of trials involving farmers."
Smaller trials have been going on for eight years with forage crops such as barley, pearl millet, sorghum, buffel grass, and triticale, which is a cross between wheat and rye. The centre has screened nearly 1,000 types of pearl millet. Of these, just 20 or so were found to grow well in salty water, with one third the salinity of seawater. About 40 types of barley have been selected, from an initial list of 2,400.
Once the scientists have completed three years of large-scale trials, they hope to select a handful of varieties of each plant. Work will then begin to find the best way of planting them, and what pattern of irrigation yields the best crop. "The most interesting is pearl millet," Dr Rao said. "It's highly productive in terms of yield per unit. It's not as salt-tolerant as barley but it can be grown in mildly [salty] water.
"Pearl millet can be grown throughout the year and it's one of the most heat-tolerant crops. It's got very good prospects in several countries." Dr Nurul Akhand, an irrigation management scientist at the centre, said buffel grass, which is native to this part of the Arabian Peninsula, is also promising. "It's a wild plant and it's highly productive and salt-tolerant, but it's never been tested as a forage crop," he said.
Barley is very salt-tolerant, but only one crop can be grown a year. Some other crops can be grown and harvested up to three times a year. Salt-tolerance is important because groundwater in the UAE is very saline up to 10 times as salty as drinking water. "In the UAE, the question is freshwater availability," Dr Rao said. "So you need to have crops that consume less water and are equally productive."
Salinity is increasing for a number of reasons, including over-extraction of groundwater, which allows seawater to take its place. Irrigation of land for farming also leads to a build-up of salt. Currently, to feed dairy cattle here, thousands of tonnes of alfalfa - which is mixed with wheat, cotton seed, soybean meal, molasses, canola meal and ground maize - are imported each month. Many farmers also grow a plant native to Africa, Rhodes grass. However, this consumes three to four times as much water as pearl millet or barley.
Finding the best forage crops is not just about which plant species grow the best. The consumers - the animals - have to give their verdict, too. "We have to see whether the animals like them and whether there are any adverse effects," Dr Rao said. It also had to have nutritional value, he said, otherwise "there's no point feeding it to the cows". Changing which crops farmers grow in the UAE would be about more than demonstrating the agricultural benefits of certain species, Dr Rao said.
Subsidies that encouraged the water-hungry Rhodes grass to be grown might have to be rethought, and attitudes would have to change. "Farmers are very conservative," Dr Rao said. "Even if you find something very good, it's a slow process to take this to the scale to replace something." @Email:firstname.lastname@example.org