Agriculture with Brackish Water

Thursday, December 08, 2016 3:11 PM

Creating a bittersweet cocktail

Brackish water is water that has more salinity than fresh water, but not as much as seawater. In Israel, it occurs mainly in brackish fossil aquifers. Israel's Negev and Arava desert regions lack freshwater sources, but they do have underground acquifiers with brackish water. KKL-JNF, with the help of its Friends worldwide, supports research carried out at the Negev and Arava R&D stations that enable farmers to grow crops using brackish water. The two main solutions for using brackish water for agriculture include cultivating plants that thrive on brackish water, and diluting brackish water with desalinated water.

What is brackish water?

Brackish water is water that has more salinity than fresh water, but not as much as seawater. In Israel, it occurs mainly in brackish fossil aquifers. Technically, brackish water contains between 0.5 and 30 grams of salt per liter—more often expressed as 0.5 to 30 parts per thousand (ppt or ‰), which is a specific gravity of between 1.005 and 1.010. Thus, brackish covers a range of salinity regimes and is not considered a precisely defined condition.

Although Israel’s Negev Desert lacks any major freshwater sources, there are a number of underground brackish water aquifers whose water is accessible by drilling. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it is damaging to the environment. However, “necessity is the mother of invention”, and thanks to KKL-JNF’s support of agricultural research and development, scientists in Israel have invented internationally acclaimed methods of transforming brackish water from a “liability into an asset”, in the words of Itzik Moshe, KKL-JNF Southern Region Deputy Director.

Brackish Water at Ramat Hanegev

Studies conducted at the Ramat Hanegev Research and Development Station, which is supported by friends of KKL-JNF from Italy, have turned farming with brackish water into an essential component of agriculture in this arid region. According to Ziyon Shemer, director of the R&D station, there are two primary ways of using brackish water for agriculture. The first would be direct irrigation with brackish water of those crops that can thrive on its special qualities, for example, olive tree groves. Barnea is the name of a type of olive developed by local scientists that actually loves brackish water.

The second usage is for diluting desalinated water. The present source of almost all of the freshwater in this region are the desalination plants located on Israel’s coastal plain, which have radically changed Israel’s dependence on nature for its water needs. However, desalinated water is void of any minerals whatsoever, minerals that are critical for the growth of fruits of vegetables. By mixing a minimum of 15% of brackish water with desalinated water, essential minerals such as sulfur, magnesium and calcium are reinstated, and the newly-created “cocktail” is perfect for growing various crops.

Today, all Ramat Hanegev farmers have a “management junction” – two sources of water, brackish and fresh, and a means of combining them in the way most beneficial for any particular crop at any given time. And in fact, different crops like different combinations of brackish and sweet water – for example, just becoming ripe for picking, cherry tomatoes like 60% brackish water and 40% fresh water. Brackish water makes the cherry tomatoes tastier, smaller and also increases the percentage of antioxidants.

One of the greatest advantages of brackish water for farmers is its relatively low cost. The price of fresh water is ILS 2.50 per cubic meter, while brackish water costs only ILS 1.00 per cubic meter. However, as Ziyon Shemer points out, it’s not so simple. At the present time, Israel actually has a surplus of desalinated water that the government is obligated by contract to sell, so the state prefers that farmers buy expensive desalinated water rather than investing in costly water drills. The fact that no crops will thrive in desalinated water if its mineral content is not replenished doesn’t always interest government officials.

“I don’t think there is a data base of know-how for the usage of brackish water similar to ours anywhere in the world,” Ziyon Shemer says. “Countries around the world ask us to share our discoveries with them. Many countries are confronted by the problem of water scarcity. Thanks to KKL-JNF’s financial support for our research, we can share our findings with both local farmers and also with professionals from abroad free of cost.”

Arava Agriculture and Brackish Water

The Arava region in the Negev is further away from an urban center than any other region in Israel. As a result, there is a severe water problem here. Desalinated water is not piped to the Arava as it is to the Ramat Hanegev region, so brackish water wells are all there is in terms of local water sources. Since, as previously noted, brackish water alone is usually not healthy for most plants, it must be mixed with fresh water. As a result, a number of farmers have installed scaled-down desalination plants on their property or in partnership with other farmers. These installations are costly, and there is a very real problem of what to do with the brine that is a by-product of the desalination process.

Researchers at the Central Arava R&D Station are working on how to deal with this and other challenges, although it is clear that there must be a steady supply of fresh water to this region in order for agriculture in the Arava to survive. 

One of the solutions to the Arava’s water scarcity problem is the reservoirs that KKL-JNF has built in this region.

Installations such as the Zukim and Hatzeva Reservoirs were built to store floodwater, and Mekorot, Israel’s national water company, installed equipment that mixes water from the reservoir with local brackish water for agricultural purposes. This water is used to
irrigate the agricultural fields of nearby Moshav Hatzeva. When the reservoir is full, additional water continues flowing down the channel and is collected in two additional reservoirs -the Idan reservoir and the Ne’ot Temarim reservoir -and is used to irrigate the fields of the Sedom Plain. These three reservoirs also supply water for supplementing the groundwater.

KKL-JNF Southern Region Deputy Director Itzik Moshe adds that brackish water can also be used to water plants that grace public spaces. “KKL-JNF supports research that is open to exploring different and sometimes unexpected directions. We must remember that things change over time, so situations have to constantly be revisited and reconsidered. For example, KKL-JNF funded an experiment in which fish were raised in a brackish water reservoir at a Negev kibbutz. The kibbutz decided not to continue the experiment, so the brackish water was rechanneled to the kibbutz’s jojoba plantation. Since KKL-JNF is a non-profit organization, we can finance research that learns by trial and error. Water is life. This is our contribution to making agriculture and life in the Arava possible.”