Assessing biomass production of acacia ampliceps using different water salinity levels in entisols under hyperarid conditions of United Arab Emirates

Salinity problem in crop production will become worse in areas with rapidly growing human population and limited water resources, which necessitates the use of saline water for irrigation. Cultivation of salt tolerant perennial trees using saline water is potentially an important strategy to save fresh water resources and maximize the forage yield of small-scale farms in the marginal and saline environments. With the population growth, increased per capita consumption, higher living standards the meat consumption will rise to nearly 73% and dairy consumption 58% by 2050 over current levels. Therefore, livestock numbers are expected to be doubled by 2050, which means 30% more forage would be required to meet this increased demand, which will be major challenge because salinity and fresh water scarcity are becoming major constraints to agricultural productivity, with most of the rangelands already under stress from overgrazing. To exploit alternate forage production systems, a three-year (2014-2016) trial has been conducted on Australian tree ‘Acacia ampliceps’ which has diversified benefits and highly salt tolerant. A. ampliceps have extensive root system and can fix atmospheric nitrogen, survive for many years after establishment and are resilient to high temperatures, salinity and strong winds. The A. ampliceps was grown with and without fertilizer application owing to its leguminous nature (atmospheric nitrogen fixation) to evaluate the difference in biomass production. The trees were irrigated with three water salinity levels (10, 20, 30 dS/m) over three years (2014-2016). The trees were harvested once a year and fresh as well as dry biomass determined to evaluate forage production under salt stress and hyperarid sandy soils ‘Entisols’ environment of United Arab Emirates. Comparison of fresh biomass production with the application of different salinity waters clearly shows that the salinity increase has devastating effect on the reduction of fresh biomass, the highest being with 10 dS/m salinity water and the lowest with 30 dS/m. This reduction is universal with the increase of salinity regardless of whether fertilizer was applied or not. The fresh biomass with 10 dS/m water salinity ranged between 14.49 and 17.64 tons/ha/year compared to the lowest fresh biomass range between 4.80 and 5.96 tons/ha/year with the highest water salinity application (30 dS/m). With 20 dS/m water application fresh biomass ranged between 7.77 and 8.83 tons/ha/year. The results have shown great promise to introduce A. ampliceps in infertile sandy desert soils owing to its adaptability in hot environment and nitrogen fixation capacity to save fertilizers.