Effect of irrigation water on agricultural soil in Jordan valley: An example from arid area conditions

In Jordan, water rather than land is the determining factor for increasing the size and the productivity of the irrigated areas. Traditional surface irrigation is the general practice and the farmers themselves have been managing their water in terms of distribution and scheduling. The major developments in irrigation started in the 1950s, aiming at integrated rural development of the Jordan Valley, which would utilize Jordan's share of the water resources of the Jordan River System. Currently, irrigation is practiced in two main areas: the Jordan rift valley (JRV) and the Upland. The soil characteristics are subject to continuous changes based on a number of environmental factors. Many types of soil play a large part in classifying the plants into environmental groups. The macronutrients (N, P, K) and some of the heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) have been investigated in soil profiles irrigated by different water qualities. Two agricultural areas were selected for this purpose; one irrigated with fresh water from the Yarmouk River and the other irrigated with treated wastewater from King Talal Dam. In all farms, three trenches (inlet, middle and outlet of the row) were dug in the irrigated area, while in the non-irrigated area one trench was dug as a control. Each trench was 60 cm wide and 60 cm deep. Nine samples from each trench were collected at 20 cm intervals horizontally and vertically, making a total of 486 samples from all farms and control points. The results showed that the concentrations of the heavy metals in the soils from the selected farms lie within the accepted values. The results indicate that there are no adverse impacts of irrigation water for agricultural practices. It was also found that there was an increase in the concentration of nitrogen, potassium and phosphate in most of the selected farms, which reflects the extensive use of fertilizers. An awareness program is highly recommended in order to draw the attention of farmers to this serious problem.