1. Introduction
Soil salinity is defined as the accumulation of salts in the soil (Rengasamy, 2010). Soil salinity is a major environmental catastrophe caused by both natural and anthropogenic reasons (Rapp, 1986). Nearly 20% of all land globally is salinity affected and has raised huge concerns for governments bodies worldwide to introduce timely land reclamation measures (Ringler, Bhaduri, & Lawford, 2013). Land reclamation for salinity affected areas requires timely monitoring of salinity status of soil and its indicators in an efficient manner to curb the causative factors (Vogt et al., 2011). Though not as damaging initially as other hazards like earthquake, volcanic eruption or floods, soil salinity can take a heavy toll on lives in the long run (Dumanski  Samuel Pieri, Christian Agriculture and Agri-Food Canada, 1998).
Today food security is a highly debated topic and with increasing salinity in soil for areas which depend upon artificial irrigation sources, soil salinity is causing stunted plant growth and crop failure at times (García-Tejero, Durán-Zuazo, Muriel-Fernández, & Rodríguez-Pleguezuelo, 2011; Koevoets, Venema, Elzenga, & Testerink, 2016).
Increase in soil salinity causes decrease in moisture intake capacity of plants since their root nodules get blocked by salts (Egamberdieva, Li, Lindström, & Räsänen, 2016; Etehadnia, Waterer, De Jong, & Tanino, 2008; Franzini, Azcón, Ruiz-Lozano, & Aroca, 2019). Moreover, high concentration of salts in water causes reverse osmosis resulting in the wilting of plants causing their perishing(Arora et al., 2018). This in turns affects the crop yield and causes heavy loss to farmers. Salinity in soil happened mainly due to natural causes such as frequent flooding but over the years, unscientific and improper irrigation management(Baig & Shahid, 2014). Figures indicate that the soil salinity has become a highly serious phenomenon. Primary salinity affected areas globally account for 955 M ha and secondary salinity affected areas are some 77 M ha and out of these 58% is irrigated area that shows the major cause of salinity is anthropogenic(Amin, 2004).
Increasing human population and the competition for resources has posed a heavy threat on all-natural resources including water and soil (Cassman, Dobermann, Walters, & Yang, 2003). Since soil supports almost all life on earth, proper management of soil in a scientific way becomes very important (Miltner, Bombach, Schmidt-Brücken, & Kästner, 2012). Salinity can occur out of a number of other factors apart from improper irrigation- engineering problems, soil erosion and soil dispersion(Qadir, Ghafoor, & Murtaza, 2000). For areas with a history of water logging, the soil salinity becomes more acute(Bhutta & Smedema, 2007; Shah, Molden, Sakthivadivel, & Seckler, 2001). The plants intake the moisture leaving behind the dissolved salts in water(Konukcu, Gowing, & Rose, 2006). After a period of time, this salt accumulates around the root nodules making further water intake impossible(Streeter & Wong, 1988). Salinity in soil can be determined by estimating the electrical conductivity of soil(Rhoades, Shouse, Alves, Manteghi, & Lesch, 1990; Rhoades & van Schilfgaarde, 1976). The electrical conductivity measured in milli-siemens per meter is a measure of the ionic concentration of the soil (Susha et al., 2018).
In agriculture science, soil is considered to be saline in conditions when there is sufficient amount of salts dissolved in root zone soil moisture to adversely affect the plant growth (Rengasamy, Chittleborough, & Helyar, 2003). Some studies claim soils to be saline in cases when soil electrical conductivity is more than 4dSm-1 at 25oC (Igartua, Gracia, & Lasa, 1994). Different plants have different tolerance for soil salinity levels beyond which their growth is adversely affected, as shown in Table 1(Xie et al., 2009)-
Table 1 . GENERAL SOIL SALINITY TOLERANCE RATE FOR PLANTS