New parameters for a better evaluation of vegetative bioremediation, leaching, and phytodesalination

Vegetative bioremediation of calcareous sodic and saline-sodic soils is a biological approach for soil desalination by plants. It is based on three main processes: (i) sodium release from cation exchange sites, (ii) its leaching, and/or (iii) phytodesalination (Na(+) uptake by plant roots and its accumulation in shoots). Leaching needs sufficient rainfall and/or adequate irrigation. Thus, under non-leaching conditions, phytodesalination is the only existing process in terms of sodium removal. Several works tried to evaluate these processes; used plants were grown in field, in lysimeters, or in non-perforated pots. The evaluation of vegetative bioremediation, leaching, and phytodesalination was mainly based on plant analyses (including biomass production, sodium accumulation, test culture, and co-culture) and soil analyses (porosity, salinity, sodicity...). Nevertheless, used parameters are not enough to ensure comparisons between results found in different investigations. The present study introduces new parameters like phytodesalination efficiency, yield, and rate as well as vegetative bioremediation and leaching yields and rates. Our study is also illustrated by an estimation of all parameters for several previously-published data from our own works and those of other authors. Obtained results showed usefulness of these parameters and some of them can be extended to heavy metal phytoexraction.