Wastewater Irrigation-Sourced Plant Nutrition: Concerns and Prospects

Abstract

Since the beginning of industrialization, huge changes have occurred in the critical elemental balance on earth’s surface. Chemical fertilizers, pesticides, insecticides, and wastewater application have contributed towards the unwanted addition of salt, pathogen, and heavy metals in the soil which may be taken up by the plants or may remain in the soil for a long period of time or may be leached to the groundwater. Untreated wastewater-sourced nutrition has huge concerns among global community due to toxic limits of organic and inorganic pollutants present in it. Few nutrients (Fe, Mo, Mn, Zn, Cu, Ni), though plant micronutrients, might also exceed safe limits in wastewater causing threat for human food quality. Application of untreated wastewater could be an unattended source for these metals becoming a blessing for hyper-accumulators and a curse for the rest of crop species. Once taken up, these excess metals can be accumulated into edible crop plant tissue leading to high health risks for humans upon consumption. Physical cleansing, reverse osmosis, phytoremediation, and filtration can be used to cope with excessive metal concentration. This chapter is an effort to summarize the wastewater being used for irrigation worldwide, and its characterization, use, and impacts on plant metal accumulation. Moreover, use of organic and inorganic amendments is also discussed to ensure safe amount of micronutrient delivery into soil-plant-human system. Finally, the major areas which need future concentration are discussed.