Undesirable Plant Responses with Sewage Irrigation

A farmer using sewage effluent for irrigation is faced with the management problem of an uninterrupted supply of nutrient laden water that may contain toxic heavy metals. The yield and quality of marketable produce can be reduced if moderate levels of nitrogen are applied continuously, especially if the crop is a perennial. Plants can take up many of the minerals in sewage in excess of their needs. The plant becomes either toxic to its consumer or it dies from the mineral toxicity. Heavy metals are the biggest unknowns in the use of sewage effluent for irrigation. Once heavy metals become toxic in the soil solution, they are difficult to remove from the solution. Heavy metals will accumulate in the soil and become toxic unless the source of the heavy metals in the effluent is eliminated.