Maize growth and changes in soil fertility after irrigation with treated sewage effluent. II. Soil acidity, exchangeable cations, and sulfur, boron, and heavy metals availability

The objective of this research was to study the effects of maize irrigation with secondary-treated sewage effluent (STSE) on soil pH, electrical conductivity (EC), and on the available soil concentrations of calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), aluminum (Al), sulfur (S), boron (B), and of heavy metals and to investigate the plant element accumulation, except for Al. The treatments consisted of mineral fertilization and irrigation with the STSE. After 58 days, maize plants were harvested, and soil and plant were analyzed. The STSE effectively reduced the mineral nitrogen fertilizer soil-acidifying effect, induced increases in the EC, and in the base saturation, and did not significantly alter the available concentrations of S, B, and heavy metals. The STSE irrigation did not affect the shoot S, B, copper (Cu), iron (Fe), and manganese (Mn) contents in plants properly fertilized, but it induced a decrease in shoot zinc (Zn) content. Sodium was the most affected element by the STSE irrigation.