Effect of Sewage Sludge Amended Soil on Maize Crop I. Influence on yield and mineral nutrition

The aim of the present study was to evaluate the efficiency of sewage sludge application on maize (Zea Mays L.) growth, yield and macroelements accumulation (N, P, K, Ca, Mg) when different doses of sewage were applied accompanied by mineral fertilization. The results indicated that sewage sludge fertilization produces significant increase of maize yield that are evident starting with 200 kg N/ha rate, and the highest increases were recorded in the rate of 400 kg N/ ha. The nitrogen content in the maize leaves increased significantly in the variants fertilized with sludge at a rate over 300 kg N/ha, meanwhile the potassium content of the maize leaves was significantly reduced as a result of sludge fertilization at a rate equivalent to 400 kg N/ha. Nitrogen and phosphorus contents in the maize kernels increased with sewage sludge loading, meanwhile in the case of potassium the data showed that there were no statistically significant changes in the potassium content of the maize kernels under the influence of sewage sludge fertilization. The application of sewage sludge caused a significant increase of the calcium and magnesium contents in the maize leaves at equivalent rates higher than 200 kg/N ha.