In order to evaluate the effect of an alkaline sewage sludge (ASS) as a supplement for soil chemical fertilization, an experiment with wheat crop was carried out in greenhouse. The experimental design was a 5 x 5, combining 5 rates of chemical fertilizers (0, 25, 50, 75 and 100% of rates recommended at planting) with 5 rates of dried ASS (0, 2.5, 5.0, 7.5 and 10.0 Mg ha-1). The ASS, applied 20 days before seeding, raised the soil pH above neutral. Base saturation, cation exchange capacity and the contents of P, K, Ca, Cu and Zn were increased by the ASS application, whereas the contents of Mn and H+Al were decreased. The ASS negatively affected the morphological parameters and the dry-matter yield and increased the contents of K, N, Mg, Cu and Zn in wheat plants, whereas the fertilizer application provided opposite results, suggesting the effect of concentration and dilution for the ASS and fertilizer, respectively. The increased soil pH reduced the Mn availability to wheat plants, resulting in crop damage.
alkaline biosolid; soil fertility; pH; micronutrients; yield wheat
