Effect of biological sludge and polyacrylamide on improvement of top soil aggregation in typic calcixerepts of Karkaj, Iran

Based on different studies, organic conditioners either natural or synthetic increase the biological activity of soil in order to improve soil condition. This research aimed to reveal the change in soil after using polyacrylamide and biological sludge in two rates (0.25, 0.5 gram per kilogram soil polyacrylamide and 1.7, 3.4 gram per kilogram soil biological soil sludge) and incubation times (30 and 180 days) in comparison with control. Obtained results from thin sections using polarized microscope illustrated salient alteration in aggregation and structure. Polyacrylamide in first application rate and in first incubation time made an improvement in soil aggregation with moderately developed aggregates, while second incubation time results illustrated moderately and highly developed aggregates. Structure occurred during the application approaches, the granular structure in early stage of formation and biological sludge has made remarkable improvement in aggregation just in first application rate and incubation time.