MICROBIAL ECOLOGY AND SOIL EVOLUTION. MICROBIAL ECOLOGY AND SOIL EVOLUTION

Purpose: to understand how soil generates and works. Four experimental areas: 1. dust on concrete square, 2. 30 cm of raw construction sand on this same concrete, 3. bare vegetable garden soil, 4. cultured vegetable garden same soil. Two radiation sensors were placed above these areas to measure the incoming (turned up) and departing (turned down) light - pyranometer (305-2800 nm) and pyrgeometer (4500-50000 nm) - from May to September. Temperature sensors were placed in the soil on the surface, at a depth of 0 and 12 and 30 cm. The soil was analyzed at the beginning (April) and at the end (August) of the experiment looking for: pH, totC, OC, totN, Ca, K, Mg and Na. With 3 samples per case, the following control trends were recorded: pH and CO decreased in bare soil, while they increased in the other three cases; total N increased in all cases except in vegetated soil; Ctot/Ntot increased il all cases except in bare soil; Ca increased and K decreased in all cases; Mg decreased in all except sand, while Na increased on cement and sand, and decreased in soil and vegetated soil. Using the primers 16S for bacteria, 18S for Eukaryotes and ITS for fungi, the content in Operational Taxonomic Units of these categories of living organisms clearly distinguishes the dust of the concrete square from the other substrates, which in turn separate along a gradient that goes from sand to bare and cultivated soil. Some organisms prefer dust on concrete (Cyanobacteria and Actinobacteria; Chloroplastida and Stramenipiles), others real garden soil (Chloroflexi and Acidobacteria; Eucaryota, Rhizaria and Amoebozoa; Glomeromycota). The radiative balance is different in the 4 situations, with a shift in the balance towards redder emitted radiation when the complexity of the system increases. The reason for the more advantageous balance in soils with and without vegetation compared to sand and cement is linked to the quantity of water that real soil (vegetable garden soil) can retain in hot periods even when bare