Biological, Physicochemical, and Spectral Properties of Aerated Compost Extracts: Influence of Aeration Quantity

The goal of this experiment was to investigate the effect of aeration quantity (0, 11, 33, 55, and 77 L·min−1) on the growth of aerated compost extracts from a pig manure–straw compost. When the aeration quantity was 11 L·min−1, lettuce root growth enhancement of normalized compost extracts was at a maximum. As the aeration quantity increased, the total water-soluble organic carbon (TWSOC), total nitrogen (TN), total phosphorus (TP), humic carbon (humic C) content, and humification degree of compost extracts improved gradually. No differences in functional group structure were found among the aerated compost extracts. The positive root growth could be attributed to physicochemical and spectral characteristics, such as TN content, humic substances content, humification, aromaticity, and the low content of carboxyl groups. In conclusion, the aeration quantity of 11 L·min−1 was suitable for the production of aerated compost extracts, which obtained much greater promotion growth.