In this study, we used hydrothermal reactions to produce liquid manure from crop residues, thereby effectively utilizing biomass, and investigated the influence of raw material properties on the liquid manure. Three types of residues were used: dried sugarcane leaves, broad bean stems and leaves, and discarded pak-choi (Chinese cabbage). Each sample was adjusted to a 1:20 dry-weight-to-water weight ratio (kg) and heated at 170 ℃ at 0.7 MPa for 30 min in a hydrothermal reactor. The reaction products were filtered through 2-mm mesh to obtain a filtrate that could be used as liquid manure. The quantity and composition of nutrients and organic acids in the filtrate differed among the materials. Differences in the carbon migration rate might be a result of different quantities of neutral detergent fiber (NDF) in the materials. Differences in inorganic nitrogen and organic acid composition in the filtrate might be due to differences in nutrient contents of the starting materials. Germination experiments were also performed. Mesh filtrates from broad bean stems and leaves and pak-choi inhibited root growth of Japanese mustard spinach, but filtrate from dried sugarcane leaves did not. These findings suggest that the influence of liquid manures on plant growth differs according to the materials used to produce the filtrate. For mesh filtrate to be used as liquid manure, the mechanisms by which different residues inhibit root growth must be determined.
