Effect of chicken manure addition on humification of vegetable waste in composting process composting process

In this paper, melon seedlings (control, CK) were composted aerobically at high temperature with different percentages of chicken manure (25% and 50%). The effect of chicken manure addition on the degradation of lignocellulose and humus and seed germination index during composting was analysed by analysing the temperature, carbon and nitrogen changes, lignocellulose, humus and seed germination index. The experiment was carried out in the laboratory of the Luancheng Agroecosystem Experimental Station of the Chinese Academy of Sciences using a 50 L stainless steel composting reactor. The reactor was equipped with air inlet and outlet ports at the bottom and top of the reactor respectively, and a temperature sensor was built into the reactor and connected to a temperature logger to monitor and record temperature data in real time. The composting experiment was carried out with melon seedlings as the main material and chicken manure as the supplementary material, with the aim of investigating the effect of different chicken manure addition ratios on compost humification. Three treatments were set up: 0% (CK), 25% (CM25) and 50% (CM50) of chicken manure (fresh weight, w/w) were added, and the initial moisture content of each treatment was adjusted to about 60% with water. The material ratios and physicochemical properties of each treatment are shown in Table 2. The compost was turned and sampled at d 0, d 3, d 7, d 14, d 21, d 28 and d 35, and seven samples were collected. One sample was air-dried and sieved through 80 mesh for the determination of organic matter (OM), total nitrogen (TN), lignocellulose (Lce), humus (HS), fulvic acid (FA) and humic acid (HA). The other was stored frozen at -20 °C and the samples were collected for the determination of pH, electrical conductivity (EC), germination index (GI), moisture content (MC), soluble organic carbon (DOC) and water-soluble nitrogen (SN). The compost temperature was measured by a temperature sensor fixed in the centre of the composting tank and recorded automatically every 1 h. The water content was measured by drying at 105 °C. The fresh sample was mixed with distilled water at a ratio of 1:10, shaken for 30 min at room temperature and filtered to obtain the extract. The germination index was determined by adding 10 watercress (Oenanthe javanica) seeds and 10 mL of compost extract to a Petri dish lined with filter paper and incubating the Petri dish at a constant temperature (25 °C) for 48 h to measure germination and root length, while distilled water was used as a blank control, Elementar, Germany) to determine DOC and soluble nitrogen (SN) content. Organic matter (OM) was determined by burning at 550 °C in a muffle furnace and the remaining fraction was determined as ash; total nitrogen (TN) was determined by Kjeldahl method; lignocellulose was determined by paradigm washing; humus (HS) and fractions (HA, FA) were determined by flocculation volumetric method.