Uncertainty remains over composting time and maturity degree for compost production. The objectives of this study were to establish maturity indicators for composting based on spectral and chemical components and to provide a reference for future composting management. Several indicators of composting were assessed for three commercial composts at 0, 7, 15, 30, 45, and 60 days during the germination of Chinese cabbage, including (1) central temperature, (2) moisture content, (3) pH, (4) electrical conductivity, (5) C/N ratio, (6) E4/E6 ratio, (7) fluorescence humification index (HIX), and (8) germination index (GI). We evaluated the optimal composting time using these indicators, reflecting the changes in hog manure, chicken manure, and agricultural by-product composts throughout their composting process to provide a basis for maturity time. The results showed that the E4/E6 ratio, C/N ratio, humic acid (HA), fulvic acid (FA), and germination rate, which reached a stable status after 30 days of composting, could be the indicators of “early-stage” maturity. In contrast, central temperature, electrical conductivity, HIX, and GI reached stable values after 45 days of composting and thus could be more suitable indicators of full maturity. Based on our results, we recommend a minimum composting time of 30 days to achieve primary maturity, while fully matured compost may be obtained after 45 days.

When the soil at the plant roots is poorly ventilated due to few pores, the root system will grow short and shallow, leading to poor growth. In this paper, we developed a shockwave soil-loosening device. It can first drill a hollow drill bit containing multi-directional holes into the soil near the roots of the crops and then generate high-pressure gas to impact the soil outside the drill bit to increase the soil pores. Therefore, this can quickly improve soil aeration. We conducted numerical simulations of shockwave loosening to explore how 3.4 atm shockwaves are emitted from the drill bit’s porous nozzles and analyze the behavior and efficiency of shockwave loosening. We also performed visual observation experiments of shockwave multi-directional impact in a transparent acrylic water tank. Furthermore, we used eight pressure sensors to automatically measure the range of shockwave impact and found that when the storage tank volume was 5000 cm³, we could achieve a soil loosening range of 30 cm. Finally, this shockwave-loosening mechanism ensures that the soil surface will not be damaged during the loosening process, thus avoiding large-scale tillage disturbance of the soil. This will reduce carbon emissions stored in soil and released into the atmosphere.