Application of CO₂ enrichment by agricultural wastes composting in greenhouses and its environmental benefits

In the present study, a simple composting unit based on the use of crop residues and animal manure (CRAM) compost was developed to elevate greenhouse CO2 concentrations. Through the methods of fungi inoculation and pH regulation, concentration of CO2 in the composting greenhouse was increased by more than 100% of that in the control greenhouses. Moreover, the release of CO2 from a heap of fermentation in present unit could last nearly 3 weeks. Consequently, the vegetable yields for all vegetable species including celery (Apium graveolens L.), leaf lettuce (Lactuca virosa L.), stem lettuce (Lactvca sativa L.), oily sowthistle (Sonchus oleraceus L.) and Chinese cabbage (Brassica chinensis L.) were increased by 260%, 135%, 115%, 140% and 322%, respectively. Therefore, the use of CRAM compost in greenhouses not only increases farmers' income, but also provides us a new strategy for the disposal of agricultural organic wastes.