Evaluation of Compost and Biochar as Partial Substitutes of Peat in Growing Media and Their Influence in Microbial Counts, Enzyme Activity and Lactuca sativa L. Seedling Growth

Abstract

The main organic input for the elaboration of growing media is peat (Sphagnum spp.), due to its physical and chemical characteristics. However, the mining of this material creates a considerable impact in the local ecosystems from which this is obtained, along with a global impact because of the emission of greenhouse gasses. Thus, sustainable materials that can replace, or reduce the use of peat, while maintaining or improving attributes in the growing media and plant growth, are greatly needed. Therefore, this work aims to evaluate the effects of the use of different proportions of compost and biochar on the biological characteristics of growing media and (Lactuca sativa L.) seedling growth prior to transplanting. Out of the biological variables evaluated, the beta-glucosidase activity showed the greatest results in growing media based on 80% peat and based on 70% peat, 5% compost and 5% biochar. Moreover, growing media based on the combination of compost, biochar and peat maintained most of the Lactuca sativa L. (Oak Leaf variety) seedling traits obtained in the growing media based on only peat. These findings emphasize the need to further investigate further biological conditions for alternative materials to peat, and the need to pay attention to feedstock initial characteristics and processing in order to obtain high quality organic inputs for optimum growing media.