Effects of composts obtained from two different composting methods on organic tomato seedling production

Characteristics of growing medium and nutrition are the major factors affecting the seedling quality. In organic seedling production, those factors become more important due to the limitations in input use. Peat is the most common medium used in organic seedling production. However, it is a non-renewable resource and peat bog exploitation is considered not sustainable over the long terms. The objective of this experiment was to develop a growing medium for organic tomato ('Melis') seedlings with an alternative to 100% peat, using different agricultural wastes as the raw material of compost. Therefore, the mixture containing rose oil processing wastes, separated dairy manure, poultry manure, and straw was composted in (1) aerated static pile and (2) turned windrow composting methods. In the experiments, different rates (0, 25, 50, 75, and 100%) of composts obtained from the two different methods were added to peat which is locally available. Seeds were sown on July 21, 2015. Each treatment had 4 replicates and each replicate included 64 plants. After 3 days in germination room, plants were moved to a PE greenhouse which is specialized for seedling growing. Liquid organic fertilizer was used for fertilization. Some physical and chemical properties of each growing medium, germination rate of seeds and seedling vigor were determined. The effects of growing media in both types on seed germination, shoot fresh and dry weights and dry matter were found statistically different. Among the different ratios of composts, germination period was the longest in 100% compost use and shoot biomass decreased with increasing compost rate. It was concluded that the mixture of 25% of compost, produced with the turned windrow composting method could be a good alternative to 100% peat use in tomato seedling production.