2017 ASHS Annual Conference

Fermented liquid fertilizers (FLF) is a term for plant growth promoters made of fermented organic material. Fermented foliar fertilizers nourish crops directly. They can be distinguished from bio-fertilizers (based on live and latent microbial cell) that provide plant growth and resistance releasing substances that essentially enhance the soil activity. Since FLF can be produced on-farm, their use is a contribution to increase both the environmental and economic sustainability in horticultural production. The composition of FLF is not specified, but depends on available resources and on the cropped plants. In Piedras Blancas, central Mexico, in 2016, an experiment was carried out to assess the impact of four differently composed FLF (named B1, B2, B3, B4), entirely made of locally available resources, on the output and vegetative growth of fava bean (Vicia faba L.). All crop management was organic. The fava bean was intercropped with corn (Zea mays L.) and squash (Cucurbita argyrosperma C.Huber). After an initial irrigation, the crop was only rainfed. 10 t ha^-1 composted cow manure were applied before seeding. Apart from other ingredients, B1 was made of cow manure, unrefined brown sugar and maize stalks; B2 of cow manure, oat bran, and fermented agave cactus juice (pulque); B3 of stinging nettle, cow manure, and unrefined brown sugar; and B4 of chicken dung, milk, and fruit waste. The four FLF were fermented for 60 days in an airtight container with an airlock. They were compared with a solid fermented organic fertilizer (bokashi) and a control treatment. The diluted FLF were applied as a foliar spray. Results revealed a positive yield response to the foliar application of B3, which provided a total yield of 1742 kg ha^-1. In contrast, B1 underperformed the control treatment. All other treatments did not result in significant yield differences compared to the control one. Regarding vegetative growth, most variables did not indicate different responses to the respective plant nutrition management. One exception is the number of leaves, which was highest in B2, followed by B3. In this single experiment, it was proved that FLF mainly made of stinging nettle and cow manure have a positive impact on the yield of fava beans. Identifying the adequate composition of a FLF for a particular region and crop, helps the horticulturist to save money and time and leads to products that are compliant with the norms of organic farming.