Application of a liquid digestate obtained from anaerobic digestion of cow manure on tomato crop (Solanum lycopersicum L.)

Nowadays there are growing problems of soil erosion which demand greater amounts of chemical fertilizers that need petroleum and energy resources to be manufactured. An alternative to reduce the use of fossil fuels and energy to the development of these products, is to make use of organic wastes and subject them to anaerobic digestion (AD). This is a microbial decomposition process that produces biogas and organic fertilizer (digestate) as a byproduct. In this work it was set up a 120 L anaerobic digester, feed with cow manure, designed at 7% dry solids basis (DSB); it was maintained at an average temperature of 25°C during 78 days, the biogas production was monitored. At the end of AD process was determined the phytotoxicity of the liquid fraction of the digestate, and tested its efficiency as a fertilizer in tomato germination and crop. At concentrations lower than 10% the liquid fraction was not phytotoxic for seed germination, applied at 5% in tomato seed germination test the average elongation was higher than that using a commercial organic fertilizer, while applied in foliage at 50% shown the highest yield in the cultivation of tomato, getting 90% more performance than using only water without any other product and 16% more performance than using the commercial fertilizer with a similar production cost. Using anaerobic digestion cow manure could be used to produce organic fertilizer and substitute the use of chemical products in tomato crop, helping to reduce contamination in an environmentally friendly way.