Evaluation of chard yield using digestate

In Mexico manure is in most of the cases, collected and stores outdoor, this produce contamination in soil and water. We explored the anaerobic digestion of cow manure to produce digestate, the final effluent of the digestion process. Digestions was done at 7 % solids during two months, every three weeks was measured pH, electrical conductivity, methane content in biogas and germination index using lettuce seeds. After two months the effluent was filtered and we tested the liquid as chard fertilizer.

We use 30 chard plants (Beta vulgaris var cycla) for each treatment, one treatment was watered weekly with the liquid fertilizer, second treatment was prepared adding 30% compost and the third treatment was only watered with water (control). Soil used was form Tlaxcala, Mexico. After two months we measured the aerial elongation and weight biomass and root.

Soil from Tlaxcala has a pH=5.2, this value was no recommended for chard yield, because this kind of plants need pH in soil from 6.0 to 7.5; by this reason plants in control had a low growth. Plants in treatment with compost improve a little the growth, and plants watered with liquid fertilizer growth very well, the aerial biomass and root were the longest.  This is an interesting result that digestate produced with cow manure could be used even in acid soil and help to improve the yield like in the case of chard.