Effect of a culture of “native” micro-organisms, biochar and biodigester effluent on the growth of maize in acid soils

Lylian Rodríguez, Patricia Salazar and T R Preston 

Finca Ecológica TOSOLY, AA48 Socorro, Colombia
lylianr@utafoundation.org

Abstract

A biotest under farm conditions, with maize as the indicator plant, was used to evaluate three additives with potential to ameliorate soil fertility and health: biochar (the residue from gasification of sugar cane bagasse), NM (a culture of native micro-organisms derived from fertile soils on the farm) and biodigester effluent.  The treatments in a completely randomized 2*2*2*2 factorial arrangement with 3 replications were: Soil type (surface soil from a coffee plantation [SC]  or sub-soil [SS]); Biochar (None [NB] or 2% of soil [B]); Effluent (With [E]  or without [NE]); and Native micro-organisms (With [M] or without [N]).  There were three repetitions of each treatment in a completely randomized design. The two soils were placed in plastic bags used for germinating coffee (capacity 1.5 liters). According to treatment biochar was mixed with the soil prior to placing it in the bags. Three maize seeds were placed in each bag and according to treatment the culture of NM was sprayed on the soil (50 ml on day of planting the maize and 50 ml 10 days later), followed by biodigester effluent in quantities to provide the equivalent of 50 kg N/ha divided in 10 equal applications. The NM was prepared by mixing fertile soil with rice bran, biochar, sugar cane juice, goat milk yogurt and biodigester effluent.  The maize did not germinate uniformly in the NM treatments, therefore all the maize seeds/plants were removed and new seeds planted 10 days after the last application of NM. The soil in the bags was irrigated as necessary. The maize (after germination 1 or 2 plants were removed to leave only one for the test) was harvested after 50 days of growth and measurements made of above-ground biomass and root development.

Biochar increased root development but did not affect yield of the above-ground biomass. The NM increased maize foliage growth three-fold root development two-fold. Effluent increased maize foliage growth by 70% and root weight by 100%. There were cumulative effects of each of the interventions with the combination of biochar, NM and effluent supporting more than ten-fold increases in weights of maize foliage and roots compared with the control treatment of no intervention (Figures 1 and 2). 

Key words: Amelioration, biotest, EM, gasification, local resources, rice bran sugar cane juice, yogurt