BIOCHAR FROM COCONUT RESIDUES ENRICHED WITH UREA AS A SOIL CONDITIONER AND ITS INFLUENCE ON THE DEVELOPMENT OF Acmella oleracea
coconut crop residues; thermodegradation; nitrogenous biofertilizer; soil microbiology; plants production
Coconut farming is a major generator of waste, especially green coconut husk, resulting from processing in agro-industrial plants. These residues can be converted into biochar (BC), a carbonaceous product, obtained by the thermodegradation of biomass of animal or vegetable origin. When enriched with urea, BC can be a sustainable alternative for the use of these residues and as a potential nitrogenous biofertilizer, which when added to the soil, improves the soil quality and plants growth. In this context, the objectives were: to characterize and evaluate the adsorption capacity of N-NH4+ and N-NO3- in solution, from biochars from coconut residues produced at 400, 500, 600 and 700 °C; evaluate BC doses of green coconut with the same dose of urea, on the fertility of soils with different textures, mineralization processes and immobilization of microbial N and C, nitrification and ureolytic activity; and investigate the effect of BC application with urea doses on soil fertility, phytometric, nutritional and physiological performance of Acmella oleracea plants. The bichar produced at a temperature of 400 °C, for having adsorption capacity of N-NH4+ and N-NO3- similar to those at higher temperatures, was used in the last two experiments. Raising the temperature to 700 °C produced more alkaline BCs (pH=10.8) and with pHPCZ 2x higher compared to that produced at 400 °C. Although CTC and CTA were maximized 2 and 4 times greater in 700 °C BCs, the maximum adsorption capacity of BCs was similar for N-NH4+ and N-NO3-. It is also expected to define the best dose of green coconut biochar to be applied to the soil, as well as the amount of urea to be used together with the biochar. Thus, we developed a nitrogenous biofertilizer, from the residues of the industrial production of green coconut water.