Microalgae biofilm in soil: Greenhouse gas emissions, ammonia volatilization and plant growth

Abstract

Microalgal biofilm in soils represents an alternative fertilization method for agricultural sustainability. In the present study, greenhouse gas emission, soil ammonia volatilization, and the growth of Pennisetum glaucum were evaluated under the effect of a microalgal biofilm, commercial urea, and a control (without application of a nitrogen source). CH emissions were equal for the three treatments (p>0.05). CO emissions significantly increased in microalgal biofilm treatment (p<0.01), which was also responsible for the highest NO emissions (p<0.01). The ammonia (NNH) volatilization losses were 4.63%, 18.98%, and 0.82% for the microalgal biofilm, urea, and control treatments, respectively. The main differences in soil characteristics were an increase in nitrogen and an increase in cation exchange capacity (p<0.01) caused by the algal biomass application to the soil. The soil organic matter content significantly differed (p<0.05) among the three treatments, with the microalgal biofilm treatment having the greatest increase in soil organic matter. Significant differences were observed for shoot dry matter mass and nitrogen content in the plants from both treatments where nitrogen sources were applied. All treatments differed from each other in leaf dry matter mass, with the urea treatment increasing the most. Chlorella vulgaris was the dominant microalgal specie in the soil.

Production of Microalgal Slow-Release Fertilizer by Valorizing Liquid Agricultural Digestate: Growth Experiments with Tomatoes

“…Indeed biomass production of 153 g and 547 g were respectively noticed for the fertilization at the time of transplant and 22 days prior the time of transplant [25]. According to many authors [26,46,47], even growing plants with microalgae biomass wasn't better than those grown with synthetic fertilizers or digestate, the use of microalgal biomass for fertilizing purposes presents some important advantages. Microalgal biomass can be considered as a slow-released fertilizer since the application of dried biomass to soils would not result in emissions Table 4.…”

Distributed parameter modelling of phototrophic bioreactor systems

“…The study also alluded to the necessity in understanding and using the interactions between mass and radiative transfer, physiology of the microorganisms, and their radiation and substrate kinetics and dynamics. In addition to these components, we have also identified that biofilm formation is important, whether it is a structure to be avoided or fostered as a design feature [66].…”

“…There is a net increment of biomass production yield compared to typical activated sludge processes. This could have an impact in energy recovery (through biogas) but also in sludge waste disposal expenses, which can be partially counteracted by downstream production of high value-added bioresources as proteins, prebiotics and probiotics[31] or bioplastics, as well as energetic resources as third generation liquid biofuels[66].…”

Applications of artificial neural networks in three agro-environmental systems: microalgae production, nutritional characterization of soils and meteorological variables management

“…Microalgae biomass application in soils is beneficial for crops and yields (Shaaban, 2001), the organic matter, carbon content and biological activity in soils increase with these microorganisms (Castro et al, 2017;Miralles et al, 2012;Xie et al, 2007). Microalgae, specifically when they are obtained from wastewater treatments (De-Bashan and Bashan, 2004), contains several nutrients removed from the treated sewage.…”

“…Considering that CSA is oriented to reduce GHG emissions and enhance the productivity of agricultural ecosystems, microalgae culture and production can be a decisive factor for future scenarios. Several experiments were conducted to study the benefits of microalgae in agriculture, from the fertility perspective (Mulbry et al, 2005;Raposo and Morais, 2011;Renuka et al, 2016;Shaaban, 2001) to the environmental approach (Castro et al, 2017;Egle et al, 2016;Renuka et al, 2016).…”