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.

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The loss of nitrogen through volatilization leads research to the search for new technologies that release nutrients in a manner synchronized with the crop demand, minimizing losses and increasing efficiency of its use in agriculture, as is the case with the stabilized slow-release nitrogen fertilizer. This work sought to evaluate the losses of volatilized N-NH 3 in stabilized slow-release nitrogen fertilizer applied to the soil. The treatments followed a 5 × 3 × 2 factorial as follows: five nitrogen fertilizer sources (conventional urea -CU; urea combined with zeolite -UZ; sulfur coated urea -US; NBPT coated urea -U NBPT , and urea combined with organic material -OU); three application times; and two managements (surface and incorporated applications) with three replications. The experiment was conducted using a collection chamber to capture NH 3 for 25 days, with samples taken at 2, 4, 7, 9,