Effect of Biofertilizers on Broccoli Yield and Soil Quality Indicators

High rates of fertilizer applications potentially have significant environmental consequences,
such as soil and water contamination and biodiversity loss. This study aimed to compare the
use of biofertilizers and inorganic fertilizers in a broccoli crop to determine their impact on soil
microorganism abundance, microbial community structure, functional gene diversity, yield, and
greenhouse gas emissions. Four different fertilization treatments were designed: (i) inorganic
fertilizers applied at a rate to cover the nutritional demands of the crop (F100); (ii) 50% of the rate of
inorganic fertilizers added in F100 (F50); (iii) F50 + the application of a formulation of various bacteria
(BA); and (iv) F50 + the application of a formulation of bacteria and non-mycorrhizal fungi (BA + FU).
The results showed that reduced fertilization and the addition of both biofertilizer products had no
significant effect on soil nutrients, microbial population, microbial activity, or yield when compared
to conventional inorganic fertilization. Thus, microbial inoculants were ineffective in enhancing
soil microbial abundance and activity, and there were no changes in GHG emissions or crop yields.
Nonetheless, crop yield was positively related to total soil N, microbial activity, and CO2 emissions,
confirming the positive effect of soil biodiversity on production. The application of biofertilizers can
help reduce mineral fertilization in a broccoli crop with no negative effect on yield.

This work was funded by the European Commission Horizon 2020 project SoildiverAgro [grant agreement 817819].