Bio‐based composite granules with simultaneous biocontrol and phosphorus fertilization roles: Outcomes from a lab‐scale in vitro assessment

Abstract

The use of phosphate rocks as low‐solubility phosphorus fertilizers has been promoted to reduce the environmental impacts of agriculture, but adequate nutrient uptake by plants depends on solubilization of the rock, driven by soil microorganisms. Here, investigation was made of the microbial solubilization of low‐solubility phosphate rocks, together with simultaneous bioprotective action involving the biocontrol of microorganisms. The aim was to enhance function and value by delivering two effects using a single bio‐based product, in accordance with the concept of a “bioreactor‐in‐a‐granule” system. A composite structure was developed, based on a starch matrix, comprising a combination of Trichoderma asperelloides, as a biocontrol agent, and Aspergillus niger, as an acidulant. A significant increase of up to 150% in P solubilization was achieved, indicating the positive effect of the microorganism‐composite interaction. In vitro assays showed that the ability of T. asperelloides to inhibit Fusarium oxysporum mycelial growth was maintained in the presence of A. niger. Moreover, the estimated cost of the composite granule (0.35 US$/kg of product on a dry basis) revealed competitive. The results indicated that the association of T. asperelloides and A. niger is an effective way to increase nutrient availability and to inhibit plant pathogens, opening up possibilities for the design of multifunctional bio‐based fertilizer composites.

Effects of the application of microbiologically activated bio-based fertilizers derived from manures on tomato plants and their rhizospheric communities

“…The activation of BBFs with ad hoc microbial consortia led to an enhanced total productivity of tomato fruits in all the trials, overcoming phytotoxicity and scarce nutrients bioavailability concerns of BBFs. This further supports the thesis that, similarly to what has been reported with synthetic fertilizers 49 , microbial activation is an efficient technique to increase nutrient availability. It is therefore of the utmost importance to follow the less pursued strategy and design new fertilizers in combination with ad hoc consortia to improve the yields deriving from organic fertilizer usage and to substitute synthetic fertilizers and dependence on primary raw materials 50 .…”

Economic Aspects on the Production of Biofertilizers as Granular Composites

“…In contrast, in SM-NE and DM-NE cases, the inclusion of rice byproduct (which has significant fractions of hydrolyzed starch in its composition) reduces the need for starch inclusion to 5% in the final product. 27 Thus, the encapsulation step accounts for 7 and 6.9% of the total OPEX of SM-NE and DM-NE cases (Figure 5D,F, respectively). However, as mentioned above, rice is part of the biofertilizer composition produced by SM-NE and DM-NE cases (about 25% on a mass basis).…”

“…Although representing only 15 wt % of the gel composition, starch increases raw material costs since 27.4% of the OPEX in the SM-WE case (Figure B) is attributed to the encapsulation. In contrast, in SM-NE and DM-NE cases, the inclusion of rice byproduct (which has significant fractions of hydrolyzed starch in its composition) reduces the need for starch inclusion to 5% in the final product . Thus, the encapsulation step accounts for 7 and 6.9% of the total OPEX of SM-NE and DM-NE cases (Figure D,F, respectively).…”

“…Solid-state cultivation in rice was used for largescale fungus growth and spore production. The simulations considered three different biofertilizer compositions based on Favaro et al 27 The first case study (Figure 1) is called a ″single microorganism with an extraction step (SM-WE)″ since, after the SSF step, the spores of T. asperelloides are separated from the cultivation medium. The second case study (Figure 2) is called a ″single microorganism with no extraction step (SM-NE)″ since it uses the whole SSF medium containing spores of T. asperelloides and the substrate in the biofertilizer formulation.…”

“…Solid-state cultivation in rice was used for large-scale fungus growth and spore production. The simulations considered three different biofertilizer compositions based on Favaro et al The first case study (Figure ) is called a ″single microorganism with an extraction step (SM-WE)″ since, after the SSF step, the spores of T. asperelloides are separated from the cultivation medium.…”