Responses of active soil microorganisms facing to a soil biostimulant input compared to plant legacy effects

Abstract

Agriculture is changing to rely on agroecological practices that take into account biodiversity, and the ecological processes occurring in soils. The use of agricultural biostimulants has emerged as a valid alternative to chemicals to indirectly sustain plant growth and productivity. Certain BS have been shown to select and stimulate plant beneficial soil microorganisms. However, there is a lack of knowledge on the effects and way of action of the biostimulants operating on soil functioning as well as on the extent and dynamic of these effects. In this study we aimed to decipher the way of action of a seaweed and amino-acids based biostimulant intended to be applied on soil crop residues to increase their microbial mineralization and the further release of nutrients. By setting-up a two-phase experiment (soil plant-growing and soil incubation), our objectives were to (1) determine the effects of the soil biostimulant over time on the active soil bacteria and fungi and the consequences on the organic carbon mineralization in bare soils, and (2) assess the biostimulant effects on soil microorganisms relatively to plant legacy effects in planted soils. We demonstrated that the soil biostimulant had a delayed effect on the active soil microorganisms and activated both plant growth promoting bacteria and saprophytes microorganisms at the medium-term of 49 days. However, the changes in the abundances of active microbial decomposers were not associated to a higher mineralization rate of organic carbon derived from soil and/or litter. The present study assessed the biostimulant beneficial effect on active soil microbial communities as similar as or even higher than the legacy effects of either A. thaliana or T. aestivum plants. We specifically showed that the biostimulant increased the active fungal richness to a higher extent than observed in soils that previously grew the two plants tested.

Microbial Biostimulants as Response to Modern Agriculture Needs: Composition, Role and Application of These Innovative Products

“…[126]. Furthermore, it was reported that seaweed extract-based biostimulants had an interesting beneficial effect on the activation of native soil microorganisms, including saprophyte bacteria, fungi, and PGPRs [8].…”

“…Agro-ecology is based on the conservation of biodiversity, on the strengthening of biological processes, and on the looping of biogeochemical cycles. Fitting with the agroecological principles, is the use of biostimulants, products that are able to not only act directly on plants, but also sustain productivity through the selection and stimulation of beneficial soil microorganisms [ 8 ].…”

Use of Biostimulants: Towards Sustainable Approach to Enhance Durum Wheat Performances

“…Various agricultural approaches can be used within an integrated farming system to increase grain yield as well as quality, and alleviate stress-induced limitations. Recently, the use of agricultural biostimulants (BSs) has emerged as a valid alternative to agrochemicals and to indirectly sustain plant growth and productivity [ 1 ]. BS was defined as products of biological origin and included many products that are described as metabolic enhancers, phyto-stimulators, biofertilisers, biogenic stimulants, plant growth regulators, plant strengtheners, biocontrol agents, elicitors, allelopathic preparations, and plant conditioners [ 2 ].…”

“…In fact, BSs enhance the crop’s physiological and biochemical processes by regulating hormones balance, enhancing photosynthetic activity, nutriment uptake, and nutritional efficiency [ 12 , 13 , 26 ]. Furthermore, BSs could improve the physicochemical properties of soil, the activity of rhizosphere microbes and soil enzymes, and therefore the nutrient bioavailability [ 1 ]. Although BSs are beneficial for crop production systems, their modes of action remain largely unknown [ 27 , 28 ].…”

Seaweed extract effect on arbuscular mycorrhizae spore in soil engineered by earthworm, and the soil effect on upland rice growth

“…However, the difference between the other four treatments was not significant (LSD test at level p> 0.05). The highest development performance of upland rice at a concentration of 80% indicated a greater availability of sufficient nutrients, due to their level of substances such as growth hormones, being more suitable than other treatments[38].…”