Effects of biostimulant application on soil biological and physicochemical properties: A field study

Abstract

IntroductionDespite their potential benefits, it is not well understood how the application of biostimulants influences soil biological properties and their microbial communities in field conditions. In this study, we aimed to evaluate the impacts of biostimulants on soil biological and physicochemical properties relevant to soil health.Materials and MethodsTo achieve this, we conducted a field study to investigate the effects of two types of commercially available biostimulants, Universal Natural Plant food (UNP) and Converte Seed Primer (CSP), on microbial activity, bacterial and fungal abundance, community structure and diversity, and soil chemical and physical properties across two depths (0–10 and 10–20 cm) from five sites under either wheat or pasture cultivation.ResultsOur findings suggest that application of UNP stimulated microbial activity by 40.1% in surface (0–10 cm) and 36.4% in deeper (10–20 cm) soil, but was dependant on site. Effects were generally greater in grasslands compared with arable soils. At sites where UNP stimulated microbial respiration, substrate‐induced respiration was also stimulated in surface soils and was associated with increased soil moisture content and higher total carbon and nitrogen. At the one site where UNP was combined with CSP, soil enzymes associated with carbon and nitrogen cycling were stimulated in UNP and UNP + CSP treatments. Total bacterial and fungal abundance and their alpha diversity did not respond to biostimulant treatment. However, microbial indicator communities were identified that responded positively to UNP and CSP addition across the two depths. Bacterial indicator species included Elsterales, Propionibacteriales, Solibacterales, Candatus, Reyranellales and Sphingomonadales, but differed between depths. For the fungal indicator species Filobasidiales (Basidiomycota) and Pleosporales (Ascomycota) were strong responders and common across both depths.ConclusionOverall, our results suggest some positive effects of biostimulants on soil biological and physicochemical properties. Further long‐term studies should be conducted to evaluate the effects of biostimulants on crop yield and farm resilience.

Impacts of biostimulants on crop yield and biological activity under drought conditions

“…When considering the two soil types used in the present study, intensively managed soil that had been under crop rotation for >10 years, showed lower microbial activity and abundance compared to the extensively managed unimproved pasture soil. Effects of biostimulant were less pronounced in the more intensively managed soil, supporting findings from a previous field study (Wadduwage et al, 2023) that suggests that benefits of biostimulant additions may take longer to be seen in such soils as it takes longer to build up soil microbial biomass than in soils with higher microbial biomass (Pahalvi et al, 2021).…”

Moving towards a mechanistic understanding of biostimulant impacts on soil properties and processes: a semi-systematic review

“…Both of these fields resulted in significant basal respiration responses in biostimulant-treated soils at surface soil layers, but had different multiple SIR responses. Biostimulant-treated soils at one of the grassland fields had significantly higher multiple SIR in surface soil layers, whereas the other field had significantly higher multiple SIR at the greater soil depth, when compared to their respective control (Wadduwage et al, 2023). The individual respiration responses to the substrates were not given, so presumably the "higher multiple SIR" was in response to all of the substrates used in the MicroResp method.…”

“…The other microcosm experiment used planted wheat (Chen et al, 2003). There were four field experiments (Alam et al, 2014;Yousfi et al, 2021;Wadduwage et al, 2023), one of which ran alongside a corresponding glasshouse trial (Alam et al, 2013). One experiment was solely based in a glasshouse (Renaut et al, 2019).…”

“…For example, Renaut et al (2019) Biostimulant application dosage and frequency varied strongly between experiments. For example, within the field experiments, Wadduwage et al (2023) applied 2.5 L ha −1 just once at the start of the experiment to different types of field sites (grassland and arable), whereas Yousfi et al (2021) applied 10 L ha −1 every 20 days to ryegrass. There was no general consensus in these articles (or in the wider literature) as to why these application regimes were selected.…”

“…In another field trial, Wadduwage et al (2023) investigated the effects of a biostimulant containing seaweed extracts, mineral trace elements, phytoproteins, vitamins, molasses, and plant hormones. The authors measured biostimulant effects on microbial activity at two soil depths (0-10 and 10-20 cm).…”