Glomalin

The large network of fungal hyphae from arbuscular mycorrhizal fungi which spreads from mycorrhizal roots into the surrounding soil, affects the physico-chemical characteristics of soils and represents stabilizing agents in the formation and maintenance of soil structure. The objective of this work was to evaluate the glomalin related soil protein (GRSP) content, the GRSP / Organic carbon ratio (GRSP / Cox) and soil aggregates mean weight diameter (MWD). A mensurative test was carried out in Carlos Casares, province of Buenos Aires, Argentina, with sixteen Entic Hapludoll soils used in livestock production. The content of GRSP was positively correlated with the content of Cox (R 2 = 0.60). GRSP / Cox ratio decreases as Cox increases (R 2 =0.71), increasing the recalcitrant carbon proportion (GRSP) as the soil carbon decreases. The MWD of soil aggregates correlated positively with the GRSP content (R 2 = 0.59).

Water erosion is one of the main forms of soil degradation, causing economic, environmental, and social damage. This study evaluated the effects of different formation stages of gullies (initial-IG; juvenile-JG; mature-MG; and senile-SG) on the chemical, organic carbon and microbiological attributes of soil, using a secondary forest (SF) and two areas of pasture as references in the "Mar de Morros" environment of the Brazilian Atlantic Forest biome. Soil samples (depth 0-0.05 m) were collected at the end of the rainy and dry seasons. Gullies in different stages of formation promote a decrease in soil fertility and modification of microbiological attributes, particularly when compared with secondary forest areas. Reductions of over 60% in total organic carbon (TOC), oxidizable organic carbon (POXC), FDA activity, β-glycosidase, acid phosphatase, C and N from microbial biomass, basal soil respiration (BSR) and glomalin-related soil protein (GRSP) were observed in gullies in early (IG) and intermediate (JG and MG) stages when compared to SF. It was found that the effect of erosion on soil chemical and microbiological attributes is more intense in gullies in the initial and intermediate stages compared with those in the senile stage (SG). Using multivariate PCA, the microbiological and chemical attributes of the soil are discriminated between gullies with distinct formation stages. Chemical attributes, TOC, POXC, FDA activity, β-glycosidase, acid phosphatase, MBC and MBN, BSR, and GRSP are good indicators for evaluating the process of erosion stabilization in gullies.

The activity of bacteria and fungi is a relevant issue in the process of humification of organic matter and physical stability of the soil, standing out the role of arbuscular mycorrhizal fungi (AMF). AMF synthesize a recalcitrant glycoprotein called glomalin, with hydrophobic characteristics. GSRP (glomalin soil-related protein) is the generic product of proteins extracted from soil. The aim was to quantify GSRP and evaluate its share in the total soil organic carbon (TOC). GSRP presented a direct and positive association with soil TOC (R²:0.73). The quantitative participation of GSRP regarding TOC (GSRP / TOC) revealed that as TOC content decreases, GSRP proportion increases. Within the TOC range explored in this paper (1.3 to 3.2%), the glomalin related protein pool of soil changes about 9%, representing between 27% and 36% of TOC. This behavior would indicate an increase of resistant carbon forms counteracting the effects of carbon loss.

Abstract Deforestation of native ecosystems causes microclimatic changes at the edge of the remaining forest fragments. This “edge effect” can modify soil attributes, although there is little information on this. Thus, this study aimed to evaluate the edge effect on soil microclimate conditions, chemical, microbiological and arthropod community attributes and their relationship with litter attributes in a fragment of Semideciduous Seasonal Forest, in Pirai, RJ, Brazil. In the middle of the dry period (June/2019), four ranges of distances parallel to each other were established from the edge of the forest fragment: Edge: 0 m; Range 1: 50 m; Range 2: 100 m; and Interior: 160 m. In each range, five sampling points were established, spaced 10 m apart, where soil samples were collected in the 0–5 cm layer and litter samples. This material was employed to determine microclimatic, chemical and biological (arthropod community and microbiological attributes) attributes of the soil; and litter stock, concentration and content of nutrients. Forest fragmentation altered litter attributes and consequently soil moisture and nutrients, the communities’ attributes of soil arthropods and microorganisms. These modifications in such aspects of nutrient cycling could compromise the forest functioning and the conservation of local biodiversity. Thus, we suggested the planting of non-pioneer native tree species in distances closest to the forest edge and installing of ecological corridors to connect the forest fragment to other remnants, in order to diminish the edge effect.

Study aimed to (i) assess the impact of analog agroforestry (agrofor) on arbuscular mycorrhizal fungi (AMF), easily extractable glomalin-related soil protein (EE-GRSP), soil organic matter (SOM), and aggregate stability compared with a pasture system and (ii) investigate the chemical, physical and OM properties that explain the differences in soil microbiology between sites. The study was conducted in an agrofor and pasture area. Soil samples were collected in the dry season. A total of 12 AMF taxa were identified. Mean richness was positively correlated with soil pH, Mg 2+ , sum of bases (SB) and moisture. Mean richness and diversity were higher in the analog agroforestry site. Pasture soil had higher EE-GRSP content and spore abundance, variables that were found to be positively correlated with soil temperature, P, K + , and H + Al. EE-GRSP also showed a positive correlation with total organic carbon. Aggregate stability was greater in soil under analog agroforest than pasture. SOM properties did not differ between sites. It is concluded that agrofor changes the evaluated soil physical and microbiological attributes, and the microbiological attributes are influenced by the pH, Mg +2 , K + , SB, P, H+Al, soil moisture and TOC.

Healthy Agricultural Land Is A System With Resistance To Stress Due To Its Biological Diversity, An Active Cycling Of Nutrients And Energy And A High Physical Stability. The Activity Of Bacteria And Fungi Is Essential In The Humification Processes. One Of The Most Relevant Relevant Groups Of Soil Fungi Is The Arbuscular Mycorrhizals (AMF). AMF Synthesize A Glycoprotein Called Glomalin Or GRSP (Soil Protein Related To Glomalin), Which Is Not Secreted By The Mycelium, But Being The Release By Lysis Of Post Mortem Tissues The Main Route Of Its Deposition In The Soil. The Objective Of This Work Was To Evaluate The GRSP Content, The GRSP / Carbon Ratio, The Amount Of Dry Matter And The Foliar Phosphorus Content Of Festuca Arundinacea At Various Levels Of Inoculation, Fertilization And Soils With Different Sand Proportion In A Greenhouse Experiment. The Carbon Content Of The Soil Had A High Correlation With The GRSP Content (R2 0.93). This Result Indicates That GRSP Could Be A Biological Indicator Of Soil, With The Accumulation Of Soil Carbon Simultaneously With GRSP Enrichment. The Amount Of Dry Matter And The Concentration Of Foliar Phosphorus Increased With The Practice Of Inoculation When Fertilizer Was Not Applied, But Before The Application Of Nitrogen And / Or Phosphorus The Differences In These Variables Between Inoculated And Non-Inoculated Treatments Were Diluted, Evidencing The Increased Activity Of AMF Inoculated In Soils With Low Nutrient Contents.

Salinity is a major abiotic stress that can adversely affect plant growth, yield, other physiological parameters, and soil health. Salinity stress on biomass production of salt-sensitive crops, like snap bean (Phaseolus vulgaris), is a serious problem, and specifically in South Florida, USA, where saline soils can be found in major agricultural lands. Research studies focused on the 'snap bean-Rhizobium-arbuscular mycorrhizal fungi (AMF)' relationship under salinity stress are limited, and fewer studies have evaluated how this tripartite symbiosis affects glomalin production (GRSP), a glycoprotein released by AMF. A shade house experiment was conducted to elucidate the effects of three microbial inoculations (IC = inoculation control; IT1 = AMF and IT2 = AMF + Rhizobium) on three salinity treatments (SC = salinity control 0.6 dS m −1 , S1 = 1.0 dS m −1 , and S2 = 2.0 dS m −1) on snap bean growth and yield. Our results indicate that S2 reduced 20% bean biomass production, 11% plant height, 13% root weight, and 23% AMF root colonization. However, microbial inoculations increased 26% bean yield over different salinity treatments. Maximum salinity stress (S2) increased 6% and 18% GRSP production than S1 and SC, respectively, indicating the relative advantage of abiotic stress on AMF's role in soil. Dual inoculation (IT2) demonstrated a beneficial role on all physiological parameters, biomass production, and GRSP synthesis compared to single inoculation (IT1) treatment with all three salinity levels.