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The addition of organic amendments contributes substantially to improvements in soil quality and prevents soil degradation. However, very little is known about the responses of dominant fungal strains to organic fertilizers or their functions in the nutrient transformations and crop growth promotion. Here, soils and maize roots were collected from a 35‐year field experiment treated with composted soybean cake. The fungal communities in the bulk soil, rhizosphere, and endosphere were analyzed by deep amplicon sequencing of the internal transcribed spacer region gene. Overall, the soil fungal community was dominated by the phyla Ascomycota, Basidiomycota, and Zygomycota. Organic amendments changed the fungal community composition, with significant increase in the relative abundances of Mortierella, Fusarium, and Chaetomiceae in the bulk and rhizosphere soils. Mortierella elongata was the most successful fungi responding to organic inputs as seen by the surge in abundance. Genome characteristics of M. elongata indicated that M. elongata possessed the functional capacity to degrade a range of toxic organics, and thereby improve soil health. Furthermore, M. elongata's capacity to compose recalcitrant substances that can contribute to pools of long‐term stable SOM was confirmed. These findings suggest that M. elongata may be mechanistic in sequestering C in soil. Inoculations of M. elongata into soil significantly increased the levels of plant indole acetic acid and plant biomass. Soil phosphatase and β‐glucosidase activities were also improved. Our study suggests that M. elongata can defend against soil degradation, improve soil health, and stimulate production of plant growth hormones.

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Miscanthus is a low input energy crop suitable for low fertility marginal arable land and thought to provide carbon sequestration in soil. We analysed a long-term field experiment (14-year) to determine whether differences in genotype, growth habit, and root distribution affected soil carbon spatially under different Miscanthus genotypes. Soil cores were taken centrally and radially to a depth of 1 m, and divided into six vertical segments. Total root length (TRL), root dry matter (RDM) and d 13 C signature of soil organic carbon (SOC) were measured directly, and root length density (RLD), fractions of Miscanthusderived soil organic C (SOC M ), and residual soil carbon (SOC orig ) were calculated. Genotype was found to exhibit a statistically significant influence on spatial allocation of SOC. Grouping varieties into 'tuftforming' (T) and 'non-tuft-forming' (NT) phenotypes revealed that respective groups accumulated similar amounts of RDM over 14 years (11.4 AE 3.3 vs. 11.9 AE 4.8 Mg ha À1 , respectively). However, phenotype T allocated more carbon to roots in the subsoil than NT (33% vs. 25%). Miscanthus genotypes sequestered between 4.2 and 7.1 g C 4 -SOC kg À1 soil over the same period, which was more than the average loss of C 3 -derived SOC (3.25 g kg À1 ). Carbon stocks in the 'A horizon' under Miscanthus increased by about 5 Mg ha À1 above the baseline, while the net increase in the subsoil was marginal. Amounts of Miscanthus root C in the subsoil were small (1.2-1.8 Mg C ha À1 ) but could be important for sustainable sequestration as root density (RLD) explained a high percentage of SOC M (R 2 = 0.66).Abbreviations: AGB, above ground (dry) biomass (Mg ha À1 ); BGB, below ground (dry) biomass (Mg ha À1 ); G, gap; P, plant; RLD, root length density (cm cm À3 ); RDM, root dry matter (g m À2 ); RD, root diameter (mm); SOC, soil organic carbon (%); TRL, total root length (km m À2 ); T, tuft forming Miscanthus genotypes; NT, non-tuft forming Miscanthus genotypes.

Soil extracts usually contain large quantities of dissolved humified organic material, typically reflected by high polyphenolic content. Since polyphenols seriously confound quantification of extracted protein, minimising this interference is important to ensure measurements are representative. Although the Bradford colorimetric assay is used routinely in soil science for rapid quantification protein in soil-extracts, it has several limitations. We therefore investigated an alternative colorimetric technique based on the Lowry assay (frequently used to measure protein and humic substances as distinct pools in microbial biofilms). The accuracies of both the Bradford assay and a modified Lowry microplate method were compared in factorial combination. Protein was quantified in soil-extracts (extracted with citrate), including standard additions of model protein (BSA) and polyphenol (Sigma H1675-2). Using the Lowry microplate assay described, no interfering effects of citrate were detected even with concentrations up to 5 times greater than are typically used to extract soil protein. Moreover, the Bradford assay was found to be highly susceptible to two simultaneous and confounding artefacts: 1) the colour development due to added protein was greatly inhibited by polyphenol concentration, and 2) substantial colour development was caused directly by the polyphenol addition. In contrast, the Lowry method enabled distinction between colour development from protein and non-protein origin, providing a more accurate quantitative analysis. These results suggest that the modified-Lowry method is a more suitable measure of extract protein (defined by standard equivalents) because it is less confounded by the high polyphenolic content which is so typical of soil extracts.