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New Mexico State University (2021)

Management, Microbial Diversity, and Soil Health : A Case Study in an Arid Region

Swanson, Angelica L

Titre : Management, Microbial Diversity, and Soil Health : A Case Study in an Arid Region

Auteur : Swanson, Angelica L

Université de soutenance : New Mexico State University

Grade : Master of Science (MS) 2021

Knowledge of how microbial community composition is different in a native soil and managed soil in dryland ecosystem is limited. Microbial life can vary greatly depending on inherent soil properties and management decisions. This case study aims to understand how soil health properties may be associated with soil microbial abundance and diversity. Three sites were chosen, two with the same soil type (desert and turf pathway) and two are managed (organic farm and turf pathway). Physical and chemical soil characteristics (pH, electrical conductivity, moisture, carbon, nitrogen, phosphorus, texture, and aggregation) were quantified in addition to microbial phospholipid fatty acid (PLFA) biomass for both surface (0 – 1 cm) and subsurface (1 – 5 cm) samples. Multivariate and non-parametric statistics were used to examine the trends between sites and depths considering the measured parameters. The results of the permutational analysis of variance (PERMANOVA) lend evidence to a difference between sites (p = 0.001) and depths (p = 0.001) when considering PLFA total biomass data. The principal component analysis (PCA) compressed environmental variables into principal component axes and ordinates multivariate sample scores for each site and depth. Soil health measurements positively associated with the first principal component axis PC1, in order of impact on the axis, were total carbon, organic matter, clay, nitrogen, phosphorus, aggregate mean weight diameter, moisture, and active carbon. The farm site was strongly positively correlated with PC1, while the desert site was strongly negatively correlated, and neither had clear differentiation of sample scores between the surface and subsurface. The turf pathway site had a weak negative correlation with PC1, but the turf surface soil strongly positively correlated with the PC axis 2, which was associated with water resistant aggregates, electrical conductivity, and pH. Non-metric multidimensional scaling (NMDS) of PLFA site and depth ranks ordinated differently than the PCA of environmental variables. Sample ranks in the NMDS were clearly separated by depth, but when considering whole site data ranks, the farm and turf sites overlapped, indicating similar microbial community structure. While the turf pathway soil was the same soil type as the desert, the bare soil adjacent to the turf plots is more similar to the organic farm in microbial community structure. The turf pathway soil may be gaining subtle residual benefits of the management, which isn’t clear when looking at the measured environmental properties alone.


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Page publiée le 3 décembre 2021