Evaluation of Presumed Drought Impacted Soils through Phospholipid Fatty Acid (PLFA) Biomarkers in the Sahel Region

Abstract

Aims: The aim of this study is to utilize biomarkers to detect drought induced changes in soil microbial communities within presumed drought impacted soils in selected regions of the Sahel. Study Design: A correlational study design was used to examine the influence of soil pH in relation to other soil properties (e.g., organic carbon, nitrogen and Phosphorus), while PLFA biomarkers were analysed using principal component analysis and descriptive statistics. Place and Duration of Study: The study, conducted from May to October 2021, focused on the Sahel region of sub-Saharan Africa, specifically within the territorial boundaries of Nigeria and the Niger Republic. Methodology:  A study using phospholipid fatty acid (PLFA) biomarkers investigated drought-induced changes in soil microbial communities in the Sahel region. Analysis of 90 soil samples revealed significant correlations between PLFA profiles and soil properties. Results: The study highlights the significance of site-specific soil management techniques, particularly in regions characterized by low nutrient levels and depleted soil organic matter (SOC) and carbon (SOM). In such regions, targeted applications of organic and inorganic amendments can be necessary to improve soil fertility. While sandy soils in G/Doki (87.1%) would benefit from organic additions for better water retention and nutrient-holding capability, Nkonni's high clay concentration could necessitate better drainage management to avoid waterlogging. Certain PLFA indicators are linked to bacteria and fungi, including C18:1cis9 and C18:1ω9. PLFA biomarkers are impacted by drought's alteration of soil microbial populations. To promote soil health and fertility conservation, it is essential to monitor soil microbial dynamics and implement sustainable agricultural methods. Conclusion: Soil microbial populations are greatly impacted by drought, which alters PLFA indicators. While certain biomarkers, like C18:0 and C18:1, suggest broad microbial activity, others, including C18:1ω9 and C18:1cis9, are linked to fungi. The following markers are linked to Gram-positive bacteria: i15:0, a15:0, i16:0, i17:0, and cy17:0 for Gram-negative bacteria, which are useful tools for evaluating the effects of soil management techniques, environmental stressors, and climatic variability on agricultural soils. These changes demonstrate the potential of PLFA analysis to connect soil microbial dynamics with soil health and fertility. Drought affects soil microbial communities, affecting soil pH. Higher pH increases organic carbon, organic matter, and calcium levels, while nitrogen and phosphorus levels are minimally affected.