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This paper examines time-varying market efficiency in the agricultural commodity futures markets using an advanced technique known as the Adjusted Market Inefficiency Measure (AMIM). Employing a range of statistical tools, including OLS, Logit, and Tobit regressions, as well as GSADF and recursive residuals tests, we explore whether the Adaptive Market Efficiency Hypothesis (AMH) can provide insights into the explosive behavior of agricultural commodity prices during speculative bubbles and the COVID-19 pandemic. Our analysis uncovers periodically collapsing bubbles in all agricultural commodity futures markets, particularly during the Global Financial Crisis (GFC) and the COVID-19 pandemic. Consistent with the AMH, our results highlight the time-varying nature of market efficiency as a microstructure feature. Additionally, we observe a non-uniform response of efficiency across similar markets to global events. Notably, when contrasted with other financial crises, the outbreak of COVID-19 pandemic has a more pronounced effect on the inefficiency of specific agricultural commodities futures markets, such as corn and soybean, compared to wheat, soybean-oil and oats futures markets. these findings carry important implications for asset allocations, investors, and policymakers during periods of health and financial instability.