<p>What is more effective in improving soil health indicators under limited moisture conditions: a feedstock or its biochar?. A soil rich in organic carbon (SOC-rich) and an SOC-poor soil, having similar texture, were amended with corncob (feedstock) or their biochar and incubated under optimum or low moisture conditions for 67 days. Residues increased cumulative respiration in both soils by 217–259%, whereas biochar increased it in SOC-poor soil only, by 28 &amp; 55% under low and optimum moisture respectively. Moreover, both the amendments induced a positive priming effect (PE) in SOC-poor soil at both moisture levels. Whereas biochar induced a slightly positive or significantly negative PE in SOC rich soil at low and optimum moisture respectively. Moreover, biochar increased nitrate and residues increased ammonium content at optimum and low moisture respectively in SOC-poor soil whereas no effect of either amendment on nitrogen availability was found. These results indicate that microorganisms in SOC-poor soil were so C limited that biochar, a recalcitrant material, alleviated this limitation and induced a positive PE and increased respiration. However, SOC-rich soil microorganisms were unable to utilize this ‘recalcitrant’ material. Neither residues nor biochar changed the extracellular enzyme activity (EEA) in SOC-rich soil, whereas biochar and residues significantly increased chitinase activity in SOC-poor soil. Moreover, moisture deficit significantly reduced leucine aminopeptidase activity in SOC-poor soil only. Both organic amendments stimulated microbial activity, and EEA in SOC-poor soil particularly at optimum moisture leading to improved soil health. Moreover, SOC-poor soil was also improved more by amendments than SOC-rich soil at low moisture.</p>