Cover cropping and minimum tillage improved microbial functional resilience to compaction stress in an acidic soil

Sustainable agriculture requires maintaining soil health, yet conventional management (CM) practices may not protect soils from stresses such as compaction. This study compared microbial resilience to compaction in two soils collected from sugarcane farms under improved management (IM: minimum tillage, cover cropping and stubble retention) and CM (conventional tillage, no cover crop and stubble retention) practices. Samples were placed in 96-well deep-well plates and compacted using a bespoke device to achieve bulk densities of 0.9 (control), 1.1 (low), and 1.2 g cm⁻³ (moderate). Microbial resistance was assessed 14 days after compaction, and resilience 14 days after stress relief. Under low and moderate compaction, IM soils showed 49.5 % and 45.7 % higher CO₂ emission resistance indices (i.e., the ability of soil to maintain microbial respiration under compaction stress) than CM, indicating greater stability. Microbial biomass carbon and nitrogen were 56.2 % and 47.9 % higher in IM soils under low compaction, compared to CM. Soil microbial metabolic quotient ( q CO₂) was similar across compaction levels within each system, but was 19.5 %–36.3 % lower in IM soils than CM at equivalent compaction, indicating lower microbial stress under IM. Fourteen days after stress relief, q CO₂ in moderately compacted CM soil increased by 41.1 % and 25.0 % compared to control and low compaction. In contrast, IM soil under moderate compaction had 40.6 % lower q CO₂ than CM. The CM showed no effects of compaction on hot water extractable organic carbon content, while compaction of IM showed a 13 % decline compared to its control. Hot water extractable total nitrogen did not vary with compaction within the management systems but was 12 %–15 % higher in IM than CM under the same compaction during the resistance phase. Total mineral nitrogen was unaffected by compaction treatments under each system but was 11 %–13 % higher in IM than CM during resistance phase. These findings highlight the potential of improved management practices to sustain soil health and resilience under compaction stress. • A novel test used to assess microbial functional resilience to compaction stress. • Improved management had higher respiration resistance than conventional management. • Improved management reduced microbial metabolic quotient under compaction stress. • Improved management enhanced microbial functional stability and nutrient retention.