Long-term interactions of reduced tillage and different amounts of residue retaining improved soil environment in a semi-arid tropical climate

Soil quality degradation caused by intensification is threatening the sustainability of banana (Musa acuminata Colla) production in South China. Hence comprehensive information about the benefits of conservation management on soil quality is urgently needed. This study aimed to assess the effects of tillage and residue on soil biological properties in a banana plantation for 25 yr. Treatments consisted of three tillage methods (conventional tillage, CT; reduced tillage, RT; no tillage, NT) combined with three residue levels (0, NR; 50%, HR; 100%, TR). Soil samples were taken in 2018-2019 from 0-40 cm depth. Soil moisture, pH, total organic C and total N in NT were 28.8%, 22.4%, 39.9% and 34.3% higher than in CT. However, NT decreased available P by 16.7% compared with CT. HR had higher NH4-N and available K and lower bulk density compared with NR. Microbial biomass C and N were on average 39.2% higher in TR than those in NR. Urease, dehydrogenase and β-glucosidase obtained a mean increase of 34.3% in RT compared to CT. Invertase and catalase were on average 32.9% greater when residue was applied than no residue input plots. CO2 and N2O emissions decreased around 37.6% in different tillage treatments, but increased from 39.9% to 62.6% in all residue input plots. In general, soil biological properties are sensitive characters to changes caused by tillage and residue, and consequently they are well-established as soil physicochemical indicators for soil quality evaluation in conservation tillage systems.