High biomass production with abundant leaf litterfall is critical to ameliorating soil quality and productivity in reclaimed sandy desertification land

摘要

Long-term data regarding soil properties and crop growth are powerful resources substantially contributing to our knowledge of soil-forming processes of reclaimed sandy desertification land. Generalized ecological principles derived from long-term observations that help to maintain or improve soil quality and productivity is critical for guiding field management practices while suitable for newly reclaimed sandy desertification land still need to be evaluated. Here, a 14-yr old experiment showed that soil quality index (SQI) had an "increase-decline-recovery" tendency in irrigation and fertilizer addition desertification lands while it remained at constantly low levels in desertification land with only irrigation. Stably decent yield and net incomes were obtained after 3-4 years' consecutive irrigation and fertilizer addition management. Correlation between crop productivity and SQI followed a saturation characteristic curve with threshold at 0.5, corresponding to soil organic carbon (SOC) ～5.0 g kg~(-1), below which crop productivity was linearly declined. 60% of observed inter-annual variations in SQI were explained by quantity of leaf litter, which was three times higher than explanatory power of root residue. No substantial changes occurred in soil mechanical components while the soil microbial biomass carbon, water-stable aggregate and heavy carbon pool in SOC were significantly improved by 2-9 folds in reclaimed desertification lands. Results revealed that increased biomass production with abundant residue retention is crucial for ameliorating soil quality, stabilizing high yield and economic gains, supporting the "High Biomass Cropping System" ecological hypothesis. Ecological limitations and opportunities to sustainable utilization of sandy desertification land were discussed.