旱区连作砂田土壤质量和土地生产力演变与调控研究进展OA北大核心CHSSCDCSTPCD

Gravel mulching,a special insulation,has been regarded as an indigenous agricultural technique in the arid and semi-arid areas of northwest China,was used to retain soil moisture and elevate soil temperature by retarding the diffusion of water vapor and energy exchange through mulching on surface soil.Also,gravel have the potential to improve soil nutrient environment through promoting internal deterioration under continuous seasonal freeze-thaw drying and wetting effects.However,large portion of the gravel layer is intermixed with varying amounts of soil due to the prolonged tillage,unreasonable irrigation and wind erosion.These changes will result in the destruction of mulch textural composition and an increase in the invalid loss of soil moisture and nutrients.As such,the sustainability of gravel-sand mulched field is experiencing a crisis of negative economic returns and energy use.In this study,the effects and possible mechanisms of continuous cropping on gravel layer structure,soil physical structure,soil water-salt-heat,soil nutrient status,soil enzyme activity,soil microbial characteristics,crop physiological characteristics,yield,and quality were systematically addressed,aiming to provide reference and inspiration for the healthy and sustainable development of gravel-sand mulched field as well as ecological environment protection in the arid and semi-arid areas of northwest China.We found that the soil ecological environment and land productivity in gravel-sand mulched field have generally shown a degradation trend under the disturbance and destruction of human activities and natural erosion,but the responses process to farmland management measures,including different mulch conditions,fertilizer levels,and planting structures have shown differences.Subsequently,the degradation mechanism of continuous cropping gravel-sand mulched field was deeply studied based on the synergistic and interactive effects of soil quality and land productivity,and the biological,agricultural,and engineering regulation and control measures for the degraded gravel-sand mulched field were briefly discussed.Lastly,the key scientific problems,future development directions and proposals that need to be solved in the degeneration process of gravel-sand mulched field were provided.It mainly includes the basic process and mechanism of soil quality evolution,the superposition and interaction effects of gravel-soil-microbial-plant system as well as its molecular mechanism,and the quantification of soil improvement and biological control measures as well as their regulation mechanisms.Notably,with the global climate change,vegetation succession,and land degradation,the mechanisms of cracking and fertilizing of waste weathered gravel as well as its environmental effects will be the focus of future research.