Pastures play vital roles in carbon (C) sequestration and the global C balance. Partial root-zone drying (PRD) is widely known to reduce water consumption with a minimum impact on alfalfa productivity in the field. A 2-year field experiment was used to investigate the effects of PRD on C retention in the soil-plant systems of alfalfa. This field experiment consisted of two factors (irrigation modes and irrigation volumes) in a split-plot design. The two irrigation modes were PRD and conventional furrow irrigation, and the four irrigation levels were 70%, 85%, 100%, and 115% alfalfa potential evapotranspiration. This study showed that PRD increased the C in alfalfa plants due to higher C in alfalfa roots. PRD led to higher soil organic C storage, whereas it led to lower soil total C and soil inorganic C storage. PRD was found to decrease the C retention in the soil-plant systems of alfalfa. The findings of this study display a pattern of PRD influencing C retention in the soil-plant systems of perennial crops, and imply that PRD reduces the C sequestration potential of alfalfa pastures.

牧场在碳 (C) 封存和全球碳平衡中发挥着至关重要的作用。众所周知，部分根区干燥（PRD）可以减少水的消耗，同时对田间苜蓿生产力的影响最小。通过为期 2 年的田间试验研究了 PRD 对苜蓿土壤-植物系统中碳保留的影响。该田间试验由裂区设计中的两个因素（灌溉模式和灌溉量）组成。两种灌溉方式为PRD和常规沟灌，四种灌溉水平分别为70%、85%、100%和115%苜蓿潜在蒸散量。这项研究表明，由于苜蓿根部的碳含量较高，PRD 增加了苜蓿植物的碳含量。PRD 导致土壤有机碳储量较高，而土壤总碳和土壤无机碳储量较低。研究发现，PRD 可以降低苜蓿土壤-植物系统中的碳保留量。本研究的结果显示了 PRD 影响多年生作物土壤-植物系统中碳保留的模式，并意味着 PRD 降低了苜蓿牧场的碳固存潜力。