Irrigation can increase crop yields and could be a key climate adaptation strategy. At present, under the background of increasing food demand and continuous expansion of irrigation cropland, there still uncertainties about the soil carbon dynamics under the change of irrigation water volume and irrigated area in view of large-scale spatial heterogeneity. Therefore, this paper uses space-for-time + meta-analysis and a two-step methodology based on the residual trend analysis to quantitatively analyze the relationship between soil organic carbon (SOC) and soil respiration (Rs) in response to fluctuations in irrigation water volume and irrigated land extents. Here we show that the irrigation water volume within 100–1000 mm had a negative impact on SOC, and the impact was correlated with the irrigation water volume. Different levels of irrigation water manifest distinct effects on SOC content across varying soil depths. When irrigation water quantities are less than 700 mm, the impact on SOC content in the 0–30 cm depth layer surpasses that in the 30–200 cm depth layer. Conversely, when irrigation water quantities equal or exceed 700 mm, this pattern is reversed. The overall impact of irrigation on SOC stock at a depth of 0–200 cm was −14.88±6.7%. Tillage, planting intensity, topography, and soil type within irrigated cropland all exert variable impacts on SOC content. Whether these influences are deleterious or beneficial hinges predominantly upon the balance between the augmentation of SOC stock due to heightened carbon inputs from crops and the reduction of SOC through alterations in microbial activity. Mann-Kendall trend analysis showed that from 2000 to 2015, the overall Rs of cropland showed an increasing trend, with an increase rate of 3.67 g/m2/year. The increase of global Rs is mainly driven by climate change factors (temperature, precipitation and solar radiation), while the decrease of Rs in a small number of areas is mainly driven by management practices (fertilizer nitrogen, irrigation, and tillage). Our study further quantifies the impact of irrigation on soil carbon dynamics, thereby offering potential pathways and data support for the advancement of sustainable agriculture.

Xiaochen Yao

Zhiyu Zhang

Fenghui Yuan

Changchun Song

Agricultural Water Management

该杂志发表与农业水资源管理的科学、经济学和政策相关的具有国际意义的论文。在所有情况下，手稿都必须解决影响并提供有关农业水资源管理的见解。

The journal "Agricultural Water Management" publishes internationally significant papers related to the science, economics, and policies of agricultural water resource management. In all cases, submitted manuscripts must address issues affecting agricultural water resource management and provide insights into the topic.

《Agricultural Water Management》期刊发表与农业水资源管理相关的科学、经济学和政策方面的国际性论文。所有提交的手稿必须探讨影响农业水资源管理的问题，并提供相关的见解。

Category	Quartile
农林科学	1
农林科学, 农艺学	1
农林科学, 水资源	1

The impact of global cropland irrigation on soil carbon dynamics

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Journal Info

Category	Quartile
WATER RESOURCES	1