Climate change adaptation strategies are needed for agriculture, one of the most vulnerable human activities. In Navarre, North of Spain, ongoing adaptive management practices were identified and promoted in the framework of a regional adaptation strategy. Most include practices aiming to increase topsoil organic carbon (SOC) in agricultural land. In this work, the effectiveness of these practices (conservation agriculture, crop rotations, additions of organic matter, irrigation, and controlled grazing management) was assessed by means of monitoring SOC in a network of 159 agricultural fields across the region. These fields were selected across bioclimatic zones, where soil vulnerabilities and land-uses were previously assessed, to represent the most widespread conditions in the region. A sampling protocol designed to compare SOC stocks in plots with equal soil conditions within each zone, and with or without adaptive practices, allowed the determination of their effect size (measured as response ratios, RR). Exogenous organic matter addition was the most effective practice for SOC storage (RR 95% confidence interval (CI) [1.25–1.37]) across the region. Controlled grazing also resulted in net SOC gains (RR CI [1.13–1.42]) in temperate and semiarid grasslands. Conservation agriculture seemed to be more effective in the driest zone (RR CI [1.30–1.53]) than in the more humid ones (RR CI [0.98–1.21]). Irrigation also displayed a net positive effect (RR CI [1.17–1.34]), modulated by irrigated crop management, whereas crop rotations had an overall negative impact vs. monoculture (RR CI [0.84–0.96]), likely by their interaction with irrigation. These results confirm the variability in SOC responses to changes in management, and SOC as an indicator for assessing regional adaptation practices, although other biophysical, agronomic, and socio-economic factors also need to be accounted for.

农业是最脆弱的人类活动之一，需要气候变化适应战略。在西班牙北部的纳瓦拉，在区域适应战略的框架内确定并推广了正在进行的适应性管理实践。大多数包括旨在增加农业用地表土有机碳 (SOC) 的做法。在这项工作中，通过监测该地区 159 个农田网络中的 SOC 来评估这些做法（保护性农业、作物轮作、添加有机物质、灌溉和受控放牧管理）的有效性。这些田地是跨生物气候区选择的，之前评估了这些区域的土壤脆弱性和土地利用，以代表该地区最普遍的条件。采样协议旨在比较每个区域内土壤条件相同的地块中的 SOC 储量，无论是否采用适应性措施，都可以确定它们的影响大小（以响应比测量，RR）。添加外源有机物是该地区 SOC 储存最有效的做法（RR 95% 置信区间 (CI) [1.25–1.37]）。控制放牧还导致温带和半干旱草原的 SOC 净增加（RR CI [1.13–1.42]）。保护性农业在最干燥的地区（RR CI [1.30-1.53​​]）似乎比在更潮湿的地区（RR CI [0.98-1.21]）更有效。灌溉也显示出净正效应（RR CI [1.17-1.34]），受灌溉作物管理的调节，而轮作与单一栽培相比具有整体负面影响（RR CI [0.84-0.96]），可能是因为它们与灌溉的相互作用。这些结果证实了 SOC 对管理变化的反应的可变性，并将 SOC 作为评估区域适应实践的指标，尽管其他生物物理、农艺和社会经济因素也需要考虑在内。