历史牛粪遗产调节高镉岩溶土壤中马铃薯产量和镉生物有效性对短期施肥的响应

中国西南地区是典型的喀斯特地形，具有自然升高的地质重金属背景浓度。研究区域位于西南喀斯特高原，是一个大面积的连片农业区，土壤质量管理严格。当地农民普遍施用牛粪，马铃薯在这里广泛种植，然而马铃薯块茎中镉的积累威胁着食品安全。本研究探索了在地质成因高镉岩溶土壤中，对比长期田间牛粪遗产如何驱动不同的短期镉生物有效性和马铃薯产量对有机无机结合施肥的响应。在贵州喀斯特地区采集了两种具有不同历史施肥背景的农田土壤样品:连续施用牛粪数十年的土壤(WH土壤)和从未施用过牛粪的土壤(黑土)。采用相同施肥梯度的短期盆栽试验比较两种土壤的内在差异，包括5个处理:不施肥对照(CK)、单施牛粪(CM)、单施化肥(CF)、单施牛粪加单施化肥(CMF1)和双施牛粪加单施化肥(CMF2)。我们测定了马铃薯块茎产量、组织镉浓度、土壤镉组分、CaCl2可提取镉、土壤理化性质、溶解有机物(DOM)光谱特征、土壤酶活性和根际微生物群落组成。Spearman相关和Bayesian回归模型被用来确定造成WH和WO土壤块茎镉差异的土壤特定因素。两种土壤在CMF1下表现出适度的产量促进和镉减少，但它们对高粪肥剂量(CMF2)表现出显著的不同反应，表明固有的土壤历史背景超过了一般的施肥改良效应。对于WO土壤，CMF2显著增加CaCl2——可提取态镉，块茎镉相对于CK上升23.48%(p < 0.05), accompanied by enriched labile DOM and simplified bacterial co-occurrence networks. In contrast, WH soils derived strong buffering capacity from long-term historical manure inputs, and tuber cadmium concentrations remained comparable to CK despite increased soil organic matter. Bayesian models revealed soil physicochemical properties and enzymes best explained tuber cadmium variation (Bayesian R2= 0.719,p < 0.05). Regulatory factors differed markedly across soil types: pH and cation exchange capacity more effectively immobilized cadmium in WH soils, while dissolved organic carbon and nutrient-related enzymes primarily triggered cadmium mobilization in WO soils. Our short-term pot results indicate that historical manure legacy, instead of fertilization amendments, dominates soil cadmium mobilization and immobilization balance. Though CMF1 mitigated tuber cadmium risk in both soils, excessive manure input induced completely opposite outcomes. WO soils without long-term organic accumulation lacked buffering ability and were prone to DOM-mediated cadmium activation under heavy single manure application, whereas WH soils maintained steady cadmium retention capacity. These findings verify that historical manure backgrounds alter soil functional properties and modulate cadmium responses to organic fertilizers, suggesting fertilization strategies tailored to soil manure history are more suitable than unified manure dosages for potato cultivation in geogenic high-cadmium karst regions.