Soil Calcium Speciation, Spatiotemporal Uptake, and Allocation of Nutritional Drivers in Alkaline Vineyard Ecosystems

ABSTRACT Background The eastern foothills of the Helan Mountains in Ningxia, China, are a significant viticultural area. Despite high total calcium (TCa) in soils, low bioavailability affects vine nutrition, yield, and quality. Ca dynamics in these specific ecosystems are largely underexplored. Aims We investigated Ca speciation dynamics in soils across four subregions (Yongning YN, Hongsipu HSP, Qingtongxia QTX, Xixia XX) to understand Ca allocation in Vitis vinifera L. Cabernet Sauvignon and determine soil–vine Ca flux mechanisms for precision Ca management. Methods Soil properties and Ca fractions (water‐soluble [WSCa], exchangeable [ECa], acid‐soluble [ASCa], organic‐bound [OCa], residual [RCa]) were analyzed. Grapevine parts were sampled at eight stages to determine dry matter, Ca concentration, and uptake. The analyses used principal component analysis (PCA) and structural equation modeling (SEM). Results Spatial heterogeneity in soil properties and Ca speciation was observed. YN soils showed highest bioavailable Ca (ACa = WSCa + ECa), followed by QTX, XX, and HSP, though QTX and XX had highest TCa. Dry matter followed an “S”‐shaped curve, with HSP berries showing higher accumulation at veraison (VA). Leaf Ca concentrations peaked at VA or at harvest (HV). Vine Ca uptake peaked between fruit‐set and HV, with HSP showing high uptake during VA, particularly in the roots. PCA showed that vegetative Ca was positively correlated with ACa, WSCa, and ECa. SEM revealed a strong positive association between soil calcium and plant calcium status. Furthermore, both soil WSCa and ECa fractions were closely related to the calcium nutritional status of grapevines. Vine Ca uptake displayed temporal and regional variations, emphasizing the need for site‐specific Ca management. Soil properties modulate Ca availability and plant Ca nutrition. Conclusions These findings provide a foundation for precise Ca fertilization strategies to support sustainable viticulture in this and similar regions worldwide.