Influence of Dynamic Root-Zone Nutrient Fluxes on Carbon Allocation and Yield Efficiency in Major Field Crops

Abstract

Understanding how dynamic nutrient fluxes in the root zone influence carbon allocation and yield formation has become a central question in modern crop physiology. As fertilization practices move toward precision management and soils face increasing variability due to climate shifts, the rhizosphere emerges as a highly responsive interface where nutrient flows, metabolic regulation, and carbon partitioning are closely integrated. This study investigates the physiological mechanisms through which spatial and temporal fluctuations of nitrogen, phosphorus, potassium, and micronutrients within the root-zone modify carbon uptake, assimilation pathways, and biomass distribution in major field crops, including maize, wheat, rice, and soybean. Using real field data from multi-location trials and integrating rhizosphere nutrient profiling, photosynthetic measurements, ion mobility analyses, and carbon allocation modeling, the research provides a detailed assessment of how nutrient flux patterns alter the balance between source activity and sink strength. The results reveal that nutrient fluxes in the rhizosphere are far more dynamic than traditionally assumed and strongly associated with shifts in root metabolic plasticity, photosynthetic nitrogen-use efficiency, and allocation of assimilated carbon toward grain, root, and structural tissues. Periods of nutrient enrichment in the immediate root vicinity increase the allocation of carbon to reproductive sinks, whereas nutrient oscillation or temporary depletion stimulates greater carbon flow to roots and structural components, contributing to morphological adjustments that enhance soil exploration. In addition, interactions between nutrient fluxes and soil moisture significantly modify the efficiency of carbon use in all studied crops, demonstrating that nutrient-driven carbon allocation is not only chemically regulated but also environmentally modulated. This study highlights the need for nutrient-flux-oriented fertilization strategies that go beyond total nutrient application rates and focus instead on the temporal behavior of nutrients in the rhizosphere. By integrating field-based nutrient flux measurements with physiological indicators of carbon use, the findings offer practical pathways for increasing yield efficiency in field crops under variable soil fertility conditions. The outcomes support the development of dynamic, root-zone-centered nutrient management frameworks aimed at optimizing both resource use and crop productivity.