Uncovering Soil Health Responses to Short-Term Crop Rotation under Deficit Irrigation in Cold and Semi-Arid Agroecosystems

Abstract

Crop rotation (CR) is a fundamental sustainable management practice, yet the temporal dynamics of soil recovery, particularly the synchronization between physical and chemical properties, remain poorly understood, especially in the fragile soil of semi-arid agroecosystems. This field study evaluated the impact of 0, 1, and 2 years of CR (0CR, 1CR, and 2CR) on soil organic carbon (SOC), soil total carbon (STC), soil total nitrogen (STN), macroaggregate formation, and soil water holding capacity (SWHC) under limited (75%) irrigation regime in a barley-bean- sugar beets cropping system in northwest Wyoming. Results revealed a distinct “multi-speed” soil recovery process, in which physical and chemical attributes responded on asynchronous temporal scales. Physical properties proved highly responsive to short-term management: macroaggregate content (> 250 µm) increased progressively across both bean and barley fields after two rotation cycles (2CR; p < 0.001). Additionally, SWHC in barley fields increased significantly by 13.4 % under 2CR (p < 0.05). In contrast, chemical properties exhibited a slower and less consistent response. Bean fields showed a progressive 12.9% increase in STN under 2CR (p < 0.05), likely driven by biological nitrogen fixation, whereas SOC remained statistically unchanged across treatments for both crops, despite a significant mid-rotation recovery in STC within barley fields (p < 0.05). Pearson correlation analysis revealed a temporal decoupling between structural and chemical indicators (r = -0.04 to 0.31), demonstrating that physical matrix restructuring precedes detectable carbon accumulation during early stages of CR. These findings highlight macroaggregate formation and SWHC as sensitive early-stage soil health indicators, providing timely metrics for evaluating conservation management success before long-term SOC accrual can be detected.