Impact of Soil Ameliorants on Soil Chemical Characteristics, Sugar Beet Water Productivity, and Yield Components in Sandy Soils Under Deficit Irrigation

In many sustainable agricultural systems, combining soil ameliorants with deficit irrigation is a viable strategy. However, little is known about how this approach affects soil quality, crop water productivity (CWP), and sugar beet (Beta vulgaris L.) yield in sandy soils. This study investigates the effects of different soil ameliorants―potassium polyacrylate (PPA), polyacrylamide (PAM), and humus (HA)―on the soil chemical properties, water productivity, and sugar beet yield under three irrigation regimes (100%, 80%, and 50% of crop water requirement (CWR). The results demonstrated that applying these amendments signficantly enhances soil pH, cation exchange capacity (CEC), organic matter (OM), and the availability of essential nutrients (N, P, and K). Notably, the combination of PAM and HA under 50% CWR resulted in the highest improvements in sugar beet biomass, increasing shoot and root growth by 73.43% and 71.68%, respectively. It also led to a 97.91% increase in sugar yield and a 4.22% improvement in sugar quality. However, this treatment had the lowest economic benefit, with a negative outcome. In contrast, PAM treatment under 50% CWR produced a 61.49% increase in sugar yield and a 2.44% improvement in sugar quality, ensuring economic viability. These findings suggest that the use of PAM under reduced irrigation conditions can optimize water use efficiency and sustain crop productivity in sandy soils.