Enhancing soil ecosystem multifunctionality (EMF) is vital for achieving sustainable agricultural productivity. Yet, the mechanisms by which organic amendments regulate EMF through microbial and biochemical pathways remain insufficiently understood, especially in nutrient-poor sandy soils. To address this knowledge gap, we conducted a field experiment in the Yellow River Basin of eastern China to assess the impacts of manure, biochar, and their combination on soil physicochemical properties, enzyme activities, microbial nutrient limitations, EMF, and wheat yield. Our results showed that organic amendments markedly increased soil organic carbon by 4.8–5.6%, total nitrogen by 3.7–17.0%, and available phosphorus by up to 35%. Relative to mineral fertilization, applying manure (NM) alone or together with biochar (NMB) enhanced soil carbon- and nitrogen-related enzyme activities by 3.4–20.3% and 28.8–69.6%, respectively, with the greatest increases observed under the NMB treatment. Enzymatic vector length decreased from 0.85–0.86 to 0.83–0.84, and vector angle declined from 75° to 66°, indicating reduced carbon and phosphorus limitation under organic amendment treatments. Compared with mineral fertilization, NM and NMB treatments elevated EMF by 158–160% and wheat yield by 15.0–19.4%. EMF was positively correlated with wheat yield ( p < 0.05). Random-forest and partial least-squares path modeling suggested that the key soil nutrients, N-acetyl-glucosaminidase activity, and vector angle were the primary predictors of EMF (R 2 = 0.65) and yield (R 2 = 0.57). These findings indicate that organic amendments enhanced soil multifunctionality and crop productivity primarily through improving nutrient availability, stimulating enzyme activities, and alleviating microbial nutrient limitation. Overall, integrating manure with biochar proved to be an effective approach to optimize soil biochemical functioning, strengthen microbial resource use efficiency and sustain crop productivity. • Manure-biochar co-application enhanced soil multifunctionality by 160% and wheat yield by 15%. • Organic amendments improved nutrient availability and enzyme activities, reducing microbial C and P limitations. • Soil nutrients, N-acetyl-glucosaminidase activity, and enzymatic stoichiometry were key predictors of EMF and yield.
Miao et al. (Tue,) studied this question.