Optimizing organic fertilizer substitution is essential for enhancing the sustainability of agriculture and achieving a balance between crop productivity, nutritional quality, and environmental safety. Here, we conducted an 11-year field experiment to evaluate the effects of substituting 50% of mineral fertilizers with pig manure (PM) or cattle manure (CM) on the nutritional quality of wheat grain, heavy metal (HM) accumulation, and associated human health risks. The yield and protein content were highest in the mineral fertilizer (MF) treatment, and grain micronutrients (Fe, Mn, Cu, Zn) were 6.7–13.8% higher under organic substitution (PM/CM) than in the MF treatment. The Ni, Pb, and As contents were 35.4–43.0% higher in the PM treatment than in the MF treatment, which stems from the higher HM content in pig manure. Health risk assessments indicated that the Hazard Index (HI) for children exceeded 1 in the PM treatment, primarily due to As, which accounted for 69.6% of the HI. All treatments remained within safe thresholds, although As and Pb posed detectable carcinogenic health risks. The higher levels of Ni and As in pig manure likewise led to a significant increase in the health risk associated with the PM treatment compared to the MF treatment. We developed a novel Grain Quality Index (GQI) that combined nutrient and HM data, which indicated that the nutritional quality of wheat grain was similar in the CM and MF treatments. The GQI was 9.1% lower in the PM treatment than in the MF treatment. These findings suggest that the substitution of mineral fertilizer with cow manure can help achieve a balance between yield, nutrition, and safety, and more stringent regulation of HMs is required for the use of pig manure. Our findings provide actionable insights with implications for sustainable wheat production policies.

Wheat production demands simplified fertilization strategies to achieve sustainable high yields. This study evaluated the effects of the one-time high-rate application of an organic–inorganic compound fertilizer on soil properties, photosynthetic characteristics, and grain yields. A multi-year field experiment was conducted with a single basal application of an organic–inorganic compound fertilizer at 3600 kg·ha⁻¹, using conventional split chemical fertilization as the control. Compared with the control, this treatment significantly increased soil organic matter and available nutrient content, enhanced the bacteria/fungi ratio, elevated soil enzyme activity, and promoted the conversion of humus into more stable forms. These improvements sustained a higher flag leaf photosynthetic capacity during the grain-filling stage and delayed leaf senescence. The multi-year average grain yield was 5.28% higher than that of conventional split fertilization. The one-time high-rate application of an organic–inorganic compound fertilizer can improve soil biological properties, maintain late-season photosynthetic function, and increase yields, serving as an effective technical measure for simplified, sustainable, and high-yield wheat cultivation in the region.

To investigate the effects of different nitrogen fertilizer management strategies on post-anthesis photosynthetic characteristics, nitrogen translocation, and yield formation of winter wheat, this study was based on a long-term fixed-site experiment established in 2013. Four treatments were set up: no nitrogen application (CK), conventional nitrogen application (FP), optimized nitrogen application (OPT), and controlled-release nitrogen fertilizer (CRF), to study their effects on the post-anthesis photosynthesis, nitrogen translocation, yield, and soil characteristics of winter wheat. Nitrogen application significantly increased flag leaf SPAD value, green leaf area index, net photosynthetic rate, and yield components ( p< 0.05). The OPT treatment achieved the highest yield of 8871.69 kg·hm⁻², which was 2.32% and 4.00% higher than that of FP and CRF, respectively, and its nitrogen use efficiency indicators were also relatively high. Nitrogen application increased urease activity and altered microbial community composition. OPT could maintain a relatively high post-anthesis photosynthetic capacity and promote efficient nitrogen utilization, suggesting that it a suitable fertilization mode for high-yield and high-efficiency winter wheat production.