Abstract: To address the issues of unclear salt component composition piggery wastewater and high risks associated with land application, this study collected piggery wastewater samples from 25 livestock farms. It analyzed the salt component profiles in piggery wastewater at different treatment stages, identified critical salt components prone to soil accumulation, and proposed application thresholds for manure land application. The research aimed to provide a scientific basis for mitigating salt accumulation risks in agricultural soils. Quantitative analysis of 16 key salt components in piggery wastewater at three stages (pre-treatment, post-treatment, and pre-land application) from 25 farms was conducted using modern chemical analysis methods such as inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography. A nitrogen-based model for soil salt component accumulation under piggery wastewater application was established through the elemental balance method, and the threshold for liquid manure application rates during land application was analyzed. The soluble salt elements/ions in piggery wastewater primarily included nine major metal elements (Na, K, Ca, Mg, Cu, Zn, Fe, Mn, Cr), one non-metal element (As), and six ions (NH₄⁺, HCO₃⁻, Cl⁻, SO₄²⁻, PO₄³⁻, NO₃⁻). The detected amounts of these 16 elements/ions accounted for 80.0%–105.3% of the total salt content in the piggery wastewater, with 74.7% of the samples showing a detection rate of over 90% for total salt components. Among piggery wastewater, six elements/ions (K, Na, Ca, Mg, SO₄²⁻, and Cl⁻) each contributed over 5% to the total salt content, collectively accounting for 78.13% of the total. The average volumetric concentration of NH₄⁺ was 922.6 mg/L, representing 25.96% of the total salt content and making it the most abundant ion, primarily derived from urea conversion in the piggery wastewater. Overall, the liquid manure treatment process and stabilization process had no significant impact on the variations in salt content within the manure. There were no significant changes in the salt components before and after treatment, as well as prior to field application (P<0.05). The anaerobic fermentation - advanced treatment method effectively removed 27% of the total salt content in piggery wastewater, establishing it as the optimal salt reduction technique. In field trials with corn, replacing 50% and 100% of nitrogen fertilizer with piggery wastewater resulted in soil salt accumulation increments of 197.0 kg/hectare/season and 670.2 kg/ hectare /season, respectively. Six elements (K, Na, Cu, Zn, As, Cl) were identified as major contributors to soil salt accumulation under liquid manure application. When the background soil salinity was measured at 0.5 g/kg, the application of liquid manure with 50% nitrogen substitution resulted in saline soil characteristics after only 7 seasons of application and led to moderately saline soil properties after 32 seasons of application. In contrast, the use of liquid manure with 100% nitrogen substitution caused soil salinization traits after merely 2 seasons and resulted in moderately saline soil characteristics after 9 seasons of application. From a salt balance perspective, applying 99.9 m³/hectare /season of piggery wastewater (equivalent to a 20% nitrogen substitution ratio) achieved total soil salt balance. However, residual accumulation of Na, Cu, Zn, As, Cr, Cl, and HCO₃⁻ persisted, totaling 49.8 kg/hectare /season, necessitating prioritized removal during piggery wastewater treatment. It was recommended to reduce the intake of key salt components in liquid manure at the source, select treatment processes with effective desalination capabilities, and enhance agronomic management practices to lower the total salt content in liquid manure and mitigate risks associated with its field application. The model was based on corn nitrogen (N) fertilizer requirements, quantitatively analyzed salt accumulation characteristics, demonstrated high accuracy and strong replicability, and provided references for promoting the resource utilization of piggery wastewater.