Although phosphate (Pi) is a necessary nutrient for the growth of aquatic organisms, the presence of excess Pi leads to water eutrophication; thus, it is necessary to accurately determine the content of Pi in water. A method for the determination of trace Pi in aquaculture water was developed based on surface-enhanced Raman spectroscopy (SERS) combined with rhodamine 6G (R6G)-modified silver nanoparticles (AgNPs) as the active substrate. The adsorption of R6G on the AgNP surfaces led to a strong SERS signal. However, in the presence of Pi and ammonium molybdate, phosphomolybdic acid formed, which further associated with R6G to form a stable R6G-PMo₁₂O₄₀³⁻ association complex, thereby hindering the adsorption of R6G on the AgNPs, and reducing the SERS intensity; this sequence formed the basis of Pi detection. The decrease in the SERS intensity was linear with respect to the Pi concentration (0.2–20 μM), and the limit of detection was 29.3 nM. Upon the application of this method to the determination of Pi in aquaculture water, a recovery of 94.4–107.2% was obtained (RSD 1.77–6.18%). This study provides an accurate, rapid, and sensitive method for the trace determination of Pi in aquaculture water, which is suitable for on-site detection.

To enhance the operation effect and working performance of our previously developed strip fertilization planter for broken straw back throwing and inter-row laying, and to improve the stability of straw crushing and consistency of straw mulching between rows (broken straw inter-row mulching), the key operation parameters of the planter were optimized in this study. On the basis of determining the transmission route and matching power consumption, the discrete element method was used to establish a mechanical model of straw particles using the EDEM software, which was then imported into the rigid–flexible coupled system of the ‘shredded straw-mechanism’. Quadratic regression orthogonal methods and rotation combination experiments were then designed to carry out a DEM virtual simulation and numerical simulation, and the optimal combination of operating parameters affecting planter working performance was obtained, which was also verified by field tests. The simulation test results showed that the smashing spindle speed (A) had the most significant influence on the coefficient of variation (Y₁) of straw crushing, followed by the planter working forward speed (C). The conveying impeller speed (B) had the most significant influence on the coefficient of variation (Y₂) of inter-row straw mulching, also followed by (C). The optimal combination of operating parameters after optimization were A = 2060.79 rpm, B = 206.25 rpm, and C = 0.95 m·s⁻¹, and the optimal working performance of the planter was obtained as Y₁ = 8.51% and Y₂ = 10.34%. The evaluation index results corresponding to the field test were Y₁ = 9.35% and Y₂ = 10.97%, which met the technical requirements of the relevant operation machinery; the relative errors of the simulation test results were 9.87% and 9.63%, respectively, indicating the effectiveness of the virtual numerical simulation and the rationality of the optimized operation parameters. Our results provide a technical reference for realizing high-quality and smooth no-tillage seeding operations.