Excessive nitrogen fertilizer application in the black soil region of Northeast China leads to nitrate leaching and gaseous nitrogen loss, posing environmental risks. This study aimed to evaluate the effectiveness of controlled-release urea (CRU) mixed with conventional urea in synchronizing nitrogen fertilizer supply with maize nitrogen requirements, improving nitrogen fertilizer use efficiency (NUE), and increasing economic benefits. A two-year field trial (2023–2024) tested six nitrogen fertilizer application strategies, all with a total nitrogen application rate of 168 kg N ha⁻¹, including no nitrogen fertilizer application (CK), conventional fractionated urea application (C0), and four controlled-release urea–urea mixed application schemes, where CRU supplied 100%, 70%, 50%, and 30% of the total nitrogen (C100, C70, C50, and C30). The results showed that the C70 treatment had the highest maize grain yield and protein yield, at 12,502.92 kg ha⁻¹ and 1567.65 kg ha⁻¹, respectively, and NUE increased by 10.07% in 2024 compared to the C0 treatment. The C70 strategy also reduced nitrate concentrations in deeper soil layers, decreasing nitrogen loss by 29.04–31.21% compared to the C0 treatment. Furthermore, the C70 strategy yielded the highest net benefit, reaching $2817 ha⁻¹. These results indicate that in black soil systems, a single basal application of C70 mixed fertilizer is an effective strategy for increasing maize yield, improving nitrogen fertilizer use efficiency, and reducing environmental risks.

Sustainable quinoa production in semi-arid regions is constrained by water scarcity and inefficient photoassimilate partitioning. This study evaluated the interactive effects of planting patterns and superabsorbent polymer (SAP) application rates (0, 60, and 90 kg·ha⁻¹) on ‘Longli 5’ quinoa source–sink dynamics. Results demonstrated that ridge-furrow planting coupled with a moderate SAP rate (60 kg·ha⁻¹, D1) synergistically optimized the soil moisture environment, enhancing the two-year average leaf area index (LAI) by 52.6–66.9% and net photosynthetic rate (Pn) by 5.45–10.64% (p < 0.05). Unlike the high SAP rate (90 kg·ha⁻¹), “water luxury consumption” and low input efficiency dynamic which induced “water luxury consumption” and low input efficiency, the D1 treatment effectively promoted photoassimilate remobilization to grains by 13.39–14.44%. Unlike high SAP rates (90 kg·ha⁻¹), which induced ‘water luxury consumption’ and low input efficiency, the D1 treatment effectively promoted photoassimilate remobilization to grains by 13.39–14.44%.This mechanism optimized source–sink coordination, resulting in a significant increase in seed yield and thousand-grain weight (p < 0.05). These findings conclude that a balanced source–sink allocation, rather than maximal source capacity alone, is the definitive driver of productivity. Integrating ridge-furrow planting with moderate SAP application (60 kg·ha⁻¹) is a highly efficient agronomic strategy for harmonizing quinoa growth and achieving sustainable, high yields in semi-arid environments.