Combining Controlled-Release Urea with Controlled-Release Potassium Chloride to Reduce Nutrient Leaching and Promote Nutrient Use Efficiency in Wheat Field

To investigate the impacts of combining controlled-release urea (CRU) with controlled-release potassium chloride (CRK) on nutrient leaching and use efficiency in wheat fields, we carried out experiments spanning three consecutive years from 2022 to 2024, utilizing a split-plot design. In this study, the control plot received neither nitrogen nor potassium applications (Control). The main plots were designated based on nitrogen fertilizer types: controlled-release urea (CRU) and conventional urea (Urea). The sub-plots were assigned potassium fertilizer rates using CRK, specifically 50 kg ha-1 (LCRK), 75 kg ha-1 (MCRK), and 100 kg ha-1 (HCRK). The findings revealed that the nutrient release pattern of CRU combined with CRK aligned well with wheat's nutrient uptake requirements. Notably, the wheat yields in CRU treatments witnessed a significant average increase of 2.2% from 2022 to 2024 compared to ordinary urea treatments. In the final season, nitrogen recovery efficiency augmented by 10.9%. Furthermore, CRU treatments significantly boosted the number of effective wheat spikes and grains per spike but had no notable influence on wheat's thousand-grain weight (TGW). Consequently, the yield enhancement observed in CRU treatments was primarily attributed to an increase in wheat's effective tiller count. CRU also markedly elevated inorganic nitrogen levels in the plow layer soil during wheat's mid to late growth stages, effectively mitigating nitrate nitrogen leaching into deeper soil layers. The application of CRU×MCRK notably and significantly improved wheat leaf photosynthesis during its mid to late growth stages, yielding substantial economic benefits and theoretical significance.