Soil Nutrient Variability Analysis of Typical Planting Patterns in Agricultural Reclamation Areas of the Southern Dianchi Lake Basin

This study investigates the effects of typical planting patterns on soil nutrient accumulation and associated environmental impacts in agricultural reclamation areas of the southern Dianchi Lake Basin. Taking the cut flower cultivation area in Dahewei Village, Jinning District, Yunnan Province, as the research site, we compared soil physicochemical properties, nutrient contents, and their correlations with environmental factors under open-field and greenhouse cultivation, and analyzed the characteristics of soil fertility changes and non-point-source pollution risks in greenhouses. We found that greenhouse cultivation is associated with altered soil physicochemical properties, including smaller aggregate sizes, increased soil moisture content (from 30.15% to 32.20%), elevated pH values (from 7.11 to 7.23), and 79% higher electrical conductivity compared to open-field conditions (620.82 vs. 347.60 μS cm−1, p < 0.01). Compared with open-field systems, greenhouse cultivation exhibited greater nutrient accumulation, particularly for total nitrogen (TN) and available potassium (AK) in the 0–10 cm topsoil layer, demonstrating pronounced surface enrichment. Additionally, greenhouse conditions showed weaker correlations between soil nutrients and meteorological factors but stronger inter-nutrient coupling. Enhanced soil moisture and temperature conditions were associated with reduced nutrient leaching but simultaneously increased surface nutrient enrichment and salinization risks. These findings provide quantitative evidence for precision fertilization strategies, optimized irrigation management, and targeted soil health interventions in intensive greenhouse systems. The results have practical applications for preventing surface nutrient accumulation and long-term salinization in protected agriculture.