Changes in Soil Elements and Nutritive Value of Cool-season Turfgrass during Green-up

Turfgrass plays a crucial role in urban landscaping, and Poa pratensis L. is widely used across Asia. This study used correlation and principal component analyses to investigate soil nutrient dynamics during the green-up phase, with particular emphasis on turfgrass nutrition and soil element changes. Nutrient dynamics were critical for promoting optimal green-up. For instance, on sandy clay loam, which is rich in nutrients, the green-up date occurred approximately 7 days earlier than that on sandy loam. Differences in the principal components of soil nutrients and interactions between organic elements were observed across various soil types. Changes in soil nutrient composition in the upper soil layers were more pronounced than those in deeper layers. Notably, all six soil elements studied showed positive correlations with the principal nutrient components, particularly organic matter, available phosphorus, and urease. The most significant depletion of soil nutrients occurred when turfgrass was approximately 25% to 35% green. After this point, nutrient decreases slowed and became more gradual as the green-up phase continued.