KINETIC RESPONSES OF PSEUDOROEGNERIA ROOTS TO LOCALIZED SOIL ENRICHMENT

Soil patches on opposite sides of Pseudoroegneria spicata plants in the field were treated with either distilled water or a nutrient solution containing N, P, or K. Roots from these enriched and control patches were tested three days later for their capacities of ammonium, phosphate, and potassium uptake. When phosphate was augmented in the enriched patches, rates of phosphate uptake increased significantly, but not rates of ammonium or potassium uptake. When the enriched patches were augmented with nitrogen, uptake capacities of both ammonium and potassium increased significantly (mean increases of up to 88% and 71% for ammonium and potassium, respectively). Potassium augmentation did not lead to increased soil-available K and, correspondingly, did not induce changes in the capacity for uptake of K, N, or P. The potential importance of nutrient uptake kinetics in the exploitation of nutrient-rich soil patches is discussed.