Effects of Various Soil Amendments on the Growth of Red Clover (Trifolium pratense L.)

Uniform and rapid seed germination is essential for successful plant establishment and growth. Previous studies have shown that both organic and mineral amendments can improve germination rates and early plant development. This study investigated the effects of zeolite, bentonite, and potassium nanochelate on the growth characteristics of Trifolium pratense through a factorial pot experiment based on a Completely Randomized Design (CRD). Treatments included zeolite (2, 4, and 6 g/kg), potassium nanochelate (30, 60, and 90 mg/kg), bentonite (2, 4, and 6 g/kg), and combined applications of potassium nanochelate and zeolite. Soil samples were randomly collected from the Fandqalou rangelands of Ardabil, Iran. The prepared soil was then added to pots, where 20 seeds of T. pratense were sown per pot. After the growth period, plant height, volume, dry and fresh weight, root weight (fresh and dry), root length, root volume, root surface area, establishment rate, chlorophyll content, electrolyte leakage, leaf relative water content, and membrane stability index were measured. Results indicated that the highest fresh weight of aerial parts (124.28g/pot), dry aerial weight (34.11g/pot), dry root weight (14.30g/pot), and fresh root weight (56.84g/pot) were achieved using 30mg/kg potassium nanochelate + 2g/kg zeolite, 60mg/kg potassium nanochelate + 4g/kg zeolite, 60mg/kg potassium nanochelate, as well as with 90mg/kg potassium nanochelate, respectively. The longest root length (27.33 cm) was observed with 6 g/kg zeolite, while the greatest root volume (61.67 mm³) and root surface area (71.06 cm²) were recorded with 6 g/kg bentonite. The combination of 60 mg/kg potassium nanochelate + 4 g/kg zeolite yielded the highest establishment rate (84%). Findings suggest that targeted use of mineral amendments can significantly improve red clover growth and may be beneficial for rangeland restoration and pasture establishment in degraded or low-yielding rain-fed areas.