A biological experiment proceeded on yellow corn (Zea mays L.) in plastic pots during the agricultural season on August 4, 2021, which included adding organic matter (0% and 5%) and bentonite mineral (0%, 10%, and 20%) of soil weight and potassium (0, 50, and 100 kg ha^-1) as potassium sulfate. After 90 days of planting, the amount of soluble and exchangeable potassium measured revealed results that adding organic matter with bentonite minerals increased soluble potassium by 38.46%. Meanwhile, exchangeable potassium decreased by 1.61% and dry matter increased by 6.5%. As for adding bentonite, the 20% level was the most effective compared with 0% and 10%, in reducing soluble potassium by 25% and 50%. It also increased exchangeable potassium by 1.62% and 2.45% and dry weight of the plant by 95.04% and 48.32%. As for the effect of the added potassium levels, the results showed 100 kg ha^-1 was superior to 50 and 0 kg ha^-1 in soluble potassium (92.86% and 440%, respectively). The drained potassium was the highest at the level of 100 and 50 kg ha^-1 (5.88% and 5.04%) in the direction of the contact line, and 100 kg ha^-1 was superior to 100 and 50 kg ha^-1 in the dry weight of the plant (9.85% and 4.80%). The results of the double and triple interaction showed significant differences.

Keywords: Yellow maize (Z. mays L.), organic matter, bentonite, potassium fertilizer, growth traits

Key findings: The addition of organic matter and bentonite to sandy soils can improve potassium availability and reduce the values of exchangeable potassium, aside from improving the yellow maize corn (Z. mays L.) growth.