Amend the soil around the corn plants to increase long-term soil nutrition. Lay 3 inches of organic compost on top of the soil in a 10-inch circle around each plant, and turn it into the top 3 inches of natural soil. This amendment adds gentle, safe organic material with vitamins, minerals, and moisture retention.
Fertilize the corn plants. Yellow leaves mean a lack of nitrogen and potassium in the soil. Apply a complete fertilizer like 12-12-12, or a nitrogen-heavy fertilizer like 10-5-5, according to manufacturer directions. Turn the fertilizer into the top 3 inches of soil.
Water the corn after soil amendment and feeding to help the nutrients soak down to the roots. Give each corn stalk 2 to 3 inches of water. Sprinkle the water around the 10-inch circle you built with the compost, to hit all the amendments.