If your agave leaves are turning yellow, it could be due to a few different reasons. One possibility is that the plant is not getting enough water. Agaves are native to arid regions and can withstand long periods of drought, but they still need some moisture to stay healthy. If the soil around your plant is dry, try giving it a good watering. Another possibility is that the plant is getting too much sun. Agaves like plenty of sunlight, but if they are in direct sunlight all day long, their leaves can start to turn yellow. Try moving the plant to a spot where it will get some shade during the hottest part of the day. Finally, yellowing leaves can also be a sign of nutrient deficiency. If your plant is not getting enough nitrogen or other essential nutrients, its leaves will start to turn yellow. You can try fertilizing the plant to see if that helps. If you can't figure out why your agave leaves are turning yellow, it's best to consult with a professional. A gardening expert will be able to diagnose the problem and give you specific advice on how to fix it.