My new yard has a citrus tree...

Citrus trees need sun and well-drained soil. Most folks plant citrus trees in a slight mound, with a three- to four-inch-deep earthen basin around the tree. Citrus trees are sensitive to wet soil and overwatering. When you water, make sure the water does not rise to the level of the trunk if you can help it. Water thoroughly and deeply. Maintain a two-inch-deep mulch of grass clippings, sawdust, wood chips, or ground bark on the soil around the tree.