Classicly

Beyond the city lay the desert with its fretwork of canals and its pathetic patches of green growth, pathetic because where once grain had grown as far as the eye could reach now only a few patches were under cultivation. It was not the failure of the soil or of the water that made the desert bare. This soil would still grow lush vegetation. But the grains, though lush, would be worthless, incapable of supporting life. The minerals had been virtually exhausted from the top-soil of Mars.

Had Malovar begun to doubt him? Was the Martian ruler considering what action he might take at the next time of the testing? At the thought, a slight shudder passed over the tall trader as if the desert wind had suddenly become tinged with a trace of bitter chill. No, that could hardly be the source of the trouble he sensed. He was no telepath, he could not read Martian minds, nor they his.