This has been said 50 different times 50 different ways in, probably, close to 50 different countries. All over China, africa, middle east, south america the farmland/grounds dont have the ability to absorb rain. They stay dry even when heavy rain comes. They were overfarmed and any vegetation that grows is eaten by cattle immediately. Ground dries out and becomes sand that repels water. There are some amazing documentaries on this i highly recommend. Especially “Re-greening the desert” with john liu