The resulting intense accumulation of salts in the soil presents some difficulties to spring sowing and the normal growth of summer-harvested crops. It is very difficult under these circumstances to gain high yields without irrigation. Yields of fall crops are low and unstable, with no harvest at all guaranteed in the depressions. The light and heat conditions of this region are suitable for two crops a year or three crops in two years. Water and soil are the predominant elements in the ecological environment of the plain.
Water is the more active of the two.
Drought, flooding and salinization are all closely related to water and are exhibited through the soil. The regulation and management of water is the key to the control of these natural hazards. If there is too little water in the soil there is drought, while too much leads to waterlogging. A series of comprehensive measures combining irrigation and drainage and making joint use of wells and canals have had pronounced effects in preventing drought, flooding and salinization. Soil fertility has also been raised in this way and the ecosystem has been improved.