Relating Crop‐Yield Response to Water‐Table Fluctuations

Field data of water‐table depth fluctuations under cotton grown in Egypt arc used to relate water‐table depth frequency of occurrence to yield. Daily water‐table levels are measured. A multiple linear regression analysis is used to develop site‐specific population parameters that allow evaluation of the effect of various water‐table depths on yield. Low water tables and high water tables affect yields in different ways, and both effects can be represented. The procedure for analysis of the data is illustrated with an example. The potential use of the method is to determine drain spacings that will keep water‐table fluctuations within limits that result in the best yields.