Input data to AnnAGNPS are organized into groups such as cell, field, feedlot, soil, etc. At the beginning of data for each group is a control word signifying data group. Also on this record is a number indicating how many items follow such as number of cells, number of soils, etc. Data may be entered in English or SI units. Conversions to SI units are made internally. Data records are checked for range of value, illegal character, missing values, imbedded blanks, and data dependencies. All groups of data are described in the input specifications to AnnAGNPS including format of each data record.