Classification and Mapping of Agricultural Land for National Water-Quality Assessment

By Robert J. Gilliom and Gail P. Thelin

U.S. Geological Survey Circular 1131

Table 2. Row crop census data codes and national harvested area used to develop classification system.

[Data from 1987 Census of Agriculture]

--------------------------------------------------------------------------------------------

Individual row crops    Individual crops as         Census    National     Percentage of
  or aggregations       recorded in census           data     harvest    national total for 
                                                     code     (acres)   row crops classified

--------------------------------------------------------------------------------------------
Primary crops                                                                   
                                            
Corn                    Corn for grain or seed       2107    58,701,505       23.05
                        Corn for silage or green     2777     5,785,360        2.27
                          chop.                                            
                        Popcorn                      2207       268,018        0.10
                        Total corn                           64,754,883       25.42
                                           
Wheat and other 
  grains                Wheat                        2127    53,224,174       20.90
                        Barley                       2137     9,178,410        3.60
                        Buckwheat                    2147        81,206        0.03
                        Emmer and spelt              2157        31,361        0.01
                        Flaxseed                     2167       429,690        0.17
                        Mixed grain                  2177         2,842        0.00
                        Mustard seed                 2187        19,691        0.01
                        Oats                         2197     5,981,247        2.35
                        Rye                          2237       545,868        0.21
                        Proso millet                 2217       291,845        0.11
                        Small grain hay              2737     3,496,166        1.37
                        Safflower                    2247       210,629        0.08
                        Triticale                    2267       152,400        0.06
                        Wild rice                    2277        31,393        0.01
                        Total wheat and other                73,676,922       28.93
                          grains.                                          
                                         
Soybeans                Soybeans                     2307    55,291,205       21.71
                                          
Alfalfa                 Alfalfa hay                  2727    23,629,792        9.28
                        Total primary crop area             217,352,802       85.35
                                            
Secondary crops                                                                                                             
Sorghum                 Sorghum for grain or seed    2117     9,760,574        3.83
                        Sorghum cut for dry forage   2787       101,538        0.04
                          or hay.                    
                        Sorghum for silage or green  2797       507,417        0.20
                          chop.                                            
                        Sorghum for sirup            3991           987        0.00
                        Sorghum hogged or grazed     4001        13,886        0.01
                        Total sorghum                        10,384,402        4.08
                                            
Cotton                  Cotton                       2287     9,826,081        3.86
                                            
Rice                    Rice                         2227     2,424,864        0.95
                                            
Dried beans and peas    Dry edible beans excluding   2317     1,670,097        0.66
                          dry limas.                                           
                        Dry lima beans               2327        44,423        0.02
                        Dry edible beans             2337       232,847        0.09
                        Dry cowpeas & dry southern   2347        31,896        0.01
                          peas.                                         
                        Lentils harvested            2357       161,588        0.06
                        Total dried beans and peas            2,140,851        0.84
                                            
Sunflowers              Sunflowers                   2257     1,982,357        0.78

Field and grass seeds   Field seed and grass seed    2457     1,725,743        0.68
                          crops

Peanuts                 Peanuts for nuts             2447     1,436,034        0.56
                                            
Potatoes                Irish potatoes               2367     1,309,963        0.51
                                           
Sugar beets             Sugar beets for seed         2387         4,731        0.00
                        Sugar beets for sugar        2397     1,249,200        0.50
                        Total sugar beets                     1,253,931        0.50
                                            
Sugar cane              Sugar cane for seed          2407        43,566        0.02
                        Sugar cane for sirup         2417            27        0.00
                        Sugar cane for sugar         2427       779,249        0.31
                        Sugar cane not harvested     2437        95,777        0.04
                        Total sugar cane                        918,619        0.37
                                            
Tobacco                 Tobacco                      2297       633,310        0.25
                                            
Vegetables              Land used for vegetables     2806     3,264,343        1.28
Total secondary crop area                                    34,036,155       13.37
                                           
Total crop area in primary                                  254,653,300      100.00
and secondary crops                                                                 
------------------------------------------------------------------------------------