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Experimental Work

Samples of cabbage, lettuce, snapbeans, spinach, and tomatoes were obtained from commercial fields of these crops in Georgia, South Carolina, Virginia, Maryland, New Jersey, New York (Long Island), Ohio, Indiana, Illinois, and Colorado.5 The total number of samples examined was 204.

The collecting had to be done during the midsummer months, and this made it impossible to obtain samples of all five crops from all 10 states. Fortunately, samples of snapbeans and tomatoes were taken from every state. This report, therefore, deals primarily with the findings on these two crops. Bountiful snapbeans and Rutgers tomatoes were chosen for collecting and most of the samples belonged to these two varieties. So far as possible, the cabbage, lettuce, and spinach samples were confined to the Golden Acre, Grand Rapids, and Savoy varieties, respectively.

All samples were collected at the stage of growth when they were being harvested for market. Field collection was followed by as rapid transportation to the laboratory as possible. Only the edible portions were prepared for analysis, the outer leaves of cabbage and lettuce being discarded. All samples were rinsed in cold distilled water. The tomatoes were rubbed also with a clean cloth. The samples were dried in a hot-air convection oven at temperatures ranging between 70 and 80°C. Samples of the vegetables were wet-ashed with a mixture of nitric and perchloric acids and made up to volume. Aliquots were then analyzed for the major nutrient elements by standard procedures, including the use of the flame photometer for determining Ca, K, and Na. Another sample was dry-ashed at between 600 and 700°C and analyzed for the minor mineral nutrient elements by the use of a spectrograph.6

Next: Characteristics of Soils on Which Vegetables Were Grown