The Use and Effectiveness of Various Copper Bearing Materials for Application to Everglades Organic Soils
1954
Kretschmer, Albert E. | Forsee, W. T.
One of the classic examples of plant response to Cu is found in the vast area of organic soils of Peninsular Florida. Most crops failed to grow on these soils until the middle 1920's when the need for Cu was first demonstrated. Tremendous growth response of various leafy vegetables, cruciferous plants, root crops, eggplant, tomatoes, and certain forage crops have been obtained with initial applications of 50 pounds an acre of copper sulfate. In recent years it has been found that copper oxide is at least as effective as copper sulfate in supplying sufficient copper for maximum plant growth. Results of greenhouse tests indicated that either source is as effective when added to the soil in mixed fertilizer as when added separately. Further work showed that plant response to Cu on virgin peaty muck soil was the same whether 12 or 24 pounds of Cu per acre was applied. A field experiment comparing two rates of copper oxide and copper sulfate showed the effects of plant varietal differences with respect to Cu deficiency symptoms. Southland oats and ryegrass were seeded in the test area where St. Augustinegrass cuttings had been planted. Copper deficiency symptoms of oat plants growing on the no-Cu plots were much more pronounced as indicated by reduced yields and chlorosis than were the symptoms for ryegrass. Copper contents of the oat plants were lower for the no-Cu plots but no differences were noted for plants treated with the oxide or sulfate at 12 or 24 pounds of Cu. St. Augustinegrass and pangolagrass (fertilized in a similar manner) showed similar findings. Copper analyses of various forages grown in the greenhouse with additions of 1,000 pounds of copper sulfate per acre, indicated that St. Augustinegrass, caribgrass, and paragrass, absorbed more Cu than bahiagrass, fescuegrass and “giant” pangolagrass. Copper contents of red clover and subterranean clover growing in the field, were significantly greater than ryegrass, oats, vetch, alfalfa, and hubam clover. Copper contents of forages taken from various soils in the area indicated that Cu deficiency, per se, of cattle should not be widespread in this area under proper fertilization, including Cu additions.
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