On-line version ISSN 1678-4499
FRANCO, Coaracy M.. Effect of exclusive and continuous application of mineral fertilizers on the fertility of a soil. Bragantia [online]. 1970, vol.29, n.unico, pp. 139-151. ISSN 1678-4499. http://dx.doi.org/10.1590/S0006-87051970000100013.
Although largerly employed for economical reasons, it has been suggested that a continuous and exclusive application of mineral fertilizers is deleterious to coffee plantation. To investigate such a possibility, an experiment was carried out in Mitcherlich pots filled with Podzolized soil on Calcareous Sandstone, Marilia variation, which is one of the most commonly used soil for coffee. Ten plantings of corn, used as indicator plants, were made successively in these pots. Plants were harvested when about 80 cm high, and after each harvesting the soil of individual pot was removed, sifted, replaced and heavily fertilized. Prior to new planting, the soil was well watered, dried, then excess o salts being removed by a generous supply of water. A balanced mixture of fertilizer was applied to the plants, as done normally in field cultures. At the end of the experiment, each pot has received a maximum of 440 g of mineral fertilizer which is equivalent to ca. 880 kg of fertilizer applied to an individual coffee plant, under field conditions, in a period of 10 years. Such amount represents roughly a hundredfold dose usually recommended for coffee crop. Nevertheless, corn planted in soils treated with such heavy excess of mineral fertilizer, grew better than those cultivated in control pots. These received only normal level of fertilizers, and had the soil replaced several times during the experiment.