Journal of Applied Horticulture. 2004: 6(2): 58-61

Environmental impact of phosphorus overfertilization in tomato greenhouse production.

Giuffre, L; Alconada, M; Pascale, C; Ratto, S

Catedra de Edafologia, Facultad de Agronomia, Universidad de Buenos Aires, Av. San Martin 4453, 1417, Buenos Aires, Argentina.

An experiment was conducted to evaluate the effect of overapplication of phosphorus fertilizers on soil properties in commercial greenhouses for tomato production and to study the relationship between soil extract P values and yields. Twenty commercial greenhouses with continuous tomato production were analysed in the horticultural belt of La Plata, Buenos Aires, Argentina, with Vertic Argiudoll soils, and compared with a control site. Composite soil samples were extracted at 0-20 cm of depth in 2 sampling dates: initial (tomato transplantation) and 6 months later (harvest). Oxidizable C, total N, Bray extractable P, and exchangeable bases in ammonium acetate extracts, were determined in dry soil samples. Electrical conductivity and pH were measured in saturated soil paste extracts. Tomato yields were determined at each experimental site. Overapplicaton of fertilizers was associated with physical-chemical degradation of the vertic soils of the region with visual symptoms of chlorosis, calcium deficiency, and fruit problems in plants. Unnecessary overapplication of P fertilizers must be avoided, as tomato yield did not increase with further addition of fertilizer, and soil properties as pH, EC, Na and SAR must be carefully monitored.