Response of Clover Trifolium fragiferum L. cv. ‘Salina’ To a Heavy Urban Compost Application

Abstract

The clover, T. fragiferum L. cv. ‘Salma’ was grown for two years in a greenhouse under a heavy rate of urban compost application at sowing (1001 ha⁻¹ year⁻¹). An inorganic fertilizer was also applied for comparison (8N-15K₂O-15P₂O₅, 1.21 ha⁻¹ year⁻¹). The legumes Medicago rugosa Des. cv. ‘Paragosa’, Trifolium subterraneum L. ssp. subterraneum, T. subterraneum L. ssp. brachycalycinum were also grown for comparison. The combined N applied with the inorganic fertilizer did not impair either seedling emergence or growth of any of the legumes. Seedling emergence of legumes was in general higher under the urban compost treatment than under the inorganic and control treatments, with that of T. fragiferum being the highest. This latter species was the only one with a higher dry matter production under the urban compost treatment than under the other treatments. Urban compost application significantly increased N, P, Cu and Zn concentration and export of T. fragiferum, in relation to the inorganic and control treatments. A similar trend was observed for K, but without significant differences, with clover also showing a reasonable capacity to absorb Na (natrophilic character). Significant increases in Ni and Cr concentrations, in relation to the control, were also observed in the last cut carried out in the second year, although phytotoxic or toxic levels for cattle were never registered for any metal analyzed in T. fragiferum.