Fertilisation of potted geranium with a municipal solid waste compost

A greenhouse pot study was conducted to evaluate the use of a municipal sol id waste compost (MSWC) as a fertilizer for potted geranium (Pelargonium x hortorum Bailey) cv. Meridonna. MSWC was mixed with a peat-based growing-me dia at rates of 0%, 10%, 20%, 30%, 40% and 50% by volume. Plants grew in th ose mixes for 90 days, with no additional fertilization. MSWC increased the electrical conductivity (saturated extract) of the growt h-media linearly from 1.4 mS cm(-1) at 0% to 12 mS cm(-1) at 50% MSWC. 10% and 20% MSWC promoted the highest plant growth, although these plants showe d low leaf concentrations of nitrogen and phosphorus. The lowest yield was obtained at 0% MSWC caused by a low level of available nutrients in the gro wth-media. Application rates of MSWC >20% reduced plant growth as a consequ ence of the high level of salts, and rates greater than or equal to 40% res ulted in high levels of copper. The results of this experiment showed that potassium, magnesium, calcium and micronutrients requirements of geranium w ere provided with 20% MSWC, indicating that this crop could be grown in pea t-based substrates with 15-20% of MSWC, as long as adequate amounts of nitr ogen and phosphorus were being provided. (C) 2000 Elsevier Science Ltd. All rights reserved.