Effects of municipal waste compost and nitrogen fertilizer on growth and mineral composition of tomato

Purpose Since simultaneous use of organic and mineral fertilizers on the basis of their chemical compositions can lead to better plant growth and soil fertility, the roles of municipal waste compost (MWC) and nitrogen (N) fertil- izer on growth and mineral composition of tomato and some soil properties were evaluated under greenhouse condition. Methods Treatments involved four MWC rates (0, 1, 2, and 4% on the basis of soil dry weight) and four N levels (0, 50, 100, and 200 mg kg - 1 soil). Red cloud variety of tomato was sown in treated soils and 9 weeks later dried plant shoots and soil sub-samples were subjected to analysis. Results Combined use of MWC and N led to better growth of tomato than sole application of either MWC or N fer- tilizer. Plant concentration and/or uptake of nitrogen, phosphorus, zinc, copper, iron, and manganese were increased by both MWC and N. The beneficial effect of MWC on nutrients uptake was more pronounced with N addition. Plant and soil concentrations of cadmium and lead were under the detection limit of atomic absorption spectrophotometer. Soluble salts, organic matter, sodium, chloride and DTPA-extractable zinc, copper, iron, and manganese in the soil were effectively increased with addition of MWC. Conclusions Due to high soil pH and calcium carbonate equivalent (CCE) values of the calcareous soil, MWC heavy metals had no hazardous effect on tomato and even played a nutritional role. The most important problem raised from MWC application was the accumulation of soluble salts in the soil which must be monitored when making repeated application of MWC over an extended period of time