The influence of municipal solid waste compost on yield, soil phosphorus availability and uptake by two vegetable crops grown in a Pugwash sandy loam soil in Nova Scotia

Organic materials applied to soils can influence soil phosphorus (P) dynamics. The purpose of this study was to evaluate the effects of municipal solid waste (MSW) compost on soil P availability and uptake by potato (Solanum tuberosum) and sweet corn (Zea mays) crops grown in a Pugwash sandy loam soil in Nova Scotia, Canada. Three rates of compost (MSW1, MSW2 and MSW3), one rate of chemical fertilizer (NPK) and one mixture of 1/2 MSW compost and 1/2 NPK fertilizer (MIXTURE) were used on both crops according to soil P test results. During the second year, another treatment with the recommended levels of NK fertilizer was added. The experimental design was a randomised complete block design with four replications. The NPK and MIXTURE treatments produced significantly(P < 0.05) higher yields (both crops) than the MSW compost treatments in 1996, while in 1997, the yields were not significantly different for all treatments (both crops). All the MSW compost treatments had lower tissue N compared to the inorganic fertilizer and MIXTURE treatments. The MSW compost and the MIXTURE treatments resulted in statistically equivalent concentrations of tissue P as the NPK treatment in both crops and both years. Tissue P concentration in potatoes ranged from 1.92 to 2.25 and 2.60 to 3.17 g kg−1, while in corn it ranged from 3.08 to 3.46 and 2.32 to 3.16 g kg−1 in 1996 and 1997, respectively. The MSW compost and MIXTURE treatments generally resulted in equivalent concentration of Mehlich-3 extractable soil P compared to the inorganic fertilizer. In addition, the application of both inorganic fertilizer and MSW compost decreased P adsorption by the Pugwash soil by up to 30%. Municipal solid waste compost may be a good source of P for both potatoes and sweet corn. However, the low availability of compost-N means that supplementary N in the form of inorganic fertilizer may have to be added together with compost in order to enhance N availability to crops.