TESTING A LOW-QUALITY URBAN COMPOST AS A FERTILIZER FOR ARABLE FARMING

A coarse urban compost, low in organic matter but mature, was tested f or agricultural use. The response of Tewera ryegrass to this compost ( applied at 12 and 48 t/ha) was evaluated in a field trial over two yea rs. For a satisfactory yield the larger dose was necessary. This dose also gave greater values for the apparent recovery of N in both years. However, the N concentration in ryegrass was always below the suffici ency ranges proposed for N. The values of the potentially mineralizabl e N of the compost showed that the applied N at the greater rate of co mpost application was not sufficient to cover crop removal of N. In co ntrast, concentrations of P, S, K, Mn and Zn were within their corresp onding sufficiency ranges. The dose of 48 t/ha did not increase Cu, Ni , Pb and Cd concentrations in the ryegrass.