Leaching From Land Municipal Composts: 3. Inorganic Ions

Abstract

The leachates from 17 lysimeters containing compost of varying origin, age (3 and 12 months), and packing depths (15—50 cm) were monitored for a 2.5-year period. This paper reports on the results on Na, K, Ca, Mg, Mn, Fe, Cl, SO₄ and to a lesser extent specific conductivity, total dissolved solids, F, B and P. High initial leachate concentrations exceeding the drinking water standards several-fold were observed for all constituents except B and F. Sulphate and K were identified as the most serious pollutants of the ions studied but they were found to be less critical than N compounds and organic matter previously reported in the leachate. The leaching of most constitutents increased with increasing amounts of compost per square metre. The origin of the compost affected the leaching of K, Mn, Fe, Cl, Mg and SO₄. The first year of leaching released significant parts of the Na, K, Mg, Cl and SO ₄ but only minor parts of the Mn, Fe, F and P present in the compost.