Assessment of benefits and risks of landfill materials for agriculture in Eritrea

In Eritrea, farmers have applied landfill materials as fertiliser to their fields for several decades. A sampling scheme in the landfill site of Asmara and selected farmers’ fields was carried out to investigate the benefits and risks of using landfill materials for agriculture. Soil samples were collected from farmers’ fields (7 samples) and from the Asmara landfill site (12 samples). The samples were analysed for major plant nutrients, heavy metals (Cd, Cr, Cu, Pb, Ni, Hg and Zn), and some physical properties. Nearly 65% (by weight) of the total landfill material mined from the landfill site constituted waste fractions of various substances. The remaining 35% was composed of soil-like materials, which are apparently used to fertilise agricultural soils. The average organic matter, total nitrogen, and available phosphorus contents of soils with landfill material measured 2.4%, 0.13%, and 45 mg kg−1, respectively. However, soils without landfill material consisted of 1.1 % organic matter, 0.04% total N, and <40 mg kg−1 of available P. Except for Hg, all the other heavy metals in the landfill site showed values above the permissible limits. In particular, the average concentrations of Cu (913 mg kg−1) and Pb (598 mg kg−1) in the landfill site were nine-fold and four-fold greater than the allowable limits, respectively. It is, therefore, suggested that composting fresh organic wastes should be considered and tested as an alternative material for fertilising agricultural soils and to maintain the quality of the environment.