Inorganic fertilisers

Normal agricultural practices generally cause an enrichment of heavy metals in soil, particularly Zn, Cu and Cd, due to the application of manure or its derivatives, compost or sludge and inorganic fertilisers and other human activities such as... 

There are many reports of the beneficial effects on plant growth of applying organic wastes to land. Brechin and McDonald [5] demonstrated that pig slurry was as effective in increasing barley yield as conventional inorganic fertiliser. The major benefit appeared to be the increase in N concentration of the barley plant. 

Nitrous oxide contributes severely to global warming and the depletion of ozone in the stratosphere (Crutzen 1981, Bouwman 1996). Almost 90% of the global atmospheric N2O is formed during the microbial transformation of nitrate (NO ) and ammonia (NH ) in soils and water. In OECD countries the agricultural contribution to N2O emissions is estimated at 58% (IPCC 2001). Soils fertilised with inorganic fertilisers and manure stores are seen as the largest sources (Chadwick et al. 1999, Brown ef al. 2002). 

Possible solutions include the use of inorganic fertilisers or imported topsoil, which can be very expensive depending on location and availability. An alternative solution is the use of organic wastes such as sewage sludge, which is already used in the UK as well as Sweden and Finland. 

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