Relationships Between Nutrient Recycling, Environmental Impacts and Agricultural Production

Keywords: biodiversity, bioenergy, biofuels, manure, nitrogen, phosphorus, recycling, residues.

Intensification of agriculture, for which the use of agro-chemicals, water and energy are indispensable components, has increased yields per unit area and in most parts of the world has evidently limited the risk of famine. However, intensification has so far failed to feed the ever growing number of people adequately. Mankind thus continues to claim more resources at the expense of wild flora and fauna. Bio-energy production will further aggravate this problem, because carbon sequestration by photosynthesis can be used to produce plants for feeding humans, livestock or wild animals, or for bio-energy production, but not for all four at the same time. The general lack of a win-win situation makes choices inevitable.

Even if there was an immediate standstill in human population growth and in the multitude of products mankind expects agriculture to generate, agriculture would still not be sustainable as long as it is relying on finite resources, phosphorus (P) and fossil energy in particular. Thus we should save as much as possible on the use of P and energy-demanding nitrogen (N) through a more precise management of crops and livestock. Currently many plant nutrients are lost to the environment and this one way flow needs to be reversed. An improved utilisation of nutrients could yet buy the necessary time to redirect agriculture to a production method based on recycling and renewable resources. The fertiliser industries too will be increasingly challenged to participate in corresponding initiatives.

J J Schröder and J F F P Bos, Plant Research International, Agrosystems Research Department, Wageningen University, PO Box 16, 6700 AA Wageningen, The Netherlands.

27 pages, 11 figures, 4 tables, 53 references.