TY  - BOOK
AU  - Kirchmann, H.
AU  - Ryan, M. H.
TI  - Nutrients in Organic Farming: are there advantages from the exclusive use of organic manures and untreated minerals? 
U1  - e-book (MDP) 
CY  - Australia
PB  - Swedish University of Agricultural Sciences, 
KW  - 1. Nitrogen input 2. Soil fertility, 3.Yield 4.Waste recycling, 5. Rock phosphate, 6. Nitrate leaching, 7. Nutrient recycling, 8. Fertilizers
N1  - Includes bibliographical references
N2  - Abstract
Nutrient additions on organic farms are designed to maintain soil fertility, but not to directly feed plants.
Hence, nutrients are applied in organic or low solubility inorganic forms in the belief that plants will
obtain balanced nutrition through the actions of soil microbes. This review examines the implications of
organic farming fertiliser practices for the sustainability of farming systems using two contrasting
regions, Europe and Australia. In both these regions, mean yields are generally 20-45% lower on organic
farms than conventional farms primarily due to reduced levels of plant available nutrients. Changes in the
soil biological community do not overcome this limitation. Nutrient inputs are lower on organic farms,
although in Europe there is a tendency on organic farms for increased application of purchased, approved,
nutrient sources other than fodder. However, these inputs simply allow organic farms to gain nutrients
that originated from conventional farms. If organic farming were to be widely adopted, lower yields
would require more land (25-82%) to sustain production. In Europe, organic practices increase nitrate
leaching, both per unit area and per unit of food produced, due to lower N use efficiency. Despite their
aim of maximizing nutrient recycling, organic farming systems recycle only on-farm wastes and approved
food wastes, with most municipal wastes excluded due to concerns about pollutants. In future, easily
soluble inorganic fertilizers will be extracted from organic wastes through new nutrient recovery
technologies and this will make conventional agriculture more sustainable whereas organic farming
excludes itself from non-farm recycling, no matter how environmentally clean and safe the new fertilizer
products are. In conclusion, the current promotion of organic principles irrespective of environmental
outcomes means organic farming has become an aim in itself. This approach is ideological, not scientific,
and may exclude other more effective solutions to the environmental problems afflicting current
agricultural systems
ER  -