Nutrient Management on Organic Farms
Introduction
The management of nutrients in organic farming systems presents a formidable challenge, as the use of inorganic fertilisers is not permitted. Therefore organic farmers must optimise a range of soil, crop, rotation and manure managements to ensure a nutrient supply which will guarantee optimum crop yields and minimise losses to the environment. To achieve this objective, an appreciation of the nutrient cycles in farming systems is essential.
This booklet gives an overview of soil nitrogen (N) phosphorus (P) potassium (K) and pH management in Irish organic agriculture and horticulture. As for many other aspects of organic agriculture, it is not ‘a recipe’ of how to grow organic crops, but more of a guide on ‘how to farm’. It must therefore be combined with other sources of production information as well as farmers own experience to create a nutrient management strategy that is tailored to the climate, soils and production system of an individual farm or holding.
With organic agriculture only having been a small proportion of total agriculture to date, and with its role as a counterpoint to mainstream farming, the volume of scientific research into organic agricultural techniques is disproportionably small. Therefore, much of the information in this booklet can only be of a more general nature, as the detailed research that is required to make firm recommendations does not yet exist.
There is little doubt that when great care is taken with the storage and spreading of animal manures on the farm, soil fertility can be protected to a considerable extent. Areas used for silage production must get priority when spreading animal manures and ideally the grazing and silage areas should be rotated annually. However, with the best will in the world, there will still be some loss of nutrients. In order for organic agriculture to be sustainable in the long term, these losses must be replaced.
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