Keywords: phosphorus, fertiliser use efficiency, fertiliser application methods, fertiliser placement, cereal crops, tillage farms.
Phosphorus (P) is essential for all life on the planet and in recent decades concerns have grown around the security of P supplies for future food production, increasing global P fertiliser prices and P loss to the wider environment This has encouraged the development of more sustainable approaches to P management to deal with the on-farm and off-farm impacts of P use. In Ireland P fertiliser use has been declining since the late 1990s and soil P levels have been declining also since the mid 2000s. If this depletion of soil P reserves continues it could pose a serious threat to the competitiveness of Ireland’s agricultural industry. Phosphorus fertiliser is required to maintain and improve the P status and productivity of many soils for crops growth. However, P transfer from soils to water needs to be minimised as it is a major cause of P-induced eutrophication in surface waters resulting in degradation of water quality and aquatic ecology resulting in negative environmental and economic consequences. On tillage farms adequate soil P supply is critical for high yielding crops, particularly during crop establishment and early season growth. The P attenuation capacity of different soil types can vary significantly which can affect the P availability and use efficiency of the P fertiliser applied. However, better knowledge of the P dynamics of different soil types would help to improve P advice and to target P fertiliser management appropriately. Soil P testing was shown to be a good indicator of P availability and crop response to P fertiliser, and is an important tool for farmers to assess the fertility status of their soils and to plan an effective P fertiliser management strategy for their farms. Consideration should also given to how fertilisers are applied to soils in order to maximise P use efficiency, especially on low P fertility soils. The placement of P close to the seed can offer significant advantages over more common place broadcast application methods. Other technologies that enhance the efficiency of P fertilisers should also be considered, but not before rigorous evaluation to ascertain their overall effect. As the future of P fertiliser supply is uncertain it is necessary to develop our knowledge and management practices to maximise the efficiency of its use. The aim is to have better knowledge to help make the correct decisions to safeguard future crop yield potential and economic viability of tillage farms and to minimise negative economic and environmental effects arising from its misuse.
D P Wall1, M Plunkett1, R Hackett2 and S T J Lalor1.
1 Teagasc, Crops Environment and Land Use Programme, Johnstown Castle, Wexford, Ireland.
2 Teagasc, Crops Environment and Land Use Programme, Oak Park, Carlow, Ireland.
28 pages, 7 figures, 7 tables, 49 references.