Improving the sustainability of phosphorus use in arable farming
Current systems of production rely on inputs of highly water-soluble fertilisers to maintain large reserves of background P in the soil. Recovery of applied P by crops is consequently low (<30%) and this inefficiency is not only wasteful of resources but also increases the risk of eutrophication through increased P loss in runoff from land.
ADAS, Agrivert Ltd, Bangor University, Carrs Fertilisers, Michael Payne Environmental Consultants, Omex Agriculture, SAC, Severn Trent Water, Speciality Fertiliser Products, Virotec Europe Ltd
The project will address two key hypotheses:
a) Modification of fertiliser P-release patterns, better targeting of P inputs to meet crop P demand and more selective crop/soil management will improve the utilisation efficiency of soil and applied P by arable crops, allowing them to be grown on soils of lower P fertility without sacrificing farm profitability.
b) The adoption of novel soil and fertiliser management strategies on soils lower in P will reduce emissions in land runoff of P from applied fertilisers and soil stocks and lessen the wider negative environmental impacts of arable farming.
This is project LK09136 in DEFRA’s Sustainable Arable LINK programme.
- The most effective means of physically targeting fertiliser P was found to be through fertiliser placement, but this only increased the yield response to P of barley and potatoes, not of winter wheat or winter OSR.
- The best way of enhancing recovery of fertiliser P was to use struvite (a slightly soluble P compound recovered from wastewater) instead of TSP and place it close to the seed, but best recoveries were still <10%. Placement of struvite proved significantly better than placement of TSP at just one of the ten sites (with potatoes).
- In the ten field-response experiments, AVAIL®-treated TSP seldom gave different yields from TSP alone (yield increased at one site and decreased at another), but responses to less soluble struvite P were often slightly better than TSP.
- Even in experiments on soils of low P status, crops gained far more of their P requirements from inherent soil P reserves than from fresh fertiliser.
About this project
Aim: To develop profitable and sustainable farming systems that maximise the efficiency of utilisation of soil and applied phosphorus by arable crops and minimise negative impacts on the wider environment.