Evidence from AHDB-funded research shows that current guidance to target a soil phosphorus (P) index of 2 is, for most crops, generous
Whilst current recommendations are ‘safe’ in terms of avoiding crop deficiencies, they are grossly inefficient and will be unsustainable in the long term, according to Roger Sylvester-Bradley of ADAS.
Recent trials work has shown that in many instances, a soil P index of below 2 produced comparable yields to those soils with a P index of 2 or above. However, experts said more research is needed to identify the optimum P index.
Natalie Wood, country agronomist at Yara, explained that a key area to consider when re-evaluating applications is the uptake of phosphate from the soil. “Our research shows that as much as 90 per cent of applied phosphate does not reach the crop. Targeted applications, based on farm evidence and carefully managed crop nutrient plans are the way forward if farms are considering minimising inputs to maximise returns.”
Ian Matts, arable director at Brixworth Farming has successfully reduced the average P index across his farm from the middle of index 2 to the top of index 1. In doing so, he has reduced his input costs, without having to compromise on yield. Speaking at CropTec Show, he said: “Growers need to work out what nutrient management strategy will work for them, rather than relying on an RB209 table that covers all of England and Wales and all the various soil types.”