LAST YEAR’S massive hike in fertiliser prices has given farmers and agronomists every incentive to look at ways of making crop nutrients more effective, writes Ewan Pate, farming editor.

There are also environmental pressures to make sure that there is the minimum amount of leaching into watercourses, especially of nitrogen.

These problems are as pressing on the other side of the Atlantic as they are here and American crop scientist Jake Sanders is in Scotland this week to share information about two new products he believes can improve yields while in some cases using less fertiliser.

Vice-president of Kansas City-based research company SFP, Mr Sanders is here for tomorrow’s Potatoes In Practice event at SCRI’s Balruddery farm at Invergowrie.

This is his second visit to what has now become a major industry event. In recent years his company has developed two polymer-based coatings for fertiliser, one designed to prevent phosphate becoming locked in the soil and the other to reduce volatilisation of nitrogen from urea. Both are being marketed in the UK by Carrs Fertilisers Ltd.

Trials are under way this season in Scotland with the phosphate product, known as Avail, and as yet there is no independent evidence of its effectiveness but Mr Sanders expects it to perform as well as it has in the US under a range of conditions and crop types.

The theory is that when phosphate fertilisers are applied conventionally only between 5% and 25% is immediately available to plants. The rest is attracted to positive ions on the soil and attaches itself to a range of metals such as aluminium, iron and magnesium.

Avail is a water soluble, negatively charged polymer coating which attracts these positive ions, leaving the phosphate free to be taken up by the crop.

Mr Sanders has results from Kansas showing yield increases in wheat of up to one tonne per hectare where the phosphate had been treated and where the fertiliser had been applied in a band close to the seed.

Trials in Idaho showed that potatoes joined across the drills more quickly and matured earlier when more phosphate was available at an early stage in crop development.

Bill Petrie, manager in Scotland for Carrs, said that it should be possible for potato growers to reduce the amount of phosphate applied which would be a significant saving for those renting ground and who are thus unlikely to benefit from residual phosphate left in the ground.

Trials of Avail are currently under way with SAC, Scottish Agronomy and Harper Adams University but results are unlikely to be available until the turn of the year.

The other product in Mr Sander’s portfolio is one called Nutrisphere-N, which he described as a “nitrogen fertiliser manager.”

“Farmers can lose up to 50% of applied nitrogen through leaching and volatilisation, partly because soil-borne bacteria convert the fertiliser into nitrates,” he said.

“The ideal is to protect the nitrogen fertiliser in its ammonia form.”

Mr Petrie believes that using the product will have particular relevance where urea is used as the fertiliser.

“Urea is only 90% as effective as ammonium nitrate fertiliser. All the work in the UK during the 1950s pointed towards using ammonium nitrate and the industry has developed around that but for the rest of the world urea is the most important source of nitrogen.”

Ammonium nitrate production, Mr Sanders confirmed, has almost stopped in the US for security reasons. The fertiliser was used as a base for the explosives used in the Oklahoma bombing.

The Nutrisphere-N treatment is likely to add £40 per tonne to the price of urea fertiliser.