Release of 'locked in' soil phosphorus could deliver major savings for potato producers this season

Potato growers could cut phosphate applications by up to 40 kg/ha, equivalent to a saving in phosphate of £51/ha, by using a soil complexing agent that unlocks nutrient reserves already in the soil, Agrii trials suggest.

Across three seasons and a range of soil textures, crops that received Agrii Start-Release pre-emergence have delivered a positive yield response, explains, the company's national fertiliser manager Tom Land.

“Phosphorus take-up is often influenced by a range of factors such as the soil’s calcium content, pH and temperature.

"Regardless of these, the use of Agrii Start-Release has been overwhelmingly positive in our latest trials with increases to the marketable fraction and tuber bulking."

The result builds on experience seen in earlier trials with field vegetables and salads, he explains.

"Use of Agrii Start-Release has delivered yield increases in a range of crops including spinach, onion, leek, carrot and cabbage.

"Agrii’s trials intentionally targeted sites with both high and low pH levels because pH affects different ions but the effect on phosphate availability is the same.

"In high pH soils, calcium and magnesium have been shown to interfere with phosphorus availability while on low pH soils it is aluminium and iron ions."

Compelling results

Even without any applied phosphate, crops that received Agrii Start-Release delivered a significant yield increase, demonstrating its ability to release previously unavailable soil nutrients, he points out.

"Across a range of growing conditions, Agrii Start-Release delivered yield increases of 17-30% and improvements in tuber bulking.

"We conservatively estimate an average saving of 30-40 kg P/ha from a 4-litre/ha application of Agrii Start-Release.

“The savings in fertiliser costs, estimated at as much as £51/ha for phosphate purchased in TSP at prices of £590/t, alone justify its use.

"Any improvement in the marketable yield fraction arising from increased soil availability, further support these gross margin benefits."

To avoid having to make a standalone spray application, Agrii has investigated the tank-mix compatibility of Agrii Start-Release with a range of other products typically applied at this timing.

“It can be applied in-furrow with Rhizoctonia solani treatments such as azoxystrobin or fluxapyroxad or across the ridges with either pre- or post-emergence herbicides or liquid fertilisers," Tom Land explains.

"A single application will be active for about 60 days post-application."

Agrii Start-Release uses proven technology to free phosphorus particles from positively charged cations that bind with them, making them immobile and unavailable to the plant, he adds.

"Agrii Start-Release frees the phosphorus from its bond with these major cations, typically calcium (Ca), aluminium (Al) and magnesium, and thereby making it available to the crop.

"It has significant benefits in helping growers' fertiliser management at sites where phosphate levels may be a limiting factor or where existing soil levels don’t allow the use of further phosphate applications."