• Farm name:  Gloag & Son Ltd, 3800 acres (combinable crops)
• Farmer:  Andrew Gloag
• Location:  Stokesley, North Yorkshire
• Agrii CIS:  John Charlton, Agrii CIS

John Charlton, Crop Inputs Specialist at Agrii, brought this product to the attention of Andrew Gloag in Autumn 2023. 
Farming in the North East on mainly clay soils, with high degree of phosphate lock up, has demanded routine application of rock phosphate products.

With growing pressures on margins and sustainability, alternative phosphate sources have been appraised on the farm. The water solubility, plant availability and overall value of alternative sources has always been a challenge, compared to fully water-soluble sources like triple super phosphate (TSP).

Clay soils hold significant levels of unavailable phosphate that is tied up in complex bonds, with calcium and magnesium.

• Is there a way to access these reserves?
• Can we utilise organic sources of phosphate effectively?
• Can we target nutrient availability to crop demand?

Agrii-Start Release could provide an alternative to water soluble phosphate products. 

Agrii-Start Release

Agrii-Start Release reduces the need to use finite rock phosphate, which can be replaced with lower cost, citrate soluble phosphate products like manures and digestate.

The reduction in CO₂ emissions from reduced fertiliser production and importation as well as financial advantage makes Agrii-Start Release an outstanding product for UK agriculture.

"The use of Release, targeted together with our management of soil structure - provide the opportunity for a new and more efficient phosphate system."

Andrew Gloag, Farmer

Trial set up:

• Selected field was sown in autumn oilseed rape.
• 12t/ha of pig farm yard manure (FYM) was applied on 1st August 23, prior to sowing oilseed rape in early August.
• One 36m tramline up the center of the field was treated with 4l/ha of Agrii-Start Release, in 200l/ha of water, on the 27th October 2023.
• There was 22mm of rain after application.
• The treated and untreated tramlines were sampled on the 26th October and at the end of every month since then.
• Soil samples were sent to lab for analysis of Olsen’s P. The Olsen P test is a widely used soil test to determine the phosphorus availability in soil. It measures the bicarbonate-extractable phosphorus in soil, which is available to plants in the short term. 

Results:

• The single application of Agrii-Start Release has increased Olsen P availability over a 5 month period. 
• The resulting equivalent phosphate availability was over 300kg/ha of phosphate (P2O₅ ) in the treated tramline over and above the untreated tramline in the field (see graph below).
• The base phosphate level in the field, from the latest soil analysis, is around 16-20ppm of Olsen phosphate (see table below). This is conducive with the untreated tramline results throughout the trial. 

The trial area moved the Olsen’s P from 18 to 26ppm, which is one full P Index. 

• The increase in soil phosphate levels suggests Agrii-Start Release has a positive effect on soil phosphate availability. This effect is attributed to its ability to mimic microbial activity and root exudates, which supply organic acids into the rhizosphere, thus breaking down complex phosphate bonds to generate available phosphate.
• Agrii-Start Release allows for targeted phosphate release, enabling precise timing based on crop requirements. This can be timed before periods of high demand, such as rooting after sowing or during stem elongation and biomass building in the spring for winter-sown cereals.
• The combination of Agrii-Start Release with low water-soluble phosphate products like P-Grow and Fibrophos offers a balanced approach to delivering the required phosphate to crops. While low water-soluble phosphate products provide the necessary phosphate removed annually by the crop, Agrii-Start Release generates phosphate availability as needed, optimising nutrient uptake.
• In conclusion, the use of Agrii-Start Release alongside low water-soluble phosphate products offers a strategic approach to managing soil phosphate availability, optimising crop nutrient uptake, and promoting sustainability in agriculture.