Spring 2024

Veg trials show yield benefit of Agrii-Start Release

Trials with Agrii-Start Release in field vegetable crops show potential for reduced phosphorous applications, reports Don Pendergrast, Agrii technical manager for non-combinable crops.

The use of Agrii-Start Release, a soil-applied cation complexing agent used to improve the availability of phosphorous, has improved marketable yields by at least 10% in carrots, bulb onions and white cabbage.

In field trials over the past three years, Agrii has investigated the contribution to performance of a pre-emergence application of Agrii-Start Release. As a cation complexing agent, Agrii-Start Release breaks the bind between the metal ions in the soil and phosphorous molecules thereby improving the availability of the latter to the growing crop.

Many species of vegetable crops, especially alliums, are known to be highly responsive to phosphorous. As such, fertilisers high in phosphorous are often applied as starter fertilisers as an aid to establishment. However, many soils are already high in phosphorous, but crops are not always able to access it. This apparent contradiction between nutrient status and nutrient availability coupled with the prospect of tighter application restrictions intent on protecting water courses, prompted Agrii to investigate technologies that might lead to a reduction in the fertiliser needed to be applied by improving access to what is already present.

Results to date have remained positive. Soil analysis performed post-application revealed increases in the available quantity of phosphorous. This served as confirmation of its potential. Yield results support this hypothesis with increases in both gross yield and the percentage of crop meeting market specifications.

TreatmentMarketable onions
Marketable onions
Yield as %
of control
Agrii-Start Release
(4 l/ha)
Reference: Agrii, 2023. Agrii-Start Release applied pre-emergence.
TreatmentAverage head
weight (kg)
Yield as % of
Agrii-Start Release
(4 l/ha)
Reference: Agrii, 2023. Cv. Kalorama. Agrii-Start Release applied 1 day before planting
TreatmentGross yield
yield (%)
Agrii Release
(4 l/ha)
Reference: Agrii, 2022. Cv. Nazareth. Agrii-Start Release applied 1 day before sowing
Carrots lifted from beds treated with Agrii Release were typically longer and heavier than those in the untreated. There were also fewer carrots outside market specification.