AVAIL – what is it?

AVAIL is a phosphorous fertiliser enhancer. It has been specifically designed to protect fertiliser P from being fixed into unavailable forms in the soil by antagonistic elements such as iron, aluminium, calcium and magnesium. By reducing the risk of fixation, AVAIL increases the availability of fertiliser applied phosphorous for greater uptake by the crop. This enhanced nutrient efficiency can lead to improved crop establishment, higher yields and better overall returns on P fertilisers.

AVAIL is coated onto granular phosphorous by Origin Fertilisers and is available in any fertiliser grade containing P, providing a simple solution to a complex problem – as evidenced by extensive independent UK field trials.

AVAIL – how does it work?

Plants take up phosphorous in its water-soluble phosphate form. Phosphate has a strong negative charge which fixes it to positively charged metals in the soil, e.g. iron and aluminium in acidic soils and calcium and magnesium in alkaline soils. The AVAIL coating is negatively charged and adsorbs the positive antagonists, thereby shielding the phosphate from becoming fixed.

The Avail Effect

The Avail effect has been shown through independent work from Harper Adams University College.

Better Rooting = Greater Yield Potential

In 3 weeks from planting there was over a 40% increase in root mass where Avail treated phosphate was used.

The Avail Difference

In study after study, Avail has been shown to reduce phosphate fixation and boost potential yields – as much as 10-15%.

Average Yield Increase

Wheat: 9%
Grass: 15%
Maize: 9%
Potatoes: 13%
Swedes: 16%
Sprouts: 11%
Carrots: 29%
Beetroot: 4%
Overall Average: 13%

Avail Wheat Trial 2012 – Velcourt, Yorkshire

Yield (tonnes per ha)

1: 10.1
1: 11.12
2: 10.17
2: 10.94
3: 10.37
3: 10.99
4: 9.4
4: 10.85
Average: 10.01
Average: 10.98

Maize Yields t/ha

Trials carried out by Harper Adams at four separate sites showed significant yield responses to the use of Avail.

The results below show how a lower rate of phosphate treated with Avail outperformed the “standard” rate of untreated DAP (50 kg per acre), yielding on average 2.3 tonnes/ha more.

Fresh YieldsStandard P & N56.2350.1239.2250.59
25kg + AVAIL59.2753.4541.0651.61
Dry YieldsStandard P & N16.2614.6616.9315.99
25kg + AVAIL16.5515.3017.6717.00

AVAIL Maize Fresh Yield t/ha

Chester - Standard P & N: 56.23%
Chester - 25kg P + AVAIL: 59.27%
Lackham - Standard P & N: 50.12%
Lackham - 25kg P + AVAIL: 53.45%
Harper - Standard P & N: 39.22%
Harper - 25kg P + AVAIL: 41.06%
Petworth - Standard P & N: 50.59%
Petworth - 25kg P + AVAIL: 51.61%

2008 Harper Adams University College

AVAIL Maize Dry Yield t/ha

Chester - Standard P & N: 16.26%
Chester - 25kg P + AVAIL: 16.55%
Lackham - Standard P & N: 50.12%
Lackham - 25kg P + AVAIL: 53.45%
Harper - Standard P & N: 39.22%
Harper - 25kg P + AVAIL: 41.06%
Petworth - Standard P & N: 50.59%
Petworth - 25kg P + AVAIL: 51.61%

2008 Harper Adams University College

Frequently Asked Questions


What is Avail?

AVAIL® Enhancer is a water-soluble additive for granular or liquid phosphorus fertiliser that enables phosphate to remain free in the soil, providing opportunity for greater plant uptake with minimal costs. AVAIL is the only phosphorus fertiliser enhancement of its kind.


What are the major benefits of AVAIL?

Research has shown 75 to 95 percent of phosphorus fertiliser is tied up, or fixed, in the soil. AVAIL is a revolutionary technology that helps solve the long-standing problem of poor phosphate availability. AVAIL provides: Greater phosphate efficiencies Improved yield potential Increased profitability.


Does AVAIL tie up the nutrients in the soil?

AVAIL is only effective in the very small zone around the phosphorus. It does not change the overall nutrient availability in the soil.


For crop producers, what are the benefits of AVAIL?

Numerous research studies have been conducted on the effects of AVAIL on key crops, including cereals, potatoes, oilseed rape, maize, onions and sugar beet.


What are the relevant crops for which AVAIL may be applied?

AVAIL is currently being applied with proven response to barley, carrots, grass, maize, oilseed rape, onions, potatoes, red beet and wheat.


Can AVAIL be used directly on the soil?

No. AVAIL is designed to prevent the fixation of applied phosphorus in the soil. Once untreated phosphorus has been applied to the soil and becomes fixed, there is no way to set it free.

What is the environmental impact of AVAIL?

There is no environmental footprint with the use of AVAIL. It is a water-soluble and biodegradable phosphorus-enhancement product. Studies show that the AVAIL polymer is destroyed during the 12 to 15-month period between field crops, with no residual effect on subsequent crops.


Can AVAIL be leached out of the fertiliser application zone by rain or excessive moisture?

Work with flooded rice has shown that AVAIL gives season-long protection without being moved out of the nutrient zone by rain or irrigation.


Can AVAIL be used on manures?

With manure’s extremely variable nutrient composition, as well as high volume usage, Verdisian does not recommend using AVAIL on solid or liquid manures.


Does the use of AVAIL lessen the amount of fertiliser needed?

Research work is under way to establish how the use of AVAIL may be able to lead to reduced phosphate fertiliser usage without compromising the unique benefits of AVAIL treated phosphate. Indications are that some reduction will be possible, however a number of studies have shown that using recommended phosphorus rates plus the AVAIL technology can lead to higher yields and increased profitability.


Should I broadcast or place AVAIL?

AVAIL is effective in both broadcasting and placement/banding applications.


Should AVAIL be used in the autumn or spring?

Research shows that AVAIL is equally effective applied in the autumn as it is in the spring.


AVAIL was developed in the US. Is it effective in the UK?

Phosphate fixation is a global issue, and AVAIL is proven to work in any crop, soil type and climate. There is an increasing body of research which is demonstrating that AVAIL is just as effective in the UK as anywhere.

Can I use AVAIL in Organic farm systems?

No. Although AVAIL is biodegradable and leaves no environmental footprint, it does not meet the requirements of Organic certification bodies.

Avail is now available from your local Origin Fertilisers site. Please see the Contact Us page.