• Excellent drought tolerance
  • Twining, climbing growth habit
  • Productive over a wide range of soil types
  • High quality hay (nutritive value)
  • Suited to cut and carry
  • High nitrogen fixation
  • Sowing Rate 3-6kg/ha as a sole pasture & 2-5kg/ha as a mixed pasture
  • Growing Seasons Autumn, Spring, Summer
  • Grazing Seasons Spring, Summer, Autumn
  • Rainfall Minimum 700mm per annum
  • Pasture Life 5 years+
  • Soil Fertility Medium (Olsen P 15-20)

Summer active, fast establishing companion legume

Aztec Atro is a highly summer-active, tropical legume with improved rust resistance. A competitive legume that is capable of high yields under the right growing conditions. It is suitable for hay and silage in tropical pasture production and suitable to grazing situations. Aztec Atro is highly palatable with good livestock acceptance. Manage grazing in late summer to allow seed set for long term persistence.

Aztec Atro siratro


Aztec Atro suits a medium textured soil but can grow in a wide range of soil types ranging from dark cracking clays to yellow and red clays, red sands and gravels. Preferring soils of moderate fertility with a pH ranging from 5-8, Aztec Atro is responsive to potassium, sulphur and molybdenum.

Additional phosphorus may be required at establishment on soils with less than 8 ppm available phosphorus. During establishment, apply 20‒30 kg/ha P and and additional 10‒20 kg/ha/year P for maintenance. Aztec Atro thrives in friable soils and will decline apidly in hard-setting soils. It has stronger tolerance of salinity in comparison to most tropical forage legumes, as well as a tolerance to moderate levels of soil Aluminium.


Sow Aztec Atro pasture seed in areas that experience between about 700mm and 1,500mm rainfall per annum. Featuring a deep taproot, Aztec Atro is well adapted to drought and has the ability to minimise evapotranspiration through leaf hairs and reduction in leaf size. Although generally intolerant of flooding or waterlogging, Aztec Atro can adapt to poor drainage by developing an extensive, shallow root system in the better-drained soil surface. If sowing Aztec Atro in higher rainfall environments, leaf disease can be a problem. 


Aztec Atro grows best in the subtropics (to latitude 30º) and higher altitude tropics with warm season growth. Production is higher with day/night temperatures of 27‒30/22‒25 ºC and growth is poor below 18/13 ºC day/night. Severe frost can kill the plant back to the crowns and leaves may be burnt by light frost. Recovery may be seen with the onset of warm, moist conditions.

Sowing and establishment

Aztec Atro is vigorous through establishment and can be established through minimal cultivation. Seed is best sown into a well-cultivated, fallowed seedbed with good subsoil moisture and prior weed control. Sow pasture seed at 3-6kg/ha for a sole pasture, into a well-prepared seedbed or, 2-5kg/ha within a mixed pasture.

Reducing competition for the developing seedling is ideal for legume establishment. Depending on the Phosphate levels within the soil, it is best practice to sow with 20-30kg/ha Phosphate at sowing.

For pasture seed sowing rates specific to your farming needs, contact your local PGG Wrightson Seeds Sales Agronomist here.

Agronomic production

When Aztec Atro is provided with sufficient nutrients and moisture, dry matter yields range between 5‒10 t/ha/year although yields will be lower under poor grazing management. Aztec Atro combines best with erect or tussock grasses and legumes requiring similar grazing management.  It is less compatible with aggressive creeping grasses such as Rhodes and Bothrichloa.

Grazing management

 Aztec Atro is suited to light stocking rates and/or rotational grazing. A rotational grazing system of 2 weeks on, 4 weeks rest has shown good results in the humid subtropics.  Stands deteriorate within a year or two under regular heavy grazing due to loss of bud sites, shorter plant life, reduced seed set and declining soil seed reserves.

Even under good management, pastures tend to become less productive over 5‒7 years. Pastures benefit from periodic spelling (every 2‒3 years) during seed set to bolster soil seed reserves and reinvigorate plants. Aztec A tro spreads seed by forcibly ejecting them from the pod, and they can be thrown for several metres. Seed can spread great distances through water movement and following ingestion by cattle.

Animal production

Aztec Atro is readily accepted by cattle when grazed early in the growing season. Liveweight gain (LWG) per hectare is good at medium stocking rates but yields/ha are moderate because of legume decline and loss at high stocking rates. Nutritive values are generally good, although crude protein, mineral content and digestibility can be increased by providing optimal Phosphate, Sulphur and Molybdenum.

Average crude protein levels in leaves in the top 15 cm of growth have been measured at 25% and in stems at 15%. In subtropical eastern Australia, annual LWG can be improved from 100 kg/hd to 140‒200 kg/hd when native pastures of tussock grass are replaced with improved species such as Buffel grass and 'Siratro'.

Available with the Envirogro seed treatment process

The Envirogro seed treatment process gives PGG Wrightson Seeds tropical and subtropical seed varieties a better start. Envirogro is a tailored process, that cleans, treats, and improves the bare seed count and purity of tropical, subtropical grasses and legumes.

If the species requires, the bare seed is taken through a process of de-hulling leaving only the caryopses, before being coated and cleaned again to achieve high purity. 

Envirogro benefits

  • Coated with insecticide, polymer and talc/lime
  • Improved seed flowability and ballistic properties
  • Improves seed quality and purity
  • Increases bare seed count for a higher return on investment
  • Produces a clean, uniform seed
  • Reduced risk of establishment failure 
  • Removes seed husk from the caryopsis (if required)
  • Removes weed seed, waste material and contaminants 

Click here for more information on the Envirogro seed treatment process


Minimum 700mm rainfall per annum unless irrigated

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