The inclusion of a 100% water-soluble source of calcium early in the growing season is the secret to producing high quality and nutritious avocados.

Yara Crop Nutrition sales agronomist, Southern Queensland and North Coast NSW, Chris Rutland, says avocado trees need a source of plant-available calcium during flowering and early fruit-set for optimal plant health, fruit quality and marketable yield.

“Calcium plays a vital role in cell structure and strength,” Mr Rutland said. “It helps to create a strong cell wall and maintain the integrity of the cellular membrane – which in turn, increases resilience to insects and disease.

“Calcium also optimises fruit quality and shelf life. Conversely, low calcium levels in the fruit are associated with sensitivity to cold damage, quick ripening, fruit softening and pulp discolouration.”

Mr Rutland said calcium is primarily taken up by the roots and moves upwards via the xylem. “The transport of calcium in the tree is a one-way process – it moves upwards to the higher parts of the plant and doesn’t return.”

“For this reason, it is essential to deliver plant-available calcium to the root zone during the root flush, which generally precedes flowering and early fruit development. This will maximise calcium content of the developing fruit, supporting fruit quality.

“Calcium helps to maintain soil structure in the root zone and maintain root cell wall integrity. Calcium also helps to reduce sodium uptake under saline conditions, as well as regulating plant water levels via its role in opening and closing stomata.”

Mr Rutland said powdered forms of calcium, such as calcium sulphate (gypsum) and calcium carbonate (lime) should be considered as soil amelioration products for addressing acidity or sodicity.

“They have low solubility and release calcium too slowly to support fruit quality,” he said. “By comparison, calcium nitrate fertilisers provide a rich source of plant-available nitrogen and soluble calcium.”

Examples include YaraLiva Tropicote (15.5% N + 18.8% Ca) and YaraLiva Nitrabor (15.5% N + 18.3% Ca + 0.3% B), which are typically applied as ground applications.

The free-flowing, evenly-sized granules feature a unique coating technology to prevent the absorption of moisture during storage and handling, yet dissolve readily once in contact with soil moisture, humidity or night dew.

Alternative calcium nitrate products include YaraTera Calcinit (15.5% N + 19% Ca), YaraTera Calcinit B (15.5% N + 18.6% Ca + 0.1% B) and Yara Liquids N-Cal 15+18Ca.

Yara provides technical support to growers and their advisors via a team of regionally-based sales agronomists, customer service representatives and technical support staff.

“Our goal is to deliver integrated crop nutrition solutions that genuinely increase the productivity and profitability of our customers,” Mr Rutland said. “All of our products are backed by innovative decision-making tools to help you get the best return from your investment in quality crop nutrition.”

Yara markets a comprehensive range of fertilisers, including YaraMila (NPKs), YaraLiva (calcium nitrates), YaraVita (foliar micronutrients), YaraTera (fertigation fertilisers), YaraRega (soluble NPKs) and Yara Liquids.