May 29, 2020

Micronutrients have major bearing on profitability of brassica

BRASSICA growers should not forget the importance micronutrients have on vegetable brassica quality, storage life and nutrition.

Yara Crop Nutrition Sales Agronomist – North Island Sales Agronomist, Mark Redshaw, says while all producers are aware of the importance of nitrogen, phosphorus, potassium and calcium, micronutrients often receive less attention.

“Crop nutrition directly influences the external appearance of brassica crops, including compactness, vegetable size, weight and colour,” he says.

“In turn, this has a significant effect on marketable yield, grade, price and ultimately, profitability. 

“By getting crop nutrition right, growers can bring harvest forward and improve head, curd and leaf quality.”

Mark says nutrition programs for brassica crops need to be based on each crop’s specific requirements to produce a unit of yield, the ratio of the nutrients that are taken up by the plants and the amount which is actually removed from the field at harvest.

“This level of removal has a significant impact on the nutrition of the following crop,” he says.

“While much lower levels of micronutrients are needed to satisfy yield, the correct balance of these trace elements throughout the crop cycle is essential.”

The key micronutrients are boron, zinc, manganese and molybdenum.

Micronutrients have an important impact on storage quality by ensuring a high dry matter content and reducing moisture loss. 

“Compared to other vegetable crops, broccoli and cauliflower are perishable and can only be stored for relatively short periods if plant health has been compromised by nutrient deficiencies,” Mark says.

“Ensuring good green, strong plants will help secure good quality and a long shelf life.

“Adequate potassium and calcium help to reduce moisture loss during storage.”

Micronutrients have a direct bearing on taste and the nutritional value of brassica vegetables.

“Sulphur, manganese, molybdenum and zinc have important roles in the production of sugar and taste,” Mark says.

“It is important that micronutrients are provided in balance with macronutrients. 

“For example, excessive use of phosphorus can restrict zinc uptake, which is required for sugar production.

“Likewise, crops that are well supplied with manganese and potassium have higher vitamin C content.

Most brassicas have a high requirement for boron as low levels in plants leads to water-soaked areas, tip-burn and hollow stem disorder.

Molybdenum has a critical role for efficient utilisation of nitrogen. Shortages lead to plants not being able to convert nitrogen into protein, reducing plant growth, reducing vigour and produce quality.

Yara has developed specific crop nutrition programs for brassica crops, including broccoli, cauliflowers and cabbages, using the latest research and decades of commercial experience.

Each program includes the use of YaraMila compound NPK fertilisers, YaraBela  nitrogen fertilisers and YaraLiva calcium nitrate fertilisers to provide plant-available nitrogen, phosphorus, potassium and calcium throughout the crop cycle, as well as YaraVita foliar fertilisers to deliver micronutrients at critical stages of crop growth.

Yara has developed YaraVita BRASSITREL PRO specifically for brassica crops to optimise nutrient levels such as boron, magnesium, manganese and molybdenum during rapid growth phases. Optimised nutrient levels support brassica yield and quality.

YaraVita BORTRAC should be applied at 2–3 L/ha during the 4–6 leaf stage, followed by one or two applications of YaraVita BRASSITREL PRO at 3–4 L/ha between the 8–10 leaf stage and early head development.

Additional applications of YaraVita MOLYTRAC at 250–300 mL/ha or YaraVita ZINTRAC at 1–2 L/ha during the 4–6 leaf stage may be beneficial.

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,” Mark says.

“All of our products are backed by innovative decision-making tools to help you to get the best return from your investment in quality crop nutrition.”