Plan for brassicas


Brassica crops benefit from early planning

October 2, 2012

Plan for brassicas

Brassica crops provide high-quality forage for stock, but balancing production goals with input costs is vital to ensure planting a paddock of kale or turnip is a cost effective alternative to pasture.

New Zealand farmers grow about 300,000 hectares of brassicas a year, often as a break crop when pasture quality or performance starts to decline.

Ballance Agri-Nutrients Lower North Island Technical Extension Officer Jeff Morton says that to achieve the best result with a brassica crop, nutrient deficiencies need to be resolved well ahead of sowing.

The first step to focus on is a soil test, ideally at least 6-12 months ahead of sowing.

“Farmers need to think ahead with this and consider where their crops are going to be on the farm. Testing well ahead gives enough time to apply lime to correct pH, so early paddock selection is important.

Mr Morton says brassicas, and the pastures that will follow them, require pH levels between 5.8 and 6.2 and lime applications to achieve the right balance can take up to a year to take full effect.

The soil should also be tested for levels of nitrogen, phosphorus, potassium, sulphur magnesium and boron in the six months before sowing.

“All of these nutrients can have an impact on achieving the optimal crop yield or feed quality and if the mix is wrong it’s possible you won’t fulfil the expectations you have on the level of dry matter or animal performance you’ll achieve from your crop.”

Mr Morton says farmers don’t need to work in isolation when making these decisions.

“There is a wealth of information and targeted advice available to ensure the right decisions are made for each specific farm.”

Ballance Technical Sales Representatives are readily available to provide assistance in making decisions to manage nutrient requirements effectively and efficiently. They have at their fingertips New Zealand’s only decision support tool for brassicas – the Ballance Brassica Calculator – which is backed by a decade of research and more than 30 field trials. The calculator estimates how much of each fertiliser nutrient is required for an economically optimal yield on a particular farm.

“Brassica crops can be expensive to grow. While fertiliser is likely necessary to ensure the best crop, it should only be applied at a rate that will ensure an economically optimal yield rather than the maximum yield.

“It doesn’t necessarily make a lot of sense to maximise your yield because it gets to the point where the small yield gain you’ll get over what is economically optimal will unlikely cover the extra cost of achieving it.

However, on the flip side as the value of the feed you grow increases the difference between ‘economically optimum yield’ and ‘maximum yield’ diminishes. The brassica calculators are great tools for evaluating these scenarios and optimising return on investment for your needs.”

Mr Morton says Ballance Technical Sales Representatives can also provide advice on the kind of nutrient product that should be applied. There are a range of factors that need consideration including placement of phosphate close to the seed for root uptake, and even distribution of boron for maximum effect.

2 October 2012

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