Maize crops need a lot of nutrients in the early part of the growing season. Typically, three fertiliser dressings are made to meet this demand. However, adverse weather and environmental losses, damage from machinery and contractor availability can all challenge efforts to deliver the nutrients when the plants need them, especially when it comes to applying the third (side) dressing.
Colin Mclean (Mac) checking out a maize crop grown using Fertco's 2-Step Maize Programme.
Maize
Maize (Zea mays) has been around a long time. It is the most abundantly grown cereal in the world, and one of the most efficient crops at converting the sun’s energy into biomass. Of course, in NZ we grow maize predominantly for animal food, and it’s an important supplement to our pasture-based system.
Nutrient supply
Maize is a nutrient ‘hungry’ crop, requiring large amounts of nitrogen and potassium as well as phosphorus, calcium, magnesium, sulphur, and trace elements like zinc and copper. Every cropping site is different, so it’s important to soil test before planting time to work out how much of these nutrients are actually needed.
In order to support their phenomenal growth rate, maize plants need a steady release of nutrient. If sufficient nutrient is not available during the 6th week of growth when plants reach the 5th leaf stage (V5), they will be stunted, and yield will be significantly reduced.
To meet these needs, fertiliser is typically applied in three dressings: a base dressing at cultivation, a further starter dressing at planting time, and a side-dressing when the crop is at V5 stage (red-band height).
In theory, this programme sounds ideal. And the first two dressings are often straight forward enough. However, adverse weather conditions and nutrient loss, along with damage from machinery and/or contractor (un)availability, can create problems with the application of the side-dressing.
Weather conditions
Farmers and growers are always at the mercy of the weather. For maize growers, very wet weather in early spring can mean that cropping sites become inaccessible, delaying the application of the side-dressing, and thereby missing the critical V5 growth stage of the young maize plants.
Adverse weather conditions can also reduce the effectiveness of traditional nitrogen fertilisers such as urea and DAP which are prone to loss. If it is too dry and the urea sits on the soil surface, the nitrogen in the urea can volatilise. If on the other hand it is too wet, the nitrogen will be washed through the soil and may leach into waterways. Either way, costly nutrients are lost and end up where they shouldn’t, while the plants don’t get the nutrients they need at crucial growth points.
Machinery damage
Plants can also suffer machinery and tyre damage during the application of the side-dressing. In cases where the fertiliser is buried, knifing of the roots can be a problem. Where fertiliser is surface spread, the leaf whorls can end up scorched from fertiliser sitting on the leaves.
In sum, it would be great if we could forgo the side-dressing altogether but still get the necessary nutrients to the maize plants at the right time. Happily, there is a product which allows us to do just that.
The right product
The product for the job is a polymer coated urea, or PCU as it’s known.
This fertiliser changes the way that plants get their nitrogen because the coating controls the way the nutrient is released. When it is dry, the coating prevents the urea from being volatilised. When it is wet, water moves in through the coating and dissolves the urea. The dissolved nitrogen is then able to move out through the coating at a controlled rate, closely matching the growth demands of the maize.
So with PCU, we no longer need to side-dress. We can forget about adverse weather conditions and nutrient loss, machinery damage and contractor availability.
Instead, we can swap a three-step maize programme for a two-step one like that offered by Fertco. With reports of maize silage yields around 25 to 30t/ha from growers following this programme, it’s simply a smarter way to grow.
This article was published in the Coast & Country News.
