Understanding marginal return from growing maize silage
Much has been discussed in recent seasons about the rising costs of production on dairy farms, and rightfully so.
This is especially true when you compare this year with the previous two seasons where a drier-than-normal winter was followed by a relatively dry spring. Whenever we get wet springs, we get the same question from growers, "...it is now early November, is it too late to plant my maize silage?" And like it seems is true for most important things in life, the answer is "it depends". So, before I seek to answer this question let me cover off a few points that will help frame the answer for you.
When it is too risky to plant small seeds, you can usually plant maize.
Unlike the seed of many crops including brassicas and chicory, maize seed is large. Big seeds have greater reserves and can be planted deeper. This means maize can be successfully established across a wide range of soil conditions resulting in a wide planting window. In most areas of New Zealand maize silage crops can be planted into December and still produce reasonable yields. In seasons where brassica crop establishment has failed and the planting window for brassicas has closed, maize silage is often planted as a substitute.
Maize is a warm weather tolerant plant.
Maize has a different way of producing sugars to grow, compared to most other crop species (e.g. turnips). This biological advantage, combined with a deep rooting system, means that during summer months, maize silage can produce much more dry matter than other plants that prefer cooler, wetter growing conditions. Also, because maize development is largely driven by temperature, planting later in spring means that there is more heat available each day. The warmer the weather gets, the faster maize grows.
Maize roots travel deep into the soil to get water
We used to say that maize roots grew to a length that was up to two thirds the height of the plant. New Zealand research conducted by the Pioneer team shows maize roots can grow much deeper. In fact, where there was no soil impediment, maize roots were recorded growing to more than 3.5m allowing them to aggressively scavenge water and nutrients.
Maize hybrids come in a wide range of maturities giving increased flexibility.
The length of time it takes for the maize plant to go from a given planting date to a harvested crop is determined by three main factors. These are hybrid maturity (which impact the amount of heat units the specific hybrid needs to reach maturity), the weather (especially moisture) and temperature. You cannot control the temperature or weather, but you can control the hybrid you plant. The Pioneer line-up includes hybrids that require relatively small amounts of heat to reach maturity right through to hybrids that need a lot of heat to get them to harvest maturity. This gives the grower more options to match their target planting and/or harvesting dates.
New Zealand research has helped us quantify how late growers can plant maize.
As part of his PhD, my colleague Dr Rowland Tsimba looked at the impact of planting date on maize yields across a range of maize hybrid maturities. He found that the planting window for each hybrid maturity was far wider than we first thought.
Rowland used data collected from field trials plus long-term weather data to develop a model to predict potential yield loss due to delayed planting. This showed that provided the right hybrid maturity was selected, maize planted in late November in the Northland, Waikato, Bay of Plenty or Manawatu in a had >90% chance of successfully reaching silage maturity and yield between 85% and 94% of its maximum yield potential.
Rowland and his team conducted some field research where they compared maize planted 20 October versus 20 November.
Despite a month's difference in planting date, there was only a 15-day difference to silking time. By silage harvest time, the difference had further decreased to just over a week.
So, from a maize development or yield perspective, late November is not too late to plant maize.
If you need to plant any later than this, contact your seed merchant or local Pioneer area manager and they will be able to help you make an informed decision.
Ian Williams is a Pioneer forage specialist. Contact him at This email address is being protected from spambots. You need JavaScript enabled to view it.
