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Despite the cost of growing a maize silage crop rising about 30 per cent in the last four years, growers should not be tempted to cut corners which could result in a reduced yield, Corson Maize national research manager Mike Turner says.
“When you are growing a high-cost, high-input crop, doing the basics right is more important than ever,” he told a Foundation for Arable Research maize winter workshop.
From 2021-22 to 2025-26, his analysis shows that total maize silage costs, from spray out to covering the silage stack, rose from $4026 a hectare to $5143/ha. Fertiliser/lime and seed related inputs both recorded the biggest increase, at about 41 per cent.
“When costs are going up you need to protect that investment and yield at harvest.”
Base fertiliser increased from $450/ha in 2022 modelling to $850/ha now. “In comparison, the cost of a soil test is very cheap. So, if you are getting your fertiliser spend wrong, either too much or too little, it can have a big impact on costs.”
When growers get the basics right, a higher yield dilutes their costs, Mike Turner says.
For example, a 17 tonne of drymatter/ha maize silage crop equates to 31.9 cents a kg of drymatter. At 25 tonnes/ha this falls to 21.7 cents/kg/DM and at 28 tonnes/ha 19.4 cents/kg/DM.
“Yield spreads cost across more kg of feed. This is the strongest reason for growers to protect crop establishment and the basics. Most costs in a maize silage crop are fixed. So, the only real way to offset that is to get a good yield.”
When choosing a CRM hybrid for silage, growers need to be aware that while silage yields increase for longer-maturing hybrids, so can the risk, especially in environments that can get dry and disease pressured.
Some growers are choosing a CRM out of habit, he says. “It is worth asking your seed supplier about what hybrid best suits your system.
“Shorter CRM is not about giving up yield potential, it is about providing a more reliable return and a less risky yield. A crop that finishes cleanly, dries down, stands well and meets the harvest window usually protects margin better than a theoretical top-yield option.”
Predictions of a super El Nino weather pattern producing hot, dry conditions later this season means it is recommended that growers without good moisture-holding soils shorten their CRM to get their crop well into grain fill or dry down phase before it comes under too much pressure. Some hybrids can better cope with dry conditions later in the season. A lower plant population could also be considered, Mike Turner says.
FAR senior maize researcher Rene van Tilburg says that growers need to factor soil nitrogen into their input calculations and if they are applying more nitrogen than what their crop can take up, they are wasting money. “Maximise your soil N; use it or lose it.”
Growers generally make some allowance for soil N, but often this is anecdotal and what they have always done, rather than being based on actual soil test results. Instead, growers should measure nitrogen supply rather than guess it and trust the result.
Growers are recommended to use a Mineral N test to determine soil N as well as a Potentially Mineralisable Nitrogen (PMN) test which indicates how much N may become available during the growing season. This allows side-dress N applications to be better matched to crop demand and soil N supply, improving profitability.
In a FAR maize grain production trial at the Corson Research site at Newstead, near Hamilton, large differences in soil N supply between plots in 2024-25 resulted in side-dress N inputs ranging from just 75 kg to 360 kg SustaiN/ha. Soil testing showed the soil supplied from $599 to $1016 worth of N at a SustaiN price of $1400/tonne.
Despite these large differences in N inputs, grain yields remained remarkably similar, with all treatments producing about 16 tonne/ha of grain. The result saved $446 to $805/ha if no allowance had been made for soil N, with the lowest SustaiN rate having one of the higher yields though not significantly so, indicating no yield penalty for using the soil N tools.
Growers, particularly on good-structured soils, can also consider their cultivation intensity, saving diesel and machinery costs and labour. FAR work shows no yield penalty moving to strip till or no-till on sites with high quality soil. However, transitioning to strip-till or no-till has its challenges and may not be practical for many growers, Rene van Tilburg says.
Instead, a pass in a conventional system may be eliminated or a reduction in cultivation depth and subsequent increase in speed made instead. “A key point when making any of these changes is to ensure a seed bed that will result in consistent seed depth and good seed to soil contact.”
FAR trials show that the combination of reduced cultivation intensity and the use of Mineral N and PMN testing have the potential to save $300 or more per hectare, he says.