Instead, many farmers divide the cost per hectare of growing the maize by the gross yield.
Costs vary but the calculation would look something like this:
- Costs of $3500/ha divided by a gross gain of 22 tonnes (yield) DM/ha = 16 cents/kg DM.
If the pasture that paddock would have grown, say 6-10 tonnes, and a 10% loss of maize silage in the pit are factored in, the net gain from maize could halve. The numbers would look more like this:
- Costs of $3500/ha divided by a net gain of (22t-2t-8t) 12t DM/ha = 29 cents/kg DM.
“It’s very misleading to completely ignore the pasture [lost] on your paddock for nine months of the year when you’re doing your costing,” Robinson said. “Cost could be 100% higher than you think it is.”
She said maize was still one of the most reliable forms of extra energy food at a competitive cost though, especially when palm kernel prices were high. Maize is also one of the most reliable and least temperamental crops to grow in a dairy farming system. Grown correctly it should yield at least 20-25t/ha, combating the relatively high production costs of $3000-$4000/ha.
Maize production costs vary between farms, depending mostly on soil condition and the amount of fertiliser required.
“Effluent still has an opportunity cost as it could have been applied to pasture to reduce fertiliser inputs elsewhere.”
If your maize silage crop was going to cost 30 cents/kg DM it could be more expensive than palm kernel this season, Robinson said.
The risks of planning to buy palm kernel instead of sowing maize were the product’s changeable price and availability but Robinson said these could be mitigated with purchase contracts.
Farm consultant Kim Robinson says maize is one of the most reliable forms of extra energy food at a competitive cost.
She said palm kernel had a much higher protein content than maize, making it a good summer feed as well as a good supplement for improving milksolids production and cow condition in late lactation.
“Trial work has shown that cows require about 20% less palm kernel to gain one body condition score than maize silage. This must also be considered in the cost comparison.”
After 25 years of farm consultancy in Northland Robinson still believed maize was a useful crop.
She didn’t advise her clients against growing maize if it was the right fit for their business. Many fed both maize silage and palm kernel to their cows.
“A lot of my clients grow maize but it’s a calculated, informed decision – we know what the costs are and it’s not 15 cents/kg DM.”
Robinson is a trustee of the Northland Dairy Development Trust, which has just started researching ways to reduce reliance on imported feed. The trust’s three-year trial will compare three farming systems – one importing 20-30% of feed (mostly palm kernel), one feeding pasture only and the third a self-contained farm growing all its own feed including maize, turnip and fodder beet crops.
Robinson said many farmers were interested in ways to farm without palm kernel.
“Farmers definitely want to know if there is a profitable alternative to palm kernel.”
Top crop
Maize grows really well on alluvial silt and peat soils which is why it is so popular in Waikato. At good yields it is competitive on price with other supplements but to make the best decision it pays to calculate the true cost of any feed.
