Maize benefits dairy industry
Date: 29 May 2014
Maize holds the key to building profitable and environmentally sustainable dairy systems of the future according to Raewyn Densley, Forage and Nutrition Specialist for Pioneer® brand products.
The majority of Nitrogen (N) leached on dairy farms comes from cow urine. Dairy cows are estimated to urinate 10-12 times per day. Each time they deposit around 2 litres of urine on an area that is just 0.2m2 in size. The volume of nitrogen in a urine patch (1000 kgN/ha) is greater than the annual plant uptake (300-700 kgN/ha/year) and this results in the build-up of soil nitrogen. Leaching losses from urine patches are high especially in the winter when rainfall is high.
Part of the problem is ryegrass-clover pasture which frequently contains more nitrogen than cows can utilise. The bigger the nitrogen surplus in the diet, the higher the amount of nitrogen excreted in the urine.
"Maize silage is a low crude protein, and therefore a low nitrogen feedstuff" says Densley. "Feeding maize silage in conjunction with pasture dilutes dietary protein levels and this in turn reduces the amount of nitrogen excreted in the urine".
Reducing dietary protein is not the only way maize can improve the environmental sustainability of dairy farms.
A two year on-farm study showed that maize silage crops grown on effluent paddocks with no additional fertiliser (no base, starter or sidedress) yielded an average of 26.1 tDM/ha and removed a massive 340 kg of nitrogen per hectare.
"Because it produces very high drymatter yields, the maize plant has a large requirement for nitrogen" says Densley. "Its deep (1.8 m) root system allows it to retrieve and utilise nitrogen which would otherwise leach into the ground water because it has dropped beneath the root zone of shallow-rooted pasture species".
Most farmers can significantly reduce N-leaching by growing maize silage on their effluent paddocks and feeding it to their herds over the autumn to spring period. Even greater reductions are possible when the maize silage is fed on a stand-off pad that allows cows to be kept off pasture.
For farmers who prefer to buy in feed, maize silage (7 - 9% crude protein) or maize grain (8% crude protein) will bring less nitrogen onto the farm than most other commonly available supplements including palm kernel (14% crude protein), wheat or barley (11% crude protein).
"Maize is a cost-effective option which allows farmers to meet environmental targets whilst remaining financially viable" says Densley. "Put simply you can have your cake and eat it too".