Minimising risk of nitrate poisoning
Coming into autumn, maize and summer crops have been harvested/ grazed and farmers are planting their next crop or establishing new permanent pasture.
The challenge for dairy farmers is to build environmentally sustainable systems which can make plenty of profit in the high payout years but are resilient enough to remain financially viable when the milk price falls.
While pasture remains the cornerstone of New Zealand dairy systems it has some limitations. Yield is relatively low – an estimated average genetic gain of just 0.5% per year (*1). While variable costs (including fertiliser and weed control) are relatively low, high dairy land prices and the associated interest cost mean the fixed cost of growing pasture is high.
Pasture yields vary between and within seasons. While pasture is generally a high quality feed, there are times of the year when supply is limited by poor grass growing conditions (e.g. too cold or too dry) and often these cannot be predicted ahead of time.
In recent years it has become clear that intensive pasture-based systems can leach high amounts of nitrogen. For much of the year pasture contains more crude protein (or nitrogen) than cows require. Excess protein is excreted in the urine.
When a cow urinates, up to 1000kg N/ha falls onto an area the size of an A4 piece of paper. Plants cannot take up all the nitrogen the urine contains and the surplus quickly drops below the root-zone of pasture (about 600mm), eventually ending up in the groundwater.
Farmers looking for solutions to these and many other farming challenges have discovered maize silage – a cost-effective, high quality supplement which can be home-grown on the milking platform or run-off.
Maize silage can help build profitable dairy systems by stabilising milk production levels and therefore allowing farmers to dilute fixed costs. The end result is a profitable farm system with plenty of milk produced at a moderate cost per kilogram of milksolids (kgMS).
How can maize silage help?
A growing number of farmers have built very profitable yet simple systems which incorporate maize silage into their feeding system. Maize silage can help by:
Lowering feed costs.
Growing and harvesting more home grown feed (pasture and crops) dilutes fixed costs (including interest), reduces total feed costs and increases returns. Maize is a drought tolerant crop that produces reliably high yields. Most dairy farmers can grow maize silage crops yielding 18-26 tDM/ha for 11.2-16.2 c/kgDM in the stack (*2). Crops grown on repeat cropping ground or in low fertility paddocks will cost around 4c/kgDM more. Maize silage can be used to displace concentrates and other supplements which have a higher cost per kilogram of drymatter and unit of energy.
Improving pasture renewal
Maize not only produces high drymatter yields but it can help you establish higher performing pastures. Fertiliser and lime can be applied and incorporated in the cultivation process and it’s a great time to address drainage issues. Cropping removes the normal feed source for pasture pests such as black beetle, Argentine stem weevil and pasture nematodes. This interrupts their breeding cycle and reduces insect pressure on seedling plants during the pasture renewal process.
Improving pasture control
Because maize silage is a forage, you can vary the amount you feed to control pasture residuals, keeping ryegrass in its most productive growth stage. If pasture cover levels are low, increase the maize silage feeding rate and leave more pasture behind to prevent overgrazing. If you have plenty of grass on hand, reduce the feeding rate and clean up paddocks better. The combination of maize silage and a stand-off pad or a wintering barn allows you to restrict access to pasture, minimising pasture pugging without compromising animal welfare.
Filling feed deficits
Supplements will deliver the greatest return when they are fed during genuine feed shortages or used to increase days in milk. While many crops such as brassicas must be fed when they are mature, maize silage can be stacked and fed when you are short of feed. Well compacted and sealed maize can hold its quality for several seasons, providing nutritious feed exactly when you need it.
Increasing cow condition score
The ideal body condition score (BCS) at calving is 5.5 for first and second calvers and 5.0 for older cows. Cows which calve at the ideal condition score will produce more milk and cycle faster than cows too thin at calving. Maize is the best option to put weight on cows for three key reasons. The energy in maize silage is used 50% more efficiently to put weight on cows than energy in autumn pasture. Maize silage can be fed at up to 50% of the drymatter intake allowing faster liveweight gains. And, feeding maize silage results in substitution so winter pasture cover targets can be achieved.
Delivering more return from your run-off
Many dairy farm run-offs are not farmed to their full potential. Growing maize on your run-off allows you to grow and harvest more drymatter which can be easily transported to the milking platform. Plant a short to medium-maturity maize hybrid and sow annual ryegrass when it is harvested and this will ensure you have plenty of high quality pasture for the winter months.
Making the most of effluent
Applying dairy shed effluent to pasture often results in a build-up of soil potassium and a higher risk of milk fever. It can also increase the risk of nitrogen leaching. Maize thrives on the nutrients contained in effluent, and the maize plant can mine excess soil nitrogen and potassium, reducing the risk of milk fever and nitrogen loss to water.
Reducing nitrogen leaching
Most of the nitrogen leached on dairy farms comes from cow urine. Ryegrass-clover pasture frequently contains more nitrogen (or crude protein) than cows can utilise. The bigger the nitrogen surplus in a cow’s diet, the higher the amount of nitrogen excreted in her urine. Feeding low nitrogen maize silage in conjunction with pasture dilutes dietary protein levels, and this in turn reduces the amount of urinary nitrogen.
To learn how maize silage can fit into your farming system or to find out the optimal amount of maize silage for your farm call 0800 PIONEER (0800 746 633).
*1 Lee et al, 2012. Perennial ryegrass breeding in New Zealand: a dairy industry perspective. Crop and Pasture Science 63: 107–127.
*2 Pioneer brand ‘Maize for Silage 2016-17’
