Pushing for fodder
Article printed September 26, 2023. For the latest version, please go to: https://www.feedinglivestock.vic.gov.au/2022/09/28/pushing-for-fodder/
Fodder conservation should only occur when there is surplus feed on the farm.
However, where fodder reserves have diminished after a long dry summer/ autumn or wet winter pasture growth has been slow people may be looking to boost their pasture growth artificially. This can help create a pasture surplus to ensure adequate fodder supplies for the coming summer.
If you need to create a surplus for fodder production, urea is often one of the cheapest methods of doing so. The best time to apply urea is immediately after a grazing event. The nitrogen requirements of a pasture are at its highest during the rapid growth phase in the two weeks after grazing. Research has shown applications of urea between 65-108 kg/ha (30-50kg N/ha) at any one application are most efficient.
The response rate expected from the application of urea depends on soil temperature, soil moisture levels, general fertility of the soil and species present. Table 1 summarises expected response rates to urea in Gippsland, South West Victoria and the Northern Irrigation regions (source: www.nitrogen.unimelb.edu.au).
Response rates are expressed as kgDM/kgN – a 10:1 response will result in 10kgDM pasture grown for every 1 kg N applied. If the application rate is 80kg urea/ha (or 36.8kg nitrogen/ha, urea is 46 per cent nitrogen), then at a 10:1 response, expect to grow an additional 10 x 36.8 = 368 kgDM/ha
Table 1: Average expected N response Gippsland (kgDM/kgN)
|Response time (days)||14-28||14-21||14-28||21-32|
Table 2: Average expected N response Western Victoria (kgDM/kgN)
|Response time (days)||14-28||14-21||14-28||18-32|
Northern Irrigation District
Table 3: Average expected N response Northern Irrigation District (kgDM/kgN)
|Response time (days)||21-30||18-24||21-28||21-28|
Low = <30% ryegrass, <12mg/kg Olsen P, <80mg/kg Colwell K
High = >60% ryegrass, 20-25mg/kg Olsen P, 250+mg/kg Colwell K
*= assumes either irrigation or rainfall significant enough for active pasture growth
nr = not recommended on these pastures at this time of year
Some things to consider if using urea to boost your pastures for fodder production
- Pasture response to urea will be limited if other nutrients are lacking
- For the best response, target paddocks with higher fertility
- Avoid applying to waterlogged paddocks as this will increase the denitrification rate – one of the pathways of loss that can occur when using nitrogen based fertilisers.
It has been found that low to moderate rates of nitrogen (those recommended above) can be used to strategically increase pasture production without long term adverse effects on clover persistence and its ability to fix nitrogen.
How can you determine if you have a surplus of feed available to cut for silage or hay?
First you need to know the area of the farm required to supply the energy needs to the current stock. To do this, use the following equation:
Area for stock (ha) = stock consumption (kgDM/day) ÷ pasture growth rate (kgDM/ha/day)
Then subtract this area from the total farm or grazing area. This remaining area could be cut for fodder.
For example – 300 head of cattle that weigh 400kg liveweight, growing at 1kg/day, consuming a total of 2850 kgDM/day on 100 ha grazing area. If the pasture is growing at 45kgDM/ha/day, then:
Area for stock (ha) = 2850 ÷ 45 = 63ha
Area for possible fodder (ha) = 100 – 63 = 37ha
Please note, this is based on current growth conditions. If conditions change significantly (ie soil profile dries rapidly) the area available for harvest will change.
Don’t forget – don’t leave the paddock locked up for too long, resulting in grass that has been “too long for too long”. When grass is ‘too long for too long’, canopy closure happens.
If the paddock has reached canopy closure and leaves are tipping over, sunlight won’t be reaching the base of the plant. For a plant to tiller, sunlight needs to reach the base of the plant. This is the main way perennial grasses reproduce andSpring is the time of greatest tillering in the plant. If the paddock has reached canopy closure and is left this way for an extended period before harvesting (with machinery or stock), subsequent plant density in the pasture will be compromised due to the reduced tillering. This could lead to an increased number of weeds appearing over summer and autumn. If paddocks have reached canopy closure but you are unable to harvest them for fodder in the near future, it would be better for the pasture if you let the stock in to graze, allocating a different paddock for fodder production.
Information on stock feed requirements can be found in the following publication:
Further information on nitrogen use can be found at: