With the dry Summer and Autumn last year, many farms exhausted their home grown fodder supplies and faced buying in significant amounts of hay. With reports of El Nino weather patterns expecting to bring dry conditions again this summer now is the time to make the most of the current good soil moisture and fine, ideal grass growing weather and boost your fodder reserves going into harvest time. Those looking at re-stocking their hay sheds and silage pits this summer should be doing their sums on using fertilizer to boost pasture growth and conserved forage yields.
If you haven’t already done so, there is still a window of opportunity to use a nitrogen source such as urea to boost growth. Extensive Victorian DPI research has shown that average spring response to applied N in Spring in SW Victoria is 15-25 kgDM/kgN. Urea is 46% nitrogen, so for every 100kg of urea applied, you are applying 46 kg of nitrogen. Recommended application rates are 30 – 60 kgN/Ha per application. Best responses will be seen on actively growing, ryegrass dominant pastures, with high soil fertility (not lacking in essential nutrients, or any growth limiting factors such as soils that are too acidic), where moisture is not limiting and soil is not waterlogged.
100 kg of urea per ha will supply 46 kg of nitrogen. At $600 per tonne, that 100 kg will cost $60 per hectare. If a response of 20 kgDM pasture/kgN is achieved this will grow 20 x 46 = 920 kgDM/ha. This equals a cost per kgDM of 6.5 cents. Not all of the extra pasture will be consumed, assuming 20% wastage brings the cost up to 8.2 cents. You then need to take into the account the cost of carting and spreading the urea and also the cost of ensiling. If we work on $50-$100 per tonne of DM to ensile it this adds an extra 5-10 cents per kgDM.
Boosting pasture growth with nitrogen will also draw on reserves of other nutrients so you may want to consider using a fertilizer blend that will replace some of the other nutrients drawn from the soil to make conserved fodder. For example, for every tonne of pasture hay cut removes 25 kg Nitrogen, 2.5 kg Phosphorus, 17kg Potassium and 2.5 kg Sulphur.
Timing is Critical
Plan to conserve fodder 3-6 weeks post application. Any longer than six weeks and quality is likely to deteriorate. Ideally, conserve silage when less than 20% of plants have gone to head. Pasture quality deteriorates quite rapidly once pastures start to go reproductive. Fibre levels increase, protein and energy levels decrease. Netural Detergent Fibre (NDF) levels can increase as much as 1% per day, making the time of cutting difference between excellent quality and poor quality silage only being a matter of 10-14 days. High NDF silage limits cow’s potential intake and resulting milk production.
Below is an example of the difference in intake and resulting milk production of a high quality versus low quality silage.
February in SW Victoria, 580 kg LWT July calved cow, 210 days in milk, 120 days in calf. Protein test 3.2%, butterfat test 4.0%.
It’s not always possible to make silage at the ideal time, but any improvement you can make can lead to significant increases in your margin this Summer. Contact your local Reid Stockfeeds nutritionist to discuss your options for feeding this Spring and Summer.