Producers are likely to have run out of hay and silage reserves and starting to think about opportunities to replenish them this spring.

A golden rule of silage and hay production is that it should only be made from a true surplus of spring growth and intake of livestock not restricted to try and conserve feed. This is because grass utilisation by livestock is far cheaper and more efficient than having to make and store silage and hay. However, if grass is going to waste by not having enough mouths to eat it, then it is a very good option.

An important first step is to identify whether there will be a true surplus or if you can boost additional growth for fodder conservation. If no surplus is possible, then you will need to plan to fill future feed gaps with fast growing winter fodder crops or purchased feed.

There are five main pasture management considerations in making hay or silage:

1. Identifying a true surplus.
2. What silage or hay quality can be achieved?
3. Which paddocks to cut?
4. Fertiliser needs to boost growth and create a surplus.
5. Pasture recovery of paddocks cut.

Identifying a true surplus.

Cut silage or hay when you have at least a 20% surplus across the farm. This means pasture growth is exceeding animal requirements by 20%. When this occurs, a paddock can be dropped out of the grazing rotation and closed for silage or hay. There are a few ways to anticipate or check for surpluses.

• Develop a whole farm feed budget
  • Monthly budgets accounting for livestock demand and pasture growth allow you to anticipate surpluses, so you are ready to lock up paddocks and optimise fodder quality.
  • Spring growth will normally quickly get ahead of what the livestock can eat by mid to late September.
  • In a normal season, pastures are starting to grow at 50 kg DM per hectare per day. Autumn calving beef cows will be requiring about 12 kg DM/day in September and if you have a stocking rate of 1.5 cows/ha, there could be a requirement of 30 kg DM/day. This is 40% of pasture in excess of animal requirements.
  • Pasture growth can be highly variable in spring due to moisture so weekly checks of predicted growth will be necessary to fine tune feed budgets.
• Paddock indicators that a surplus is occurring
  • Pasture is long surrounding dung or urine patches. This indicates that pasture growth is exceeding demand. Stock wont graze close to these areas if they can help it but they will graze the tops off surrounding pasture when hungry.
  • Grazing heights in pastures are starting to exceed 10 to 12cm (2200-2500 kg DM/ha). This is best avoided as this starts to cause shading and decreases pasture growth and tillering.
  • Average height of the residual pasture left behind after grazing is starting to increase. It may have been 5cm, now its 7cm.
  • Pasture is becoming longer between clumps or clumps are getting bigger in set stocked paddocks.

What silage or hay quality can be achieved?

Consider the potential quality of when the surplus pasture can be cut. It is more cost efficient to produce higher quality silage and less of it, than achieve high quantity of a poorer feed. This is because feed quality governs both the amount the animal can eat and energy for livestock growth.

Very good quality silage is made early in the season (3 -5 weeks before hay) in the late vegetative to early reproductive growth stage targeting a metabolisable energy content of 9.5-10 MJ/kg DM before quality decreases with advancing maturity. It has a short shut up period of 4 to 6 weeks. Poor quality pastures never become good quality silage.

Which paddocks to cut?

Paddocks that will provide a surplus of growth and have good quality, so they will tend to be your better pastures. And ones that have good critical nutrient levels so they will not require a lot of nutrients to boost growth.

Locking up for hay benefits phalaris, as the process of stem elongation drives the production of dormant buds. But in ryegrass and cocksfoot this can limit tiller production because shading reduces new vegetative tiller development and seeds for potential seedling recruitment. Lack of available moisture following cutting also prevents recovery.

If perennial species have been lost during the dry period and opened up pasture to annual grass invasion, then silage or hay production can be effective ways to reduce carryover weed seeds.

Applying fertiliser to boost growth and create a surplus

Nutrient uptake by pasture peaks during spring as growth rates increase. Fertilisers including nitrogen helps to grow more dry matter in spring, but phosphorous, potassium and sulphur may also be needed to lift critical levels to drive pasture growth and replacement of the nutrients removed in the hay and silage will need to also occur.

Where nitrogen is used in a blend, rates should be based on supplying 25-50 kg/ha of nitrogen for best nitrogen use efficiency. When determining rates, potassium should be kept below 60 kg/ha per application. Pastures can take up luxury quantities of potassium, which can lead to poor returns on investment.

If no soil tests are available to check levels, then a useful indicator can be to check the responsiveness of growth to nutrients contained in urine patches or dung patches. Urine patches contain good levels of N, K and S and dung patches also contain P.

Table 1. provides a guide to the potential nutrient removal rates from pasture hay and silage. For example, if a 3 t DM/ha grass/clover silage crop is cut, 75 kg/ha of potassium may be removed from the property or to a different paddock when it is fed back to stock.

Table 1: Nutrients removed from typical pasture crops in spring.

	Nitrogen (kg N/t DM)	Phosphorous (kg P/t DM)	Potassium (kg K/t DM)	Sulphur (kg S/t DM)	Calcium (kg Ca/t DM)
Grass/clover hay	21	2	18	1.7	5.3
Grass/clover silage	26	2.8	26	2.3	5.9
Lucerne hay	28	2	24	2.6	9.9

Source: ‘Nutrient Concentrations in Harvested Agricultural Commodities’ from the National Land and Water Resources Audit Project, Appendix 6, September 2001.

Pasture recovery

Hay or silage production comes at a cost of production in the following year, from the removal of nutrients and a decrease in tiller production. Shading during lock ups restricts light from reaching plant crowns which is a trigger for tiller production. Tiller replenishment is needed for plant survival because tillers may only survive for 3 months (ryegrass) to one year (phalaris or tall fescue).

Some ways to encourage pasture recovery are:

• Avoid cutting the same paddocks consecutively.
• After cutting rest pastures to replenish carbohydrate reserves before grazing. This will be indicated by the regrowth of 3 live leaves per tiller (or 4 if phalaris/cocksfoot).
• In the following year, encourage annual clover seed set by removing excess pasture trash to maximise germination, keep pastures short over winter and lighten grazing pressure during flowering.
• Soil test and replenish depleted nutrients in autumn.
• Practice rotational grazing allowing rest periods from grazing of up to about 6 weeks in winter and 2 to 3 weeks in spring to favour grass recovery.

 

Photo taken in early September, showing longer pasture surrounding dung but the tops have been gazed indicating that animal demands are still higher than paddock growth so avoid locking up paddock for silage.