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Harvesting of first-cut silage will be well advanced at this point. While grass growth has increased in recent weeks, many farmers report that first-cut yields were lighter than normal following cold weather during May.
On farms that harvested lower than normal yields of first-cut silage, now is the time to think about making up any fodder deficit, just as fields are closed off for a second cut.
Working out how big the deficit is gives farmers more options and time to make sure ample silage is saved over the remainder of the summer and early autumn.
Options
For instance, in the case of a deficit, is there an option to close off extra ground for a second cut? If so, this decision needs to be made now.
If this is not an option, aim to take an early second cut at the beginning of August to provide a window for a small third cut of bales in September.
For farmers working on heavier land with a six- to seven-month winter, taking early action may provide an opportunity to buy standing grass during the summer
On drier land, there may be an option to grow a forage crop, such as kale, to extend grazing late into the year and reduce silage demand. But such a crop needs to be established this month.
For farmers working on heavier land with a six- to seven-month winter, taking early action may provide an opportunity to buy standing grass during the summer to boost fodder reserves.
This grass could be ensiled with second-cut silage and may be more practical than buying bales through the winter.
Early action
The key is to act early. If your farm is short on silage after a cold spring, chances are that quite a few neighbouring farms will be in the same boat and possibly looking to buy silage during the winter.
Therefore, farmers who are proactive in addressing a silage deficit are less likely to be caught short when it comes to winter feed reserves.
As a means of gauging how much silage will be required for winter feed, follow the outlined steps.
The first step is to work out how much silage cattle will require during winter.
Work on the basis of a normal winter period and factor in an extra month for security.
Next, work out how many cattle are housed over winter.
It is better to overestimate numbers, rather than underestimate and run short of fodder.
Feed intakes
Spring-calving cows that are dried off at housing will typically eat 30kg to 35kg/day of silage, or approximately one tonne per cow every month.
Cows in strong body condition can have silage restricted for a period, which will obviously reduce demand. Likewise, high-quality fodder means cows will need less silage to maintain condition.
For autumn-calving cows with a calf at foot, intakes are more typically 45kg to 50kg/day, or around 1.5t per cow every month. Silage intake will be reduced by around 5kg with every 1kg of concentrate fed.
Strong weanling cattle will consume between 20kg and 25kg/day, or around 0.6t to 0.75t/month. Finishing cattle on high levels of concentrates will consume similar amounts of forage.
Calculate silage requirements as per the example outlined in Table 1.
Alternatively, you can work out fodder requirements and silage stock by clicking here.
The next step is to work out what tonnage of silage is on-farm after the first cut has been saved. Count in bales saved from surplus grass on grazing ground, as well as any silage carried over from last winter.
For pit silage, work out the volume of grass ensiled by measuring the length, width and average height of the clamp. To convert this figure to tonnes of grass, multiply by 0.64 for grass at 30% DM.
For example, a grass clamp measuring 20m x 9m x 2m will have 230t of 30% DM silage on a freshweight basis.
Bales
Silage bales will vary in weight depending on whether they are 4x4 or 4x5, as well as having grass chopped and packed tight. A good guide to work to is 800kg for silage bales at 30% to 35% dry matter.
Having worked out how much silage is needed for winter and the tonnage currently on-farm, the next step is to work out if the second cut will fill any deficit.
Silage yields for a second cut grown over seven to eight weeks will be around 7t to 8t/ac freshweight on productive grassland. On older swards, allow for yields being closer to 5t to 6t/ac.
Close off as much silage ground as can be spared as early as possible after first cut. The earlier the ground is closed off, the earlier it can be cut in late summer.
This will allows covers to regrow for grazing cattle into autumn.
If necessary, a small area could be used to produce a third cut of bales, if there is still a silage deficit after the second cut is harvested.
Second-cut fertiliser
If slurry is being spread on aftermath to grow a second cut, the nitrogen content will be much lower compared to an early spring application.
This has a bearing on how much chemical N is required.
However, the phosphate (P) and potash (K) content will be the same in a summer slurry application. Every 1,000 gallons/ac of slurry applied by a splash plate provides around five units of P and 30 units of K.
Requirements
For second cut made on soils at index 2 for P and K, apply around 75 units/ac of N, 15 units/ac of P and 80 units/ac of K.
Spreading 2,500 gallons/ac of slurry will provide around 10 units of nitrogen, 12 units of P and 75 units of K, topping up with 2.5 bags/ac of a product such as CAN. Top up with three bags/ac of a product such as 22-2.5-10, or something close to this level.
Sulphur
Don’t forget about sulphur. Choose a fertiliser with added sulphur and apply 10 to 15 units/ac for second cut.
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