Is Your Silage Pit And Effluent Management Up To Scratch?

In many parts of the country, the silage season is already upon us.

Farmers should ensure that silage storage facilities are fit for purpose. This means that the silage pit and silage effluent collection and storage facilities meet the standards required by the Department of Agriculture and Food (DAFM).

At the time of writing – under the COVID-19 restrictions – the DAFM considers that some limited projects that are essential for animal welfare should continue. Examples of works that are considered critical include work on silage pits (storage of fodder) or urgent calf housing.

Cut the risk factors - Pit heights should not be increased if there is any question of farm safety being compromised

Cut the risk factors – Pit heights should not be increased if there is any question of farm safety being compromised

Silage pits

Slabs and walls need to be structurally sound to ensure ensiling is completed in a safe environment.

Silage effluent-collection channels and tank storage must be capable of managing the volume of effluent generated.

Silage effluent is a highly polluting liquid and can cause fish kills in watercourses and rivers. It can also cause serious water contamination of wells if it is allowed access to them.

Now, while silage pits are empty, is the time to examine the silage slab, effluent tanks, channels, silo floors, walls and wall-floor joints channels for any maintenance and repairs needed before the pit is used again.

Silage slabs should be cleaned thoroughly (for example, power washed) to identify any problems. Slabs and channels must be leak-proof, and all silage effluent must be collected and safely stored.

Common defects in slabs include cracks that allow seepage through the concrete, and effluent channels being cracked or blocked.

Defects or problems should be rectified before silage making commences. If the pit is not fit for purpose, don’t use until all repairs are completed. For guidance, repair works should be completed to DAFM specifications for Concrete Silage Bases S128 and Resurfacing of Silo Floors S128A.

These can be obtained at

Safety guidelines - The silage harvest season sees a big increase in machinery-related injuries and fatalities every year

Safety guidelines – The silage harvest season sees a big increase in machinery-related injuries and fatalities every year

Making silage

It is important that you know how much silage your slab is capable of storing.

Take into account any remaining silage in the clamp following the winter and the capacity of the pit to store this season’s silage yield. A lot of the problems with effluent arise from farmers attempting to ensile more silage than the slab is designed to hold.

The edge of the silage clamp should not extend further than the effluent channel and result in seepage of effluent to the environment. All effluent should enter the channels under the cover of the silage polythene, and the edge of the ensiled grass should not extend onto or over any channel.

The open channel space is maintained by placing a plastic slotted drainage pipe in the channel. Ensure effluent is diverted to an effluent tank or slatted tank. Check any effluent tank levels on a daily basis when effluent is being produced and take action if necessary to prevent it from overflowing.

To prevent effluent from flowing out over silage walls in the few days following ensiling, it is important not to pile the grass too high over the walls and to slope the grass back at 45˚ from the top of the walls.

If the capacity of the silage slab would be exceeded due to the size a silage crop any additional silage should be stored on another slab or made into round bales.

Wilting of silage is recommended in order to raise the sugar content of the silage water fraction and improve preservation. This has the added benefit of reducing silage effluent.

Alert - Traffic cones at the point of egress from the field onto the road to warn road users in advance are effective.

Land spreading of silage effluent

When land spreading silage effluent, dilute the silage effluent with one part water/slurry to one part effluent. Do not spread if rain is forecast in the following 24 hours.

Don’t spread the mix within five metres of any watercourse, 10 metres where field slope exceeds 10 per cent, 20m from lake/main river, 25-200m from well/public water supply.

Round Bale storage

Generally, round bales have higher dry matter content than pit silage and do not generate effluent.

However, where round bales are made in wet conditions, then these bales can generate silage effluent.

The effluent from round bales is treated the same as from silage pits and must be collected and stored in same way. Under cross-compliance regulations, silage bales should not be stored within 20m of any water body where there are no facilities to collect effluent.

Kevin O Sullivan & David Webster, Teagasc

(Source – Irish Independent – Indo Farming – Kerryman – Kevin O Sullivan & David Webster – 13/05/2020)

A Teagasc survey in January revealed that 25pc of farmers nationally are currently short of silage

How Much Should You Be Paying For Silage Ground?

The spring often the time of year where deals are done on renting of ground for making silage, but how much can we afford to pay for this ground and when does it become too expensive?

To try attempt to put a cost on the making of silage from rented ground involves a huge number of variables; how much is the land rental, what is the ground quality like, is it reseeded ground or old pasture, what is the soil fertility like, how much will the contractor charge, how much fertiliser will be applied, how much will the fertiliser cost and on the lists goes.

So to make any attempt at this calculation is going to involve a lot of assumptions, so I am going to do this with two sets of assumptions.

The first set is the ideal scenario whereby high performance is achieved and the second set is probably closer to national average figures and typically of poorer performing silage fields. Both sets of assumptions are set out in table 1.

The high performing paddocks are ryegrass pastures with high ryegrass content and are on target for soil fertility. They are also free draining meaning that a mid-May cutting date is highly likely. The poor performing fields are low in soil fertility, are mostly old grasses and heavy in nature, leading to a likely cutting date of in the second week of June. This is due to the time allowed for the crop to “bulk up” and for trafficability reasons.

The high performing fields receives the recommended levels of all key nutrients, whereas the poor performing fields receive the typical three bags Cut Sward/acre for first cut and two bags/acre for the second cut. The knock on effect of this is that the high performing field is cut in mid-May with a DMD of 72pc whereas the second field is cut in mid-June with a DMD of 64pc.

Table 1 - Silage Ground Cost

Table 1 – Silage Ground Cost

Second Cut

We are assuming that the second cut is cut about seven weeks later (around mid-July) on the high performing field giving a DMD of 72pc again whereas the poorer performing field is left grow for a further nine weeks (cut late August) with a DMD of 68pc.

In energy terms, the overall end result is that the poorer performing field only has a total output of three quarters the energy of the high performing field.

What I haven’t factored in here is the fact that the high performing field has six weeks longer to grow aftergrass, which should provide two extra grazings. So what does all this mean? The only way to fairly compare both situations is to analyse the cost of producing a unit of energy from each situation, and in this case this is the cost of a UFL on a cent/UFL. Table 2 shows that the cost of producing silage from the high performing field ranges from 16c to 19c (per unit of energy) depending on the rent paid per acre whereas the poor performing paddock ranges from 21c to 25c.

If we compare this to feeds such as Rolled Barley, Soya Hulls or Palm Kernel which can be purchased for around 24c/UFL (on a dry matter basis), then we can only justify higher rents where the performance is guaranteed to be top class. In all other situations, purchasing feed may be as economical.

Silage Ground Cost 2

There are, however, other factors to be considered:

  • Poor quality silage will most likely need to be supplemented, thereby distorting the figures on this page
  • Adequate feed space is needed when feeding meal instead of silage
  • Every farmer is going to need to secure a minimum of 50pc+ of a cows diet in the form of forage
  • Renting ground now will involve a payment in the next few months, whereas the meal purchased may not have to be paid for another 12 months.


So, how much can we afford to pay for this ground and when does it become too expensive? As you can see, there is no easy answer to this question. Every farmer has to do their own sums with their own set of assumptions before paying over the odds.

Joe Kelleher is a Teagasc advisor based in Newcastle West, Co Limerick

(Source – Irish Independent – Indo Farming – Joe Kelleher – 19/05/2020)


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