While chopping silage may still be weeks away, now is the time to start planning where and how you’ll store it. Taking time to evaluate silage storage location before harvest can pay big dividends when it comes to forage quality, feed efficiency, and cost control. 

Location, Location, Location 

Because feeding occurs at least daily and is a major demand on farm labor, proximity to feed delivery routes or livestock pens needs to be considered to reduce hauling time, fuel use, and wear and tear on equipment. There’s more to selecting a good site than the pile location being close to a feeding area, though. 

The first step in choosing a good site for your silage pile is to look for an elevated, well-drained area with a firm base and good year-round access for equipment. Avoid areas prone to standing water or flooding, or anywhere with poor natural drainage. Even minor depressions can create problems over the course of a feeding season.  

Think about access and traffic flow for both harvest and daily feeding. You want room for equipment to work without backing into trouble. Ideally, the site should provide or accommodate: 

• Space to pile, pack, and load silage without interfering with other farm traffic 
• All-weather access roads for trucks and tractors 
• Safe access by and operation of silage wagons or dump trucks, packing equipment, and feeding equipment 

The silage pile will generate leachate, which has a high nutrient concentration.  To avoid contaminating fresh water sources, the site needs to maintain a buffer around sensitive areas—like wells, streams, or property lines—as a first line of defense for protecting water quality and meeting regulatory expectations. 

Site Preparation 

Next, consider surface preparation for achieving a firm base. At a minimum, you’ll need an even, relatively flat surface that can support heavy equipment without rutting or sinking. If the pile will be built directly on the soil, this may mean you’ll need to compact the soil or work in crushed lime or gravel to firm up the base and possibly do some grading. For producers looking to minimize shrinkage and losses in feed value, upgrading to a concrete or asphalt pad becomes attractive as a more durable and functional way to reduce mud and feed contamination.  

Sizing the Silage Pile: A Step-by-Step Guide 

Once you've identified a good site, the next step is designing a pile that meets your feeding needs while minimizing spoilage. 

A key goal when designing a silage pile is ensuring you're removing enough feed from the face daily to prevent spoilage. As a rule of thumb, aim to remove 6–12 inches per day from the face, depending on weather (more in summer, less in winter). Let’s walk through an example for a typical drive-over pile.¹ 

Example:  

Number of cows: 100 head 

Target silage intake: 12lbs. dry matter (DM) per head per day  

Feeding period: 180 days (mainly over winter) 

Assume: 

Silage moisture content is 65%  

Silage bulk density = 40 lbs./cu ft (common for well-packed piles) 

Or about 14 lbs. DM/cu ft (= 40 x (1-0.65)) 

DM loss during storage = 15% (estimate for packed and covered pile) 

Face removal rate (winter feeding) = 6 in. (0.5 ft.) of feeding face thickness per day 

Pile height = side-slope height of 8 feet 

Side slope of pile = 3:1 (run:rise) 

Why a 3:1 Side Slope? 

When building drive-over piles, a 3:1 side slope is widely recommended. This means for every 1 foot of vertical rise, the pile extends 3 feet outward. Why use this? 

• It’s safer for equipment packing and feedout — reducing the risk of rollover accidents. 
• It allows for more effective packing and edge sealing. 
• It reduces erosion and spoilage along the sides. 
• It's easier to cover, especially when using plastic with overlap. 

Steeper side slopes may save space, but steep side slopes increase risks of accidents and complicate management. A 3:1 side slope strikes the best balance between safety, silage preservation, and usability. 

Step 1: Calculate silage volume removed daily 

When estimating from ration values: 

DM fed: 100 head × 12 lbs. DM/head/day = 1,200 lbs. DM/day 

DM removal rate: DM fed ÷ (1 - DM loss%/100%) with storage loss 

1,200 lbs. DM/day ÷ (1-0.15) = 1,410 lbs. DM/day 

Volume removal rate: DM removal rate ÷ Silage DM density 

1,410 lbs. DM/day ÷ 14 lbs. DM/ft³ = 100 ft³/day 

When estimating from as-fed weights: 

Volume removal rate: As-fed usage ÷ Silage bulk density 

4,028 lbs./day ÷ 40 lbs./ft³ = 101 ft³/day 

Step 2: Determine area of feeding face 

Feeding-face area: Volume removal rate ÷ Feeding-face removal rate 

101 ft³/day ÷ 0.5 ft/day = 202 ft² 

Step 3: Calculate ‘top width’ of pile 

To simplify calculations, the mounded-top, drive-over pile is assumed to have a trapezoidal cross-sectional shape – with a flat top and the side-slope height representing the pile height. 

Top width: (Feeding-face area ÷ Side-slope height) – (3 x Side-slope height) 

(202 ft² ÷ 8 ft) – (3 x 8 ft) = 1 ft Very narrow! 

For an 8’ pile height, the pile face looks triangular, which is not practical to achieve as a well-packed, drive-over pile. 

Re-running the calculations for a 5’ side-slope height, the top width comes out to 25 ft (= 200/5 - 3x5), which now suggests a mound shape that could be achieved on most operations.  Building a very shallow mound, however, increases the ratio of the exposed surface area to the silage volume, which makes the silage more prone to spoilage, while at the same time increasing the area to cover. 

Step 4: Calculate bottom width of pile 

Since the assumption of an 8’ side-slope height was not practical, remaining calculations assume a 5’ side-slope height and 25’ top width. 

Bottom width: Top width + (2 x (3 x Side-slope height)) 

25 ft + (6 x 5 ft) = 55 ft 

Step 5: Calculate bottom length of pile 

Assume the pile has a 3:1 side slope on each end. 

Bottom length:  (Feeding period x Face removal rate) + (2 x (3xSide-slope height)) 

   (180 days x 0.5 ft/day) + (6 x 5 ft) = 120 ft 

So, a pile covering a roughly 55’x 120’ area of ground is needed to match the targets for daily feeding-face removal (6 inches) and silage feeding rates (12 lbs. DM per head or 4,000 lbs. total as-fed).  If this pile shape doesn’t fit well in the space available, some flexibility exists in selection of the pile height, feeding period, or face removal rate.  Tradeoffs need to be considered, though, since each adjustment can affect the resulting feed value of the silage. 

This example illustrates a few practical considerations that must be made when planning a silage pile, which can be especially challenging for smaller herds.  For example, at twice the number of cows – 200 head – and amount of silage, a similar top width (26 ft) would work with an 8’ side-slope height and less than 20 feet of additional width and length would be required. 

Bottom Line 

Silage harvest is a busy time, but decisions made now can make a huge difference in silage feed value later. Planning ahead to size the pile properly and build the pile on a suitably selected and prepared site can help maximize return on feed investment, minimize waste, and deliver high quality feed to your livestock. 

References 

1. Roach, J. & Holmes, B. (2025). Drive-over silage pile construction. University of Wisconsin. https://cropsandsoils.extension.wisc.edu/articles/drive-over-silage-pile-construction/#:~:text=Size%20the%20pile%20so%20you,per%20day%20is%20even%20better.  

2. Goplen, J. & Drewitz, N. (2024). Don’t get robbed by hay and silage storage losses. Minnesota Crop News. University of Minnesota. https://blog-crop-news.extension.umn.edu/2020/01/dont-get-robbed-by-hay-and-silage.html