Legumes are the richest source of home-grown protein a livestock farm can produce, and preserving them as legume silage captures that protein for year-round feeding at a fraction of the cost of bought-in concentrates. Beans, peas, lupins, clovers, lucerne, and more can all be ensiled as whole plants. But legume silage carries a challenge that grass and maize silage do not, and understanding it is the difference between a high-protein feed and a spoiled one.
Why Legume Silage Is Worth Making
The appeal of legume silage runs beyond protein, though protein is the headline.
- High protein. Legume forages are substantially higher in protein than grasses, which reduces the need for purchased protein concentrates.
- Nitrogen fixation. Legumes host rhizobium bacteria in their root nodules, which fix atmospheric nitrogen. This feeds the crop, cuts fertilizer costs, and leaves residual nitrogen in the soil for the following crop.
- Dual cropping. Legumes can be grown with cereals or whole-crop small grains. The combination balances the cereal’s starch with the legume’s protein, spreads the harvest window, and eases fermentation, since the cereal contributes the sugar legumes lack.
- High yield per hectare and strong appeal to organic systems, which rely on legumes for nitrogen rather than synthetic fertilizer.
Common legume forages include lucerne (alfalfa), red and white clover, lupins, peas, beans, sainfoin, and bird’s foot trefoil (Lotus corniculatus).
The Catch: Legumes Are Harder to Ensile
Here is the point most articles skip, and it is the one that decides whether your legume silage succeeds.
Legumes are more difficult to ensile than grass or maize, for two reasons. First, they are lower in water-soluble carbohydrate, the sugar that lactic acid bacteria ferment into the acid that preserves silage. Less sugar means less fuel for a good fermentation. Second, their high protein content gives them a high buffering capacity, meaning they resist the drop in pH that preservation depends on.
Put together, this makes legumes prone to a slow, incomplete fermentation, which opens the door to clostridia and the butyric fermentation that degrades protein and spoils silage. The very protein that makes legumes valuable is also what makes them harder to preserve.
This does not mean legume silage is not worth making. It means it has to be made carefully, with steps that specifically address the sugar and buffering problem.
“Farmers who have only made grass or maize silage sometimes assume legumes behave the same way, and they do not. Legumes fight the fermentation because they are low in sugar and high in protein buffering. The successful legume silage producers are the ones who wilt properly, use an inoculant, and often grow the legume with a cereal to supply sugar. Get those right and you have an outstanding protein feed. Skip them and legumes will spoil where grass would have forgiven you.”
— Sue Su, Marketing Director of Silopak
How to Make Legume Silage Successfully
The techniques all target the same goal: help the fermentation overcome the low sugar and high buffering that work against it.
Wilt to the right dry matter
Wilt the crop to around 30 to 45% dry matter before ensiling. A mower conditioner with rubber rollers speeds wilting by crimping the stems. Wilting concentrates the sugars and reduces the water that dilutes the acid, both of which help the fermentation and reduce the risk of clostridial spoilage that wet legumes are especially prone to.
Use an inoculant
An inoculant is more valuable for legumes than for most crops, because it directly supplies the lactic acid bacteria that legumes struggle to feed. Lactic acid bacteria ferment the plant’s sugars into lactic acid, dropping the pH to preserve the crop. They do not destroy the plant; they preserve it by acidifying it. Inoculants combining lactic acid bacteria with enzymes are particularly useful, as the enzymes break down fiber into additional fermentable sugar, giving the bacteria more to work with.
Consider growing legumes with cereals
Growing a legume alongside a cereal solves the sugar problem at the source. The cereal contributes the water-soluble carbohydrate the legume lacks, so the mixed crop ferments more reliably than pure legume, while still delivering high protein. This dual-crop approach has been used for years and remains one of the most dependable ways to make legume silage.
Fill, pack, and seal fast
The universal silage rules apply with extra force to legumes, which have less margin for error:
- Fill quickly to limit air exposure.
- Pack tightly to exclude oxygen.
- Seal completely and immediately.
Preventing Losses in Storage
Legume silage, like all silage, shrinks and loses quality over storage if oxygen is present. Losses occur mainly during the initial fermentation phase and through aerobic decay when air reaches the silage. As it deteriorates, the valuable nutrients, soluble protein, sugar, and starch, are consumed first, leaving a higher proportion of ash and fiber. In other words, spoilage strips out exactly the nutrients you made the silage for.
The defenses are the same anaerobic fundamentals: fast filling, tight packing, prompt sealing, and an intact barrier maintained throughout storage. For bales, the preservation is only as good as the film seal. Silopak has manufactured LLDPE silage film since 2011 from premium virgin resin, holding a reliable oxygen barrier for more than 18 months. The legume ensiling process itself follows the same approach as grass silage, with the added attention to sugar and buffering that legumes require.
Why Protein Matters So Much
The reason legume silage is worth the extra care comes down to what protein does for the animal.
Protein underpins the immune system, reproduction, milk production, and the function of vital organs. A protein-deficient animal becomes lethargic, loses appetite, and grows vulnerable to disease. Ruminants generally need a diet of at least around 7% crude protein simply to keep rumen microbes functioning, and considerably more for productive animals; below that threshold, the rumen microbial population itself cannot work properly, which reduces the animal’s ability to digest anything.
For dairy cows, the link is direct: mammary gland cells draw amino acids from the diet to synthesize milk protein, so a protein shortfall cuts milk protein output. In pregnant animals, chronic protein deficiency can result in weak calves. Legume silage addresses this at source, providing high protein from feed the farm grows itself.
When protein sources are scarce, farmers sometimes fall back on grazing low-quality forage supplemented with molasses-based urea licks. These non-protein nitrogen supplements have a role, but substituting them for genuine protein can reduce reproductive performance, including conception rates in heifers. Home-grown legume silage is usually the more reliable and economical answer.
Frequently Asked Questions
Q: Why is legume silage harder to make than grass silage?
Because legumes are low in water-soluble carbohydrate and high in protein. The low sugar gives lactic acid bacteria less fuel to produce the acid that preserves silage, and the high protein creates a high buffering capacity that resists the necessary pH drop. Together these make legumes prone to slow, incomplete fermentation and clostridial spoilage. Success depends on wilting properly, using an inoculant, and often growing the legume with a cereal to supply sugar. Made carefully, legume silage is an excellent high-protein feed.
Q: What dry matter should legumes be wilted to for silage?
Around 30 to 45% dry matter. Wilting concentrates the sugars and reduces the water that would dilute the fermentation acids, both of which help legumes overcome their natural resistance to good fermentation. A mower conditioner with rubber rollers speeds wilting by crimping the stems. Wilting also reduces the risk of clostridial fermentation, which wet legumes are especially prone to because of their low sugar and high buffering capacity.
Q: Which legumes can be made into silage?
Many, including lucerne (alfalfa), red and white clover, lupins, peas, field beans, sainfoin, and bird’s foot trefoil. All are high in protein and host nitrogen-fixing rhizobium bacteria in their root nodules. They can be ensiled as pure legume or, more reliably, grown and ensiled together with a cereal that supplies the sugar legumes lack. The choice depends on your climate, soil, and whether the crop is grown for grazing, hay, or silage.
Q: How much protein do ruminants need?
As a general minimum, ruminants need a diet of around 7% crude protein just to keep their rumen microbes functioning, with productive animals such as lactating dairy cows needing considerably more. Below that minimum, the rumen microbial population cannot work properly, which impairs digestion of the whole diet, not just protein. Protein deficiency shows as lethargy, poor appetite, reduced milk production, weak calves, and greater disease susceptibility. Legume silage is an effective, home-grown way to meet protein needs economically.
Reviewed by Sue Su, Marketing Director of Silopak, on 15 September 2026. This guide has been revised to explain why legumes are harder to ensile than grasses and to correct the description of lactic acid bacteria and legume species names.
