The Effect of Corn Ensiling Methods on Digestibility and Biogas Yield

Abstract

This study investigates the impact of different corn silage preparation methods, namely the traditional and Shredlage methods, on digestibility and biogas yield in anaerobic digestion and its nutritional value—the first complex study of its kind. Key parameters of both silage types were analyzed, including chemical composition, fiber content, and elemental makeup. Methane and biogas production were assessed under standardized fermentation conditions. The results showed that the Shredlage method, characterized by more intensive chopping, led to higher biogas and methane yields per unit of organic dry matter compared to traditional silage. This improvement is attributed to enhanced digestibility due to the lower content of neutral detergent fiber (NDF), acid detergent fiber (ADF), and crude fiber in Shredlage. An elemental analysis revealed slight differences in carbon-to-nitrogen (C/N) ratios, with both silages showing values suitable for efficient fermentation. Despite minor variations in mineral content, Shredlage demonstrated greater efficiency in biogas production, particularly for rapid fermentation processes. The findings underscore the importance of silage preparation techniques in optimizing biogas yield and suggest Shredlage as a superior option for enhancing energy recovery in biogas plants. Future work should explore the economic trade-offs and scalability of these methods.

1. Introduction

Biogas production through anaerobic digestion (AD) has recently gained significant attention as an efficient and sustainable method for converting organic waste into renewable energy [1]. Corn silage is frequently used as a feedstock for biogas production, being one of the most popular substrates in Europe, including in Poland, alongside animal manures [2,3]. The use of corn silage in methane fermentation is growing in interest due to its high biomass yield, favorable chemical composition, and the increasing demand for renewable energy sources [4].

Corn silage, made from fermented whole-plant corn, is rich in carbohydrates, proteins, and fibers, which make it a suitable substrate for anaerobic digestion. It is primarily composed of cellulose, hemicellulose, lignin, and starch, which are broken down during the fermentation process [5]. The biochemical composition of corn silage influences the methane yield, as the efficiency of microbial degradation may vary significantly depending on the availability and digestibility of these compounds [6].

Corn silage usually contains 20–35% starch [7], which is easily fermentable and leads to higher methane production rates [8]. On the other hand, the high fiber content in corn silage can present some challenges for fermentation. Lignin, as a complex and recalcitrant polymer, is particularly resistant to microbial degradation. However, proper inoculation with suitable microbial communities or some pre-treatment methods can enhance the breakdown of fibrous components [9,10].

Corn silage has an optimal carbon-to-nitrogen (C/N) ratio for methane production (about 25:1), which supports balanced microbial activity in anaerobic digesters. Imbalances in the C/N ratio can inhibit the growth of methanogens and other key microorganisms involved in the fermentation process [8].

The anaerobic digestion of corn silage is highly dependent on the substrate’s characteristics, as well as the environmental conditions (pH, temperature, moisture, and microbial diversity) of the digester [11]. Optimal temperature and pH conditions are crucial for maximizing methane production from corn silage. Mesophilic conditions (30–40 °C) are generally preferred, though thermophilic conditions (50–60 °C) can be used for enhanced microbial activity and faster digestion, albeit with higher energy costs for maintaining temperature [12]. The quality of the corn silage, including its fermentation process, directly influences the methane yield [13]. Poorly preserved silage with high concentrations of butyric acid or other inhibitors can reduce the efficiency of methane production. Ensuring proper ensiling techniques that limit oxygen exposure and promote lactic acid bacteria growth is essential [14].

Pretreatment methods such as mechanical, thermal, or enzymatic treatment can enhance the digestibility of corn silage. These methods break down the lignocellulosic structure, making the starch and cellulose more accessible to the microbes [15].

Methane Potential and Yield

Studies have shown that corn silage can produce substantial methane yields under optimized conditions. Typically, methane yields range from 150 to 250 Nm³ per tonne of silage, depending on the variety of corn, the environmental conditions, and the method of digestion [16,17]. The co-digestion of corn silage with other organic materials (e.g., livestock manure, food waste) can improve the methane yield by enhancing microbial diversity and balancing the C/N ratio [18]. Co-digestion has been found to boost the efficiency of methane production by providing complementary nutrients and buffering against potential process instability [16].

Yu et al. (2023) [19] indicated that, under optimal anaerobic conditions, corn silage can provide an efficient and high-yield anaerobic digestion process, particularly when co-digested with other substrates such as manure, which is also becoming one of the substrates used in biogas plants in times of energy crisis [20]. The study found that methane production could increase by up to 20 % when silage was co-digested with cattle slurry, emphasizing the synergistic benefits of multi-feedstock digestion [21].

While corn silage presents a promising substrate for methane fermentation, several challenges need to be addressed:

• Lignin and Cellulose Degradation: The recalcitrant nature of lignin and cellulose in corn silage can slow down the fermentation process, requiring pretreatment to improve digestibility and methane yield.
• Volatile Fatty Acid Accumulation: During digestion, the accumulation of volatile fatty acids (VFAs) can inhibit methanogenesis and lead to process instability. This issue can be mitigated through the careful monitoring and control of operational parameters such as feedstock loading and retention time [22].
• Seasonal Variability: The quality of corn silage can vary seasonally, affecting its methane production potential. Silage made from corn harvested during optimal growth periods generally results in higher methane yields compared to silage from off-season crops [23].

The use of methods facilitating silage digestion (such as Shredlage) can reduce the occurrence of the above-mentioned problems through the more effective decomposition of lignin-cellulosic compounds, shortening the retention time, reducing the risk of VFA accumulation, and also reducing the differences in fermentation efficiency between silages of different quality (due to the effective disruption of their structures). All this should also result in a generally significant increase in methane production from 1 ton of fresh corn silage.

The article aims to investigate the differences between traditionally and Shredlageproduced corn silage in the context of its suitability for biogas production and digestibility parameters affecting the efficiency of the anaerobic digestion process. Corn silage is one of the most popular cattle feeds in the EU, which is why various innovations are being carried out to increase its nutritional value, such as the Shredlage method. The novelty in the presented research is a comprehensive comparison of the nutritional value of traditional silage and that produced by the Shredlage method, including an evaluation of its suitability as a substrate for biogas plants. It should be emphasized that corn silage is also the most commonly used substrate for biogas plants in many Western European countries (e.g., Germany, France, Italy).

2. Materials and Methods

The study involved corn silage ensiled in two ways: traditional and Shredlage.

The SHREDLAGE^® method by CLAAS (Harsewinkel, Germany), an advanced technology for conditioning corn for silage, was developed in the United States and is now widely used in Europe. It involves chopping corn plants into longer fragments of 26 to 30 mm in length, and then intensively crushing the material using special corn-cracker SHREDLAGE^® rollers. These rollers, equipped with counter-rotating spiral grooves, completely crush the cobs and grind the grains, which increases the availability of starch in the cow’s rumen. Additionally, the stalk structure is effectively broken down longitudinally, and the stalk bark is stripped off, which increases the surface area of the chopped material and improves bacterial fermentation during ensiling and digestion. Research conducted by the University of Wisconsin has shown that the use of SHREDLAGE^® technology significantly increases the structural efficiency of corn silage in the cow’s rumen, improving starch availability and leading to an increase in daily milk yield by up to 2 L per cow. In addition, the structure of silage is beneficial to animal health, and the possibility of reducing or eliminating the addition of straw in the feed ration leads to further savings. SHREDLAGE^® technology is available in CLAAS JAGUAR forage harvesters, which, thanks to special crushing rollers, enable the achievement of the described benefits in milk production and herd health [24].

Both silages underwent preliminary tests to determine the necessary parameters for estimating the sample size for methane fermentation (inoculum to test material ratio). For this purpose, a TIN-TF200 laboratory dryer (PHOENIX Instrument, Berlin, Germany) was used, in which the silages were dried at 105 °C for 24 h, as well as a L40/11 muffle furnace (Nabertherm, Bremen, Germany), in which the samples were burned at 550 °C for 3 h [21,25].

After checking the substrate parameters, the silage was subjected to methane fermentation. The process was carried out until the daily biogas yield did not exceed 1%. The results of the substrate biogas efficiency were presented in accordance with the DIN 38 414/S8 standard [16]. For elemental analysis and digestibility testing, silages were ground in an SM200 cutting mill (Retsch, Haan, Germany) using a sieve with 2 mm openings.

The analysis of the elements was carried out using an X-ray spectrophotometer with an SDD detector in the GOLDD XRF Niton XL5 technology from Thermo Scientific (Waltham, MA, USA) (Figure 1). The XRF analyzer works on the principle of measuring fluorescent (or secondary) X-ray radiation emitted by a sample excited by a primary X-ray source. Each of the elements present in the sample produces a set of characteristic fluorescent X-ray rays, unique to each of the elements. The emitted rays are captured by the detector; then, the obtained spectra are processed by a processor, and the final result is the qualitative and quantitative composition of the sample [26].

The in vitro digestibility of NDF (neutral detergent fiber) (dNDF) was determined in a Daisy incubator (ANKOM Technology—Daisyll Incubator (Macedon, NY, USA)). The digestibility was determined by placing a feed sample in filter bags (F 57 Filter Bags), which were placed in four glass jars. Then, a buffering solution and rumen fluid collected from 3 shunted cows were added. The whole was incubated in an anaerobic environment at a temperature of about 390 °C for 24 h. Digestibility was calculated based on the loss of NDF from the bag during incubation. Digestibility (digestibility coefficient) determines which part of NDF is digested in the digestive tract of the animal. NDF digestibility (dNDF, 0/0) was determined as a percentage of the amount of the ingredient in the weighed portion (% NDF). The NDF determination before and after incubation was performed using the ANKOM 2000 apparatus.

3. Results and Discussion

This chapter presents the relationships between the silages tested. The results are presented in the form of tables and graphs. The substrate parameters were the first to be determined. Thanks to them, it was possible to determine the size of the sample necessary to carry out biogas efficiency measurements.

Table 1. Substrate parameters.

Parameter Analyzed	Unit	Maize Silage: The Traditional Way	Maize Silage: Shredlage
pH	-	3.84	3.82
Dry matter	% d.m.	39.00	40.98
Organic dry matter	% o.d.m.	95.52	95.84

below presents the parameters of the silages tested.

As indicated in Table 1, studies show that the optimal pH range for corn silage is 3.8–4.2, which promotes effective fermentation and biogas production. The pH level affects the methanogenesis process during anaerobic digestion—a pH that is too low can inhibit the activity of microorganisms. The study by Czubaszek et al. (2023) on the co-fermentation of corn silage with other substrates confirms that corn silage in this pH range promotes methane production [10]. The dry matter content in corn silage has a significant impact on biogas efficiency, because matter with a higher dry matter content promotes better quality of the anaerobic digestion process and methane production. As shown in the table, traditionally ensilaged corn silage is characterized by both lower dry matter and organic dry matter and a slightly higher pH value compared to corn silage ensilaged using the Shredlage method. Based on the above parameters, corn silage was subjected to biogas efficiency tests according to DIN 38 414/S8.

Table 2. Biogas efficiency measurement results.

			Fresh Mass		Dry Matter		Organic Dry Matter
Sample	Repetition	Methane Content (%)	Cumulative Methane (m3 Mg−1 f.m.)	Cumulative Biogas (m3 Mg−1 f.m.)	Cumulative Methane (m3 Mg−1 d.m.)	Cumulative Biogas (m3 Mg−1 d.m.)	Cumulative Methane (m3 Mg−1 o.d.m.)	Cumulative Biogas (m3 Mg−1 o.d.m.)
Maize silage: the traditional way	I	52.16	119.42	228.93	306.19	586.97	320.54	614.49
	II	52.34	119.22	227.79	305.68	584.09	320.01	611.42
	III	52.59	120.37	228.86	308.62	586.79	323.09	614.30
	Mean	52.37	119.67	228.52	306.83	585.95	321.21	613.40
	Standard deviation	0.18	0.50	0.52	1.28	1.61	1.65	1.72
Maize silage: Shredlage	I	52.14	139.54	267.61	340.54	653.08	355.34	681.46
	II	51.65	139.44	269.94	340.29	658.79	355.08	687.42
	III	51.48	134.65	261.57	328.60	638.36	342.88	666.10
	Mean	51.76	137.87	266.37	336.48	650.08	351.10	678.32
	Standard deviation	0.34	3.39	4.32	6.82	10.54	7.12	11.00

shows the measurements of cumulated methane and biogas in terms of fresh matter, dry matter, and organic dry matter.

As observed, in the sample subjected to traditional ensiling, the average methane content (52.37) was higher than in the sample ensiled using the Shredlage method (51.76). For biogas efficiency, higher levels of both cumulative biogas and methane are observed in maize silage ensiled using the Shredlage method. This tendency was observed throughout the entire scope of the conducted research. In terms of fresh mass, these values were at the level of 119.67–137.87 m³ Mg⁻¹ f.m. (cumulative methane) and 228.52–266.37 m³ Mg⁻¹ f.m. (cumulative biogas). For dry mass, these dependencies were 306.83–336.48 m³ Mg⁻¹ d.m. (cumulative methane) and 585.95–650.08 m³ Mg⁻¹ d.m. (cumulative biogas). The range of biogas yield results in terms of organic dry matter was between 321.21–351.10 m³ Mg⁻¹ o.d.m. (cumulative methane) and 613.40–678.32 m³ Mg⁻¹ o.d.m. (cumulative biogas). The use of long cutting and intensive crushing processes for corn grains and stalks improves digestibility, which leads to higher biogas production. In studies such as those conducted by Vitez et al. (2021), the results indicate the better efficiency of Shredlage in biogas production [27]. In the research of Jančík et al. (2022), it was shown that the use of Shredlage technology significantly improves the digestibility of corn silage, which directly translates into increased biogas efficiency. The authors pointed out that intensive shredding of corn plants in the Shredlage process results in a reduction in the content of neutral detergent fiber (NDF) and acid detergent fiber (ADF), which makes it easier for microorganisms to access nutrients. Thanks to this, the methane fermentation process is more efficient, generating higher methane and biogas yields compared to traditional ensiling methods. These results confirm the potential of Shredlage technology as an innovative approach to optimizing biogas production from corn biomass, indicating its advantage in installations focused on energy efficiency [28].

Based on the measurements, the graphs on the daily biogas and methane yield were made (Figure 2 and Figure 3).

As shown in the graphs, the average fermentation time was similar. The graphs of daily biogas efficiency show what the daily production looked like and at what point the process collapsed. In Figure 3, it can be seen that the biogas efficiency initially increased, and then there was a decrease in productivity. In the case of corn silage ensiled in a traditional way (Figure 2), an initial slight decrease in biogas productivity was observed, and then, as in the case of corn ensiled with the Shredlage method, a gradual decrease in value occurred.

Although the results indicate the superiority of the Shredlage method in terms of biogas production efficiency, certain limitations affect its practical application. Firstly, the Shredlage technology requires specialized equipment, such as SHREDLAGE^® rollers, which entails additional costs for purchase and maintenance. Vitez et al. (2021) note that the greater particle length in the Shredlage method may hinder silage compaction, increasing the risk of heating and complicating the homogenization process in biogas plants, ultimately leading to higher operational costs [27].

Nevzorova and Kutcherov (2019) note that the lack of qualified specialists and companies specializing in the design and operation of biogas plants constitutes a significant barrier to the adoption of new technologies in the biogas sector. Additionally, they emphasize that high investment costs and the lack of political support hinder the implementation of technological innovations in many regions [29].

The choice of ensiling methods often depends on the economic and technological conditions of a given farm or biogas plant. Ensiling is recognized as a promising technique for storing wet biomass before anaerobic digestion, ensuring the preservation of its biochemical potential. Franco et al. (2016) emphasize that proper preservation requires low silage moisture content, high water-soluble carbohydrate levels, and low buffering capacity, which help to maintain the quality of the silage. Moreover, practices such as high packing density and reduced particle size are crucial for minimizing energy losses during storage. However, despite its potential to boost methane yield, ensiling can involve significant challenges. Improper management may lead to organic matter losses of up to 40 %, especially due to respiration, secondary fermentation, and aerobic spoilage. These factors, along with the cost of specialized equipment and additional additives, often influence the decision to adopt traditional ensiling methods or more advanced techniques. The study also highlights that while ensiling can enhance methane potential under optimal conditions, the lack of consistent management practices and region-specific constraints often limits its broader application in biogas production [30].

Simultaneously with the fermentation process, the silages were subjected to elemental analysis.

Table 3. Elemental analysis results of corn silage.

Parameter Analyzed	Unit	Maize silage: The Traditional Way	Maize Silage: Shredlage
Ag	mg kg−1 d.m.	0.176	0.175
Al	mg kg−1 d.m.	82	44
Au	mg kg−1 d.m.	<0.137	<0.139
Ba	mg kg−1 d.m.	<1.198	<1.296
Bi	mg kg−1 d.m.	<0.059	0.071
Ca	mg kg−1 d.m.	1 164	1 147
Cd	mg kg−1 d.m.	0.328	0.232
Cl	mg kg−1 d.m.	2 560	2 840
Co	mg kg−1 d.m.	<0.564	<0.558
Cr	mg kg−1 d.m.	0.508	0.528
Cu	mg kg−1 d.m.	3	2
Fe	mg kg−1 d.m.	57	51
Hg	mg kg−1 d.m.	<0.086	<0.089
K	mg kg−1 d.m.	12 908	13 790
Mg	mg kg−1 d.m.	1 733	1 290
Mn	mg kg−1 d.m.	39	11
Mo	mg kg−1 d.m.	0.115	0.189
Nb	mg kg−1 d.m.	<0.043	0.045
Ni	mg kg−1 d.m.	<0.211	<220
P	mg kg−1 d.m.	1 866	1480
Pb	mg kg−1 d.m.	0.204	0.161
Pd	mg kg−1 d.m.	0.108	0.058
Rb	mg kg−1 d.m.	3	1
S	mg kg−1 d.m.	616	549
Sb	mg kg−1 d.m.	1	0.505
Se	mg kg−1 d.m.	<0.037	<0.038
Si	mg kg−1 d.m.	2 390	2 423
Sn	mg kg−1 d.m.	0.232	<0.180
Sr	mg kg−1 d.m.	3	0
Th	mg kg−1 d.m.	0.155	<0.060
Ti	mg kg−1 d.m.	5	4
U	mg kg−1 d.m.	<0.065	<0.086
V	mg kg−1 d.m.	<0.283	<0.182
W	mg kg−1 d.m.	<0.439	<0.511
Y	mg kg−1 d.m.	<0.032	<0.031
Zn	mg kg−1 d.m.	19	15
Zr	mg kg−1 d.m.	0.417	0.315

below shows the results of the analysis of elements present in both silages tested.

The analysis of the composition of elements in corn silage was carried out, comparing two methods of its preparation, namely the traditional method and the Shredlage method. The tests were carried out in units of mg kg⁻¹ dry matter (d.m.). In the case of silver (Ag), the content was similar in both samples, amounting to 0.176 mg kg⁻¹ in traditional silage and 0.175 mg kg⁻¹ in Shredlage, respectively. Aluminum (Al) showed a higher content in traditional silage (82 mg kg⁻¹) compared to 44 mg kg⁻¹ in Shredlage. The content of calcium (Ca) was similar, with values of 1164 mg kg⁻¹ in the traditional method and 1147 mg kg⁻¹ in the Shredlage method. In the case of potassium (K), Shredlage silage had a significantly higher content (13790 mg kg⁻¹) than the traditional method (12908 mg kg⁻¹). Magnesium (Mg) was present in significantly higher concentrations in traditional silage (1733 mg kg⁻¹) than in Shredlage (1290 mg kg⁻¹). Phosphorus (P) content was also higher in traditional silage (1866 mg kg⁻¹) compared to 1480 mg kg⁻¹ in Shredlage. Similarly, zinc (Zn) was present in higher amounts in traditional silage (19 mg kg⁻¹) than in Shredlage (15 mg kg⁻¹). When analyzing trace elements, it was noticed that most of them were present in low concentrations. Cadmium (Cd) was present in higher amounts in traditional silage (0.328 mg kg⁻¹) compared to 0.232 mg kg⁻¹ in Shredlage. Iron (Fe) also showed a higher concentration in traditional silage (57 mg kg⁻¹) than in Shredlage (51 mg kg⁻¹). The selenium (Se) content in both samples was below the detection limit (<0.037 mg kg⁻¹ and <0.038 mg kg⁻¹). Conclusions from the analysis indicate that traditional corn silage is usually characterized by higher concentrations of some minerals, such as aluminum, magnesium, phosphorus, and zinc. In turn, Shredlage silage had a higher potassium content, which may be important for the animal diet. The choice of silage method may affect the mineral profile, which should be taken into account in animal nutrition.

In addition to elemental analysis, high-temperature combustion tests were conducted. This test allows for determining the percentage share of C and N elements. In the fermentation process, it is important to maintain the appropriate proportion between the content of carbon and nitrogen C/N. If this ratio is too high (too much C and too little N), the carbon may not be completely transformed, which prevents the possible methane potential from being achieved. With an excess of nitrogen, ammonia may be formed, which, even in small concentrations, leads to the inhibition of bacterial growth. The fermentation process proceeds correctly if the C/N ratio is within the range of 10–30.

Table 4. High temperature combustion results.

	C/N Averaged	Averaged Organic Dry Matter (%)	Standard Deviation	N (% f.m.)	C (% f.m.)
Maize silage: the traditional way	35.05	93.33	0.235	1.285	45.043
Maize silage: Shredlage	34.88	93.51	0.348	1.310	45.699

below shows high temperature combustion results.

The results presented in Table 4 present the analysis of two types of corn silage (traditional and Shredlage) in terms of carbon to nitrogen ratio (C/N), dry organic matter content, and carbon and nitrogen content in dry matter. These parameters are of great importance in the context of the biogas production process, because they affect the rate and efficiency of organic matter decomposition by microorganisms in the anaerobic fermentation process. The carbon to nitrogen ratio (C/N) is one of the key indicators for assessing the quality of the raw material in the context of methane fermentation, including in relation to any biological processing technology, including composting [31]. In anaerobic digestion, microorganisms use nitrogen for growth and carbon as a source of energy. The ideal C/N ratio for an efficient methane fermentation process is in the range of 20–30, but for plant materials such as corn silage, higher C/N values (in the range of 30–40) are common. For traditional silage, the C/N ratio is 35.05, and for Shredlage silage it is 34.88, which means that the C/N level is very similar in both samples. Although both silages have a relatively high C/N ratio, these values are in the upper range, which may suggest that the digestion process may be somewhat slower because the microorganisms will have to decompose the raw materials for a longer period of time to achieve equilibrium in the decomposition of carbon and nitrogen [32]. The organic dry matter content of both silage types is very similar, with a slightly higher value in Shredlage silage (93.51%), compared to traditional silage (93.33%). The higher dry matter content may suggest that Shredlage silage has a slightly higher concentration of organic components, which may affect the higher efficiency of the methane fermentation process, especially when it comes to the use of carbon and nitrogen by microorganisms. A high dry matter content also promotes greater biogas production, because the fermentation process requires less water and more organic matter is available for conversion into biogas [33]. The nitrogen content in dry matter in Shredlage silage (1.310%) is slightly higher than in traditional silage (1.285%). Nitrogen is a key element for fermenting microorganisms, as it supports their growth. The higher nitrogen content in Shredlage can promote better development of microorganisms in the initial stages of fermentation, which can translate into faster biogas production, especially in the so-called initial fermentation phase, when microorganisms intensively decompose organic matter. The carbon content in both types of silage is very similar, with a slight advantage in Shredlage silage (45.699%) compared to traditional silage (45.043%). All these results suggest that Shredlage silage may be slightly more efficient in the long-term biogas process, due to its higher dry matter and carbon content, which may lead to higher biogas production. However, both silages show the potential for efficient biogas production, and their selection should depend on the specific requirements of the biogas installation and the expected efficiency of the fermentation process.

The next stage of the study was to test the digestibility of both silages. The study was conducted on samples ground to a size of 2 mm, dried in a laboratory dryer for 24 h at a temperature of 40 °C. The digestibility study was conducted after 24 and 48 h.

Table 5. Results of corn silage digestibility measurements.

Sample	Maize Silage: The Traditional Way	Maize Silage: Shredlage
Dry matter 105 °C (%)	94.39	94.54
Raw ash (% FM)	4.79	4.05
NDF (% FM)	38.91	31.52
NDF (digestibility NDF, 24 h) (Digestibility index NDF(after24h)) (% NDF)	41.60	41.82
dNDF (digestible NDF, 24 h) (% FM)	16.19	13.18
NDFD (digestibility NDF, 48 h) (Digestibility index NDF(after48h)) (% NDF)	47.48	45.46
dNDF (digestible NDF, 48 h) (% FM)	18.47	14.33

presents the corn silage digestibility results.

The results of the analysis of two types of corn silage, traditional and Shredlage, allow for a detailed assessment of their potential in the context of biogas production efficiency, as well as a qualitative assessment of the material in terms of fermentation processes. This study compares the basic quality parameters of both types of silage, such as the content of dry matter, raw ash, NDF (neutral detergent fiber), NDF digestibility, and NDF digestibility at different fermentation times (24 and 48 h). These results can provide an important basis for determining which type of silage is more suitable for use in biogas plants. In the analyzed samples of corn silage, both traditional and Shredlage, the results indicate differences in chemical composition and digestibility. Both samples were characterized by a high content of dry matter, with a minimal difference: traditional silage contained 94.39%, and Shredlage contained 94.54%. This means that both forms of silage have very similar levels of dry matter, indicating their comparable concentration of solids. The differences appear in the raw ash content, where traditional silage showed a higher value (4.79%) compared to Shredlage silage (4.05%). Raw ash is an indicator of the presence of minerals, and the lower amount of ash in Shredlage may suggest a higher concentration of organic nutrients. In terms of NDF (neutral detergent fiber), traditional silage showed a higher content (38.9%) compared to Shredlage (31.52%). NDF is a measure of plant fiber that is not digested by microorganisms in the digestive tract, and the higher NDF content in traditional silage may suggest that this form contains more difficult-to-digest fibers. Looking at NDF digestibility, both types of silage have similar results. In the case of NDF digestibility at 24 h (NDFD), the results are 41.60% for traditional silage and 41.82% for Shredlage, respectively, which is a minimal difference. However, considering NDF digestibility at 48 h, traditional silage had a higher value (47.48%), while Shredlage reached 45.46%, which may suggest that the fermentation process in traditional silage is slightly more efficient in breaking down the fibers after a longer period of time. A comparative analysis of both types of corn silage indicates that Shredlage silage has a lower NDF content, which makes it more “crushed” and digestible by microorganisms, which may promote a faster fermentation process. However, in the context of a long-term fermentation process, traditional corn silage shows a slightly higher NDF digestibility, which may lead to higher biogas production after 48 h of fermentation. Depending on the specifics of the biogas plant process, the choice between these two types of silage will depend on the operational goal: Shredlage may be preferred in plants aimed at faster biogas production, while traditional silage may be more effective in long-term processes leading to higher total biogas production. The results presented in Table 5 also confirm that Shredlage technology increases the digestibility of silage components, which is consistent with the research of Jančík et al. (2022). The authors indicated that silages processed with Shredlage technology are characterized by the higher digestibility of dry matter, organic matter, and NDF compared to conventional methods. In particular, Shredlage technology increases the availability of neutral detergent fibers (NDFs) and starch for microorganisms, which accelerates the fermentation process in the rumen. These results emphasize the importance of precise silage-processing technologies in optimizing its efficiency as a substrate in biogas plants and in cattle feeding [34].

The results presented in Table 5 indicate that the Shredlage ensiling method leads to the improvement of some parameters of silage digestibility, which may be important both for the efficiency of animal feeding and fermentation processes in biogas plants. Similar conclusions were drawn in the studies by Ferraretto and Shaver (2012), which showed that the Shredlage technology increases the availability of starch and improves the digestibility of neutral detergent fibers (NDFs), which has a positive effect on the lactation performance of dairy cows. The better fragmentation of corn stalks and grains in this technology promotes the faster decomposition of nutrients by microorganisms, which may also translate into higher efficiency of biogas production. These results confirm that the Shredlage method may be particularly beneficial in processes requiring fast fermentation and high substrate digestibility in plants and in cattle feeding [35].

Finally, the samples were subjected to fiber analysis tests (

Table 6. Fiber analysis.

Sample	ADF (%)	Average (%)	Standard Deviation	NDF (%)	Average (%)	Standard Deviation	Crude Fiber (%)	Average (%)	Standard Deviation
Maize silage:the traditional way	22.53	22.339	0.543	41.64	41.182	0.507	18.3	18.57	0.4639
	21.73			40.64			19.1
	22.76			41.27			18.3
Maize silage: Shredlage	18.47	18.582	0.098	35.30	35.227	0.088	15.2	15.39	0.4536
	18.64			35.13			15.9
	18.64			35.26			15.1

).

In the context of biogas production, the analysis of the results regarding the content of ADF, NDF, and crude fiber in corn silage, both in the traditional form and in the form of Shredlage, can be related to the results of studies published in the scientific literature in recent years. They show that different properties of plant fibers, such as ADF (acid detergent fiber), NDF (neutral detergent fiber), and crude fiber, have a significant effect on the efficiency of the anaerobic fermentation process and biogas production. ADF content: in traditional corn silage, the average ADF content is 22.33%, which indicates a higher level of lignocellulosic fibers, which are more difficult to decompose by microorganisms responsible for fermentation. Higher ADF content may limit the availability of organic substances for conversion into biogas, which may result in lower efficiency in the methane fermentation process. In the case of Shredlage silage, the ADF content is significantly lower, at 18.58%, which promotes the easier decomposition of the fibers and can lead to higher biogas yields, as less difficult-to-digest material allows for the faster conversion of organic matter. NDF content: In traditional silage, the NDF content is 41.18%, indicating a higher level of structural fibers. Such fibers can hinder the fermentation process, reducing the amount of substrate available for biogas production. Shredlage silage, on the other hand, contains an average of 35.2 3% NDF, which means fewer difficult-to-decompose structural fibers. The lower NDF content in Shredlage silage makes it easier for microorganisms to break down organic matter, contributing to higher biogas yields. Crude fiber content: In traditional silage, the average crude fiber content is 18.57%, which can also hinder fermentation, because the crude fibers, which are less accessible to microorganisms, slow down the biogas production process. In the case of Shredlage silage, the crude fiber content is 15.39%, which in turn indicates a smaller amount of difficult-to-digest ingredients. This limits enzymatic processes to a lesser extent, which allows for the faster decomposition of organic matter and a higher efficiency of biogas production. In summary, corn silage prepared by the Shredlage method shows more favorable parameters for the methane fermentation process compared to traditional corn silage, mainly due to the lower content of ADF, NDF, and crude fiber, which promotes the easier decomposition of organic matter and higher biogas efficiency.

The results presented in the article, concerning the influence of corn ensiling methods on biogas efficiency, emphasize the significance of the applied Shredlage technologies in the optimization of anaerobic digestion processes. The studies compared the traditional method and the Shredlage technology, indicating its advantage in terms of biogas and methane yields.

The research showed that Shredlage silage was characterized by higher biogas and methane yields in terms of dry organic matter (678.32 m³ of biogas and 351.10 m³ of methane per ton of dry organic matter). These results are consistent with the analyses presented in the literature, which indicate that the intensive shredding of plant material increases the availability of nutrients for fermentative microorganisms [36,37,38]. The use of Shredlage technology enables a more effective breakdown of the lignocellulosic fiber structure, which accelerates the fermentation process and increases biogas yield.

The elemental analysis revealed differences in potassium, phosphorus, magnesium, and zinc content between traditional and Shredlage silages. The high potassium content in Shredlage silage (13,790 mg/kg) may support the growth of fermentation microorganisms in the initial stages of the process, which is consistent with previous studies indicating the importance of macro elements in biogas processes conducted by Sun et al. 2021 and Sun et al. 2022 [39,40].

Shredlage silage was characterized by a lower content of neutral and acid detergent fibers (NDF: 35.23%; ADF: 18.58%) compared to the traditional method, which is an important factor increasing the digestibility of the material. These results are in line with studies that emphasize that lower levels of fermentation-inhibiting fibers lead to higher biogas efficiency [37,38,40].

The organic dry matter content was similar in both silages (Shredlage: 93.51%; traditional: 93.33%), indicating a comparable concentration of organic components. However, the lower NDF and ADF content in Shredlage supported the faster decomposition of organic matter, which translates into higher biogas yield in a short time. These results are in line with other studies that indicate the benefits of the structural modification of biomass [36,38].

The results of other scientists’ research have confirmed that various ensiling methods, including the use of chemical or biological additives and the optimization of fermentation conditions, can significantly affect the quality of the biogas process. Sun et al. (2021) and Larsen’s (2024) research have shown that the appropriate water content and the use of ensiling additives improve biogas efficiency by regulating pH and increasing the availability of carbohydrates [37,39]. The use of the Shredlage method may have a positive impact on the use of ensiling additives through their better access to more fragmented biomass, leading to a more efficient ensiling process.

The results indicate that the Shredlage method is more suitable for biogas plants aimed at rapid biogas yield. However, traditional silage may be more advantageous in long-term fermentation processes, providing greater substrate stability. In the future, it is worth investigating the impact of these methods on other economic and environmental parameters, such as technology cost or greenhouse gas emissions. In summary, the method of silage preparation is crucial for biogas yield. The selection of the optimal technology should be adapted to the specifics of a given biogas plant and its operational goals.

4. Conclusions

The presented research for the first time broadly covers not only the changes in the digestibility of maize silage obtained by the new Shredlage method, but also analyses its suitability as a substrate for biogas plants—in comparison to silage obtained by the traditional method.

The study demonstrated that the method of corn silage preparation significantly affects the efficiency of the biogas production process. Silage prepared using the Shredlage method exhibited higher biogas and methane yields compared to the traditional silage method. Higher values of cumulative biogas (678.32 m³ Mg o.d.m.) and methane (351.10 m³/Mg o.d.m.) indicate the superior fermentation properties of this method. The lower content of neutral detergent fiber (NDF), acid detergent fiber (ADF), and crude fiber in Shredlage silage contributed to higher digestibility over a shorter period, as confirmed by higher fiber digestibility values after 24 and 48 h of fermentation.

The elemental analysis revealed that Shredlage silage contained a higher amount of potassium (13,790 mg kg⁻¹ d.m.) but lower levels of phosphorus, magnesium, and zinc compared to traditional silage. These differences may have implications for both animal nutrition and the quality of the biogas produced. Both silage types showed similar carbon-to-nitrogen (C/N) ratios of approximately 35, which are within the suitable range for methane fermentation but may result in slower fermentation rates. The slightly higher nitrogen content in Shredlage silage (1.310% d.m.) may have supported the initial development of microorganisms responsible for the fermentation process.

Shredlage silage proved to be more suitable for biogas plants focused on rapid biogas production due to its higher digestibility and lower content of hard-to-degrade fibers. Conversely, traditional silage, with its higher NDF and ADF content, may be more effective in long-term processes, providing greater substrate stability. The study findings indicate that the Shredlage method could be more efficient for biogas plants aiming to enhance energy yield and improve the economic performance of the fermentation process. Selecting the appropriate silage preparation method should consider the specific requirements of the biogas plant and the availability of technology.

Future research should focus on several key areas. Firstly, the long-term impacts of using Shredlage and traditional silage on soil health need to be assessed, particularly in terms of nutrient cycling, organic matter preservation, and microbial dynamics. Secondly, the performance of these ensiling methods should be compared under different climatic conditions to determine their efficiency and adaptability. Additionally, the economic viability of implementing Shredlage technology in small-scale biogas plants requires further investigation to understand its potential benefits and challenges. Finally, environmental impact assessments should be conducted to evaluate the lifecycle emissions and sustainability of each method. Addressing these gaps will provide a more comprehensive understanding of the implications of silage preparation techniques for biogas production and sustainability.