Next Article in Journal
Partial Organic Substitution Improves Soil Quality and Increases Latex Yield in Rubber Plantations
Previous Article in Journal
GIA-YOLO: A Target Detection Method for Nectarine Picking Robots in Facility Orchards
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Agronomy
Volume 15
Issue 8
10.3390/agronomy15081935
agronomy-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Agronomic Potential of Compost from Unconventional Organic Waste Sources and the Effect of Trichoderma harzianum T-22 on Durum Wheat’s Early Development

by
Pilar Mañas
* and
Jorge De las Heras
Higher Technical School of Agricultural and Forestry Engineering and Biotechnology, University of Castilla-La Mancha, Avenida de España s/n, 02071 Albacete, Spain
*
Author to whom correspondence should be addressed.
Agronomy 2025, 15(8), 1935; https://doi.org/10.3390/agronomy15081935
Submission received: 23 June 2025 / Revised: 23 July 2025 / Accepted: 8 August 2025 / Published: 11 August 2025
(This article belongs to the Section Agricultural Biosystem and Biological Engineering)
Browse Figures
Versions Notes

Abstract

Composting organic waste enhances soil fertility, supports plant growth, and offers a sustainable waste management strategy. This study evaluated the agronomic potential of three compost types derived from unconventional sources: (i) sewage sludge, (ii) slaughterhouse animal by-products (ABPs), and (iii) cheese industry waste. The impact of Trichoderma harzianum strain T-22 inoculation was also assessed in relation to the early development of durum wheat (Triticum turgidum subsp. durum) under greenhouse conditions. Compost type significantly influenced plant emergence and growth, with sewage sludge-based compost showing the best performance. T. harzianum T-22 inoculation produced mixed results; it improved growth in specific combinations (CS-1/3 and CA-1/4) but inhibited it in others (particularly CW-based composts). These findings underscore the importance of compost source selection and highlight that microbial inoculation effects are substrate-dependent. This work supports sustainable composting practices and fungal waste valorization to optimize plant growth in sustainable agriculture.

1. Introduction

1.1. Regulation and Classification of Animal By-Products (ABPs)

In Regulation (EC) No 1069/2009 of the European Parliament and of the Council of 21 October 2009, the health rules concerning animal by-products not intended for human consumption (ABPs) are established. This regulation classifies ABPs into three categories based on their potential health risks. Slaughterhouse-derived waste falls into different categories depending on its origin and associated risk. Category 1 includes high-risk materials, such as parts of animals suspected of being infected with transmissible spongiform encephalopathies (TSEs) or animals treated with prohibited substances; Category 2 comprises materials posing a potential health risk, such as carcasses of animals that did not pass ante-mortem inspection or waste contaminated with hazardous pathogens; and Category 3 encompasses low-risk materials, including parts of slaughtered animals that were fit for human consumption but not intended for it, such as hides, horns, bristles, feathers, blood, raw milk, hatchery by-products, and cracked eggs.

1.2. Utilization of Animal By-Products and Composting

Among these, Category 3 waste represents the largest proportion of ABPs generated in slaughterhouses and can be used to produce processed animal proteins, fats, biogas, and other derived products.
The proper use of animal by-products generated along the meat supply chain can improve the environmental performance of meat. Animal by-products can be used to produce a variety of products, such as biofuel, pet feed, and biogas, thus reducing the need for virgin raw materials [1].
Several studies suggest that composting animal by-products not intended for human consumption can effectively reduce pathogens and stabilize waste, achieving sanitation standards and producing nutrient-rich compost, although challenges, such as temperature control, nutrient loss, and the need for validation against thermoresistant viruses, remain [2,3,4,5].

1.3. Food Industry Waste: Focus on the Cheese Industry

The diverse types of waste generated by various sectors of the food industry can be quantified based on each sector’s respective production level [6]. In this sense, another waste stream related to the food industry that may pose a challenge in terms of management is cheese industry waste, particularly saline wastewater, which poses management challenges due to its high salinity, environmental impacts, and disposal inefficiencies, necessitating a focus on salt removal and recovery [7]. Whey retains over half of the total solids found in whole milk, including whey proteins, which constitute approximately 20% of the total protein content, as well as most of the lactose, water-soluble vitamins, and minerals. As a result, whey is recognized as a valuable by-product with diverse applications in various areas.
Composting, particularly with the addition of microbial inoculants or bulking agents, can effectively convert organic waste, including cheese production residues, into high-quality fertilizers while addressing challenges like nutrient loss, odor, and emissions [8].

1.4. Sewage Sludge Management in Europe and Spain

On the other hand, the management of sewage sludge in Spain and Europe is governed by various regulations, including Directive 86/278/EEC on the protection of the environment when using sewage sludge in agriculture and Regulation (EU) 2019/1009 on fertilizing products. However, challenges persist due to the fragmentation and aging of legislation, as well as disparities in sludge production and treatment among countries [9]. The need for advanced technologies to minimize contaminants and enhance resource recovery is increasingly recognized. Although the application of sludge in agriculture and incineration remains a common practice, concerns regarding pollutants, including heavy metals and microplastics, continue to be a topic of debate [10], prompting discussions of potential regulatory updates at both European and national levels [11]. Sewage sludge management in Spain and Europe involves sludge minimization, full stabilization, hygienization, and on-site incineration [12].

1.5. Environmental Impact and Risks of Improper Waste Management

Any of the three aforementioned waste types (ABPs, sewage sludge, or waste from the cheese industry), if not properly managed, can cause serious environmental issues and, consequently, pose indirect risks to human health through disruptions in the food chain. Their improper disposal can lead to contamination of both agricultural soil and irrigation water.
To mitigate all of these negative environmental effects, one of the best solutions is composting these wastes, although, so far, composting of solid organic waste has not been widely used [13].

1.6. Composting: Process, Benefits, and Limitations

Composting is a controlled biological process that transforms degradable organic materials and waste into stable, nutrient-rich products through microbial activity. Although widely recognized as an effective waste management strategy, composting presents certain limitations that hinder its broader application and efficiency. These challenges include the persistence of pathogens, suboptimal nutrient composition, prolonged composting and mineralization periods, and the generation of undesirable odors [14].

1.7. Biological Control and Potential of the Trichoderma Genus

Moreover, if microorganisms with proven beneficial effects are added, the final product as a fertilizer could be a viable and environmentally sustainable solution. In this sense, biological control of phytopathogenic fungi has gained importance, primarily focusing on the selection of soil microorganisms with antagonistic properties against plant disease-causing agents.
The use of Trichoderma as a biological control agent is attributed to the synergistic effects of its biocontrol mechanisms [15], as well as other advantages, such as ease of isolation and cultivation, rapid growth on a wide range of substrates [16], and its non-toxic nature to higher plants [17].
Species of the genus Trichoderma are the most widely used antagonistic microorganisms for controlling plant diseases caused by phytopathogens. Trichoderma has been studied for over 70 years, but only recently have strains of this microorganism gained significant commercial value and proposed as eco-friendly alternatives against pathogens of crops [18].

1.8. Biological Characteristics of Trichoderma

The genus Trichoderma comprises a group of fungi commonly isolated from soil. Thanks to molecular and biochemical studies, up to more than 100 species have been characterized in this genera [18]. It is an anamorphic, facultative aerobic, heterotrophic filamentous fungus with a chitin-based cell wall, rapid growth, and the ability to utilize a wide variety of carbon sources, including cellulose, chitin, pectin, and starch. Trichoderma grows within a temperature range of 25 °C to 30 °C. Its strains thrive efficiently in both liquid and solid media, exhibit relative tolerance to low humidity, and tend to grow in acidic soils. Trichoderma utilizes nutrients from plant roots in the rhizosphere, establishing interactions with the surrounding environment and acting as a biocontrol agent against fungal pathogens. The targeted pathogens include Rhizoctonia, Rhizopus, Endothia, Helminthosporium, Armillaria, Botrytis, Fusarium, and Pythium [18].

1.9. Factors Affecting Trichoderma Growth

Trichoderma species promote plant growth by producing phytohormones and enzymes like ACC deaminase, enhancing nutrient uptake and stress resistance [15,19,20]. Key factors affecting Trichoderma growth are the following:
1. Phototrophy: Most Trichoderma species are photosensitive, showing increased sporulation when exposed to light [21]. However, alternating periods of light and darkness promote fungal colonization on various solid substrates [22].
2. Sporulation: Trichoderma sporulates readily on many natural and artificial substrates in a concentric circular pattern in response to alternating daylight and darkness, with conidia production occurring during light exposure [23].
3. Germination: To germinate in different culture media, Trichoderma employs enzymes, such as amylases [24], α-glucosidases, and endo- and exocellulases, which hydrolyze simple sugars to initiate germination [25].
4. Salinity: Trichoderma spp. can enhance plant growth under saline conditions by increasing antioxidant enzyme activity, which helps mitigate oxidative stress in plants [26,27].
5. pH: Trichoderma exhibits growth across a relatively wide pH range, from 2.0 to 9.0, with an optimal pH between 4.0 and 7.0. Processes like germination are affected by nutrient scarcity and pH levels exceeding 9.0. The effectiveness of Trichoderma as a biocontrol agent is significantly influenced by pH, with better performance observed in acidic to neutral conditions [19].

1.10. Mechanisms of Trichoderma in Biological Control

As a biological control agent, Trichoderma exerts biological control through three primary mechanisms: (i) direct competition for space and nutrients; (ii) production of antibiotic metabolites, which may be volatile or non-volatile; and (iii) direct parasitism of phytopathogenic fungi.
Studies have shown that Trichoderma produces hydrolytic enzymes (cellulases) as biocontrol factors, which degrade the cellulose in the cell walls of Oomycete microorganisms in vitro [28]. The diverse secondary metabolites of Trichoderma have potential applications in agriculture, such as their use as biopesticides, and in other industries as novel antibiotics [29,30]. Additionally, it synthesizes glucanases and chitinases that catalyze the hydrolysis of chitin and β-1,3-glucans in the cell walls of Deuteromycete fungi [31]. Furthermore, Trichoderma and Gliocladium species produce common compounds that target the cell wall and membrane of other fungi [32], including Alamethicin, Trichotoxin, Suzukacillin, Gliovirin, Gliodeliquescin, and, primarily, Gliotoxin.

1.11. Application of Trichoderma in Compost and Agronomic Evaluation

The incorporation of Trichoderma as a biological control agent in compost can be particularly beneficial for enhancing the quality of this substrate by producing a phytosanitary compost with added value [19], increasing crop resistance to phytopathogens, and reducing or eliminating the need for expensive and environmentally harmful control measures [20].

1.12. Study Objective and Experimental Approach

In this study, the composting process was investigated for its potential to utilize non-conventional organic materials whose waste management is challenging due to their specific characteristics and origin. The aim of this study was to assess the early growth response of durum wheat (Triticum turgidum subsp. durum) to three types of compost derived from unconventional organic waste sources: sewage sludge, animal by-products (ABPs), and cheese industry waste. Additionally, we examined the interactive effects of Trichoderma harzianum strain T-22 inoculation on plant emergence and development.
The novelty of this study lies in the combined assessment of these underutilized waste-derived composts with a plant-growth-promoting microorganism, Trichoderma harzianum T-22, and their effect on the early growth stages of durum wheat (Triticum turgidum subsp. durum). Our approach integrates microbial inoculation, agronomic performance, and compost quality parameters into a unified experimental design, offering a contribution to circular bioeconomy practices aligned with EU sustainable agriculture goals.

2. Materials and Methods

2.1. Experimental Design

An experimental design was developed to evaluate the early growth response of durum wheat (Triticum turgidum subsp. durum, cv. Vitron) cultivated in pots under greenhouse conditions. The base substrate consisted of unfertilized Sphagnum peat, to which different composts were added as organic amendments.
Three types of compost were tested (Figure 1a–c), each produced from non-conventional organic residues:
  • Sewage sludge (CS): Sewage sludge was collected from the Alcázar de San Juan wastewater treatment plant (WWTP), which serves ~29,000 inhabitants in central Spain (39°24′ N, 3°12′ W) at an altitude of 644 m. This facility employs an activated sludge process, a biological wastewater treatment method in which air or oxygen is introduced into the sewage to promote the formation of biological floc, thereby reducing the organic load. This WWTP receives mixed wastewater (70% domestic, 30% industrial). The sludge was composted with shredded cereal straw as a carbon source.
  • Cheese industry waste (CW): Whey, rich in fats, proteins, and lactose, was mainly mixed with unshredded cereal straw. This residue, due to its high organic load, was composted to reduce its environmental impact. The compost obtained from the process exhibited a humidity content of 85.5% and a total organic matter percentage of 88.6%. The pH, measured from a 1:10 extract, was 5.76. Regarding the presence of heavy metals, total cadmium and mercury were both below the detection limits (<0.10 mg kg−1 and <0.20 mg kg−1, respectively). Total copper and chrome contents were 5.91 mg kg−1 and 7.10 mg kg−1, respectively, while nickel and lead were present at 2.4 mg kg−1 and 1.1 mg kg−1. Total zinc was also below the detection limit (<50 mg kg−1). In terms of nutrients, compost contained 1.69% phosphorus and 7.77% nitrogen, as determined using the Dumas method.
  • Animal by-products (CA): By-products consisted of slaughterhouse blood pre-treated with iron sulfate to enhance organic matter degradation and reduce odors. This waste was composted with shredded straw and a portion of sewage sludge from the same WWTP to balance the C/N ratio. This composition makes it highly biodegradable. Additionally, ABP waste has, in general, a high microbial load and may contain pathogenic microorganisms, such as Salmonella spp., Escherichia coli, and Clostridium spp., requiring sanitization treatments before agricultural use. In general, the composition of these residues varies depending on the specific by-product (blood, viscera, skins, bones), influencing moisture and fat content, which affects stability and necessitates mixing with other waste materials to optimize the composting process. A significant challenge in handling this waste is its potential for odor generation due to the decomposition of proteins and lipids, leading to the release of malodorous volatile compounds, such as amines and sulfides. Therefore, implementing mitigation strategies is essential for proper management. Despite these challenges, ABP waste has high fertilizer potential, as it contains essential macronutrients, such as nitrogen (N), phosphorus (P), and potassium (K), as well as micronutrients necessary for soil fertilization. To ensure their safety and feasibility for agricultural applications, these residues must undergo appropriate treatment processes, such as composting or anaerobic digestion, to achieve stabilization and sanitization.
All composts were produced under controlled conditions, with periodic manual turning to promote aeration. Moisture and temperature were regularly monitored (Figure 2).
Each compost type was then mixed with peat at two volume ratios:
▪
1:3 (v/v) (25% compost, 75% peat).
▪
1:2 (v/v) (33% compost, 67% peat).
This resulted in six compost mixtures:
  • M1: 1/4 CS + 3/4 peat.
  • M4: 1/3 CS + 2/3 peat.
  • M2: 1/4 CW + 3/4 peat.
  • M5: 1/3 CW + 2/3 peat.
  • M3: 1/4 CA + 3/4 peat.
  • M6: 1/3 CA + 2/3 peat.
A greenhouse experiment was conducted using 3.5 L pots for the non-inoculated treatments and 2 L pots for the Trichoderma-inoculated treatments. For inoculation, Trichoderma harzianum strain T-22 was added at sowing (3 g/pot) and later applied through irrigation (1.5 g/L) at 28 and 42 DAS (Figure 2).
For the experimental design, two parallel test lines (with or without the inoculation of Trichoderma harzianum strain T-22) were conducted using the same type of durum wheat crop and the three compost types (CS, CW, and CA), each applied in two different volume/volume (v/v) proportions (a:1/4 and b:1/3) relative to the unfertilized Sphagnum peat substrate.
Durum wheat was sown at 10 seeds per pot (Figure 1d). Control pots with peat only were also included. Irrigation, temperature control, and phenological development (Zadoks scale) were monitored throughout the experiment.
The mixtures were distributed in pots on the bench inside of the greenhouse (as shown in Figure 1e).
The first test line (without Trichoderma inoculation) was conducted in 3.5 L pots (black-colored in Figure 1e), while the second test line (with Trichoderma inoculation) was carried out in 2 L pots (brown-colored in Figure 1e). The inoculated treatment was prepared by adding 3 g of T-22 to each pot, ensuring even distribution within the substrate. Peat-only controls were placed in the central section using black-colored pots.
For sowing, 10 wheat seeds were placed in each pot (Figure 1d), ensuring maximum spacing to promote germination. Immediately after sowing, all treatments received initial irrigation to support seed establishment.
A maximum and minimum thermometer was placed on the upper part of the greenhouse bench to monitor the indoor ambient temperature. Throughout the duration of the experiment, periodic recordings of maximum and minimum temperatures were taken. The recorded data are presented in the graph in Figure 3.
As observed in Figure 3, from 20 days after sowing (DAS), the difference between maximum and minimum temperatures inside of the greenhouse increased compared to the beginning of the experiment, influencing crop growth. At 14 DAS, the first shoots emerged, and manual support irrigation of 300–400 mL per pot was applied.
At 28 DAS, the first inoculation with Trichoderma harzianum strain T-22 was carried out through irrigation. For this, 1.5 g of the formulated product was dissolved in 1 L of water and evenly distributed among the rows of pots assigned to this treatment. The same process was repeated on 42 DAS.
In addition to the inoculation days, periodic manual support irrigation was applied to the remaining plants. The number of plants per replicate was recorded on eight occasions, along with the progression of phenological stages according to the Zadoks scale (emergence of the first leaf and the third leaf and the beginning of tillering).

2.2. Statistical Procedure

The experimental design involved three types of compost (CS, CW, and CA), two doses (1/3 and ¼ v/v), and two T-22 options (with or without inoculation). Data were subjected to statistical processing through an analysis of variance. This was performed to determine the factor or factors, and the possible interactions between them, that could affect any differences observed among the treatments. All of the statistical calculations were performed with Statgraphic plus 5.1. The ANOVA table decomposes the variability of the studied parameters in contributions due to several factors. In the analysis, the sum of the type III squares was chosen. Thus, the contribution of each factor was measured by eliminating the effects of the other factors. p-values proved the statistical significance of all of the factors, and those less than 0.05 indicated that these factors had a statistically significant effect on each parameter at the 95% confidence level.

3. Results

3.1. Compost

Several factors can influence the efficiency of the composting process, including temperature, aeration, moisture content, carbon/nitrogen (C/N) ratio, particle size, pH, and degree of compaction (33).
Among these, temperature plays a crucial role, as its evolution throughout the process determines its progress. Depending on the temperature range, the composting process is divided into four phases: mesophilic, thermophilic, cooling, and maturation stages [33]. However, excessively high temperatures can be detrimental; if they exceed 65 °C, most of the microorganisms responsible for organic degradation perish, halting the composting process. Therefore, the optimal temperature range for efficient composting is between 40 and 65 °C. In this regard, monitoring the temperature of composting materials not only helps determine the ongoing process phase but also provides real-time assessment of microbial activity [34].
Regarding the thermal dynamics of composting, in the initial phase, the temperature is moderate, which favors the activity of mesophilic microorganisms responsible for decomposing easily degradable soluble compounds [13]. It was observed that in CS, the temperature peaked between 108 and 129 days. In contrast, in CW, the maximum temperature occurred earlier, approximately between days 70 and 90. In CA, the temperature increased more gradually, reaching a peak of 80 °C between days 66 and 87, similar to CW, but with a prolonged duration before declining. The rise in temperature promotes the replacement of mesophilic microorganisms with thermophilic ones, which can degrade polysaccharides, proteins, and lipids [13].
Another key factor in the composting process is moisture content. An appropriate initial level is typically around 70% for most materials [35]. With respect to moisture evolution, both CS and CW started at values close to 100%, progressively decreasing to low levels (10–20%). However, in CA, the initial moisture content was lower compared to the other treatments, and its reduction occurred more gradually, reaching 15% on day 173, suggesting a slower decomposition process.
Aeration is another crucial factor in composting, as oxygen is essential for the development of aerobic microorganisms responsible for organic matter degradation. In this regard, periodic turning of compost piles is fundamental to ensuring the proper evolution of the process. The absence of oxygen (anaerobic conditions) can halt composting or lead to undesirable fermentation, negatively affecting the final compost quality [13].
The key differences observed in the composting processes indicate that CS exhibited the highest peak temperature, while CW heated up more rapidly than CA but with an earlier temperature drop. CA, in contrast, maintained high temperatures for a longer period, which could influence the stability and quality of the final compost. Additionally, moisture in CA decreased less abruptly, suggesting a more controlled drying process. From a practical perspective, CS proved to be the most efficient system in terms of reaching high temperatures and reducing moisture in a short time. This suggests that the use of sewage sludge in this process could be suitable for scenarios requiring rapid composting. CW exhibited a similar trend, although with a lower maximum temperature. On the other hand, CA showed a more gradual temperature increase and prolonged heat retention, along with a slower moisture reduction. These characteristics suggest that the ABPs waste used in this system may be more suitable for longer composting processes with a more balanced moisture management.
The C/N ratio of compost ingredients is crucial, as carbon serves as an energy source while nitrogen is essential for microbial cell structure development during composting [13]. Microorganisms use carbon 30–35 times faster than they assimilate nitrogen. A high C/N ratio means that nitrogen is not sufficient for microbial growth, which consequently slows down the composting process [13].
The results of the process can be seen in Table 1, where the main physical, chemical, and microbiological parameters of the three obtained composts are compared.
The three composts share common characteristics, being rich in organic matter, ranging from 34% to slightly over 50%. The calcium oxide content is approximately 12–13%, phosphorus oxide around 5%, and magnesium oxide above 0.9%. The pH is slightly acidic, around 6.5 in all cases, and the C/N ratio is approximately 8. No significant variations in metal concentrations were observed among them. Additionally, all samples tested negative for Salmonella spp. and exhibited no toxicity.
The main differences among the three types of compost analyzed were observed in electrical conductivity, maturity index, and Dumas nitrogen content. In decreasing order, electrical conductivity values were as follows: CA (7140 µS/cm), CS (5290 µS/cm), and CW (3530 µS/cm). In general, most crop species are sensitive to salinity. This aspect is particularly relevant, as salinity is a crucial factor for both crop growth (with varying tolerance levels among different plant species) and the application site [36]. Depending on soil characteristics, amendments with high salt content may alter soil structure and biological activity.
Regarding the compost maturity index, this parameter indicates the compost’s resistance to decomposition over time and the absence of phytotoxic compounds. Traditionally, the maturity index of compost has been measured by determining germination indices, electrical conductivity, or other chemical parameters, such as the C/N ratio [36]. Our analysis was conducted using the Solvita test ©, which measures carbon dioxide and ammonium levels to determine compost maturity and stability. This parameter is particularly useful for assessing product quality for sale and/or distribution. The maturity index (MI) is measured on a scale from one (fresh compost) to eight (fully matured compost). In our study, at the time of analysis, CA had an MI value of six, classifying it as “cured” compost, meaning it is ready for storage and considered to have an acceptable maturity level for official use. In contrast, the other two composts had an MI value of four, classifying them as “active” composts with moderate decomposition activity. Consequently, these two composts were not applied immediately after analysis, ensuring their full stabilization over time.
Finally, nitrogen content was determined using two methods: Kjeldahl nitrogen (N Kjeldahl) and Dumas nitrogen (N Dumas). The Kjeldahl method is the most used method for nitrogen analysis [37], but it only accounts for organic and ammoniacal nitrogen. In contrast, the Dumas method also includes nitrate nitrogen content. The difference between N Dumas and N Kjeldahl can be considered as the compost’s nitrate content, the most readily assimilable nitrogen form for plants [38]. In CW, this difference was slightly higher than in the other two composts (0.77%), indicating a greater nitrate contribution.

3.2. Plants

A high overall germination and emergence rate was observed. However, as the weeks progressed, significant differences in growth and development among treatments became evident. Plants grown in CW, regardless of its proportion, exhibited a progressively deteriorating visual appearance, characterized by leaf yellowing that ultimately led to complete desiccation in a large proportion of replicates.
In contrast, plants cultivated in a substrate containing CA displayed early signs of leaf tip yellowing at 39 DAS but gradually regained their color over time. Meanwhile, plants grown in substrates with CS demonstrated the best overall appearance and the most rapid phenological development.
Control treatments, which lacked an additional nutrient source beyond the organic matter present in the peat substrate, exhibited minimal development.
A factorial ANOVA revealed that the type of compost mixture was the most influential factor affecting wheat’s emergence and early development (p < 0.001 across all time points). The presence of Trichoderma harzianum T-22 had a significant effect at specific stages (notably, at 18, 25, and 28 DAS) but not consistently throughout the experiment. A significant interaction between compost type and Trichoderma inoculation was observed at 39 DAS, suggesting a substrate-dependent response to microbial addition. These results indicate that while compost’s composition largely determines plant development, microbial inoculation can enhance or inhibit growth depending on the substrate used.
Table 2 also shows the analysis of the main effects and their interactions at different stages of plant development (first leaf: 25 DAS; three leaves: 39 DAS; started tillering: 46 DAS). The effect of the mixture (A) was statistically significant across all three stages studied, as indicated by the low p-values (p ≤ 0.0005). Regarding the inoculation with Trichoderma (B), the results (p > 0.3) indicate that substrate inoculation had no significant effect on plant development at any monitored stage. However, the interaction between the mixture and the presence or absence of Trichoderma in the substrate is noteworthy. At 39 DAS, the interaction of (A)–(B) was highly significant (p = 0.0000), suggesting a crucial interaction between both treatments at this stage. At 25 and 46 DAS, the p-values were higher (p = 0.3977 and p = 0.2157, respectively), indicating no significant interaction at these stages. Therefore, it appears reasonable to conclude that the type of mixture has a significant impact at all stages of development, whereas Trichoderma inoculation alone does not. Studies have shown that Trichoderma spp. is one of the fungi with the greatest impact on plant growth improvement [39]; however, in our study, we observed that the interaction between the mixture type and inoculation was only significant at 39 DAS, suggesting a relevant relationship between both treatments at this specific stage. This effect appears to be specific to the strain under study, as the establishment of synergies is highly dependent on the substrate’s composition [40].
This information is further illustrated in Figure 4. Studies have shown that Trichoderma spp. inoculation significantly increases germination and emergence percentage and index and could help improve seedling health and vigor [41]. Figure 5 shows that the CS-1/3 substrate inoculated with T-22 significantly enhanced plant emergence compared to the other treatments. Inoculation with Trichoderma in CA substrates at both studied proportions also increased the number of emerged plants compared to the non-inoculated control of the same substrate. In contrast, CS-1/4, CW-1/4, and CW-1/3 showed no significant changes with the T-22 treatment.
Figure 5 shows the values obtained with and without T-22 in the different compost mixtures 39 DAS.
As expected, in the case of control plants, crop development was slowed during the initial stages due to the absence of additional nutrient input.
The highest number of plants with more than three leaves per replicate was observed earlier in those cultivated on the CW-1/3 substrate without T-22, with no significant differences compared to those grown without T-22 in the CA-1/3 and CS-1/4 mixtures.
A positive effect of T-22 application was observed in some mixtures, as evidenced by the significant increase in plant numbers for CS-1/3 with T-22 (2.5 to 5.8) and CA-1/4 with T-22 (4 to 6.6). In contrast, no notable effect was observed for CS-1/4 or CA-1/3, as their values remained almost unchanged. Additionally, a marked decrease in the number of plants at the three-leaf stage was recorded for CW-1/3 with T-22 (8 to 2.4), and a less pronounced but still evident reduction was noted for CW-1/4.
Most of the references indicate that Trichoderma spp. interacts in a positive way with the substrates used, favoring the growth of the plants. However, on a few occasions, some studies have observed variable or even negative results depending on the specific conditions of the substrate and other factors [42,43]. In our case, Trichoderma inoculation had a positive impact on some mixtures (CS-1/3 and CA-1/4), promoting an increase in the number of plants. However, it reduced performance in others (CA-1/3, CW-1/3, CW-1/4). CS-1/4 showed no significant changes with the treatment, while CW-1/3 exhibited the greatest decline with T-22, suggesting that this combination is not favorable. It seems that the composition of the compost that comes from cheese industry waste or ABPs is not beneficial for the correct development of this fungus and its consequent benefits in the plant material.
Figure 6 clearly illustrates that the compost produced from sludge obtained from the Alcázar de San Juan wastewater treatment plant supports statistically superior crop development compared to the other substrates, regardless of whether they were inoculated with Trichoderma or not.
Additionally, as observed in Figure 6, Trichoderma application enhances plant development compared to the non-inoculated counterpart in the case of compost derived from cheese whey sludge at both studied concentrations, as well as in the compost containing ¼ ABP compost. This result is consistent with other references showing that sewage sludge composting promotes plant growth and that inoculation with Trichoderma can further enhance this effect [44,45,46].

4. Conclusions

To assess the agronomic suitability of three types of compost produced from a mixture of straw with sewage sludge from a wastewater treatment plant (CS), animal by-products (CA), and cheese factory waste (CW), a greenhouse experiment was conducted using durum wheat (Triticum turgidum subsp. durum, cv. Vitron). The experiment also included the inoculation of Trichoderma harzianum T-22. The main findings were as follows.
Initial seedling emergence was adequate across all tested substrates. However, as plant growth and development progressed, significant differences emerged among treatments. In CW-based substrates, regardless of the proportion used, plant growth slowed until a large proportion of the plants completely dried out. In CA substrates, leaf tips began to yellow during the early growth stages but later regained their color. Plants grown in CS substrates showed the best overall appearance and the most rapid development. Control treatments, which lacked an additional nutrient source beyond the organic matter present in the peat, exhibited minimal growth.
The most influential factor in crop growth and development was the type of compost mixture. The application of CS in any proportion improved seedling emergence compared to other treatments. The addition of T-22 inoculum to substrates containing CS-1/3 or CA-1/4 enhanced emergence compared to their non-inoculated counterparts. No significant differences were observed between inoculated and non-inoculated substrates in the other cases. The CW-1/3 substrate without T-22 promoted the earliest appearance of plants with more than three leaves compared to the other treatments.
Therefore, compost derived from sewage sludge from the Alcázar de San Juan wastewater treatment plant (CS) had the greatest capacity to support crop development, with statistically superior performance compared to the other compost types, regardless of Trichoderma inoculation.
Trichoderma inoculation improved plant development compared to its non-inoculated counterpart in compost derived from CW at both studied concentrations, as well as in the CA-1/4 substrate.
In conclusion, the type of compost mixture was the key determinant of crop growth and development. Among the tested substrates, compost derived from sewage sludge (CS) demonstrated the greatest agronomic potential, supporting superior plant development regardless of Trichoderma inoculation. While Trichoderma harzianum T-22 improved emergence in specific treatments, its effectiveness was not consistent across all substrates. As a living organism, its performance is greatly influenced by the nutrient source on which it is inoculated, highlighting that its application as a soil enhancer does not always guarantee positive results. These findings underscore the importance of selecting appropriate compost sources to optimize plant growth in agricultural applications. Moreover, it contributes to the valorization of organic waste and supports sustainable waste management policies aligned with EU directives.

Author Contributions

Conceptualization, J.D.l.H. and P.M.; methodology, J.D.l.H. and P.M.; formal analysis, J.D.l.H. and P.M.; research, J.D.l.H. and P.M.; resources, J.D.l.H.; writing—original draft preparation, P.M.; writing—review and editing, J.D.l.H. and P.M.; supervision, J.D.l.H.; project administration J.D.l.H.; funding acquisition, J.D.l.H. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Spanish Ministry of Economy, Industry, and Competitiveness (MINECO), 2012-COB-4456.

Data Availability Statement

Data will be made available upon request.

Acknowledgments

The work described in this paper was funded by the Spanish Ministry of Economy, Industry, and Competitiveness (MINECO). The authors are grateful to the municipally owned company “Aguas de Alcázar”, GESREMAN, and to the Alcázar de San Juan Town Hall for their financial support through project “Aptitud para uso agrícola del agua y lodos procedentes de la depuradora de aguas residuales de Alcázar de San Juan”.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Al-Zohairi, S.; Knudsen, M.T.; Mogensen, L. Utilizing Animal By-Products in European Slaughterhouses to Reduce the Environmental Footprint of Pork Products. Sustain. Prod. Consum. 2023, 37, 306–319. [Google Scholar] [CrossRef]
  2. Barrena, R.; Artola, A.; Vázquez, F.; Sánchez, A. The Use of Composting for the Treatment of Animal By-Products: Experiments at Lab Scale. J. Hazard. Mater. 2009, 161, 380–386. [Google Scholar] [CrossRef]
  3. Arrigoni, J.; Paladino, G.; Garibaldi, L.A.; Hedenström, E.; Zhang, W.; Laos, F. Performance of Small-Scale Composting in Low Ambient Temperatures: Effects of Adding Animal by-Products and Recycling Leachates. Waste Manag. Bull. 2024, 2, 309–317. [Google Scholar] [CrossRef]
  4. Khodaei, D.; Álvarez, C.; Mullen, A. Biodegradable Packaging Materials from Animal Processing Co-Products and Wastes: An Overview. Polymers 2021, 13, 2561. [Google Scholar] [CrossRef]
  5. Greff, B.; Szigeti, J.; Nagy, Á.; Lakatos, E.; Varga, L. Influence of Microbial Inoculants on Co-Composting of Lignocellulosic Crop Residues with Farm Animal Manure: A Review. J. Environ. Manag. 2021, 302 Pt B, 114088. [Google Scholar] [CrossRef] [PubMed]
  6. Russ, W.; Meyer-Pittroff, R. Utilizing Waste Products from the Food Production and Processing Industries. Crit. Rev. Food Sci. Nutr. 2004, 44, 57–62. [Google Scholar] [CrossRef] [PubMed]
  7. Chen, G.Q.; Talebi, S.; Gras, S.; Weeks, M.; Kentish, S. A Review of Salty Waste Stream Management in the Australian Dairy Industry. J. Environ. Manag. 2018, 224, 406–413. [Google Scholar] [CrossRef] [PubMed]
  8. Xu, M.; Sun, H.; Chen, E.; Yang, M.; Wu, C.; Sun, X.; Wang, Q. From Waste to Wealth: Innovations in Organic Solid Waste Composting. Environ. Res. 2023, 229, 115977. [Google Scholar] [CrossRef]
  9. Kelessidis, A.; Stasinakis, A. Comparative Study of the Methods Used for Treatment and Final Disposal of Sewage Sludge in European Countries. Waste Manag. 2012, 32, 1186–1195. [Google Scholar] [CrossRef]
  10. Koumoulidis, D.; Varvaris, I.; Pittaki, Z.; Hadjimitsis, D. Sewage Sludge in Agricultural Lands: The Legislative Framework in EU-28. Sustainability 2024, 16, 10946. [Google Scholar] [CrossRef]
  11. Neri, A.; Rizzuni, A.; Garrone, P.; Cagno, E. Influence of Policymakers and Civil Society Stakeholders on Sewage Sludge Management Strategies: Empirical Results from European Utilities. J. Environ. Manag. 2024, 364, 121396. [Google Scholar] [CrossRef]
  12. Mininni, G.; Blanch, A.; Lucena, F.; Berselli, S. EU Policy on Sewage Sludge Utilization and Perspectives on New Approaches of Sludge Management. Environ. Sci. Pollut. Res. 2015, 22, 7361–7374. [Google Scholar] [CrossRef] [PubMed]
  13. Chen, T.; Zhang, S.; Yuan, Z. Adoption of Solid Organic Waste Composting Products: A Critical Review. J. Clean. Prod. 2020, 272, 122712. [Google Scholar] [CrossRef]
  14. Ayilara, M.; Olanrewaju, O.S.; Babalola, O.; Odeyemi, O. Waste Management through Composting: Challenges and Potentials. Sustainability 2020, 12, 4456. [Google Scholar] [CrossRef]
  15. Ty, R.; Kiewicz; Nowak, A.; Ozimek, E. Trichoderma: The Current Status of Its Application in Agriculture for the Biocontrol of Fungal Phytopathogens and Stimulation of Plant Growth. Int. J. Mol. Sci. 2022, 23, 2329. [Google Scholar] [CrossRef]
  16. Vindas-Reyes, E.; Chacón-Cerdas, R.; Rivera-Méndez, W. Trichoderma Production and Encapsulation Methods for Agricultural Applications. AgriEngineering 2024, 6, 2366–2384. [Google Scholar] [CrossRef]
  17. Verma, M.; Brar, S.K.; Tyagi, R.D.; Surampalli, R.Y.; Valéro, J.R. Antagonistic Fungi, Trichoderma spp.: Panoply of Biological Control. Biochem. Eng. J. 2007, 37, 1–20. [Google Scholar] [CrossRef]
  18. Asad, S.A. Mechanisms of Action and Biocontrol Potential of Trichoderma against Fungal Plant Diseases—A Review. Ecol. Complex. 2022, 49, 100978. [Google Scholar] [CrossRef]
  19. Asghar, W.; Craven, K.; Kataoka, R.; Mahmood, A.; Asghar, N.; Raza, T.; Iftikhar, F. The Application of Trichoderma spp., an Old but New Useful Fungus, in Sustainable Soil Health Intensification: A Comprehensive Strategy for Addressing Challenges. Plant Stress 2024, 12, 100455. [Google Scholar] [CrossRef]
  20. Woo, S.; Ruocco, M.; Vinale, F.; Nigro, M.; Marra, R.; Lombardi, N.; Pascale, A.; Lanzuise, S.; Manganiello, G.; Lorito, M. Trichoderma-Based Products and Their Widespread Use in Agriculture. Open Mycol. J. 2014, 8, 71–126. [Google Scholar] [CrossRef]
  21. Steyaert, J.; Weld, R.; Stewart, A. Isolate-Specific Conidiation in Trichoderma in Response to Different Nitrogen Sources. Fungal Biol. 2010, 114, 179–188. [Google Scholar] [CrossRef]
  22. Li, Y.; Meng, X.; Guo, D.; Gao, J.; Huang, Q.; Zhang, J.; Fischer, R.; Shen, Q.; Yu, Z. A Simple and Low-Cost Strategy to Improve Conidial Yield and Stress Resistance of Trichoderma Guizhouense through Optimizing Illumination Conditions. J. Fungi 2022, 8, 50. [Google Scholar] [CrossRef]
  23. Schrüfer, K.; Lysek, G. Rhythmic Growth and Sporulation in Trichoderma Species: Differences within a Population of Isolates. Fungal Biol. 1990, 94, 124–127. [Google Scholar] [CrossRef]
  24. Shain, Y.; Mayer, A. Activation of Enzymes during Germination: Amylopectin-1,6-glucosidase in Peas. Physiol. Plant. 1968, 21, 765–776. [Google Scholar] [CrossRef]
  25. Vukelić, I.; Radić, D.; Pećinar, I.; Lević, S.; Djikanović, D.; Radotić, K.; Panković, D. Spectroscopic Investigation of Tomato Seed Germination Stimulated by Trichoderma spp. Biology 2024, 13, 340. [Google Scholar] [CrossRef]
  26. Han, Z.; Chen, L.; Wang, W.; Guan, X.; Song, J.; Ma, S. Biochemical and Transcriptomic Analyses Reveal Key Salinity and Alkalinity Stress Response and Tolerance Pathways in Salix linearistipularis Inoculated with Trichoderma. Agronomy 2024, 14, 2358. [Google Scholar] [CrossRef]
  27. Saha, K.C.; Uddin, M.K.; Shaha, P.K.; Chowdhury, M.A.H.; Hassan, L.; Saha, B.K. Application of Trichoderma Harzianum Enhances Salt Tolerance and Yield of Indian Mustard through Increasing Antioxidant Enzyme Activity. Heliyon 2024, 11, e41114. [Google Scholar] [CrossRef] [PubMed]
  28. Rai, S.; Solanki, M.K.; Solanki, A.C.; Surapathrudu, K. Biocontrol Potential of Trichoderma spp.: Current Understandings and Future Outlooks on Molecular Techniques. In Plant Health Under Biotic Stress: Volume 2: Microbial Interactions; Ansari, R.A., Mahmood, I., Eds.; Springer: Singapore, 2019; pp. 129–160. ISBN 978-981-13-6040-4. [Google Scholar]
  29. Keswani, C.; Mishra, S.; Sarma, B.; Singh, S.; Singh, H. Unraveling the Efficient Applications of Secondary Metabolites of Various Trichoderma spp. Appl. Microbiol. Biotechnol. 2013, 98, 533–544. [Google Scholar] [CrossRef] [PubMed]
  30. Schuster, A.; Schmoll, M. Biology and Biotechnology of Trichoderma. Appl. Microbiol. Biotechnol. 2010, 87, 787–799. [Google Scholar] [CrossRef] [PubMed]
  31. Kappel, L.; Yu, L.; Escobar, C.; Marcianò, D.; Srivastava, V.; Bulone, V.; Gruber, S. A Comparative Cell Wall Analysis of Trichoderma spp. Confirms a Conserved Polysaccharide Scaffold and Suggests an Important Role for Chitosan in Mycoparasitism. Microbiol. Spectr. 2024, 12, e0349523. [Google Scholar] [CrossRef]
  32. Mehta, D.; Saini, V.; Bajaj, A. Recent Developments in Membrane Targeting Antifungal Agents to Mitigate Antifungal Resistance. RSC Med. Chem. 2023, 14, 1603–1628. [Google Scholar] [CrossRef] [PubMed]
  33. Ho, T.K.T.; Tra, V.-T.; Le, T.; Nguyen, N.-K.-Q.; Tran, C.-S.; Nguyen, P.-T.; Vo, T.; Thai, V.; Bui, X. Compost to Improve Sustainable Soil Cultivation and Crop Productivity. Case Stud. Chem. Environ. Eng. 2022, 6, 100211. [Google Scholar] [CrossRef]
  34. Nakasaki, K.; Shoda, M.; Kubota, H. Effect of Temperature on Composting of Sewage Sludge. Appl. Environ. Microbiol. 1985, 50, 1526–1530. [Google Scholar] [CrossRef]
  35. Ge, M.; Shen, Y.; Ding, J.; Meng, H.; Zhou, H.; Zhou, J.; Cheng, H.; Zhang, X.; Wang, J.; Wang, H.; et al. New Insight into the Impact of Moisture Content and pH on Dissolved Organic Matter and Microbial Dynamics during Cattle Manure Composting. Bioresour. Technol. 2021, 344 Pt A, 126236. [Google Scholar] [CrossRef]
  36. Kong, Y.; Zhang, J.; Zhang, X.; Gao, X.; Yin, J.; Wang, G.; Li, J.; Li, G.; Cui, Z.; Yuan, J. Applicability and Limitation of Compost Maturity Evaluation Indicators: A Review. Chem. Eng. J. 2024, 489, 151386. [Google Scholar] [CrossRef]
  37. Bremner, J.M.; Mulvaney, C.S. Nitrogen—Total. In Methods of Soil Analysis; John Wiley & Sons, Ltd.: Hoboken, NJ, USA, 1982; pp. 595–624. ISBN 978-0-89118-977-0. [Google Scholar]
  38. Gautam, V.P.; Mishra, S.; Ahmed, H. Comparison of Total Nitrogen Estimation by Kjeldahl Method and CHNS Analyzer in Dry Tropical Grassland. Int. J. Plant Environ. 2023, 9, 180–182. [Google Scholar] [CrossRef]
  39. Halifu, S.; Deng, X.; Song, X.; Song, R. Effects of Two Trichoderma Strains on Plant Growth, Rhizosphere Soil Nutrients, and Fungal Community of Pinus sylvestris var. mongolica Annual Seedlings. Forests 2019, 10, 758. [Google Scholar] [CrossRef]
  40. Vinci, G.; Cozzolino, V.; Mazzei, P.; Monda, H.; Spaccini, R.; Piccolo, A. An Alternative to Mineral Phosphorus Fertilizers: The Combined Effects of Trichoderma Harzianum and Compost on Zea Mays, as Revealed by 1H NMR and GC-MS Metabolomics. PLoS ONE 2018, 13, e0209664. [Google Scholar] [CrossRef] [PubMed]
  41. Kaveh, H.; Jartoodeh, S.V.; Aruee, H.; Mazhabi, M. Would Trichoderma Affect Seed Germination and Seedling Quality of Two Muskmelon Cultivars, Khatooni and Qasri and Increase Their Transplanting Success? J. Biol. Environ. Sci. 2011, 5, 169–175. [Google Scholar]
  42. Marín-Guirao, J.I.; Rodríguez-Romera, P.; Lupión-Rodríguez, B.; Camacho-Ferre, F.; Tello-Marquina, J.C. Effect of Trichoderma on Horticultural Seedlings’ Growth Promotion Depending on Inoculum and Substrate Type. J. Appl. Microbiol. 2016, 121, 1095–1102. [Google Scholar] [CrossRef]
  43. Naseby, D.C.; Pascual, J.A.; Lynch, J.M. Effect of Biocontrol Strains of Trichoderma on Plant Growth, Pythium Ultimum Populations, Soil Microbial Communities and Soil Enzyme Activities. J. Appl. Microbiol. 2000, 88, 161–169. [Google Scholar] [CrossRef] [PubMed]
  44. Perez-Murcia, M.D.; Moral, R.; Moreno-Caselles, J.; Perez-Espinosa, A.; Paredes, C. Use of Composted Sewage Sludge in Growth Media for Broccoli. Bioresour. Technol. 2006, 97, 123–130. [Google Scholar] [CrossRef]
  45. Cotxarrera, L.; Trillas-Gay, M.I.; Steinberg, C.; Alabouvette, C. Use of Sewage Sludge Compost and Trichoderma asperellum Isolates to Suppress Fusarium Wilt of Tomato. Soil Biol. Biochem. 2002, 34, 467–476. [Google Scholar] [CrossRef]
  46. Ortega-Quispe, K.; Ccopi-Trucios, D.; Lozano-Povis, A.; Llanos-Del-Pino, A.; Gabriel-Campos, E.; Ortega-Quispe, K.; Ccopi-Trucios, D.; Lozano-Povis, A.; Llanos-Del-Pino, A.; Gabriel-Campos, E.; et al. Sustainable Management of Wastewater Sludge Through Composting with Effective Microorganisms: Enhancing the Growth of Tecoma stans. Org. Farming 2024, 10, 108–119. [Google Scholar] [CrossRef]
Agronomy 15 01935 g001
Figure 1. Images of compost: (a) CS; (b) CW; (c) CA; (d) distribution of 10 wheat seeds in pots; (e) distribution of treatments on the bench inside of the greenhouse: M1 (1/4 CS + 3/4 peat); M2 (1/4 CW + 3/4 peat); M3 (1/4 CA + 3/4 peat); M4 (1/3 CS + 2/3 peat); M5 (1/3 CW + 2/3 peat); M6 (1/3 CA + 2/3 peat).
Figure 1. Images of compost: (a) CS; (b) CW; (c) CA; (d) distribution of 10 wheat seeds in pots; (e) distribution of treatments on the bench inside of the greenhouse: M1 (1/4 CS + 3/4 peat); M2 (1/4 CW + 3/4 peat); M3 (1/4 CA + 3/4 peat); M4 (1/3 CS + 2/3 peat); M5 (1/3 CW + 2/3 peat); M6 (1/3 CA + 2/3 peat).
Agronomy 15 01935 g001
Agronomy 15 01935 g002
Figure 2. Temperature and moisture evolution during the composting process for the three mixtures: CS, CW, and CA.
Figure 2. Temperature and moisture evolution during the composting process for the three mixtures: CS, CW, and CA.
Agronomy 15 01935 g002
Agronomy 15 01935 g003
Figure 3. Maximum, minimum, and average temperatures inside of the greenhouse during the study period.
Figure 3. Maximum, minimum, and average temperatures inside of the greenhouse during the study period.
Agronomy 15 01935 g003
Agronomy 15 01935 g004
Figure 4. Mean value of the number of plants that emerged 25 DAS per pot according to the mixture used. Different letters indicate statistically significant differences between treatments (with T-22 and without T-22) according to the LSD test.
Figure 4. Mean value of the number of plants that emerged 25 DAS per pot according to the mixture used. Different letters indicate statistically significant differences between treatments (with T-22 and without T-22) according to the LSD test.
Agronomy 15 01935 g004
Agronomy 15 01935 g005
Figure 5. Mean value of the number of three-leaved plants 39 DAS per pot according to the mixture used. Different letters indicate statistically significant differences between treatments (with T-22 and without T-22).
Figure 5. Mean value of the number of three-leaved plants 39 DAS per pot according to the mixture used. Different letters indicate statistically significant differences between treatments (with T-22 and without T-22).
Agronomy 15 01935 g005
Agronomy 15 01935 g006
Figure 6. Mean value of the number of tillering plants 46 DAS per pot according to the mixture used. Different letters indicate statistically significant differences between treatments (with T-22 and without T-22).
Figure 6. Mean value of the number of tillering plants 46 DAS per pot according to the mixture used. Different letters indicate statistically significant differences between treatments (with T-22 and without T-22).
Agronomy 15 01935 g006
Table 1. Composition of composts (CS, CW, and CA).
Table 1. Composition of composts (CS, CW, and CA).
UnitsMethodologyCSCWCA
Electrical Conductivity (1/10 Extract))µS/cm 20 °CConductimetry on 1:5 extract529035307140
Moisture% 38.316.824.5
Maturity Index-Solvita test ©446
Total Organic Matter%Walkley Black Method41.453.634
Calcium Oxide%CaOBernard Method13.012.811.6
Phosphorus Pentoxide%P2O5Olsen Method5.424.704.40
Magnesium Oxide%MgOSpectrophotometry Atomic absorption0.980.890.84
Potassium Oxide%K2OAtomic emission spectrophotometry0.370.500.62
pH (1/10 Extract)-Potentiometry in 1:2.5 extract6.426.676.36
C/N Ratio- 7.9118.4517.538
Metals
Total Aluminummg kg−1Spectrophotometry Atomic absorption944297898083
Total Cadmiummg kg−1Spectrophotometry Atomic absorption0.360.180.35
Total Chromiummg kg−1Spectrophotometry Atomic absorption27.120.226.5
Total Ironmg kg−1Spectrophotometry Atomic absorption19,98321,77868,870
Total Mercurymg kg−1Spectrophotometry Atomic absorption0.460.200.31
Total Nickelmg kg−1Spectrophotometry Atomic absorption20.412.519.9
Total Leadmg kg−1Spectrophotometry Atomic absorption29.516.134.2
Total Zincmg kg−1Spectrophotometry Atomic absorption371228543
Nitrogen and Phosphorus Forms
Dumas Nitrogen% 3.033.682.61
Kjeldahl Nitrogen%N 2.892.912.43
Others
Toxicitymg L−1 <500,000<500,000<500,000
Microbiological Parameters
Salmonella spp. Detection/25 g AbsenceAbsenceAbsence
Rec. E. coli β-glucuronidase+MPN g−1 234343
Table 2. ANOVA for number of plants that emerged and number of plants on the first leaf (25 DAS), three leaves (39 DAS), and the start of tillering (46 DAS). (*) Denotes significant differences with a confidence level > 95%, as the p-value < 0.05 according to the LSD test. Mixture: CS-1/3, CS-1/4, CA-1/3, CA-1/4, CW-1/3, CW-1/4. Trichoderma: presence/absence. DAS: days after sowing.
Table 2. ANOVA for number of plants that emerged and number of plants on the first leaf (25 DAS), three leaves (39 DAS), and the start of tillering (46 DAS). (*) Denotes significant differences with a confidence level > 95%, as the p-value < 0.05 according to the LSD test. Mixture: CS-1/3, CS-1/4, CA-1/3, CA-1/4, CW-1/3, CW-1/4. Trichoderma: presence/absence. DAS: days after sowing.
Main Effects14 DAS18 DAS21 DAS25 DAS28 DAS32 DAS39 DAS46 DAS
Number of Plants that Emerged
Mixture (A)0.0004 *0.0002 *0.0000 *0.0000 *0.0000 *0.0000 *0.0000 *0.0000 *
Trichoderma (B)0.07430.0486 *0.08700.0195 *0.0332 *0.32410.12560.1181
(A)–(B)0.45990.19350.27640.41390.21150.23360.0379 *0.6428
Number of plants on the first leaf (25 DAS), three leaves (39 DAS), and the start of tillering (46 DAS)
Mixture (A) 0.0005 * 0.0000 *0.0000 *
Trichoderma (B) 0.3072 0.54560.3411
(A)–(B) 0.3977 0.0000 *0.2157
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Mañas, P.; De las Heras, J. Agronomic Potential of Compost from Unconventional Organic Waste Sources and the Effect of Trichoderma harzianum T-22 on Durum Wheat’s Early Development. Agronomy 2025, 15, 1935. https://doi.org/10.3390/agronomy15081935

AMA Style

Mañas P, De las Heras J. Agronomic Potential of Compost from Unconventional Organic Waste Sources and the Effect of Trichoderma harzianum T-22 on Durum Wheat’s Early Development. Agronomy. 2025; 15(8):1935. https://doi.org/10.3390/agronomy15081935

Chicago/Turabian Style

Mañas, Pilar, and Jorge De las Heras. 2025. "Agronomic Potential of Compost from Unconventional Organic Waste Sources and the Effect of Trichoderma harzianum T-22 on Durum Wheat’s Early Development" Agronomy 15, no. 8: 1935. https://doi.org/10.3390/agronomy15081935

APA Style

Mañas, P., & De las Heras, J. (2025). Agronomic Potential of Compost from Unconventional Organic Waste Sources and the Effect of Trichoderma harzianum T-22 on Durum Wheat’s Early Development. Agronomy, 15(8), 1935. https://doi.org/10.3390/agronomy15081935

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop