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Article

Separately Collected Organic Fraction of Municipal Solid Waste Compost as a Sustainable Improver of Soil Characteristics in the Open Field and a Promising Selective Booster for Nursery Production

by
Santina Rizzo
1,2,
Adolfo Le Pera
3,
Miriam Sellaro
3,
Luca Lombardo
1,* and
Leonardo Bruno
2
1
Research Centre for Olive, Fruit and Citrus Crops, Council for Agricultural Research and Economics, 87036 Rende, Italy
2
Department of Biology, Ecology and Soil Science, University of Calabria, 87036 Rende, Italy
3
Calabra Maceri & Servizi S.p.A, 87036 Rende, Italy
*
Author to whom correspondence should be addressed.
Agronomy 2025, 15(4), 958; https://doi.org/10.3390/agronomy15040958
Submission received: 11 March 2025 / Revised: 10 April 2025 / Accepted: 12 April 2025 / Published: 15 April 2025
(This article belongs to the Special Issue Composting for Soil Improvement and Removal of Soil Contaminants)
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Abstract

:
The Separately Collected Organic Fraction of Municipal Solid Waste (SC-OFMSW) is the biodegradable kitchen and canteen waste fraction that is separately collected at source and classified by the European Waste Catalogue under code 20 01 08. The utilization of SC-OFMSW Compost has emerged as a sustainable approach to enhancing agricultural soil quality and supporting soil biodiversity and productivity, while also serving as a viable option for disposing of treated urban waste. This study investigates the dose effect of SC-OFMSWC through phytotoxicity and growth assays in Arabidopsis thaliana and Lactuca sativa seeds and seedlings, as well as the impact of the same compost on the chemical and microbiological properties of soil under open field conditions. During the field trial in an agricultural orchard, soil pH, nutrient content, organic matter, and microbial activity following SC-OFMSWC and chemical fertilizer application were evaluated. In the greenhouse trial, a significant increase in germination rate and biomass production was found for L. sativa at a compost concentration of 2.5%, while neutral to negative effects were observed for A. thaliana. In the open field, results indicated significantly increased levels of organic carbon and enhanced microbial biomass and activity, accompanied by a general increase in nutrients, promoting soil health and resilience, with only limited increases in EC values and heavy metal content. These findings underscore the potential of SC-OFMSWC as an effective agricultural soil improver and a promising component in sustainable nursery management practices.

1. Introduction

Fertile soil capable of supporting plant growth is the fundamental tool of every farmer; however, in a vicious circle, modern-day farming practices are responsible for the acceleration of the rate of soil erosion, decreased telluric biodiversity, the significant loss of wildlife habitats, and water body pollution [1]. Land subjected to intensive agricultural practices for many years, particularly monocultures, is progressively depleted of organic substances and essential nutritional elements [2,3,4]. Consistently, over 1600 Mha of agricultural land worldwide (~34% of the total) have been estimated to be degraded [5,6], with an annual rate of fertile soil loss of 24 billion Mg (970 million Mg in Europe [1]). The constant growth of the human population puts the sustainability of agriculture to the test, pushing it increasingly toward practices far from tradition. If erosion rates remain higher than production rates, human society will soon be forced to choose between facing strong competition for the limited arable land or adopting sustainable agricultural methods that do not undermine soil fertility [7]. The importance and contingency of this topic can also be deduced from the FAO SoiLEX portal [8], which lists 380 laws related to “soil restoration” in 108 countries worldwide.
One of the methods that is increasingly becoming established to slow down or block the loss of fertility and to re-establish the amount of organic substance lost is the application of compost to agricultural lands through adequate fertilization plans, encouraging the replacement of more traditional practices that use manure and soil improvers of animal origin [9,10,11]. European legislation (Directive 2018/851) and, in implementation of this, Italian legislation (Law 2019/117) require that compost intended for agricultural use must be obtained through the aerobic digestion of urban bio-waste from separate collection at source, such as OFMSW since the final product is more suitable and safe to introduce into agricultural land [12]. Unseparated MSW compost (which also contains glass, paper, plastics, and metals), from a legal viewpoint in many countries, has only a few potential destinations, such as landfills, the re-vegetation of brownfield and mineral waste sites, or heavy metal-contaminated sites [13]. Compost is defined as the product of aerobic decomposition, which occurs due to the action of an intricate network of microorganisms. This process is appropriately increased and accelerated in technological applications [14]. By encouraging the use of compost produced from organic waste, in addition to improving the quality of agricultural land, the use of non-renewable resources is reduced, and so are the problems related to waste management [15]. Composting food waste provides important environmental credits in most impact categories; the benefits are mainly associated with the use of compost as a substitute for chemical fertilizers [16]. Composting allows us to reduce the increasingly problematic flow of waste destined for landfills or traded among countries (including the about 300–500 million Mg of hazardous waste traded via the so-called worldwide waste web [17]), representing an important component of the circular economy. Across the European Union, between 118 and 138 million tons of bio-waste (mainly food and garden waste) are generated annually, only about 40% of which (equivalent to 47.5 million tons per annum [Mtpa]) is currently effectively recycled into high-quality compost and digestate. The implementation of the separate collection of organic waste is key to diverting it from landfills and guaranteeing that high-quality secondary raw materials (such as compost) are consistently manufactured, so that they can be introduced to the European fertilizer market [18]. Furthermore, the use of compost as fertilizer provides long-term improvement to the terrain; changes to the structural characteristics of the soil persist for up to nine years after the initial application of compost [19].
On the other hand, one issue to consider is the potential phytotoxicity of compost for agricultural use. Components such as organic decomposition products, NH4+-N, heavy metals, pesticide residues, etc., need to be metabolized and immobilized during the maturation of compost in order to neutralize its phytotoxicity and make the compost marketable [20]. Among the phytotoxic compounds are ammonia [21]; ethylene oxide, which is synthesized during the decomposition of compost after it is added to soil [22]; organic acids, which are produced during the decomposition of organic waste and include acetic, propionic, and butyric acid; phenols, which are present in some agricultural waste; salts, which are primarily present in food waste; and, finally, heavy metals. These latter compounds are mostly present in compost derived from municipal waste since this type of waste contains a high number of potential sources of heavy metals (batteries, paints, plastics, etc.). For this reason, only compost derived from the organic fraction collected separately at the source is permitted in agriculture as a soil improver. The identification and quantification of these components require the use of time-consuming and expensive analyses. There is also the possibility that unexpected contaminants, which are not usually subject to analysis, may be present. For these reasons, biological assays appear to be a valid alternative, as they are very sensitive and low-cost, allowing the compatibility of composted materials with plants to be verified. Furthermore, their use allows for the evaluation of the cumulative or synergistic effects of compounds that are individually inert but are phytotoxic in certain contexts or when combined with other substances [20].
Within this context, the aim of this study was to evaluate the effectiveness of separately collected organic fraction municipal solid waste compost (SC-OFMSWC) in promoting agricultural soil fertility and stimulating nursery plant growth in Arabidopsis thaliana and Lactuca sativa, while taking into account its eventual phytotoxicity at different concentrations.

2. Materials and Methods

An SC-OFMSWC was produced at the Calabra Maceri & Servizi S.p.A company in Rende (Italy), which is responsible for the reception, treatment, and recovery of 950 Mg of recyclable (~80% of the total) and non-recyclable waste per day. It was produced through a composting process of separately collected food waste (European Waste Catalogue Code: 20 01 08 “biodegradable waste from kitchens and canteens”) in a biocell-type bioreactor. SC-OFMSW is specifically represented by food waste from household kitchens, canteens, restaurants, catering services, and retail premises. SC-OFMSW is mixed with green waste in a ratio of 2:1 (w/w) and composted with an Active Composting Time (ACT) of 28–30 days and a curing step of 45–50 days. The ACT phase temperature was maintained above 55 °C for at least three consecutive days to ensure the biological safety of the material, as required by Italian legislation. SC-OFMSWC was obtained through a final screening operation, which included chemo-physical and microbiological characterization and a germination test. After this phase, the obtained SC-OFMSWC was tested for its possible use in nursery production by evaluating two common herbaceous species (Arabidopsis thaliana and Lactuca sativa) and in full-field applications by analyzing the effects on the chemical and microbiological characteristics of agricultural soil, in comparison with an untreated control and a commercial ternary fertilizer.

2.1. SC-OFMSWC Characterization

The compost has undergone chemical-physical and microbiological analyses to assess whether its characteristics fall within the values established by Italian Legislative Decree 2010/75, as reported, together with the employed methods, in Table S1. Furthermore, compost quality was preliminarily evaluated using the cress (Lepidium sativum) germination test [23]. L. sativum is a model organism used in the most common biological phytotoxicity assays, as it requires a short time for germination (24 h at 27 °C) and is also characterized by the easy management of seeds because of their dimensions [20]. The germination rate and index were tested in a liquid culture obtained from an aqueous extract of the compost. The aqueous extract was prepared from a sample of approximately 200 g of compost, which was brought to a moisture content of 85%. This solution was stirred for 2 h in order to make the solution as homogeneous as possible. Subsequently, the mixture was centrifuged for 15 min at 6000 rpm, and the supernatant was then filtered. The resulting aqueous extract was stored at −20 °C until use.

2.2. SC-OFMSWC Evaluation for Nursery Production

The above-described growing media was also employed to calculate the germination rate and index in (i) Arabidopsis thaliana ecotype Columbia (Col-0) and (ii) Lactuca sativa (var. acephala Alef., cutting lettuce; commercial seeds). These species were further investigated in pot germination and growth tests with the administration of different doses of compost. A. thaliana is a reference plant in the scientific community, as it represents a model organism in the field of plant biology because it is sensitive to several potent allelochemicals. Its over 200 mutant ecotypes could be essential for identifying the plant’s response mechanisms to certain phytotoxic compounds. L. sativa is a widely cultivated species with significant nutritional importance [24] and worldwide production of 27.13 Mt in 2022 (FAOSTAT, 2022). Lettuce is also one of the major species grown in greenhouses and appears to be a model system for horticultural species due to its fast growth [25]. Furthermore, it could represent the ideal horticultural species for open field cultivation and for use in greenhouses with different types of composted soil improvers as a growth substrate.

2.2.1. Germination Rate and Index in Liquid Culture

The germination test and the phytotoxicity bioassay in liquid culture were carried out using compost extract diluted up to 30% (Annex II of Legislative Decree 75/2010). A total of 1 mL of the 30% compost extract was placed in Petri dishes containing bibulous paper. Ten seeds of each plant species, soaked in distilled water for 60 min, were added to the capsule. The plates were sealed with PARAFILM in order to prevent the evaporation of the solution. Distilled water was used as the control. The test was conducted in the dark at 20 ± 2 °C for 96 h.
The germination index (GI) is expressed by the following mathematical relationship:
GI = (RSG × RRG)/100;
where
RSG (relative seed germination; %) = the number of seeds germinated in the extract/the number of seeds germinated in the control × 100;
RRG (relative root growth; %) = the average root length in the extract/the average root length in the control × 100.
The phytotoxicity test was conducted on watercress, lettuce, and Arabidopsis for a duration between 24 and 72 h, in accordance with Gariglio [26].

2.2.2. In-Pot Germination Rate and Growth Tests

The in-pot tests were carried out using different mixtures of compost (0.5%, 1%, 2.5%, 5%, and 10%) and a commercial universal potting soil (COMPO SANA®, Compo GmbH, Münster, Germany) (w/w), along with a control treatment (no compost).
For the in-pot germination rate, fifty seeds were used for each replicate, which were vernalized at 4 °C for 48 h. The seeds were sown in 500 g of soil enriched with different doses of the compost to be tested, and an aliquot of 120 mL of tap water was added to the mixture. The seeds germinated in a growth chamber at 20 ± 2 °C, with a relative humidity rate of 50% and a photoperiod of 16/8 h. The experiment lasted for six days.
For growth tests, thirty seeds were used for each replicate, which were vernalized at 4 °C for 48 h and left to soak in water for one hour immediately before sowing. The seeds were placed in 500 g of soil enriched with different doses of compost, and an aliquot of 120 mL of tap water was added to the mixture. The seeds germinated in a growth chamber at 20 ± 2 °C, with a relative humidity rate of 50% and a photoperiod of 16/8 h. The experiment continued for a period of 21 days after sowing (DAS), at the end of which the following measurements were taken: fresh and dry weight of the epigeal part of the plants, total leaf area, and photosynthetic pigment content.

2.2.3. Evaluation of Epigeal Biomass Production

This test is based on the evaluation of the production of aboveground biomass in plants. At the end of the growth period of 21 DAS, the epigeal part of each plant was cut and weighed before and after drying at a temperature of 50 °C for 48 h. The productions detected at the different dosages were statistically compared with those obtained from plants grown in the control (no compost) substrate.

2.2.4. Evaluation of Total Leaf Area

The total leaf area was evaluated using leaves 21 DAS. The leaves were cut and placed on a solid support consisting of a mixture of water and agar at a concentration of 0.85% or on filter paper. The measurements were carried out on photographic support using ImageJ software (v1.50i) [27].

2.2.5. Determination of Photosynthetic Pigments Content

Chlorophyll a (Chl a), chlorophyll b (Chl b), and total carotenoids (Car, the sum of β-carotene, lutein, violaxanthin, and neoxanthin) content were evaluated using the method proposed by Wellburn [28]. A total of 100 mg of leaf tissue was pulverized in a mortar using liquid nitrogen, and extraction was carried out by adding 1.5 mL of methanol. Subsequently, the mixture was centrifuged at 2000 rpm for five minutes. A total of 500 µL of supernatant were taken and mixed with 500 µL of methanol, and the absorbance was determined using a spectrophotometer (Nanodrop ND-1000, Thermo Fisher Scientific, Waltham, MA, USA) at wavelengths of 470, 653, 666, and 750 nm in order to evaluate the pigment content (µg/g of dry matter (DM)) according to the following equations:
Chl a (µg) = [15.65 (OD 666 − OD 750) − 7.34 (OD 653 − OD 750)] × V;
Chl b (µg) = [27.05 (OD 653 − OD 750) − 11.21 (OD 666 − OD 750)] × V;
Car (µg) = [(1000 (OD 470 − OD 750) − 2.86 Cl a − 129.2 Cl b)/221] × V;
where
OD = optical density;
V = volume of methanol used (mL).

2.3. In-Field SC-OFMSWC Evaluation

To evaluate the produced SC-OFMSWC as a soil improver, it was applied at two different doses in a commercial agricultural orchard. The trial was arranged in a randomized complete block design (RCBD), providing four treatments and four replications per treatment (Figure 1). Thus, four agricultural plots were treated with SC-OFMSWC at 8 Mg ha−1 (C8), four with SC-OFMSWC at 16 Mg ha−1 (C16), and four with a common chemical ternary (11-22-16 NPK: NO3− 3.5%; NH4+ 7.5%; P2O5 22%; K2O 16%) fertilizer (cf) from YaraMila® (Yara International, Oslo, Norway) at 500 kg ha−1, which was the treatment the orchard was subjected to before the trial began. The remaining four plots were kept as untreated controls (ctrl). Three months after the first application, the three treatments were replicated in the same plots with the implementation of a second dose of fertilizer (cf2: an additional 500 kg ha−1) and compost (C8+8: an additional 8 Mg ha−1, and C16+16: an additional 16 Mg ha−1) to evaluate any cumulative effect. Compost concentrations were determined according to Cicatelli et al. [29], who suggested doses within the range of 10–30 Mg ha−1 for agricultural soils. The plots were not cultivated during the trial.
Soil samples for chemical and biochemical analyses were collected from the 10 cm deep layer three (T1; evaluation of first application) to six months (T2; evaluation of second application) after the start of treatments. Sampling was carried out using the quarting method described in the Italian Ministerial Decree (MD) 13/09/1999 [30]; soil samples were sieved (2.0 mm mesh) and stored at 4 °C for subsequent analyses.

2.3.1. Soil Chemo-Physical Properties

A 1:2.5 (m:v) and a 1:2 (m:v) soil-distilled water mixture were used for pH and electrical conductivity (EC) determination using a Hanna HI5222 pH and EC meter, respectively. Organic carbon (OC) was measured following the methods described by Springer and Klee (1954) [31], whereas the total nitrogen and phosphorus were determined using the Kjeldahl [32] and Olsen [33] methods, respectively. The active carbonate content was estimated using the Drouineau (1942) method [34]. In addition, the barium chloride–triethanolamine method was employed to estimate the cation exchange capacity (CEC) [30]. Eventually, the soil content of four heavy metals (Cu, Ni, Pb, Zn) was determined using an iCAP 6000 Series ICP spectrometer (Thermo Scientific, Waltham, MA, USA) following soil acid digestion.

2.3.2. Biochemical Analysis

Soil biochemical analyses were performed according to MD 23/02/2004 [35]. Microbial biomass was determined using the fumigation-incubation method, whereas soil respiration was assessed using the titrimetric method. Fluorescein diacetate hydrolysis was measured using 3,6-diacetylfluorescein as the substrate and analyzed spectrophotometrically (CECIL CE1010, Cecil Instrumentation Services Ltd., Milton Technology Centre, Cambridge, UK) by measuring the absorbance of the released fluorescein at 490 nm. Acid and alkaline phosphatase activities were assayed by measuring the hydrolysis rate of p-nitrophenylphosphate, supplied as a substrate, and then measuring the absorbance of the released p-nitrophenol at 400 nm in buffered solutions at pH 6.5 and 11.0, respectively.

2.4. Statistical Analysis

Data were subjected to one-way ANOVA after verifying the assumptions of the analysis; the eventual significant differences of the means at the 95 and 99% confidence levels were assessed with Tukey’s Honest Significant Difference (HSD) test, using Past (v. 4.10) software.

3. Results and Discussions

3.1. SC-OFMSWC Characterization

Compost characteristics are reported in Table 1. The values fall within the limits imposed by the National legislation (previously cited Italian legislation) for mixed composted soil improvers, making them suitable for the subsequent experiments. Overall, the compost is well endowed with organic carbon (25% DM) and humic and fulvic acids (11.6% DM), is microbiologically safe, and has a moderate content of soluble salts.

3.2. SC-OFMSWC Evaluation for Nursery Production

3.2.1. Germination Rate and Index in Liquid Culture

The germination test conducted allowed us to evaluate whether the phytotoxic substances present in the compost, mainly represented by labile compounds produced by intermediate transformations (acetic acid, volatile fatty acids, phenols, etc.) linked to the composting process (anaerobic conditions), could negatively influence the seed germination process. The results obtained (Figure 2) show that L. sativum reached 96% germination after 24 h, highlighting the absence of phytotoxic effects from the 30% compost extract on watercress; thus, the germination rate did not appear to be significantly altered compared to the untreated control throughout the 4-day trial. The response of A. thaliana seeds presented a different trend; in fact, 72 h later, the germination rate was 84%, and only after 96 h did the seeds reach 100% germination, indicating a delay of approximately 24 h. Regarding the response of L. sativa, there was a notable delay in germination compared to the control, and, furthermore, the percentage of germinated seeds did not exceed 60% even after 96 h. This marked decline in germinated seeds indicates a higher sensitivity of L. sativa to this type of compost. It is known that L. sativa is significantly sensitive to phenolic compounds and organic acids produced during the decomposition of organic matter [36,37]; consequently, the compost used could be excessively rich in these compounds due to its incomplete maturation. From these results, it is clear that the choice to test compost through the use of different species, perhaps expanding to include dicots and monocots, could be useful in order to thoroughly test its potential phytotoxicity. Moreover, the germination test appears to be sensitive to the stability of the compost. Pascual [38] observed that the germination rate and root length in barley were greater in mature compost than in immature compost and were negatively correlated with soluble carbon content.
Regarding the germination index, it is currently considered one of the most sensitive parameters for evaluating the phytotoxicity of compost [39], as it takes into account relative seed germination and relative root elongation, which are commonly employed in tests used to determine the phytotoxicity of compost on plant organisms [26,40]. According to Zucconi [41,42] and Emino and Warman [20], GI values lower than 50% indicate high phytotoxicity, values between 50% and 80% indicate moderate phytotoxicity, while values greater than 80% indicate the absence of phytotoxicity. When the index exceeds 100%, compost can be considered a phytonutrient or phytostimulant. Given this premise, different responses were obtained in this trial (Table 2). The RSG of L. sativum turned out to be 99.9 ± 2.3%, confirming that there were no significant differences between the seeds germinated in water and those in compost extract; the RRG, however, was slightly lower, standing at a value of 80.1 ± 10.3%. This indicates reduced primary root growth in seedlings exposed to compost. From these results, it was possible to obtain the value of the germination index (GI), which was found to be 80.0 ± 12.1%. This value suggests the absence of phytotoxicity and phytostimulation. In the case of L. sativa, however, all three parameters analyzed demonstrated that the compost had strong phytotoxicity; in fact, the GI value was 13.9 ± 3.6%. This result could be due to a greater sensitivity of lettuce to soluble compounds and/or contaminants that characterize the compost extract. In A. thaliana, although the RSG reached 84.3%, the RRG stood at 47.9%, and the GI index reached only 40.4%. Therefore, the choice of optimal compost, which determines phytostimulant effects, is certainly linked to the plant species and undoubtedly to the different sensitivities that these species present to exposure to compost. Accordingly, compost characteristics have been reported to affect GI. A relationship was found by Fang and Wong [43] between the GI and OC/N ratio in compost; this ratio tends to decrease as the compost maturation process progresses, and at lower values of this ratio, the GI germination index tends to increase. Furthermore, the GI appears to be sensitive to the maturation stage of the compost, increasing significantly when the compost undergoes greater aeration and reaches full maturation [22,26,40], accompanied by a clear reduction in the concentration of phytotoxic substances [44]. Eventually, the phytotoxicity of compost can be due not only to soluble compounds, such as salts, heavy metals, organic acids, etc., but also to non-soluble compounds linked to the solid matrix [45].

3.2.2. In-Pot Germination Rate, Growth Tests, and Evaluation of Epigeal Biomass Production

The results of the in-pot germination tests of A. thaliana and L. sativa are shown in Figure 3. In A. thaliana, the germination rate did not show significant differences at low concentrations of compost (0.5% and 1%). However, the number of germinated seeds decreased with increasing compost concentration starting from 2.5%, dropping drastically at a concentration of 10% (Figure 3a). On the other hand, it is interesting to note that in L. sativa, the plantlets subjected to 2.5% compost exhibited a high germination rate (80%), which was higher than the control, suggesting the presence of phytostimulant effects at this concentration. In contrast, germination was drastically reduced at concentrations of 5% and 10% (Figure 3b). These results could suggest a hormetic response, characterized by the modest stimulation of germination at low doses of compost and inhibition at higher doses [46]. This phenomenon has been observed in other studies on phytotoxicity, in which it has been verified that some compounds, such as certain flavonoids, at high concentrations have a phytotoxic effect on species such as L. sativum and L. sativa by inhibiting the development of the primary root. In contrast, the same compounds at low concentrations act as antioxidants and phytostimulants, promoting root growth [47,48]. A higher salt sensitivity might also cause a delay in germination, as salt stress is well known to reduce the germination rate by influencing water intake and α-amylase activity [49].
The results (Figure 3c) showed that in A. thaliana, there was a reduction in biomass with increasing compost concentration. Starting from a 0.5% concentration of compost, the dry weight underwent a drastic reduction. This suggests that unlike in soil germination—as previously observed—plant development was negatively affected by composting. In L. sativa, however, a significant increase in biomass was found at a compost concentration of 2.5% (Figure 3d). Also, in this case, it is possible to hypothesize a hormetic response related to the concentration of compost in L. sativa [48].

3.2.3. Total Leaf Area

Leaf area is a measure of light interception and is an important parameter for determining plant productivity [50]. In this regard, the measurement of the area of A. thaliana rosettes and the total leaf area of L. sativa were evaluated (Figure 4) at the end of a twentyone DAS period using ImageJ software [27]. The results obtained indicate that in Arabidopsis, leaf area reduced as the compost concentration increased. Plants exposed to 0.5% and 1% compost suffered a slight, albeit significant, reduction in leaf area, while at a concentration of 2.5%, there was a clear decrease. Moreover, as the concentration of compost increased, the number of leaf series also showed a delay in the development of a sixth leaf. In L. sativa, the leaf area showed a different trend: at 0.5% and 1% concentrations of compost, no differences were found compared with the control, despite a slight reduction due to a delay in the development of a fourth leaf. At the 2.5% concentration, there was an increase in leaf area, although this value was not significantly different from the control. A statistically significant difference was found between the compost concentrations of 2.5 and 0.5%.
Overall, these results suggest a neutral to detrimental effect of compost on A. thaliana germination and growth, as well as a possible phytostimulating effect of compost at a concentration of 2.5% for L. sativa, at which leaf area, as well as both dry weight and germination rate, reached their maximum values.
The different behavior of the plantlets of the two species in response to the application of SC-OFMSWC might somehow be attributed to their different responses to the overall amount of heavy metals present in the compost. In fact, lettuce, while able to absorb large amounts of heavy metals, has been reported to tolerate their phytotoxic effects at low doses [51,52], whereas shoot and root biomass and leaf area have been described to significantly decrease in Cd-exposed A. thaliana plants [53], with synergistic Zn and Cu toxicity negatively affecting A. thaliana growth in soil [54] and off-soil [55] trials. In this sense, the annual application of MSW compost in lettuce plants cv. in Grand Rapids enhanced the production of stress-alleviating molecules such as amino acids, phospholipids, acylcarnitines, amines, and choline, which are also implicated in plant growth [56].
A case-by-case study is therefore needed to identify the optimal compost characteristics and concentration ranges for effective nursery production. In this regard, positive experiences have been reported for marigold and basil seedling production [57] and greenhouse pepper cultivation [58].

3.2.4. Determination of Photosynthetic Pigment Content

Plant pigments have specific wavelength absorption patterns called absorption spectra. Chlorophylls (Chls) and carotenoids (Car) exhibit high absorption levels at 400–500 nm and 630–680 nm, respectively [25]. The balanced relationship between the quantities of chlorophylls and carotenoids is an essential factor in maintaining the integrity of the photosynthetic system and the homeostatic processes of plants [59]. For these reasons, the photosynthetic pigment content can be used as a parameter to indirectly determine the photosynthetic efficiency and physiological state of plants. The results obtained, surprisingly, show that in Arabidopsis, the quantity of photosynthetic pigments increased in plants subjected to greater concentrations of compost, with maximum values found in plants subjected to a concentration of 2.5% compost (Figure 5a). As highlighted by Sai Kachout [60], the increase in the content of photosynthetic pigments, specifically chlorophyll, may be due in part to a physiological response of the plant to both heavy metal stress and nutritional stress [60,61]. Heavy metals such as Cu, Ni, Pb, and Zn, which are normally present in compost, are responsible for oxidative stress, which is accompanied by growth inhibition, increased levels of lipid peroxidation, and increased carotenoid and anthocyanin content [60]. In A. thaliana there is, therefore, an inhibitory effect on growth, probably due to the higher concentrations of salts, nutrients, and heavy metals in compost. At the same time, these factors lead to a greater production of photosynthetic pigments, including carotenoids, which also play an important role in protecting plants against oxidative processes. Carotenoids are efficient non-enzymatic antioxidants because they transform singlet oxygen, which originates under stress conditions, into molecular oxygen that is no longer toxic, and convert the energy contained in the oxygen radicals into heat, which is eliminated by the plant through the leaf surface [62].
On the other hand, in L. sativa there is a moderate, although not significant, increase in the pigment content in plants exposed to the 0.5% concentration of compost (Figure 5b). Plants exposed to the other concentrations, however, show levels of pigment content comparable to the control. Although there is a physiological response of plants to different concentrations of compost, in the case of the content of photosynthetic pigments no significant differences were found, suggesting a lower sensitivity of lettuce to oxidative stress caused by heavy metals.

3.3. In-Field SC-OFMSWC Evaluation

3.3.1. Soil Chemo-Physical Properties

The results of the considered soil parameters are reported in Table 3. The soil of the untreated plot did not exhibit any particular condition of deficiency or excess of nutrients because of the pre-start routine management, showing good levels of OM and nutrient content. Both mineral and compost fertilization induced a slight decrease in pH values. The chemical fertilizer was responsible for a significant decline in OC content, which was particularly evident after the first application, in comparison with the untreated control. On the other hand, a net increase in organic C was observed in plots amended with compost, with the highest statistically significant value found in the C16+16 plot. Similarly, the C16+16 plot showed the highest electrical conductivity (EC), whereas the EC values were generally higher in composted plots, as a natural consequence of Na and salts added to the soil. However, this—albeit significant—increase in EC did not reach values that would jeopardize plant growth through osmotic potential, which would hinder water absorption. In the same regard, no significant difference was found for CEC. Active carbonate values, despite a sharp increase in plots amended with compost, never reached critical thresholds that would influence the availability of phosphorus and iron. A statistically neutral effect of treatments was also found for total N and P content, whereas SC-OFMSWC was confirmed [63,64] to produce an increase in their soil concentrations. Notwithstanding, the highest values found in the plots amended with compost may be linked to the increase in organic matter capable of immobilizing N [65,66] and possibly to an increased formation of calcium phosphates due to the high concentration of CaCO3, as already described for MSWCs [67,68].
A statistically neutral effect of the treatments was also found for total N and P content.
The capability of MSWC to increase soil organic matter (and EC) and restore the fertility of degraded soils is well documented in the literature [69,70,71]. In accordance, MSWCs have been reported to reduce the mobility of potentially toxic elements (PTEs) complexed by humic and fulvic acids, as well as a vast arsenal of functional groups in MWSC-amended soils [72,73].
However, the major identified limitation to the agricultural use of MSWCs is their typical high heavy metal content, which poses consequent risks of phytotoxicity and groundwater pollution due to leaching [74,75]. In this vein, the tested SC-OFMSWC resulted in an increase in soil heavy metal content (Figure 6), although only the total zinc concentration was significantly higher, but well below the established limits, in accordance with previous studies [76,77,78].

3.3.2. Biochemical Analysis

In order to assess the degree of microbiological activity in the soil, microbic biomass and respiration, acid and alkaline phosphatase activity, and fluorescein diacetate hydrolysis were assessed (Figure 7). In general, the plots treated with two consecutive doses of SC-OFMSWC at a concentration of 16 Mg ha−1 (C16+16) showed the highest results, with statistically significant increases in all the considered analyses in comparison with the control plots, and for FDA hydrolysis and microbial biomass in comparison to the chemically fertilized plots. Microbial respiration was significantly stimulated by both mineral fertilization and composting; nevertheless, the second dose of chemical fertilizer induced a marked reduction in this parameter. In particular, the amount of CO2 (mg·g−1·dw h−1) produced by microbial respiration increased by almost three times in fertilized soil. The FDA hydrolysis activity improved only in compost-amended plots. The analysis of phosphatase activity, both acidic and alkaline, showed no significant differences between mineral and compost fertilization. In this regard, contrasting results have been reported, depending on compost characteristics and trial scale. In a laboratory study [79], soil microbial biomass-C, glucose-induced respiration, and phosphatase and urease activities significantly increased with the growing MSWC implementation from 2.5 to 40 t ha−1. MSWC was proven to increase soil protease, urease, deaminase, phosphatase, and arylsulphatase activities in clay soil under controlled conditions [80], as well as alkaline phosphomonoesterase, phosphodiesterase, arylsulphatase, dehydrogenase, and l-asparaginase in calcareous agricultural soil at doses up to 90 t ha−1 [81]. Accordingly, a rise in nitrate reductase, urease, dehydrogenase, β-glucosidase, and phosphatase activities was observed during a 6-year study in a 12 t ha−1 MSWC-amended soil, insofar as protease activity decreased at double the compost concentration [82]. In contrast, Garcia-Gil and collaborators [83] described a decrease in urease and phosphatase activities, possibly attributable to the high MSWC heavy metal content; however, this was neutral to other soil enzymes, together with an increase in soil microbial biomass. Similarly, overall neutral (to slightly negative, at increased concentrations) effects of MSWC were reported for dehydrogenase, urease, phosphatase, catalase, protease, and b-glucosidase activities under field conditions, despite an increase in microbial biomass carbon [84].
Overall, as already observed in previous works [85,86], SC-OFMSWC resulted in increased potential metabolic activity and functional diversity of soil microbial communities, presenting only limited contraindications to its use in agricultural fields, at least in the short term, due to the accumulation of heavy metals and salts.
Finally, by analyzing the relationships that link the chemical-physical and microbiological characteristics of the soils from the plots subjected to the different treatments (Figure 8), positive statistically significant correlations were found between total phosphorus content and both acid and alkaline phosphatases (Pearson’s r = 0.80 and 0.85, respectively). This, in turn, implies a higher organic P mineralization and a greater content of bioavailable forms for plant nutrition. Similarly, phosphate activities were significantly correlated with N (r = 0.85 vs. 0.8 for alkaline vs. acid phosphatase activity) and OC (0.77 vs. 0.51) content. This could be due to the positive effects on soil microorganisms, resulting in an increased demand for phosphorus [87], and it would explain the higher values found for alkaline phosphatase, which is mainly produced by microorganisms, whereas acid phosphatase may also be of vegetal origin [88]. These findings are in accordance with studies on sewage sludge compost [89], as well as studies on subalpine forest soils [90]. On the other hand, no correlation was found between microbial biomass and acid phosphatases, whereas a moderate interdependence was recorded with alkaline phosphatase (r = 0.41); this could again be linked to the origin of the enzymes. Conversely, fluorescein diacetate hydrolysis, being a biochemical marker of the total microbial activity in soil, positively correlated with microbial biomass and respiration (r = 0.74 and 0.57, respectively), confirming what was observed in freshly amended soils [91].
A negative correlation (r = −0.61) was found between CaCO3 and cation exchange capability, as previously described in different soil types [92,93], which is likely an effect of the reduction of anionic exchange sites.
Overall, the employment of the tested SC-OFMSWC, particularly after the second dose, triggered a virtuous circle that favored the proliferation of microbial biomass, leading to an increase in its functionality, which in turn had a positive impact on soil fertility.

4. Conclusions

Urban waste management is an ever-increasing problem for a world that must move toward sustainability. The use of SC-OFMSWC in agricultural soil and for nursery production has been demonstrated here as a valid alternative to ternary fertilizers and, by extension, a viable practice that can contribute to alleviating the accumulation of recyclable urban wastes to reduce landfilling and incineration and avoid pollution and greenhouse gas emissions. Nevertheless, in the greenhouse trial, despite a common toxic effect at SC-OFMSWC concentrations over 5%, markedly different responses were recorded for the tested herbaceous species, with a significant increase in germination rate and biomass production for L. sativa at a compost concentration of 2.5% and neutral to negative effects for A. thaliana at all tested concentrations. Therefore, a case-by-case analysis is required to identify the most suitable compost characteristics and concentrations.
In the open field trial, SC-OFMSWC induced a general increase in nutrient levels and significantly increased levels of organic carbon in both the considered periods after applications. This was consequently accompanied by enhanced microbial biomass and activity, along with moderate increases in EC values and heavy metal content.
These results suggest that the tested SC-OFMSWC is a suitable soil fertility improver in the open field. Its use in nursery production should be considered for plant species that are less sensitive to soluble compounds, such as salts, heavy metals, and organic acids, due to its hormetic properties.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/agronomy15040958/s1, Table S1: Methods employed for compost analyses and maximum and minimum limits provided by the Italian legislation.

Author Contributions

Conceptualization, L.B. and S.R.; methodology, L.B., S.R. and L.L.; software, S.R. and L.L.; formal analysis, L.B., S.R., A.L.P., M.S. and L.L.; data curation, L.B., S.R. and L.L.; writing—original draft preparation, S.R. and L.L.; writing—review and editing, L.B., S.R., A.L.P., M.S. and L.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The datasets generated and/or analyzed during the current study are available for consultation upon request from the corresponding author.

Conflicts of Interest

Authors Adolfo Le Pera and Miriam Sellaro were employed by the company Calabra Maceri & Servizi S.p.A, Rende, Italy. The remaining authors declare that the research was absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

  1. UNCCD. Global Land Outlook. United Nations Convention to Combat Desertification (UNCCD); Secretariat of the United Nations Convention to Combat Desertification: Bonn, Germany, 2017; ISBN 9789295110489. Available online: https://www.unccd.int/resources/publications/global-land-outlook-1st-edition (accessed on 24 February 2025).
  2. Aziz, I.; Mahmood, T.; Islam, K.R. Effect of Long Term No-till and Conventional Tillage Practices on Soil Quality. Soil Tillage Res. 2013, 131, 28–35. [Google Scholar] [CrossRef]
  3. Bai, Z.; Caspari, T.; Gonzalez, M.R.; Batjes, N.H.; Mäder, P.; Bünemann, E.K.; de Goede, R.; Brussaard, L.; Xu, M.; Ferreira, C.S.S.; et al. Effects of Agricultural Management Practices on Soil Quality: A Review of Long-Term Experiments for Europe and China. Agric. Ecosyst. Environ. 2018, 265, 1–7. [Google Scholar] [CrossRef]
  4. Lombardo, L.; Palese, A.M.; Grasso, F.; Duffy, D.H.; Briccoli Bati, C.; Xiloyannis, C. Mechanical Tillage Diversely Affects Glomalin Content, Water Stable Aggregates and AM Fungal Community in the Soil Profiles of Two Differently Managed Olive Orchards. Biomolecules 2019, 9, 639. [Google Scholar] [CrossRef] [PubMed]
  5. Aleksandrowicz, L.; Green, R.; Joy, E.J.M.; Smith, P.; Haines, A. The Impacts of Dietary Change on Greenhouse Gas Emissions, Land Use, Water Use, and Health: A Systematic Review. PLoS ONE 2016, 11, e0165797. [Google Scholar] [CrossRef] [PubMed]
  6. FAO. The State of the World’s Land and Water Resources for Food and Agriculture—Systems at Breaking Point; Main Report; FAO: Rome, Italy, 2022. [Google Scholar] [CrossRef]
  7. Gebremedhin, M.; Coyne, M.S.; Sistani, K.R. How Much Margin Is Left for Degrading Agricultural Soils? The Coming Soil Crises. Soil Syst. 2022, 6, 22. [Google Scholar] [CrossRef]
  8. FAO Food and Agriculture Organization. FAO SoiLEXportal. Available online: https://www.fao.org/soils-portal/soilex/soil-keywords/soil-restoration/en/ (accessed on 1 January 2025).
  9. Ho, T.T.K.; Tra, V.T.; Le, T.H.; Nguyen, N.-K.-Q.; Tran, C.-S.; Nguyen, P.-T.; Vo, T.-D.-H.; Thai, V.-N.; Bui, X.-T. Compost to Improve Sustainable Soil Cultivation and Crop Productivity. Case Stud. Chem. Environ. Eng. 2022, 6, 100211. [Google Scholar] [CrossRef]
  10. Pajura, R. Composting Municipal Solid Waste and Animal Manure in Response to the Current Fertilizer Crisis—A Recent Review. Sci. Total Environ. 2024, 912, 169221. [Google Scholar] [CrossRef]
  11. Policastro, G.; Cesaro, A. Composting of Organic Solid Waste of Municipal Origin: The Role of Research in Enhancing Its Sustainability. Int. J. Environ. Res. Public Health 2022, 20, 312. [Google Scholar] [CrossRef]
  12. López, M.; Soliva, M.; Martínez-Farré, F.X.; Fernández, M.; Huerta-Pujol, O. Evaluation of MSW Organic Fraction for Composting: Separate Collection or Mechanical Sorting. Resour. Conserv. Recycl. 2010, 54, 222–228. [Google Scholar] [CrossRef]
  13. Farrell, M.; Jones, D.L. Critical Evaluation of Municipal Solid Waste Composting and Potential Compost Markets. Bioresour. Technol. 2009, 100, 4301–4310. [Google Scholar] [CrossRef]
  14. ANPA. Il Recupero Di Sostanza Organica Dai Rifiuti per La Produzione Di Ammendanti Di Qualità; Unità Normativa Tecnica; Agenzia Nazionale per la Protezione dell’Ambiente: Rome, Italy, 2012; pp. 1–214. ISBN 88-448-0052-7. [Google Scholar]
  15. Sæbo, A.; Ferrini, F. The Use of Compost in Urban Green Areas—A Review for Practical Application. Urban For. Urban Green. 2006, 4, 159–169. [Google Scholar] [CrossRef]
  16. Le Pera, A.; Sellaro, M.; Bencivenni, E.; D’Amico, F. Environmental Sustainability of an Integrate Anaerobic Digestion-Composting Treatment of Food Waste: Analysis of an Italian Plant in the Circular Bioeconomy Strategy. Waste Manag. 2022, 139, 341–351. [Google Scholar] [CrossRef] [PubMed]
  17. Martínez, J.H.; Romero, S.; Ramasco, J.J.; Estrada, E. The World-Wide Waste Web. Nat. Commun. 2022, 13, 1615. [Google Scholar] [CrossRef]
  18. ECN. Compost and Digestate for a Circular Bioeconomy; European Compost Network ECN e.V.: Bochum, Germany, 2022; ISBN 978-3-9820825-1-6. [Google Scholar]
  19. Hargreaves, J.C.; Adl, M.S.; Warman, P.R. A Review of the Use of Composted Municipal Solid Waste in Agriculture. Agric. Ecosyst. Environ. 2008, 123, 1–14. [Google Scholar] [CrossRef]
  20. Emino, E.R.; Warman, P.R. Biological Assay for Compost Quality. Compost Sci. Util. 2004, 12, 342–348. [Google Scholar] [CrossRef]
  21. Wong, M.H.; Chu, L.M.; Chan, W.C. The Effects of Heavy Metals and Ammonia in Sewage Sludge and Animal Manure on the Growth of Chlorella Pyrenoidosa. Environ. Pollut. Ser. A Ecol. Biol. 1984, 34, 55–71. [Google Scholar] [CrossRef]
  22. Wong, M.H. Phytotoxicity of Refuse Compost during the Process of Maturation. Environ. Pollut. Ser. A Ecol. Biol. 1985, 37, 159–174. [Google Scholar] [CrossRef]
  23. Busch, D.; Kammann, C.; Grünhage, L.; Müller, C. Simple Biotoxicity Tests for Evaluation of Carbonaceous Soil Additives: Establishment and Reproducibility of Four Test Procedures. J. Environ. Qual. 2012, 41, 1023–1032. [Google Scholar] [CrossRef]
  24. Shi, M.; Gu, J.; Wu, H.; Rauf, A.; Emran, T.B.; Khan, Z.; Mitra, S.; Aljohani, A.S.M.; Alhumaydhi, F.A.; Al-Awthan, Y.S.; et al. Phytochemicals, Nutrition, Metabolism, Bioavailability, and Health Benefits in Lettuce—A Comprehensive Review. Antioxidants 2022, 11, 1158. [Google Scholar] [CrossRef]
  25. Lin, K.-H.; Huang, M.-Y.; Huang, W.-D.; Hsu, M.-H.; Yang, Z.-W.; Yang, C.-M. The Effects of Red, Blue, and White Light-Emitting Diodes on the Growth, Development, and Edible Quality of Hydroponically Grown Lettuce (Lactuca sativa L. Var. Capitata). Sci. Hortic. 2013, 150, 86–91. [Google Scholar] [CrossRef]
  26. Gariglio, N.F.; Buyatti, M.A.; Pilatti, R.A.; Russia, D.E.G.; Acosta, M.R. Use of a Germination Bioassay to Test Compost Maturity of Willow (Salix sp.) Sawdust. New Zeal. J. Crop Hortic. Sci. 2002, 30, 135–139. [Google Scholar] [CrossRef]
  27. Schneider, C.A.; Rasband, W.S.; Eliceiri, K.W. NIH Image to ImageJ: 25 Years of Image Analysis. Nat. Methods 2012, 9, 671–675. [Google Scholar] [CrossRef]
  28. Wellburn, A.R. The Spectral Determination of Chlorophylls a and b, as Well as Total Carotenoids, Using Various Solvents with Spectrophotometers of Different Resolution. J. Plant Physiol. 1994, 144, 307–313. [Google Scholar] [CrossRef]
  29. Cicatelli, A.; Baldantoni, D.; Iovieno, P.; Carotenuto, M.; Alfani, A.; De Feis, I.; Castiglione, S. Genetically Biodiverse Potato Cultivars Grown on a Suitable Agricultural Soil under Compost Amendment or Mineral Fertilization: Yield, Quality, Genetic and Epigenetic Variations, Soil Properties. Sci. Total Environ. 2014, 493, 1025–1035. [Google Scholar] [CrossRef] [PubMed]
  30. Ministero per le Politiche Agricole e Forestali Approvazione Dei. Metodi Ufficiali Di Analisi Chimica Del Suolo; GU Serie Generale n.248 del 21-10-1999—Suppl. Ordinario n. 185; Gazzetta Ufficiale della Repubblica Italiana: Rome, Italy, 1999; pp. 1–222. [Google Scholar]
  31. Springer, U.; Klee, J. Prüfun g Der Leistungsfähigkeit von Einigen Wichtigeren Verfahren Zur Bestimmung Des Kohlenstoffs Mittels Chromschwefelsäure Sowie Vorschlag Einer Neuen Schnellmethode. Z. Für Pflanzenernährung Düngung Bodenkd. 1954, 64, 1–26. [Google Scholar] [CrossRef]
  32. Kjeldahl, J. Neue Methode Zur Bestimmung Des Stickstoffs in Organischen Körpern. Fresenius’ Z. Für Anal. Chem. 1883, 22, 366–382. [Google Scholar] [CrossRef]
  33. Olsen, S.R. Estimation of Available Phosphorus in Soils by Extraction with Sodium Bicarbonate. In Climate Change 2013—The Physical Science Basis; Intergovernmental Panel on Climate Change, Ed.; Cambridge University Press: Cambridge, UK, 1954; pp. 1–30. [Google Scholar]
  34. Drouineau, G. Dosage Rapide Du Calcaire Actif Du Sol: Nouvelles Données Sur La Separation et La Nature Des Fractions Calcaires. Ann. Agron. 1942, 12, 441–450. [Google Scholar]
  35. Ministero per le Politiche Agricole e Forestali Approvazione Dei. Metodi Ufficiali Di Analisi Biochimica Del Suolo; GU Serie Generale n.61 del 13-03-2004—Suppl. Ordinario n. 42; Gazzetta Ufficiale della Repubblica Italiana: Rome, Italy, 2004. [Google Scholar]
  36. Macías, F.A.; Castellano, D.; Molinillo, J.M.G. Search for a Standard Phytotoxic Bioassay for Allelochemicals. Selection of Standard Target Species. J. Agric. Food Chem. 2000, 48, 2512–2521. [Google Scholar] [CrossRef]
  37. Bettiol, C.; De Vettori, S.; Minervini, G.; Zuccon, E.; Marchetto, D.; Ghirardini, A.V.; Argese, E. Assessment of Phenolic Herbicide Toxicity and Mode of Action by Different Assays. Environ. Sci. Pollut. Res. 2016, 23, 7398–7408. [Google Scholar] [CrossRef]
  38. Pascual, J. Characterization of Urban Wastes According to Fertility and Phytotoxicity Parameters. Waste Manag. Res. 1997, 15, 103–112. [Google Scholar] [CrossRef]
  39. Barral, M.T.; Paradelo, R. A Review on the Use of Phytotoxicity as a Compost Quality Indicator. Environ. Sci. Agric. Food Sci. 2011, 5, 36–44. [Google Scholar]
  40. Tiquia, S. Evaluating Phytotoxicity of Pig Manure from the Pig-on-Litter System. In Proceedings of the ICS99: The 13th ACM International Conference on Supercomputing, Rhodes, Greece, 20–25 June 1999; CBA Press Inc.: Truro, NS, Canada, 2000. [Google Scholar] [CrossRef]
  41. Zucconi, F.; Forte, M.; Monaco, A.; De Beritodi, M. Biological Evaluation of Compost Maturity. Biocycle 1981, 22, 27–29. [Google Scholar]
  42. .Zucconi, F.; Monaco, A.; Forte, M.; De Bertoldi, M. Phytotoxins during the Stabilization of Organic Matter. In Composting of Agricultural and Other Wastes; Gasser, J.K.R., Ed.; Elsevier Applied Science Publishers: New York, NY, USA, 1985; pp. 73–86. [Google Scholar]
  43. Fang, M.; Wong, J.W.C. Co-Composting of Sewage Sludge and Coal Fly Ash: Nutrient Transformations. Bioresour. Technol. 1999, 67, 19–24. [Google Scholar] [CrossRef]
  44. Lasaridi, K.E.; Stentiford, E.I. A Simple Respirometric Technique for Assessing Compost Stability. Water Res. 1998, 32, 3717–3723. [Google Scholar] [CrossRef]
  45. Oleszczuk, P. The Toxicity of Composts from Sewage Sludges Evaluated by the Direct Contact Tests Phytotoxkit and Ostracodtoxkit. Waste Manag. 2008, 28, 1645–1653. [Google Scholar] [CrossRef]
  46. Amendola, A.; Migliore, L.; Cerioli, N. Ormesi: La Rivoluzione Dose-Risposta; APAT Agenzia per la Protezione dell’Ambiente e per i Servizi Tecnici: Rome, Italy, 2006; ISBN 88-448-194-9. [Google Scholar]
  47. An, M. Mathematical Modelling of Dose-Response Relationship (Hormesis) in Allelopathy and Its Application. Nonlinearity Biol. Toxicol. Med. 2005, 3, 153–172. [Google Scholar] [CrossRef]
  48. De Martino, L.; Mencherini, T.; Mancini, E.; Aquino, R.P.; De Almeida, L.F.R.; De Feo, V. In Vitro Phytotoxicity and Antioxidant Activity of Selected Flavonoids. Int. J. Mol. Sci. 2012, 13, 5406–5419. [Google Scholar] [CrossRef]
  49. Atta, K.; Mondal, S.; Gorai, S.; Singh, A.P.; Kumari, A.; Ghosh, T.; Roy, A.; Hembram, S.; Gaikwad, D.J.; Mondal, S.; et al. Impacts of Salinity Stress on Crop Plants: Improving Salt Tolerance through Genetic and Molecular Dissection. Front. Plant Sci. 2023, 14, 1241736. [Google Scholar] [CrossRef]
  50. Weraduwage, S.M.; Chen, J.; Anozie, F.C.; Morales, A.; Weise, S.E.; Sharkey, T.D. The Relationship between Leaf Area Growth and Biomass Accumulation in Arabidopsis Thaliana. Front. Plant Sci. 2015, 6, 167. [Google Scholar] [CrossRef]
  51. Cobb, G.P.; Sands, K.; Waters, M.; Wixson, B.G.; Dorward-King, E. Accumulation of Heavy Metals by Vegetables Grown in Mine Wastes. Environ. Toxicol. Chem. 2000, 19, 600–607. [Google Scholar] [CrossRef]
  52. Santos, C.; Monte, J.; Vilaça, N.; Fonseca, J.; Trindade, H.; Cortez, I.; Goufo, P. Evaluation of the Potential of Agro-Industrial Waste-Based Composts to Control Botrytis Gray Mold and Soilborne Fungal Diseases in Lettuce. Processes 2021, 9, 2231. [Google Scholar] [CrossRef]
  53. Sofo, A.; Bochicchio, R.; Amato, M.; Rendina, N.; Vitti, A.; Nuzzaci, M.; Altamura, M.M.; Falasca, G.; Rovere, F.D.; Scopa, A. Plant Architecture, Auxin Homeostasis and Phenol Content in Arabidopsis Thaliana Grown in Cadmium- and Zinc-Enriched Media. J. Plant Physiol. 2017, 216, 174–180. [Google Scholar] [CrossRef]
  54. Baek, S.-A.; Han, T.; Ahn, S.-K.; Kang, H.; Cho, M.R.; Lee, S.-C.; Im, K.-H. Effects of Heavy Metals on Plant Growths and Pigment Contents in Arabidopsis Thaliana. Plant Pathol. J. 2012, 28, 446–452. [Google Scholar] [CrossRef]
  55. Bae, B.; Park, H.; Kang, S. Quantitative Estimation of Synergistic Toxicity of Cu and Zn on Growth of Arabidopsis Thaliana by Isobolographic Method. Toxics 2022, 10, 195. [Google Scholar] [CrossRef] [PubMed]
  56. Abbey, L.; Ijenyo, M.; Spence, B.; Asunni, A.O.; Ofoe, R.; Amo-Larbi, V. Bioaccumulation of Chemical Elements in Vegetables as Influenced by Application Frequency of Municipal Solid Waste Compost. Can. J. Plant Sci. 2021, 101, 967–983. [Google Scholar] [CrossRef]
  57. Tzortzakis, N.; Gouma, S.; Paterakis, C.; Manios, T. Deployment of Municipal Solid Wastes as a Substitute Growing Medium Component in Marigold and Basil Seedlings Production. Sci. World J. 2012, 2012, 285874. [Google Scholar] [CrossRef]
  58. Tzortzakis, N.; Gouma, S.; Dagianta, E.; Saridakis, C.; Papamichalaki, M.; Goumas, D.; Manios, T. Use of Fertigation and Municipal Solid Waste Compost for Greenhouse Pepper Cultivation. Sci. World J. 2012, 2012, 973193. [Google Scholar] [CrossRef]
  59. Hannoufa, A.; Hossain, Z. Regulation of Carotenoid Accumulation in Plants. Biocatal. Agric. Biotechnol. 2012, 1, 198–202. [Google Scholar] [CrossRef]
  60. Sai Kachout, S.; Ben Mansoura, A.; Jaffel, K.; Leclerc, J.C.; Rejeb, M.N.; Ouerghi, Z. The Effect of Salinity on the Growth of the Halophyte Atriplex Hortensis (Chenopodiaceae). Appl. Ecol. Environ. Res. 2010, 7, 319–332. [Google Scholar] [CrossRef]
  61. Palta, J.P. Leaf Chlorophyll Content. Remote Sens. Rev. 1990, 5, 207–213. [Google Scholar] [CrossRef]
  62. Yang, S.-H.; Wang, L.-J.; Li, S.-H.; Duan, W.; Loescher, W.; Liang, Z.-C. The Effects of UV-B Radiation on Photosynthesis in Relation to Photosystem II Photochemistry, Thermal Dissipation and Antioxidant Defenses in Winter Wheat (Triticum aestivum L.) Seedlings at Different Growth Temperatures. Funct. Plant Biol. 2007, 34, 907. [Google Scholar] [CrossRef]
  63. Mkhabela, M.S.; Warman, P.R. The Influence of Municipal Solid Waste Compost on Yield, Soil Phosphorus Availability and Uptake by Two Vegetable Crops Grown in a Pugwash Sandy Loam Soil in Nova Scotia. Agric. Ecosyst. Environ. 2005, 106, 57–67. [Google Scholar] [CrossRef]
  64. Jorge-Mardomingo, I.; Jiménez-Hernández, M.E.; Moreno, L.; de la Losa, A.; de la Cruz, M.T.; Casermeiro, M.Á. Application of High Doses of Organic Amendments in a Mediterranean Agricultural Soil: An Approach for Assessing the Risk of Groundwater Contamination. CATENA 2015, 131, 74–83. [Google Scholar] [CrossRef]
  65. Plošek, L.; Elbl, J.; Lošák, T.; Kužel, S.; Kintl, A.; Juřička, D.; Kynický, J.; Martensson, A.; Brtnický, M. Leaching of Mineral Nitrogen in the Soil Influenced by Addition of Compost and N-Mineral Fertilizer. Acta Agric. Scand. Sect. B—Soil Plant Sci. 2017, 67, 607–614. [Google Scholar] [CrossRef]
  66. Holub, P.; Klem, K.; Tůma, I.; Vavříková, J.; Surá, K.; Veselá, B.; Urban, O.; Záhora, J. Application of Organic Carbon Affects Mineral Nitrogen Uptake by Winter Wheat and Leaching in Subsoil: Proximal Sensing as a Tool for Agronomic Practice. Sci. Total Environ. 2020, 717, 137058. [Google Scholar] [CrossRef] [PubMed]
  67. Traoré, O.; Sinaj, S.; Frossard, E.; Van De Kerkhove, J.M. Effect of Composting Time on Phosphate Exchangeability. Nutr. Cycl. Agroecosyst. 1999, 55, 123–131. [Google Scholar] [CrossRef]
  68. Turrión, M.-B.; Bueis, T.; Lafuente, F.; López, O.; San José, E.; Eleftheriadis, A.; Mulas, R. Effects on Soil Phosphorus Dynamics of Municipal Solid Waste Compost Addition to a Burnt and Unburnt Forest Soil. Sci. Total Environ. 2018, 642, 374–382. [Google Scholar] [CrossRef] [PubMed]
  69. Shiralipour, A.; McConnell, D.B.; Smith, W.H. Physical and Chemical Properties of Soils as Affected by Municipal Solid Waste Compost Application. Biomass Bioenergy 1992, 3, 261–266. [Google Scholar] [CrossRef]
  70. Rady, M.M.; Semida, W.M.; Hemida, K.A.; Abdelhamid, M.T. The Effect of Compost on Growth and Yield of Phaseolus Vulgaris Plants Grown under Saline Soil. Int. J. Recycl. Org. Waste Agric. 2016, 5, 311–321. [Google Scholar] [CrossRef]
  71. Domínguez, M.; Paradelo Núñez, R.; Piñeiro, J.; Barral, M.T. Physicochemical and Biochemical Properties of an Acid Soil under Potato Culture Amended with Municipal Solid Waste Compost. Int. J. Recycl. Org. Waste Agric. 2019, 8, 171–178. [Google Scholar] [CrossRef]
  72. Garau, G.; Porceddu, A.; Sanna, M.; Silvetti, M.; Castaldi, P. Municipal Solid Wastes as a Resource for Environmental Recovery: Impact of Water Treatment Residuals and Compost on the Microbial and Biochemical Features of As and Trace Metal-Polluted Soils. Ecotoxicol. Environ. Saf. 2019, 174, 445–454. [Google Scholar] [CrossRef] [PubMed]
  73. Caporale, A.G.; Porfido, C.; Roggero, P.P.; Di Palma, A.; Adamo, P.; Pinna, M.V.; Garau, G.; Spagnuolo, M.; Castaldi, P.; Diquattro, S. Long-Term Effect of Municipal Solid Waste Compost on the Recovery of a Potentially Toxic Element (PTE)-Contaminated Soil: PTE Mobility, Distribution and Bioaccessibility. Environ. Sci. Pollut. Res. 2023, 30, 122858–122874. [Google Scholar] [CrossRef]
  74. Rajaie, M.; Tavakoly, A.R. Effects of Municipal Waste Compost and Nitrogen Fertilizer on Growth and Mineral Composition of Tomato. Int. J. Recycl. Org. Waste Agric. 2016, 5, 339–347. [Google Scholar] [CrossRef]
  75. Srivastava, V.; de Araujo, A.S.F.; Vaish, B.; Bartelt-Hunt, S.; Singh, P.; Singh, R.P. Biological Response of Using Municipal Solid Waste Compost in Agriculture as Fertilizer Supplement. Rev. Environ. Sci. Bio/Technol. 2016, 15, 677–696. [Google Scholar] [CrossRef]
  76. Mbarki, S.; Labidi, N.; Mahmoudi, H.; Jedidi, N.; Abdelly, C. Contrasting Effects of Municipal Compost on Alfalfa Growth in Clay and in Sandy Soils: N, P, K, Content and Heavy Metal Toxicity. Bioresour. Technol. 2008, 99, 6745–6750. [Google Scholar] [CrossRef]
  77. Baldantoni, D.; Leone, A.; Iovieno, P.; Morra, L.; Zaccardelli, M.; Alfani, A. Total and Available Soil Trace Element Concentrations in Two Mediterranean Agricultural Systems Treated with Municipal Waste Compost or Conventional Mineral Fertilizers. Chemosphere 2010, 80, 1006–1013. [Google Scholar] [CrossRef] [PubMed]
  78. Yuksel, O. Influence of Municipal Solid Waste Compost Application on Heavy Metal Content in Soil. Environ. Monit. Assess. 2015, 187, 313. [Google Scholar] [CrossRef]
  79. Bhattacharyya, P.; Chakrabarti, K.; Chakraborty, A. Effect of MSW Compost on Microbiological and Biochemical Soil Quality Indicators. Compost Sci. Util. 2003, 11, 220–227. [Google Scholar] [CrossRef]
  80. Perucci, P. Effect of the Addition of Municipal Solid-Waste Compost on Microbial Biomass and Enzyme Activities in Soil. Biol. Fertil. Soils 1990, 10, 221–226. [Google Scholar] [CrossRef]
  81. Businelli, D.; Giusquiani, P.L.; Gigliotti, G. Long-Term Effects of Heavy Metals from Composted Municipal Waste on Some Enzyme Activities in a Cultivated Soil. Biol. Fertil. Soils 1994, 17, 257–262. [Google Scholar] [CrossRef]
  82. Crecchio, C.; Curci, M.; Pizzigallo, M.D.R.; Ricciuti, P.; Ruggiero, P. Effects of Municipal Solid Waste Compost Amendments on Soil Enzyme Activities and Bacterial Genetic Diversity. Soil Biol. Biochem. 2004, 36, 1595–1605. [Google Scholar] [CrossRef]
  83. García-Gil, J.; Plaza, C.; Soler-Rovira, P.; Polo, A. Long-Term Effects of Municipal Solid Waste Compost Application on Soil Enzyme Activities and Microbial Biomass. Soil Biol. Biochem. 2000, 32, 1907–1913. [Google Scholar] [CrossRef]
  84. Jorge-Mardomingo, I.; Soler-Rovira, P.; Casermeiro, M.Á.; de la Cruz, M.T.; Polo, A. Seasonal Changes in Microbial Activity in a Semiarid Soil after Application of a High Dose of Different Organic Amendments. Geoderma 2013, 206, 40–48. [Google Scholar] [CrossRef]
  85. Rizzo, S.; Minervino, M.; Muto, A.; Talarico, E.; Muzzalupo, I.; Araniti, F.; Chiappetta, A.; Bruno, L. Impact of Municipal Solid Waste Compost Amendment and Mineral Fertilization on Soil Properties and Cucumis melo L. Subsp. Melo Var. Cantalupensis Crop Quality. Agrochimica 2022, 66, 99–116. [Google Scholar] [CrossRef]
  86. Aguilar-Paredes, A.; Valdés, G.; Araneda, N.; Valdebenito, E.; Hansen, F.; Nuti, M. Microbial Community in the Composting Process and Its Positive Impact on the Soil Biota in Sustainable Agriculture. Agronomy 2023, 13, 542. [Google Scholar] [CrossRef]
  87. Guan, B.; Xie, B.; Yang, S.; Hou, A.; Chen, M.; Han, G. Effects of Five Years’ Nitrogen Deposition on Soil Properties and Plant Growth in a Salinized Reed Wetland of the Yellow River Delta. Ecol. Eng. 2019, 136, 160–166. [Google Scholar] [CrossRef]
  88. Spohn, M.; Kuzyakov, Y. Phosphorus Mineralization Can Be Driven by Microbial Need for Carbon. Soil Biol. Biochem. 2013, 61, 69–75. [Google Scholar] [CrossRef]
  89. Almási, C.; Orosz, V.; Tóth, T.; Mansour, M.M.; Demeter, I.; Henzsel, I.; Bogdányi, Z.; Szegi, T.A.; Makádi, M. Effects of Sewage Sludge Compost on Carbon, Nitrogen, Phosphorus, and Sulfur Ratios and Soil Enzyme Activities in a Long-Term Experiment. Agronomy 2025, 15, 143. [Google Scholar] [CrossRef]
  90. Li, J.; Xie, T.; Zhu, H.; Zhou, J.; Li, C.; Xiong, W.; Xu, L.; Wu, Y.; He, Z.; Li, X. Alkaline Phosphatase Activity Mediates Soil Organic Phosphorus Mineralization in a Subalpine Forest Ecosystem. Geoderma 2021, 404, 115376. [Google Scholar] [CrossRef]
  91. Sánchez-Monedero, M.A.; Mondini, C.; Cayuela, M.L.; Roig, A.; Contin, M.; De Nobili, M. Fluorescein Diacetate Hydrolysis, Respiration and Microbial Biomass in Freshly Amended Soils. Biol. Fertil. Soils 2008, 44, 885–890. [Google Scholar] [CrossRef]
  92. Razzaghi, F.; Arthur, E.; Moosavi, A.A. Evaluating Models to Estimate Cation Exchange Capacity of Calcareous Soils. Geoderma 2021, 400, 115221. [Google Scholar] [CrossRef]
  93. Vaudour, E.; Cerovic, Z.; Ebengo, D.; Latouche, G. Predicting Key Agronomic Soil Properties with UV-Vis Fluorescence Measurements Combined with Vis-NIR-SWIR Reflectance Spectroscopy: A Farm-Scale Study in a Mediterranean Viticultural Agroecosystem. Sensors 2018, 18, 1157. [Google Scholar] [CrossRef] [PubMed]
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Figure 1. Study area with the 4 treatments arranged according to a randomized complete block design. ctrl: untreated control, C8: SC-OFMSWC at 8 Mg ha−1, C16: SC-OFMSWC at 16 Mg ha−1, cf chemical ternary fertilizer at 500 kg ha−1.
Figure 1. Study area with the 4 treatments arranged according to a randomized complete block design. ctrl: untreated control, C8: SC-OFMSWC at 8 Mg ha−1, C16: SC-OFMSWC at 16 Mg ha−1, cf chemical ternary fertilizer at 500 kg ha−1.
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Figure 2. Germination rate of L. sativum, A. thaliana, and L. sativa in Petri dishes containing bibulous paper soaked with 1 mL of 30% diluted compost extract with distilled water (v/v) (tr). The results represent the mean value (±standard deviation) of 4 independent replicates. In the control (ctrl), the seeds are germinated in 1 mL of distilled water (n = 50).
Figure 2. Germination rate of L. sativum, A. thaliana, and L. sativa in Petri dishes containing bibulous paper soaked with 1 mL of 30% diluted compost extract with distilled water (v/v) (tr). The results represent the mean value (±standard deviation) of 4 independent replicates. In the control (ctrl), the seeds are germinated in 1 mL of distilled water (n = 50).
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Figure 3. Percentage of germinated seeds after 6 days and biomass production, expressed as dry weight, in A. thaliana (a,c) and L. sativa (b,d) subjected to different concentrations of compost in pots (w/w). Results represent the mean value (±standard deviation) of three independent replicates. Different lowercase letters indicate statistically significant differences at the 95% level.
Figure 3. Percentage of germinated seeds after 6 days and biomass production, expressed as dry weight, in A. thaliana (a,c) and L. sativa (b,d) subjected to different concentrations of compost in pots (w/w). Results represent the mean value (±standard deviation) of three independent replicates. Different lowercase letters indicate statistically significant differences at the 95% level.
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Figure 4. Leaf area in A. thaliana (a) and L. sativa (b) subjected to different concentrations of compost in pots (w/w). The results represent the mean value (±standard deviation) of three independent replicates. Different uppercase and lowercase letters indicate statistically significant differences at the 99 and 95% levels, respectively.
Figure 4. Leaf area in A. thaliana (a) and L. sativa (b) subjected to different concentrations of compost in pots (w/w). The results represent the mean value (±standard deviation) of three independent replicates. Different uppercase and lowercase letters indicate statistically significant differences at the 99 and 95% levels, respectively.
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Figure 5. Content of photosynthetic pigments (Chl a, Chl b, and Car) in A. thaliana (a) and L. sativa (b) subjected to different compost concentrations for twenty-one DAS. Results represent the mean value (±standard deviation) of three independent replicates. Different uppercase letters, where present, indicate statistically significant differences at the 99% level, with Chl a, Chl b, and Car analyzed separately.
Figure 5. Content of photosynthetic pigments (Chl a, Chl b, and Car) in A. thaliana (a) and L. sativa (b) subjected to different compost concentrations for twenty-one DAS. Results represent the mean value (±standard deviation) of three independent replicates. Different uppercase letters, where present, indicate statistically significant differences at the 99% level, with Chl a, Chl b, and Car analyzed separately.
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Figure 6. Soil concentrations of the four heavy metals were tested according to different treatments. Results represent the mean value (±standard deviation) of three independent replicates. Different uppercase and lowercase letters, where present, indicate statistically significant differences at the 99 and 95% levels, respectively. ctrl: untreated control, C8: SC-OFMSWC at 8 Mg ha−1, C16: SC-OFMSWC at 16 Mg ha−1, cf: chemical ternary fertilizer at 500 kg ha−1, C8+8: second dose of SC-OFMSWC at 8 Mg ha−1, C16+16: second dose of SC-OFMSWC at 16 Mg ha−1, cf2: second dose of chemical ternary fertilizer at 500 kg ha−1.
Figure 6. Soil concentrations of the four heavy metals were tested according to different treatments. Results represent the mean value (±standard deviation) of three independent replicates. Different uppercase and lowercase letters, where present, indicate statistically significant differences at the 99 and 95% levels, respectively. ctrl: untreated control, C8: SC-OFMSWC at 8 Mg ha−1, C16: SC-OFMSWC at 16 Mg ha−1, cf: chemical ternary fertilizer at 500 kg ha−1, C8+8: second dose of SC-OFMSWC at 8 Mg ha−1, C16+16: second dose of SC-OFMSWC at 16 Mg ha−1, cf2: second dose of chemical ternary fertilizer at 500 kg ha−1.
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Figure 7. Effect of treatment on microbial activity. The results represent the mean value (±standard deviation) of three independent replicates. Different uppercase and lowercase letters indicate statistically significant differences at the 99 and 95% levels, respectively. ctrl: untreated control, C8: SC-OFMSWC at 8 Mg ha−1, C16: SC-OFMSWC at 16 Mg ha−1, cf: chemical ternary fertilizer at 500 kg ha−1, C8+8: second dose of SC-OFMSWC at 8 Mg ha−1, C16+16: second dose of SC-OFMSWC at 16 Mg ha−1, cf2: second dose of chemical ternary fertilizer at 500 kg ha−1. T1 = evaluation of first application after 3 months; T2 = evaluation of second application after 3 months.
Figure 7. Effect of treatment on microbial activity. The results represent the mean value (±standard deviation) of three independent replicates. Different uppercase and lowercase letters indicate statistically significant differences at the 99 and 95% levels, respectively. ctrl: untreated control, C8: SC-OFMSWC at 8 Mg ha−1, C16: SC-OFMSWC at 16 Mg ha−1, cf: chemical ternary fertilizer at 500 kg ha−1, C8+8: second dose of SC-OFMSWC at 8 Mg ha−1, C16+16: second dose of SC-OFMSWC at 16 Mg ha−1, cf2: second dose of chemical ternary fertilizer at 500 kg ha−1. T1 = evaluation of first application after 3 months; T2 = evaluation of second application after 3 months.
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Figure 8. Correlation matrix of the principal chemical-physical and microbiological characteristics of the tested soils.
Figure 8. Correlation matrix of the principal chemical-physical and microbiological characteristics of the tested soils.
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Table 1. Characteristics of the compost from municipal solid waste.
Table 1. Characteristics of the compost from municipal solid waste.
HumiditypHOCHumic and
Fulvic C		Total NOrganic NC/N Ratio *P2O5K2OAggregate
Content **		Inert
Lithoids
(%) (%) *(%) *(%) *(% total N) (%) *(%) *(%) *(%) *
18.327.8825.1511.631.9498.7512.941.42.00.310.93
±1.11 †±0.21 †±1.78 †±2.41 †±0.33 †±8.44 †±2.27 †±0.13 †±0.10 †±0.02 †±0.09 †
EC1:2SalmonellaEscherichia coliSalinityCdCr6+HgNiPbCuZnNa
(dS/m)(in 25 g)(CFU/g)(meq/100 g)(mg/kg) *(mg/kg) *(mg/kg) *(mg/kg) *(mg/kg) *(mg/kg) *(mg/kg) *(mg/kg) *
4.81Absent ‣<25 ‣73.66<0.5<0.500.2610.833.671.02179.804385
±0.81 † ±5.04 † ±0.10 †±1.13 †±4.09 †±11.46 †±28.88 †±347 †
* dry matter; ** (glass, plastic and metals) > 2 mm; † instrumental uncertainty; ‣ 4 replicates.
Table 2. Relative seed germination (RSG), relative root growth (RRG), and germination index (GI) of L. sativum cultivated using compost extract diluted to 30% 24 h after sowing and L. sativa and A. thaliana 72 h after sowing. The results represent the mean value (±standard deviation) of three independent biological replicates.
Table 2. Relative seed germination (RSG), relative root growth (RRG), and germination index (GI) of L. sativum cultivated using compost extract diluted to 30% 24 h after sowing and L. sativa and A. thaliana 72 h after sowing. The results represent the mean value (±standard deviation) of three independent biological replicates.
SpeciesRSG (%)RRG (%)GI (%)
L. sativum99.9 ± 2.380.1 ± 7.280.0 ± 9.0
L. sativa45.2 ± 6.830.7 ± 3.413.9 ± 3.6
A. thaliana84.3 ± 3.347.9 ± 6.740.4 ± 5.8
Table 3. Soil physical and chemical properties according to treatment. The results represent the mean value (±standard deviation) of three independent biological replicates.
Table 3. Soil physical and chemical properties according to treatment. The results represent the mean value (±standard deviation) of three independent biological replicates.
TreatmentOC
(%) *		Total N
(%) *		Total P
(mg/kg)		Active CaCO3
(%) *		CEC
(cmol(+)/kg)		pHEC1:2
(dS/m)
ctrl0.41 ± 0.03 bcd0.08 ± 0.0217.15 ± 4.275.05 ± 1.03 d11.89 ± 3.338.07 ± 0.230.28 ± 0.04 bc
cf0.26 ± 0.05 e0.09 ± 0.0118.29 ± 3.618.21 ± 2.32 bcd10.40 ± 0.767.50 ± 0.370.34 ± 0.06 bc
cf20.32 ± 0.04 de0.09 ± 0.0118.63 ± 5.227.77 ± 2.52 cd8.93 ± 0.977.63 ± 0.300.21 ± 0.04 c
C80.43 ± 0.03 bc0.08 ± 0.0217.69 ± 4.5511.67 ± 3.11 abc10.42 ± 1.047.87 ± 0.210.44 ± 0.02 ab
C8+80.51 ± 0.04 ab0.10 ± 0.0119.91 ± 5.0310.14 ± 2.91 bcd10.35 ± 0.867.78 ± 0.180.45 ± 0.03 ab
C160.46 ± 0.04 bc0.08 ± 0.0118.99 ± 4.8316.46 ± 3.03 a9.47 ± 1.117.73 ± 0.220.36 ± 0.03 abc
C16+160.60 ± 0.08 a0.11 ± 0.0120.11 ± 2.3415.19 ± 2.24 ab9.15 ± 0.987.93 ± 0.310.56 ± 0.04 a
* dry matter. Different lowercase letters indicate statistically significant differences at the 95% level. ctrl: untreated control, C8: SC-OFMSWC at 8 Mg ha−1, C16: SC-OFMSWC at 16 Mg ha−1, cf: chemical ternary fertilizer at 500 kg ha−1, C8+8: second dose of SC-OFMSWC at 8 Mg ha−1, C16+16: second dose of SC-OFMSWC at 16 Mg ha−1, cf2: second dose of chemical ternary fertilizer at 500 kg ha−1.
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Rizzo, S.; Le Pera, A.; Sellaro, M.; Lombardo, L.; Bruno, L. Separately Collected Organic Fraction of Municipal Solid Waste Compost as a Sustainable Improver of Soil Characteristics in the Open Field and a Promising Selective Booster for Nursery Production. Agronomy 2025, 15, 958. https://doi.org/10.3390/agronomy15040958

AMA Style

Rizzo S, Le Pera A, Sellaro M, Lombardo L, Bruno L. Separately Collected Organic Fraction of Municipal Solid Waste Compost as a Sustainable Improver of Soil Characteristics in the Open Field and a Promising Selective Booster for Nursery Production. Agronomy. 2025; 15(4):958. https://doi.org/10.3390/agronomy15040958

Chicago/Turabian Style

Rizzo, Santina, Adolfo Le Pera, Miriam Sellaro, Luca Lombardo, and Leonardo Bruno. 2025. "Separately Collected Organic Fraction of Municipal Solid Waste Compost as a Sustainable Improver of Soil Characteristics in the Open Field and a Promising Selective Booster for Nursery Production" Agronomy 15, no. 4: 958. https://doi.org/10.3390/agronomy15040958

APA Style

Rizzo, S., Le Pera, A., Sellaro, M., Lombardo, L., & Bruno, L. (2025). Separately Collected Organic Fraction of Municipal Solid Waste Compost as a Sustainable Improver of Soil Characteristics in the Open Field and a Promising Selective Booster for Nursery Production. Agronomy, 15(4), 958. https://doi.org/10.3390/agronomy15040958

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