Technosol Construction for Sustainable Agriculture: Research Status and Prospects

Abstract

Soil health is vital for the stability of agricultural production and ecosystem functions. However, the rapid urbanization process and environmental pollution have led to a sharp reduction in available arable land and accelerated soil degradation. Meanwhile, human activities generate a large amount of waste, which needs to be treated for resource recovery to reduce its potential pollution risks to the environment. By upcycling waste to mimic pedogenesis, Technosols offer a sustainable platform for land rehabilitation, environmental remediation, carbon sequestration and greenhouse gases emission reduction. However, the wide range of waste sources and complex compositions pose challenges to the standardized construction of Technosols suitable for agricultural production. This review systematically examines the sources and characteristics of waste, current utilization status and challenges in Technosol construction, and puts forward suggestions for developing agriculture-oriented Technosols through waste-novel nanomaterial composites. Finally, critical research directions are proposed regarding the relationship between Technosol fabrication and farmland environmental effects, including the targeted design, nanomaterial-enhanced construction, ecological impact assessment, and economic efficiency of agricultural Technosols.

1. Introduction

Healthy soils form the foundation of agricultural production by providing essential water and nutrients for crop growth, playing a crucial role in maintaining food security and stable ecosystem functions [1,2]. However, accelerated urbanization and excessive resource exploitation have precipitated declining arable land quality, proliferating waste streams, and escalating environmental pollution, collectively constraining agricultural sustainability [3,4].

Technosols are soils containing over 20% artificial materials within the 0–100 cm surface layer, formed through deliberate blending of organic and inorganic wastes at specific ratios to fulfill designated purposes or meet crop growth requirements [5,6,7]. By stimulating natural pedogenic processes, Technosols can provide tailored fertility conditions for specific crop requirements, serving as effective supplements to natural farmland while offering novel pathways for soil remediation and carbon sequestration [8]. The construction of agriculturally suitable Technosols holds significant importance for advancing waste valorization, improving agroecosystem environments, and safeguarding food production security [5,9,10] (Figure 1).

The widespread sources and complex composition of waste materials required for Technosol construction pose significant challenges to standardized fabrication [11,12]. Meanwhile, the preparation protocols, formulation designs, and compatible waste valorization approaches for agriculturally suitable Technosols still require further clarification [4]. This review systematically examines: (1) primary waste sources and their characteristics relevant to agricultural Technosol development; (2) status and limitations of waste valorization practices; and (3) provides recommendations for Technosol formulation through waste-novel nanomaterial composites. Finally, critical research directions are proposed regarding the relationship between Technosol construction and farmland environmental impacts.

2. Waste Sources and Characteristics for Technosol Construction

The construction of Technosols for ecological restoration represents a transformative approach to valorize diverse waste streams through engineered soil formation (Figure 2). This process typically involves the systematic combination of selected inorganic and organic waste matrices (e.g., construction and demolition debris, mining tailings, or agricultural residues) with tailored amendments like biochar and specialized materials [6,7,11]. Biochar enhances the soil water retention, nutrient availability, and carbon sequestration capacity, while novel materials (e.g., metal oxides or clay composites) can improve structural stability, nutrient delivery, and contaminant immobilization [1,8]. Technosols are designed to match specific physicochemical and biological requirements, enabling their successful application in degraded environments including saline-alkali lands, arid deserts, and mining tailings sites [2,8,12]. Through such purposeful assembly, otherwise discarded materials are converted into functional soil media, thereby closing resource loops and mitigating environmental pressures.

This deliberate transformation aligns with a broader paradigm shift in waste management, where residues are viewed not as terminal by-products but as potential resources. Indeed, waste refers to materials generated through human activities and societal development that currently lack retained or utilizable value [12,13]. Wastes can be classified through various approaches. Based on their sources, they are primarily categorized into industrial wastes (e.g., blast furnace slag, coal slag, and construction debris), municipal solid wastes (e.g., food scraps, paper refuse, and used textiles), and agricultural wastes (e.g., crop straw, livestock manure, fruit and vegetable residues). According to their composition, wastes can be divided into organic wastes (mainly consisting of organic materials such as animal carcasses, waste plastics, waste paper, and waste fibers) and inorganic wastes (containing little to no hydrocarbons, such as scrap metal, furnace slag, and mining tailings) [6,8,14]. In the context of farming and soil improvement, certain substances traditionally classified as “organic waste” for disposal are now recast as “organic raw materials,” recognizing their resource potential. This semantic change highlights their repositioning from an environmental liability to a functional resource input for purposes like soil conditioning and nutrient provision.

Generally, Technosols suitable for agricultural application must fundamentally exhibit structural and fertility attributes comparable to arable soils, while being free from components demonstrating toxicity to humans and other organisms [15]. Organic wastes serve as essential components in Technosol construction, characterized by high organic matter content and abundant nutrients. These materials function as soil amendments that significantly enhance cation exchange capacity, water and nutrient retention capabilities, heavy metal immobilization through chelation and precipitation mechanisms [16]. Based on specific requirements of Technosol design, incorporation of inorganic wastes could effectively leverage their structural characteristics, adsorption properties, and mineral components to optimize critical soil physical parameters (e.g., porosity, bulk density), thereby meeting agricultural demands [8,17]. However, waste materials originate from diverse sources and exhibit significant variability in composition and functionality (

Table 1. Waste categories and their functions in agricultural Technosol construction.

Type	Category	Key Constituent	Effect	Description	Reference
Organic matter	Livestock and poultry waste	C, N, P, K.	+	(a) Improves soil structure and fertility, enhance water retention and holding capacity; (b) Provides essential nutrients for crops; (c) Promotes soil microbial activity.	[3,18,19]
			−	(a) Excessive or uneven application causes soil over-loosening and nutrient accumulation; (b) Causes soil salinization and heavy metal accumulation; (c) Increases soil-borne disease pressure.
	Crop straw	Cellulose, hemicellulose, lignin.	+	(a) Improves soil structure, water permeability, aeration and aggregate stability; (b) Organic acids from decomposition regulate soil pH and enhance cation exchange capacity; (c) Fuels soil biota with carbon and energy, stimulating their reproduction and diversity.	[10,20,21]
			−	(a) Inappropriate application prolongs the natural degradation period; (b) Straw decomposition initially immobilizes soil nitrogen, competing with crops for nutrients; (c) Increases soil pathogens.
	Biochar	C, P, K, Ca, Mg.	+	(a) Improves soil aeration and buffering capacity, reduces soil erosion; (b) Adsorbs or exchanges soil cations to regulate pH; (c) Provides habitats for soil organisms, reshapes microbial communities.	[22,23,24,25]
			−	(a) Excessive fine biochar particles can clog soil pores, impairing aeration and water infiltration; (b) Reduces natural degradation capacity and biological activity in soils.
Inorganic matter	Industrial and construction waste	P, K, Si, Al, Fe.	+	(a) Enhance soil porosity, water permeability and aeration; (b) The Si and Fe elements can form stable compounds with soil organic matter; (c) Provide habitats for soil biota.	[26,27,28,29,30]
			−	(a) Oversized aggregates require processing prior to use; (b) Poses potential heavy metal contamination risks.
	Mineral waste	Oxides of Ca, Mg, Si, Al, Fe, Mn.	+	(a) Coarse particles and aggregated structures enhance soil water retention and aeration; (b) Slag minerals undergo slow soil release, prolonging nutrient availability.	[14,17,31,32]
			−	(a) Excessive particle size and hardness disrupt soil structure; (b) Low in available nutrients with potential heavy metal contamination risks.
	Coal gangue and fly ash	P, K, Ca, Mg, Na, S, Fe, Mn, Zn.	+	(a) Modulates soil pH and improves soil structure (enhanced aeration and modified texture); (b) Boosts water retention and immobilizes heavy metals via high specific surface area; (c) Contains antimicrobial and pesticidal components.	[8,33,34,35]
			−	(a) Mineral particles with excessive or insufficient size fractions compromise soil tilth; (b) Low in organic nutrients and high in salinity; (c) Exhibits significant heavy metal contamination risks.
	Waste gypsum	Ca, S.	+	(a) CaSO4 in waste gypsum displaces soil cations (e.g., Na+), promoting soil aggregation, increasing porosity and aeration; (b) Effectively reduces pH in alkaline soils while supplying essential nutrients (Ca, S) for crops and microbial growth.	[36,37,38,39]
			−	(a) Excessive or uneven application may cause soil particle cementation, forming oversized aggregates; (b) Lead to undesirable texture shifts (overly clayey or sandy); (c) Contains narrow nutrient profile and toxic heavy metals.

). Therefore, judicious selection and management of waste resources based on specific requirements are essential for advancing Technosol construction.

2.1. Livestock and Poultry Waste

Animal-derived waste, primarily sourced from livestock and poultry farming (e.g., cattle manure, swine slurry, and poultry litter), are characterized by high organic matter content and nutrients. These materials serve as essential feedstocks for Technosol construction [33]. Through scientific composting techniques, animal manures can be transformed into environmentally friendly organic fertilizers that not only enhance soil fertility but also reduce reliance on chemical fertilizers, thereby mitigating agricultural pollution risks [18]. Previous studies demonstrated that appropriate manure applications could effectively reduce soil bulk density, improve soil pH, and enhance water-stable aggregates, soil organic carbon content, nutrient availability, enzymatic activity, and beneficial microbial abundance [33,40]. However, livestock and poultry manure may contain pathogens, antibiotics, and heavy metals, and improper handling or incorporation during Technosol construction could jeopardize ecosystems and human health [19].

2.2. Crop Straw

Crop straw, a major organic byproduct of agricultural production, is rich in cellulose and other organic compounds. Its decomposition contributes abundant carbon sources to Technosols, enhancing soil fertility, water and nutrient retention capacity, and microbial activity, thereby creating optimal nutritional conditions for crop growth. Studies demonstrate that straw incorporation elevates soil microbial biomass carbon and nitrogen, modifies bacterial and fungal community structure, and enhances crop productivity [10,21]. However, the effectiveness of straw incorporation depends on its particle size and application rate. Insufficient shredding or excessive amounts can prolong the natural decomposition cycle, hindering root penetration. Additionally, during the initial decomposition phase, straw may immobilize soil nitrogen, competing with crops for nutrients [20]. Additionally, improper straw pretreatment may increase soil pathogen loads, posing disease risks to crops.

2.3. Biochar

Biochar can be produced from diverse feedstocks, primarily including agricultural and forestry residues (e.g., crop straw, nut shells, wood chips), food processing byproducts (e.g., citrus peels, grape pomace), and municipal biosolids [40]. Its microporous structure and high specific surface area facilitate heavy metal immobilization, adsorption, and passivation of heavy metals and contaminants in soil [25]. Studies demonstrate that co-application of organic fertilizers and biochar in soils reduces the mobility of arsenic (As) and lead (Pb) by elevating soil pH and electrical conductivity, thereby decreasing their accumulation in crop roots [23,41]. Notably, the heavy metal adsorption capacity of biochar varies significantly depending on feedstock types. instance, biochar derived from oak bark pith and bamboo exhibits superior Pb adsorption, whereas rice husk-swine manure co-pyrolyzed biochar effectively immobilizes cadmium (Cd), copper (Cu), Pb, and zinc (Zn) in soils [22,42]. Qu et al. (2021) demonstrated the potential of biochar for topsoil carbon sequestration during wetland remediation [43]. Furthermore, Yang et al. (2021) revealed that biochar can significantly reduce emerging contaminants (e.g., antibiotics and antibiotic resistance genes) in livestock manure, providing a scientific approach for safe agricultural waste utilization and Technosol development [24]. While biochar is a promising soil amendment, its application is not without potential drawbacks, primarily stemming from a mismatch between its properties and specific soil–plant systems [40]. The potential drawbacks of biochar application center on its high adsorption capacity, which may lead to the short-term immobilization of essential plant nutrients such as NH₄⁺, K⁺, and PO₄³⁻, thereby reducing their bioavailability [23]. Beyond nutrient dynamics, alkaline types of biochar risk excessively elevating soil pH in neutral or alkaline environments, a change that can induce micronutrient deficiencies [25,27]. Furthermore, there is a risk of introducing pollutants; biochar derived from contaminated feedstocks like sewage sludge or treated wood may carry and concentrate heavy metals or persistent organic pollutants, including polycyclic aromatic hydrocarbons (PAHs) [2,24]. Finally, the physical and biological impacts must be considered, as fresh or low-temperature biochar can exhibit hydrophobicity that impairs soil wettability, while also potentially causing transient disruptions to soil microbial community structure and function [4,27]. Therefore, safe and effective use of biochar requires source control (clean feedstocks, optimized pyrolysis), context-specific application (matching biochar properties to soil constraints), and integrated management (e.g., co-application with fertilizers) to mitigate risks and realize its long-term benefits [22,23].

2.4. Industrial and Construction Waste

With rapid societal development, the continuous expansion of urban construction and redevelopment projects has generated substantial industrial and construction waste (e.g., excavated soil, slurry, concrete, and steel slag), whose improper disposal poses significant environmental risks [1,44]. Conventional treatment methods for industrial and construction wastes include landfilling and road construction, and these wastes have recently been found to hold potential value in Technosol fabrication. Pruvost et al. (2020) and Abbruzzini et al. (2022) reported that Technosols fabricated through controlled blending of concrete, green compost, biochar, and subsoil significantly enhance soil porosity while accelerating organic matter decomposition rates, enzymatic activity, and biodiversity [26,27]. Deus et al. (2020) demonstrated that steel slag serves dual functions as both a fertilizer and soil acidity amendment, effectively raising the pH in acidic soils while reducing Al³⁺ concentration and enhancing the availability of P, Si, and other essential nutrients [45]. Meanwhile, trace elements such as silicon, aluminum, and iron contained in industrial and construction waste can combine with soil organic matter to form stable compounds, which not only enhance soil fertility but also provide a favorable habitat for soil biota [28,30]. However, the excessively large granularity and high hardness of industrial and construction wastes can compromise Technosol structural integrity, while concurrently posing contamination risks from heavy metals (e.g., Cr, Ni, Pb) that threaten soil health [29].

2.5. Mineral Waste

Mineral waste refers to materials of little or no economic value generated during mining, smelting, and mineral processing operations, mainly including waste rock, tailings, and slag. In the process of creating Technosols based on mineral wastes, long-term application of appropriate fertilization and planting practices facilitates the formation of a humus-rich soil layer, while effectively improving bulk density, water retention capacity and structural stability [17]. For example, Technosols developed by combining limestone waste with tropical forage grass cultivation exhibit a near-neutral pH and higher Ca, Mg, and P content than natural soils. These soils not only supply essential nutrients for plant growth but also effectively restore the degraded soil layers around mining sites that have lost functionality due to extractive activities [32]. Furthermore, Technosols constructed from carbonatite and serpentine-magnesium mining wastes can continuously supply mineral nutrients to plants while significantly reducing soil acidity and the toxicity of heavy metals such as Cu and Ni. This approach provides a viable technical solution for land reclamation, degraded soil remediation, and vegetation restoration [14,31].

2.6. Coal Gangue and Fly Ash

Coal gangue and fly ash, two typical coal-based inorganic wastes generated during coal utilization, are primarily composed of silica, alumina, and other mineral compounds. These materials can supplement secondary and trace elements in soils, while their porous and friable physical properties effectively improve soil structure by enhancing aeration and water permeability, demonstrating significant potential for soil remediation [33]. Coal gangue exhibits high specific surface area, endowing it with excellent water absorption, retention, and pH buffering capacities, along with the ability to immobilize heavy metals [8]. When combined with other materials or water-retaining agents in Technosol fabrication, coal gangue further enhances moisture and nutrient retention [8]. Fly ash, predominantly consisting of silicates, aluminosilicates, and other minerals, can elevate soil pH and increase plant-available silicon content while promoting the transformation of acid-exchangeable cadmium into reducible fractions. Its remarkable adsorption and ion exchange capabilities make it an efficient soil amendment for ecological restoration of acidic and saline-alkali soils [34,35].

2.7. Waste Gypsum

During industrial processes such as flue gas desulfurization in coal-fired power plants and the phosphorus chemical industry, gypsum waste is generated, which is primarily composed of calcium carbonate and contains small amounts of phosphates, fluorides, and heavy metal residues [36,38]. Previous studies indicated that waste gypsum plays a significant role in soil pH regulation. Wu et al. (2020) investigated the effects of flue gas desulfurization (FGD) gypsum application on alkaline desert soils in the Sangong River Basin, Fukang, Xinjiang, and found that applying FGD gypsum at 30 t·ha⁻¹ significantly reduced soil alkalinity and enhanced soil carbon sequestration potential [39]. Tao et al. (2021) added phosphogypsum to an area contaminated with bauxite residue and observed decreases in soil pH, electrical conductivity, and exchangeable sodium ion content, along with an increase in the mean aggregate diameter to 193 nm [46]. Li et al. (2019) further reported that incorporating 1.50 wt% phosphogypsum into bauxite-processing red mud reduced the pH from 10.83 to 8.70 after 91 days, achieving a free alkali removal rate of 97.94% and an exchangeable sodium removal rate of 75.87% [37]. Additionally, phosphogypsum application promoted aggregate formation, increased surface Ca²⁺ content, and decreased Na⁺ and Al³⁺ concentrations, thereby accelerating the soil formation process in red mud. These findings provide valuable insights into the resource utilization of waste gypsum for land reclamation in mining areas, alkaline soil remediation, and ecological restoration [37].

3. Issues in Waste Utilization During the Technosol Construction

3.1. Soil Degradation

The properties and proportions of waste materials significantly influence the texture characteristics of Technosols, while improper addition may lead to soil degradation. For example, pig manure and cow dung contain higher levels of phosphorus and potassium compared to common minerals and straw; however, excessive application of these composts can lead to significant accumulation of phosphorus and potassium in the soil, causing problems such as soil salinization and compaction [18,47]. Additionally, the use of excessively fine biochar particles during the construction of Technosols may clog soil pores, impairing soil aeration and water permeability, and inhibiting microbial growth [42]. Furthermore, when incorporating inorganic waste materials (e.g., limestone slag), excessively high coarse particle content and hardness can disrupt the structure of Technosols, impairing soil water conductivity, retention capacity, and stability, thereby restricting crop growth [6,29].

3.2. Pest and Disease Risk

During the construction of Technosols, the treatment process is a critical factor influencing the risk of pests and diseases. Animal-derived waste materials, primarily livestock and poultry manure, can be directly applied to soil to enhance fertility after treatments such as composting fermentation. However, incomplete treatment may retain pathogens and parasite eggs, posing potential environmental risks [19]. Studies have indicated that direct application of manure and plant residues may increase the abundance of pathogens in soil and promote weed growth, thereby threatening soil health [21,24,48] Improper straw incorporation practices alter the patterns of crop diseases and pests, leading to significantly higher incidence rates in crops such as rice and wheat, with soil-borne and seed-borne diseases showing an increasing trend annually [48]. Sludge may also contain trace pathogens, although sediment and sludge-peat mixtures exhibit considerable carbon sequestration capacity [49,50]. Therefore, optimizing and innovating waste pretreatment processes is essential to mitigate pest and disease risks in the construction of Technosols.

3.3. Heavy Metal Pollution

The construction of Technosols poses a potential risk of heavy metal contamination. During the resource utilization of inorganic wastes (e.g., construction and industrial residues), improper handling of chromium, nickel, lead, and other heavy metals may lead to their migration into the soil through weathering or leaching processes, resulting in excessive heavy metal concentrations in the soil [29,51]. Furthermore, during ecological restoration using abandoned tailings, attention must be paid to the presence of multiple heavy metal contaminants in the matrix (e.g., lead, cadmium, mercury, copper, and zinc found in coal mine, pyrite, and pyrrhotite tailings). These residual heavy metals may migrate into surrounding soil and water bodies through processes such as rainwater leaching and surface runoff, causing environmental pollution. Therefore, in mine restoration, it is essential not only to control the heavy metal content in the remediation materials but also to address the persistence of heavy metals in the tailings to prevent secondary contamination [25,51].

3.4. Antibiotic Residues

Veterinary feed additives are widely used in animal husbandry to enhance growth performance, feed efficiency, and product quality. However, animals cannot fully absorb antibiotics present in feed, leading to the persistence of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) in livestock manure. Some antibiotics enter the environment in their original form or as metabolites [52,53,54]. Furthermore, residual heavy metal ions (e.g., copper, zinc) in manure and the environment can complex with antibiotic molecules (such as tetracyclines), promoting the dissemination of contaminants and their bioaccumulation through the food chain, thereby posing potential risks to environmental and human health [55,56,57].

3.5. Lack of Economic Viability

The economic feasibility of constructing Technosols is influenced by multiple factors, including raw material costs, processing expenses, and practical efficacy. From the perspective of raw materials, waste resources of different origins and compositions exhibit varying potential for Technosols construction due to differences in their effects and economic efficiency. Chen et al. (2020) [58] compared the effects of three types of organic wastes and biochar-based compound fertilizers on enhancing soil aggregate stability and organic carbon content in Northeast China. They found that although the material costs of corn straw and pig manure compost were lower than those of biochar, their improvements in soil structure were inferior to those achieved with biochar-based compound fertilizers. Furthermore, studies on wheat–soybean rotation and rice cropping systems indicated that long-term sole application of farmyard manure could increase soil phosphorus content, but its effect on crop yield plateaued after reaching a certain level. Thus, scientific fertilization standards are necessary to avoid resource waste and cost escalation [10]. Xie et al. (2021) [59] conducted a study on the amelioration of alkaline soil using sewage sludge biochar (SSB) at various application rates of 0 kg/hm², 1500 kg/hm², 4500 kg/hm², and 9000 kg/hm². They found that when applying 1500 kg/hm² of SSB, the dry weight of corn kernels increased from 32.11 g in the control group (0 kg/hm²) to 35.07 g, representing a 9.2% increase in yield. This indicates that the application of an appropriate amount of sewage sludge biochar in alkaline soils can significantly enhance corn production.

4. Application of Novel Nanomaterials in the Construction of Technosols

The construction of Technosols has conventionally relied on the strategic combination of bulk organic and inorganic wastes (e.g., construction debris, industrial by-products, composted biosolids) to engineer soils with target physical and chemical properties [3,12]. This established paradigm focuses on overcoming fundamental limitations such as poor structure, low nutrient status, or contamination [24,32,49]. Building upon this foundation, recent research trends have evolved towards the intentional incorporation of novel amendments to impart specific functionalities or enhance soil formation processes [9,28]. New materials refer to those developed through innovative design, advanced processes, or specialized equipment, which exhibit superior properties and specific functions unmatched by conventional materials. In the construction of Technosols, these materials demonstrate diverse application potential, including the improvement of soil physicochemical properties, enhancement of fertility, remediation of heavy metal contamination, and removal of organic pollutants [60]. Such materials can compensate for the functional limitations of conventional wastes, thereby providing expanded technical pathways and solutions for developing agricultural Technosols (

Table 2. Categories and functions of novel nanomaterials for the construction of agricultural Technosols.

Category	Property	Function	References
Nanozymes	(a) High catalytic efficiency and stability; (b) Robust stability across varied conditions.	(a) Enhances crop salt tolerance through osmotic and ionic regulation; (b) Reduces heavy metal bioavailability and mobility; (c) Promotes nutrient acquisition and overall crop resilience.	[64,65,66,67]
Nano-Hydroxyapatite	(a) Apatite-like structure; (b) Nanoscale-derived properties: high surface area, good dispersibility, and strong adsorption.	(a) Effectively retains heavy metals and volatile organic compounds; (b) Mitigates contamination risk by converting bioavailable heavy metals (e.g., Pb, Cd) into more stable, residual forms.	[68,69,70,71]
Nanocarbon	(a) Large specific surface area; (b) High total organic carbon content; (c) Rich in aromatic structures, oxygen-containing functional groups, and inorganic compounds (e.g., carbonates, aluminosilicate minerals).	(a) Modulates soil pH and enhances soil properties; (b) Immobilizes heavy metals (through binding/precipitation), reducing their phytoavailability; (c) Captures volatile organic compounds.	[72,73,74]
Nanoscale zero-valent iron	Large surface area enables rapid pollutant degradation.	(a) Detoxifies heavy metals in soil by reducing them to less mobile states; (b) Purifies wastewater by adsorbing and reducing both heavy metals and organics.	[9,75,76,77]
Nano-titanium dioxide	(a) Excellent photocatalytic activity via generation of highly oxidative radicals under light; (b) Outstanding chemical stability.	Photogenerated free radicals degrade soil pollutants (e.g., PAHs, petroleum hydrocarbons) into harmless substances for remediation.	[78,79,80]

) [61]. Within this context, nanomaterials have emerged as a promising frontier, offering unique physico-chemical properties that could precisely modulate nutrient dynamics, pollutant immobilization, and microbial ecology at a finer scale [8,62,63].

4.1. Nanozyme

Urbanization has led to the release of large quantities of pollutants into the environment, posing threats to ecosystem health. Although natural enzymes are currently used for efficient monitoring and removal of environmental pollutants, their high production costs and limited stability under varying operational conditions remain major drawbacks [67]. Nanozymes, a class of inorganic nanomaterials with enzyme-like catalytic activity, can mimic the active sites and mechanisms of natural enzymes. They exhibit not only high catalytic efficiency but also robust stability across a broad range of temperatures and pH levels [64,66]. In saline-alkali soil remediation, inorganic nanozymes can regulate soil ion concentration and osmotic pressure through catalytic activity, alleviating salt stress on crop roots and thereby maintaining normal cellular physiological functions to support crop growth [76]. Under drought or waterlogging stress, nanozymes may participate in regulating plant water metabolism, enhancing crop adaptability to water-related adversities. For heavy metal-contaminated soils, inorganic nanozymes can interact with metal ions to reduce their bioavailability and toxicity, while also promoting the uptake of essential nutrients and strengthening crop stress resistance [64,65,67]. In summary, the broad applicability of nanozymes offers diverse solutions for soil remediation and environmental management based on the construction of Technosols.

4.2. Nano-Hydroxyapatite (nHA)

Heavy metal pollution, such as lead, cadmium, and arsenic, is commonly found in intensive agricultural areas, tailing restoration sites, and alkaline soils, representing a widespread concern as typical soil contaminants. These pollutants tend to accumulate in crops, thereby posing risks to human health through the food chain [69,81]. The surface functional groups (e.g., hydroxyl and phosphate groups) of nano-hydroxyapatite (nHA) can form stable chemical bonds with heavy metal ions, effectively immobilizing metals such as lead, cadmium, copper, and zinc in the soil through mechanisms including surface adsorption, ion exchange, and chemical precipitation. This process significantly reduces the bioavailability and mobility of heavy metals [69,70]. Studies have shown that nHA not only improves soil physicochemical properties but also reduces heavy metal accumulation in crops such as soybeans and wheat, while simultaneously promoting plant growth [68,71].

4.3. Nanocarbon

As a new material, nanocarbon has been widely used in pharmaceutical preparation, new energy, and ecological restoration. With in-depth exploration of its properties, the application of nanocarbon in agriculture is becoming a new research focus [73]. Studies have shown that nanocarbon amendment can significantly enhance soil water retention capacity, increase soil porosity and nutrient availability in arid and semi-arid regions, thereby promoting plant growth [73,74]. Graphene, a typical nanocarbon material, consists of a two-dimensional honeycomb lattice of single-layer carbon atoms. Its addition can alter soil microbial community structure and increase the abundance of metal-reducing bacteria (e.g., Bacillus, Desulfuromonas), thereby improving the bioavailability of dissolved organic matter in the bioreduction of iron [72]. However, this material may also promote the release of arsenic and iron from contaminated soils. Experiments indicate that after adding reduced or oxidized graphene acetate, arsenic release increased by 1.37-fold and 1.15-fold, respectively, while iron release increased by 1.40-fold and 1.24-fold, respectively. Increased arsenic release may lead to environmental arsenic concentrations exceeding safety thresholds, posing risks to ecosystems and human health; increased iron release may alter soil pH through redox reactions, potentially causing soil acidification or alkalization [72,82].

4.4. Nanoscale Zero-Valent Iron (nZVI)

Nanoscale zero-valent iron (nZVI) refers to metallic iron particles with a size range of 1–100 nm, typically composed of a zerovalent iron core surrounded by an iron oxide/hydroxide shell. It exhibits strong reducibility, high adsorption capacity, low solubility, good biodegradability, and low toxicity, showing broad application potential in the removal of heavy metals, organic pollutants, and radioactive elements from soil [75,76]. In the regeneration of degraded soil and remediation of contaminated soil, an artificial amendment composed of 3% nZVI synthesized from plant extracts and 97% iron-rich soil has been shown to effectively immobilize heavy metals [9]. Furthermore, as an efficient catalyst, nZVI plays a key role in activating various oxidants and has been widely used in the remediation of contaminated sites, such as polluted soil and water bodies [75,77].

4.5. Nano-Titanium Dioxide (Nano-TiO₂)

As a widely used nanomaterial, nano-titanium dioxide (nano-TiO₂) can significantly improve the physical and chemical properties of soil. Studies have shown that low doses of nano-TiO₂ can increase the content of available nitrogen, phosphorus, copper, iron, manganese, and other nutrients in soil, while also promoting microbial growth and enhancing enzyme activity [79,80]. In addition, nano-TiO₂-based photocatalytic technology can effectively degrade polycyclic aromatic hydrocarbons, pesticides, aromatic compounds, and petroleum-based pollutants in soil. It can also reduce highly toxic hexavalent chromium to less toxic trivalent chromium through photocatalytic reduction, thereby mitigating its environmental risk [78].

5. Agroecological Impacts of Technosol Application

The application of Technosols represents a paradigm shift in sustainable land management, where engineered soils are strategically designed to restore degraded ecosystems and support agricultural productivity [28,31]. Technosols offer a multifunctional platform that integrates agronomic, environmental, and economic benefits (Figure 3). Their tailored design, often incorporating industrial by-products, organic amendments, and structural materials, enables the remediation of problematic soils while simultaneously enhancing key soil functions [4,25,27]. These functions include improved nutrient cycling, water retention, and habitat provision, which collectively contribute to enhanced agroecological performance and resource efficiency [2,20,28]. It reflects the proactive design logic fundamental to Technosols, which moves beyond mere waste utilization toward the intentional engineering of soil systems with targeted properties and services [49,51].

5.1. Soil Property Improvement and Carbon Sequestration Potential

Organic amendments, such as those produced from crop straw, biochar, and manure, are widely used in soil improvement, mine restoration, and Technosol construction. These amendments significantly enhance soil porosity, water retention, aggregate stability, and organic carbon content, thereby improving soil quality and fertility [1,44,83]. Studies on black soils have demonstrated that applications of woody/herbaceous plant materials and composted livestock/poultry manure positively influence soil structure and organic carbon accumulation [3]. Among these, woody plant materials are considered optimal due to their ability to enhance particulate organic carbon stability and promote soil organic carbon sequestration [10]. In wetland reclamation studies, straw-derived amendments, compost, and biochar improved soil physical properties (e.g., porosity, aggregates, and structure), with biochar showing the greatest enhancement in topsoil carbon sequestration rate and aggregate stability, while compost provided additional benefits for soil ecosystem function and productivity [43]. However, long-term excessive application of farmyard manure may lead to phosphorus pollution risks and is unsustainable despite short-term yield increases [18].

Inorganic wastes, characterized by their porous and loose structure, offer unique advantages in improving soil aeration and water retention. Application of steel slag and lime in no-till systems increased soil pH, reduced Al³⁺ concentration, and enhanced base saturation, with effects remaining stable for 1–2 years; steel slag additionally supplied phosphorus and silicon [45]. In mine restoration studies, Technosols constructed from coal tailings supplemented with rice husk and rice husk ash optimized soil particle arrangement and pore connectivity, significantly enhancing drainage and aeration [12].

In summary, tailoring the composition of Technosols allows for effective regulation of soil pH, base saturation, and structure, while promoting carbon sequestration, with outcomes varying across climates, farming practices, and soil conditions. However, many studies have short evaluation periods and insufficient assessment of heavy metal and organic pollutant accumulation in plants [51,84]. Thus, long-term effects of amendments on soil quality, crop yield, and their interactions require further investigation.

5.2. Soil Biological Activity

Soil microorganisms serve as the primary drivers of nutrient transformation and cycling, representing a key biological indicator for assessing soil quality. Microbial inoculants possess the dual function of managing plant nutrient supply and protecting soil health [85]. The application of organic wastes provides abundant carbon sources and polysaccharides to support microbial growth and activity [86]. For instance, biochar derived from wheat straw, rice husk, pig manure, and oyster shells, when applied as a soil amendment, enhances soil fertility and stimulates microbial activity [87]. Research has demonstrated that straw incorporation significantly alters the soil microbial community structure. Specifically, groups such as Firmicutes, Bacteroidetes and Proteobacteria are closely linked to decomposition rates, thereby enhancing the overall efficiency of straw breakdown [73]. However, the improper application of animal and plant wastes during Technosol construction poses a potential risk of introducing pathogens into the soil system [49]. Mitigation strategies span the entire lifecycle, beginning with the pre-treatment of raw wastes through thermophilic composting or anaerobic digestion to eliminate pathogens [10,11]. Subsequently, intelligent Technosol design can incorporate reactive amendments (e.g., specific biochars) and foster competitive microbial communities to create suppressive soil matrices. Finally, a post-construction curing period combined with monitoring of key hygiene indicators (e.g., fecal coliform levels) provides an essential barrier for managing residual risks in sensitive applications. Further investigation is also needed to elucidate how microbial activity dynamically influences the evolution of soil fertility over the long term and its sustained effects on subsequent crop suitability and productivity.

Soil enzymes play a critical role in ecosystem functioning by regulating the metabolism of organic and inorganic components and participating in various biochemical processes, making them effective indicators of soil health [88,89]. Common soil enzymes include oxidoreductases, hydrolases, lyases, and transferases. Among them, urease and phosphatase (both hydrolases) reflect soil fertility levels: urease, primarily derived from root exudates and microorganisms, can be enhanced through organic fertilizer application; phosphatase activity is positively correlated with soil available phosphorus content [90]. Long-term application of organic wastes such as manure (e.g., pig and cattle manure) increases available phosphorus, thereby boosting phosphatase activity [18]. Additionally, manure application can enhance the activities of sucrase and catalase [3]. In cellulose degradation, β-glucosidase plays a vital role by providing monosaccharides to soil microorganisms, improving the decomposition efficiency of cellulose-rich wastes like straw and plant residues. Furthermore, enzymes such as β-glucosidase and acid phosphatase are involved in plant-fungal symbiotic relationships, where they facilitate nutrient and water uptake by forming specialized structures around root tips, thereby enhancing plant health [90].

The selection of raw materials for Technosols is a critical factor influencing soil biological activity (microorganisms and enzymes). Organic amendments (e.g., compost, biochar) primarily serve as direct sources of carbon and energy, generally stimulating microbial biomass and the activity of key nutrient-cycling enzymes [3,20,22,23]. Inorganic matrices (e.g., construction wastes) exert indirect effects by altering the physical habitat, where properties like porosity and pH can constrain or favor specific microbial communities and processes [8,17,26,30,31]. Additionally, reactive additives (e.g., clays, minerals) often induce targeted, non-linear effects by concentrating or immobilizing substrates and cells [15,49]. Crucially, the net biological outcome arises from the interaction of these components within the composite mixture, a complexity that current empirical patterns can describe but not yet mechanistically predict. Future research should focus on uncovering the underlying mechanisms through which additives regulate microbial and enzymatic activities to drive material cycling and energy flow within soil ecosystems.

5.3. Crop Growth Response

Technosols can significantly enhance soil pH, organic carbon content, nutrient levels, and nutrient availability, thereby synergistically improving crop yield and quality [91,92]. The strategic selection of raw materials can effectively suppress heavy metal uptake by crops, reducing risks associated with their transfer through the food chain [38,93]. For instance, studies have shown that biochar produced from single-biomass pyrolysis, when applied at a 0.5% dosage, exerts significant positive effects on soil fertility and microbial biomass. It not only increases the biomass of Chinese cabbage and its leaf vitamin C content but also reduces nitrate and heavy metal accumulation [87]. In the remediation of a heavy metal-contaminated site in Europe, the combined application of biochar and compost enhanced soil fertility, reduced toxicity, promoted the growth of Salix psammophila, and alleviated stress-induced changes in leaf pigment content and root guaiacol peroxidase activity [94]. In another study, zeolite synthesized from fly ash via a simplified hydrothermal process and other novel materials were applied to cadmium-contaminated paddy fields. The results indicated that rice yields increased by 36.1% and 29.8% in the first year, and by 35.9% and 31.7% in the second year, respectively, with the materials demonstrating effective cadmium immobilization. However, the long-term impact of these novel materials on contaminated soil and the synergistic effects among cadmium and other heavy metals require further investigation [95]. In the restoration of abandoned metal mining sites, the application of amendments such as compost, biochar, zeolite, and limestone resulted in a 100% survival rate of millet grass. Among these, compost provided a high nitrogen concentration, limestone effectively raised soil pH, and zeolite regulated the balance of exchangeable ions [96]. In summary, the selection of raw materials for Technosols directly governs soil nutrient status and ultimately influences crop yield and safety quality. Therefore, ensuring the environmental stability of these materials while optimizing their yield-enhancing and safety-assuring functions represents a critical direction for future research [38,97].

5.4. Soil Pollution Remediation

An estimated 33% of global soils are degraded due to human activities such as mining, industrial production, and agriculture, leading to issues including acidification and heavy metal contamination [2,39]. Soil amendments derived from biochar and organic/inorganic wastes have been widely studied for remediation. A three-year field trial in a pyrite mining area (Ferralsol, acidic soil) demonstrated that the combined application of biochar and soda residue is an economically viable strategy. This approach reduced heavy metal bioavailability, increased maize yield, decreased Pb and Cd concentrations in grains, enhanced soil organic carbon, and contributed to carbon sequestration [97,98]. Another study utilized biochar from rice straw, wood chips, and coconut shells, modified with nitric acid-potassium permanganate, for soil remediation. The modified biochar increased soil pH, improved soil structure (e.g., specific surface area and porosity), and significantly enhanced heavy metal adsorption capacity, with modified coconut shell biochar showing the best passivation effect for Pb and Cd over the long term [99]. However, biochar derived from tree bark, while reducing Pb accumulation in plant roots, exhibited limited arsenic (As) adsorption due to its lower surface area and total pore volume [94].

Inorganic wastes such as steel slag, iron furnace slag, lime, and construction and demolition waste can also be used in constructing Technosols, significantly reducing the availability of pollutants like Pb, Zn, and Cu [51]. Beyond conventional materials, nanomaterials can immobilize heavy metal ions through adsorption, ion exchange, and surface complexation, and can catalytically degrade organic pollutants. For instance, biochar-supported sulfidized nanoscale zero-valent iron effectively immobilized Cd in contaminated paddy soil; adding 3% of this material significantly reduced the bioavailable Cd concentration from 14.99 mg·kg⁻¹ to 9.9 mg·kg⁻¹, achieving an immobilization efficiency of 33.3% [100]. Although existing research provides valuable insights for heavy metal passivation and removal, the long-term stability, biosafety, and scalability of these amendment materials require further systematic investigation.

6. Conclusions and Future Research Perspectives

With the accelerated progression of global urbanization, the demand for food, water, energy, land, and mineral resources continues to increase. Large-scale and unsustainable exploitation and utilization of natural resources have led to significant waste accumulation, exacerbating land degradation and pollution issues [101]. Technosols, defined as soils dominated by human-made materials or significantly influenced by anthropogenic activities, provide a crucial technological pathway for land reclamation, ecological soil restoration, and waste resource recovery [5,15]. The most immediate vision for Technosols lies in transitioning from a problem-solving to a service-providing paradigm within the circular economy [100,102]. This entails the deliberate design of soil recipes to deliver specific ecosystem services (such as carbon sequestration, urban cooling, or pollutant immobilization) by selecting appropriate waste-derived components based on their intrinsic properties [5,25,49]. Establishing clear linkages between target services, Technosol functions and optimized waste material streams will be crucial. However, numerous uncertainties and challenges remain regarding the formulation and application of Technosols for agricultural purposes (Figure 4). Future research should focus on the following key areas:

(1)

Targeted design of Technosols for agricultural applications. Conduct systematic research on the agricultural suitability of diverse waste materials. Develop targeted Technosols formulations to address specific soil issues (e.g., nutrient deficiency, heavy metal/organic pollution, salinization) and application contexts (e.g., tailings reclamation, desert restoration, urban soil rehabilitation). Optimize raw material pretreatment and mixing ratios to balance nutrient supply and soil physical structure [102]. Integrate techniques such as straw incorporation, green manure cultivation, and humic-promoting agents to shorten soil maturation cycles. Establish a coordinated “urban-industrial-agricultural” waste utilization chain, promote standardization of Technosols in agriculture, and formulate supportive policies to enhance ecological compensation and land restoration incentives.

(2)

Construction technologies and efficacy of novel nanomaterial-enhanced Technosols. Develop novel materials capable of passivating, adsorbing, or degrading pollutants to mitigate their translocation risks in soil-crop systems. Investigate the dispersion stability and mechanisms of materials like nano-hydroxyapatite and graphene in soils, focusing on their effects on nutrient release and microbial activity. Enhance nutrient retention and erosion resistance of Technosols through chemical modifications. Explore stimuli-responsive materials (e.g., thermo-/photo-sensitive hydrogels, shape-memory polymers) for adaptive regulation of soil aeration and water retention. Design stratified functional systems for Technosols with surface evaporation suppression, rhizosphere microbiome activation, and deep-layer pollutant immobilization. The environmental application of nanomaterials must address two intertwined challenges: their potential mobility in porous soils and the difficulty of achieving uniform dispersion at scale. In sandy or highly permeable soils, nanoparticles risk leaching or uptake by biota. This could be mitigated by immobilization strategies such as surface functionalization for strong soil binding, encapsulation within stable matrices (e.g., biochar), or in situ synthesis to create fixed reactive sites. Concurrently, the pursuit of perfect pore-scale homogeneity is being replaced by pragmatic delivery methods for functional efficacy. These include using granular composite carriers for mechanical spreading, creating targeted treatment zones (e.g., reactive barriers), and employing improved mixing techniques to ensure predictable nanoparticle performance in field-scale applications without requiring uniform dispersion.

(3)

Ecological effects and application assessment of agricultural Technosols. Integrate soil biome and microbiome design into Technosols construction to evaluate changes in soil biodiversity and functionality. Introduce functional microorganisms to accelerate soil network formation and assess their impacts on soil health and crop growth. Establish dynamic monitoring systems to study key nutrient cycles and long-term pollutant release patterns in reclaimed soils, evaluating risks to the food chain. Develop low-carbon Technosols technologies to enhance ecosystem services, carbon sequestration, and emission reduction potential.

(4)

Economic efficiency enhancement of agricultural Technosols. Utilize localized waste resources based on regional natural endowments to reduce transportation costs and associated environmental risks. Conduct comprehensive economic feasibility assessments, including life cycle analysis (LCA) to quantify energy consumption and carbon footprints from material production to waste recycling. Cultivate high-value cash crops within ecological safety thresholds to maximize overall economic benefits. Formulate engineering application specifications to support scalable implementation under varying scenarios (e.g., heavy metal-contaminated farmland, desertified land). The scalability of nano-enabled agriculture hinges on economic viability. While precision nanomaterials can be costly, research into low-cost synthesis routes is mitigating this barrier. Notably, green synthesis using plant extracts or agricultural waste provides an economical and sustainable alternative to conventional chemical synthesis. Furthermore, the direct use of engineered waste streams (e.g., nano-structured biochar from crop residues, mineral nano-by-products from industry) aligns nanotechnology with circular economy models, transforming low-value waste into high-value soil amendments. A full techno-economic assessment that accounts for reduced input costs (e.g., fertilizers) and enhanced crop resilience is needed to accurately evaluate the net benefit of these nano-formulations at scale.