Impacts of Tillage on Soil’s Physical and Hydraulic Properties in Temperate Agroecosystems

Abstract

Tillage practices critically influence soil’s physical properties, which are fundamental to sustainable agriculture in temperate climates. This review evaluates how conventional tillage (CvT; e.g., moldboard and chisel plowing), reduced tillage (RT), and conservation tillage (CT), particularly no-tillage (NT), affect six key indicators: bulk density (BD), saturated hydraulic conductivity (Ks), wet aggregate stability (WAS), penetration resistance (PR), available water capacity (AWC), and soil organic carbon (SOC). Special emphasis is placed on differentiating topsoil and subsoil responses to inform climate-resilient land management. A total of 70 peer-reviewed studies published between 1991 and 2025 were analyzed. Data were extracted for BD, Ks, WAS, PR, AWC, and SOC across tillage systems. Depths were standardized into topsoil (0–10 cm) and composite (>10 cm) categories. Descriptive statistics were used to synthesize cross-study trends. NT showed lower mean BD in the topsoil (1.32 ± 0.08 Mg/m³) compared with moldboard plow (1.33 ± 0.09) and chisel tillage (1.39 ± 0.12); however, the effects of tillage on BD were not statistically significant, while BD was higher at composite depths under NT (1.56 ± 0.09 Mg/m³), indicating subsoil compaction. Ks improved under NT, reaching 4.2 mm/h with residue retention. WAS rose by 33.4%, and SOC increased by 25% under CT systems. PR tended to be elevated in deeper layers under NT. Overall, CT, particularly NT, improves surface soil’s physical health and SOC accumulation in temperate agroecosystems; however, persistent subsoil compaction highlights the need for depth-targeted management strategies, such as controlled traffic, periodic subsoil alleviation, or deep-rooted cover crops, to sustain long-term soil functionality and climate-resilient production systems.

1. Introduction

The escalating global challenges of climate change, population growth, and worsening soil degradation underscore the urgent need for sustainable agricultural practices, particularly in temperate regions [1,2,3,4]. Temperate regions, which are characterized by distinct seasonal variations, play a vital role in global food production [5,6,7]. These regions face unique challenges in balancing the demands of agricultural productivity with the imperative to maintain soil health and ecosystem services [3,4]. Among the diverse soil management practices employed in agriculture, tillage remains one of the most significant factors influencing soil’s physical properties [8,9]. Its effects ripple through key soil attributes such as bulk density (BD), saturated hydraulic conductivity (Ks), wet aggregate stability (WAS), available water capacity (AWC), penetration resistance (PR), and soil organic carbon (SOC), directly impacting both crop productivity and environmental sustainability [10].

Historically, tillage has been widely employed for seedbed preparation, weed control, and soil aeration. However, these benefits come with trade-offs that include soil compaction, reduced organic matter content, and increased susceptibility to erosion, particularly under conventional tillage (CvT) systems. These trade-offs are exacerbated in temperate climates, where freeze–thaw cycles, precipitation variability, and temperature fluctuations influence soil dynamics and agricultural decision-making [8,11]. Consequently, understanding the nuanced effects of different tillage systems, including no-tillage (NT) and reduced tillage (RT), on soil’s physical properties is essential for developing region-specific, sustainable agricultural practices.

Emerging research highlights the potential of conservation tillage (CT) practices in mitigating soil degradation and enhancing agricultural resilience. RT has been shown to improve SOC sequestration, aggregate stability, and water retention, contributing to better resistance against droughts and floods [9,12]. For example, NT systems have demonstrated the ability to increase water infiltration rates and reduce soil compaction, particularly in semi-arid and arid regions. However, the benefits of NT and RT systems in temperate climates are highly dependent on additional agronomic factors such as crop rotation, residue retention, and the use of cover crops [13].

Despite these promising findings, significant knowledge gaps persist, particularly regarding the long-term and region-specific impacts of tillage practices on soil’s physical properties. For instance, while NT practices are often lauded for their ability to enhance SOC content, their effects on subsoil characteristics, such as deep compaction and water movement, remain poorly understood [10]. Similarly, while CT can improve surface soil health, its interaction with microbial dynamics and nutrient cycling at greater depths requires further investigation [14,15]. Furthermore, tillage practices have complex implications for greenhouse gas emissions. While RT may enhance carbon sequestration in some contexts, it can also lead to increased nitrous oxide emissions under specific soil conditions [16].

Another critical aspect of tillage research lies in its integration with broader climate adaptation strategies. With climate change projected to exacerbate soil degradation and water scarcity, understanding how tillage practices influence water-use efficiency, erosion control, and soil thermal dynamics is essential for ensuring the resilience of agricultural systems [17]. However, such insights must be contextualized within the socio-economic realities of farming communities, particularly in temperate regions where farm sizes, resource availability, and policy frameworks vary widely [18].

The overall goal of this review is to evaluate the effects of different tillage practices on soil’s physical properties, with particular emphasis on BD, Ks, WAS, AWC, PR, and SOC. Accordingly, a comprehensive literature review was conducted using peer-reviewed studies that examined tillage impacts on soil’s physical characteristics in temperate climates. Despite the extensive body of research on tillage impacts, existing review articles and meta-analyses have largely focused on individual soil properties or specific tillage systems, offering limited comparative synthesis across multiple physical indicators of soil in temperate agroecosystems. This review advances beyond previous syntheses by integrating structural, hydraulic, and carbon-related indicators within a unified comparative framework, while explicitly accounting for variability, uncertainty, and evidence gaps across regions and management contexts. This approach is particularly relevant for temperate agroecosystem management, as it supports context-specific decision-making rather than uniform tillage prescriptions.

The primary objectives of this study are to (i) comprehensively review and quantitatively assess recent literature on the effects of different tillage practices on specific physical properties of soil in temperate climates, and (ii) identify knowledge gaps and future research directions in the field of tillage practices for improving soil’s physical properties. Based on the objectives of this review, we hypothesized that reported responses of key physical indicators of soil to tillage practices in temperate agroecosystems are indicator-specific and context-dependent, rather than uniform across systems. We further hypothesized that structural indicators exhibit more consistent directional responses to conservation tillage (CT) than hydraulic indicators, for which outcomes remain more variable and uncertain due to differences in soil type, management duration, and limited evidence density. These hypotheses emphasize comparative synthesis and unresolved variability, rather than assuming universally beneficial effects of specific tillage systems.

2. Approach

2.1. Literature Identification and Appraisal Methods

A review was conducted to assess the impact of tillage practices on soil’s physical properties in temperate climates. A comprehensive literature search was performed using Web of Science, Scopus, Google Scholar, and PubMed, employing keywords such as “soil physical properties”, “bulk density”, “saturated hydraulic conductivity”, “available water capacity”, “wet aggregate stability”, “penetration resistance”, “soil organic carbon”, “no-tillage”, and “tillage”. The use of multiple databases ensured broad coverage of soil science, agronomy, and environmental research, thereby minimizing disciplinary and publication bias. The search was limited to peer-reviewed articles published in English between 1991 and 2025, a period that captures both early foundational studies on conservation tillage and more recent research addressing long-term and depth-dependent physical responses of soil; inclusion was restricted to studies conducted in temperate climates, verified using reported site locations, Köppen climate classification, and climate descriptions provided in each article. After screening approximately 300 publications for relevance and methodological rigor, a final set of 70 studies was retained, representing a balanced range of soil types, tillage systems, management durations, and geographic regions within temperate agroecosystems. This review adopted selected structured literature-search and screening practices to enhance transparency, but it was not conducted as a formal PRISMA-guided systematic review. A non-PRISMA or semi-systematic approach was adopted because the objective of this review was comparative and interpretive rather than effect-size estimation, focusing on indicator-specific responses, depth-dependent patterns, and methodological variability across studies. This approach allows integration of heterogeneous datasets, long-term field experiments, and studies reporting non-uniform depth intervals or response metrics, which are often excluded from formal meta-analyses. However, this approach does not provide pooled effect sizes and may be influenced by uneven evidence density across indicators. These limitations are explicitly acknowledged and addressed through transparent reporting of study distribution, variability, and evidence gaps within the synthesis. Studies were included if they met the following criteria: (i) conducted in temperate climates, (ii) field experiments or long-term trials (≥2 years), (iii) specified tillage methods, (iv) provided quantitative data on at least one physical property of soil, and (v) included a control or baseline for comparison. A minimum duration of two years was chosen because soil’s physical properties such as BD, PR, and near-surface aggregation can respond within multiple cropping cycles, whereas longer study durations are required to evaluate stabilization and depth-dependent trends. Studies with durations ≥ 3 years were therefore given greater interpretive weight when discussing long-term physical responses of soil.

Although SOC is often classified as a chemical property, this review included it among the physical indicators because it strongly influences soil structural behavior. SOC enhances aggregation, reduces BD, increases macroporosity, and improves water retention; thus, it is frequently integrated into soil physical quality (SPQ) frameworks assessing tillage effects [9]. Excluded studies consisted of conference proceedings, book chapters, laboratory-based experiments without field validation, and those focusing solely on soil chemical or biological properties. The final selection comprised 70 studies after an initial screening of 300 publications for relevance and methodological rigor.

2.2. Data Management and Standardization

The identified studies were cataloged using Zotero (Version 7.0.24), an open-source reference management software. Key study parameters, including location, soil texture, mean annual precipitation (MAP), mean annual temperature (MAT), tillage methods, experiment duration, soil sampling depth, and main findings, were extracted and tabulated. If MAP or MAT data were not reported, values were retrieved from the NOAA Climate Data Online (https://www.ncei.noaa.gov/ accessed on 17 September 2025) or other reliable sources.

To ensure consistency across studies, soil depth variability was addressed by categorizing data into surface and subsoil layers. When studies reported soil depth intervals that differed from our target (e.g., 0–10 cm), data were harmonized by calculating thickness-weighted averages across the reported layers so that values represented the equivalent standard depth. Data presented in graphical formats were digitized using WebPlotDigitizer (https://automeris.io/WebPlotDigitizer, accessed on 11 August 2025) to obtain numerical values. A qualitative synthesis of the reviewed literature was conducted to identify common findings, trends, and discrepancies. This approach facilitated the evaluation of hypotheses based on cumulative evidence from multiple studies, providing a comprehensive understanding of tillage effects on soil’s physical properties.

This harmonization approach, while necessary for cross study comparison, introduces conceptual limitations that warrant explicit consideration. Soil’s physical properties often exhibit strong vertical gradients, and aggregating heterogeneous depth intervals may mask localized responses, particularly at transitional layers influenced by tillage induced stratification. Similarly, differences in measurement techniques, such as laboratory versus field-based methods for Ks or AWC, varying aggregate stability protocols, and contrasting PR instruments, contribute to methodological variability that cannot be fully normalized through standardization alone. In addition, experimental duration varied widely among studies, ranging from short term trials to multi decadal experiments, and soil’s physical responses, especially those related to structure and hydraulic behavior, are known to evolve nonlinearly over time. As a result, harmonized comparisons emphasize general patterns and ranges rather than precise effect magnitudes. These limitations are addressed in this review by explicitly reporting variability, avoiding overgeneralization, and interpreting results within the context of evidence density, depth resolution, and study duration.

Given the variability in tillage terminology and reference systems across studies, tillage practices were categorized based on their relative soil disturbance intensity as described by the original authors. When moldboard plow (MP) or full inversion tillage was used as the control or baseline, systems involving less soil disturbance (e.g., chisel plow, disk harrow, etc.) were classified as RT. Conversely, in studies where a cultivator or shallow tillage served as the standard, even lower-intensity methods, such as strip-till or shallow disking, were categorized as RT. NT was frequently defined as the absence of primary tillage, with soil disturbance limited to seeding operations. In this study, minimum tillage is considered a form of RT because it represents a system with substantially lower soil disturbance than CvT. In cases where tillage intensity was not clearly labeled or systems overlapped, classification was guided by reported parameters such as tillage depth, frequency, and implement type. This context-sensitive yet systematic approach enabled consistent cross-study comparisons while respecting the agronomic context of each experiment. While we acknowledge that classification overlap (e.g., a cultivator being “reduced” in one study but “conventional” in another) was sometimes unavoidable, we prioritized internal consistency within each study and applied a transparent framework to support reliable synthesis.

To ensure consistency in comparing BD values across studies, soil depths were categorized into two groups: ‘Topsoil’ (0–10 cm) and ‘Composite depth.’ The latter included any BD value reported for depths greater than 10 cm or for extended sampling profiles such as 0–15 cm, 0–30 cm, or 0–50 cm, regardless of whether the original authors referred to these values as subsoil, deeper soil, or profile average. For visual clarity, only the terms ‘Topsoil’ and ‘Composite depth’ are used in the graph and corresponding analysis presented in this review.

3. Result and Synthesis

3.1. Distribution of Reviewed Studies and Insights into Soil Sampling Depths

The implementation of various tillage practices across diverse regions of the USA and Europe (Figure 1) significantly impacts soil’s physical properties, influencing aspects like BD, WAS, and SOC. Findings from the USA highlight that NT and RT systems often increase SOC levels and decrease BD, thereby improving soil quality. For example, studies conducted in Ohio, USA, using silty clay loam soils demonstrate that NT enhances soil structure and increases water infiltration.

Figure 1. Locations of the reviewed studies in the USA (AL, Alabama; IN, Indiana; IA, Iowa; KS, Kansas; OH, Ohio; IL, Illinois; WI, Wisconsin; MN, Minnesota; SD, South Dakota; ND, North Dakota; NM, New Mexico) and Europe (IT, Italy; DK, Denmark; NL, The Netherlands; DE, Germany; ES, Spain; CZ, Czech Republic; UK, United Kingdom; BE, Belgium; and HU, Hungary) under temperate climate. The gray horizontal lines indicate the approximate boundaries of the temperate climate zone.

Similarly, in Europe, such as in Denmark and the Netherlands, research indicates that RT tends to elevate PR in clay loam soils, pointing towards a denser soil structure under reduced disturbance. These observations suggest that the choice of tillage practice can have significant implications for soil quality and agricultural sustainability in different environmental and soil conditions.

Figure 2 illustrates the total number of studies on tillage focused on various physical properties of soil. WAS and SOC are the most studied properties, indicated by the highest counts of studies at 39 and 37, respectively. This is followed by BD with 35 studies, PR with 14 studies, Ks with 9 studies, and AWC with 5 studies. The figure highlights the prioritization of research areas within SPQ assessments under tillage conditions in temperate climates.

Figure 2. Distribution of reviewed studies (1991–2025) across physical properties of soil for tillage practices in the temperate climate zone (AWC: available water capacity; Ks: saturated hydraulic conductivity; PR: penetration resistance; BD: bulk density; SOC: soil organic carbon; WSA: water-stable aggregates).

Figure 3 illustrates the maximum soil sampling depths utilized in various tillage studies to investigate soil properties. The depth of soil sampling varied significantly across studies, ranging from as shallow as 5 cm to as deep as 60 cm. This variation highlights different research focuses and methodologies. For instance, deeper sampling depths, like those used in the studies by Fiorini et al. [19], and Zuber et al. [20], might be indicative of investigations into deeper soil layers’ physical properties or nutrient profiles, which are crucial for understanding subsoil dynamics under different tillage practices. Conversely, studies with shallower sampling depths might focus on topsoil characteristics, which are directly influenced by tillage and are critical for seed germination and root development.

Figure 3. Maximum soil sampling depths reported in studies assessing the impact of tillage methods on soil’s physical properties in temperate climate zones [11,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39].

3.2. Evaluation of Tillage Effects on Soil’s Physical Properties

Across indicators, responses to NT were not uniform but depended strongly on soil depth, texture, residue management, and duration of implementation. While NT generally improved surface structural indicators, responses of hydraulic and mechanical properties were more variable, particularly at depth.

3.2.1. Trends in Soil Bulk Density Under Different Tillage Practices

Across temperate agroecosystems, BD responses to tillage practices show a clear depth-dependent pattern rather than uniform differences among systems (Table 1). CT, particularly NT and RT, generally results in lower BD in the surface soil, reflecting improved aggregation, residue retention, and reduced mechanical disturbance. Several studies consistently report surface BD reductions under NT relative to CvT, indicating enhanced structural stability and reduced compaction in the upper soil layer [21,22]. For example, Presley et al. [21] documented substantially lower BD under NT compared to CvT in the 0–10 cm depth, highlighting the role of long-term residue accumulation and biological activity in improving surface soil structure.

Table 1. Tillage effects on bulk density (BD) under different soil types, climates, soil sampling depth, and management durations. MAP = mean annual precipitation; MAT = mean annual temperature; NT = no-tillage; RT = reduced tillage; CvT = conventional tillage; MP = moldboard plow, NSE = No Significant Effect.

Location	Texture	MAP (mm)	MAT (°C)	Tillage	Time (yr)	Depth (cm)	Major Findings	References
Kansas, USA	Silty clay loam	780	13.1	NT, CvT	Long-term	0–5	NT had lower BD	[21]
Ohio, USA	Silt loam	940	10.6	NT, Disk plow	10	0–18	CvT had higher BD	[26]
North Dacota, USA	Sandy loam	366	5.4	NT, Ripper	4	0–40	Ripper has higher BD	[40]
Kansas, USA	Silty clay loam	580	12.2	NT, RT	33	0–7.5	NT had lower BD	[41]
Illinois, USA	Silt loam	1015	11.5	NT, CvT	15	0–60	NT had higher BD	[20]
Ohio, USA	Silt loam	1016	11.1	NT, Chisel	13	0–10	NT had lower BD	[42]
Italy	Sandy loam	850	14.7	NT, CvT	15	0–10	NT had lower BD	[22]
North Dacota, USA	Loam	477	5.5	NT, CvT	27	0–15	NSE	[43]
South Dacota, USA	Silty clay loam	627	8.6	NT, CvT	23	0–15	NT had lower BD	[44]
Ohio, USA	Clay loam	845	10.9	NT, Chisel, MP	47	0–10	NT had lower BD	[31]
Germany	Loamy sand, Sandy loam	498	9	NT MP	10+	0–35	NT had higher BD	[45]
Denmark	Sandy loam	765	8.3	NT, CvT	17	0–50	NT had lower BD	[37]
Ohio, USA	Silt loam	950	11.4	NT, Chisel, MP	43	0–15	NT had lower BD	[46]

However, aggregated evidence indicates that these benefits are less consistent at greater depths. Figure 4 illustrates that differences in BD between NT and MP systems often diminish or overlap at composite or subsoil depths, suggesting that reduced disturbance alone may not alleviate compaction below the surface layer. This variability reflects differences in soil texture, legacy compaction, and the duration of NT implementation across studies. As a result, while NT frequently improves surface BD, its effectiveness in reducing deeper soil compaction remains context dependent.

Strategic tillage approaches, including OT and RT, further indicate that BD responses are influenced by both tillage intensity and the frequency of soil disturbance. Obour et al. [47] reported similarly low BD under strategic and reduced tillage, indicating that occasional soil disturbance can mitigate surface compaction without fully disrupting soil structure in certain systems. In contrast, Stavi et al. [26] observed higher BD under occasional tillage compared to continuous NT, emphasizing that the benefits of strategic tillage are not universal and depend on site-specific conditions. Collectively, these findings indicate that BD responses to tillage are controlled more by soil depth, management history, and disturbance timing than by tillage category alone, underscoring the need for context-specific interpretation of tillage effects on soil compaction.

Figure 4. Bulk density under different tillage systems (A) and study durations in NT systems (B), categorized by soil depth. ‘Topsoil’ refers to 0–10 cm, while ‘Composite depth’ includes values from extended or unsegmented profiles (e.g., 0–15 cm, 0–50 cm). The short horizontal gray lines indicate cases where only a single observation was available (N = 1), and therefore no box or whiskers could be displayed [21,31,40,41,42,45,46,48,49,50,51,52,53].

Figure 4. Bulk density under different tillage systems (A) and study durations in NT systems (B), categorized by soil depth. ‘Topsoil’ refers to 0–10 cm, while ‘Composite depth’ includes values from extended or unsegmented profiles (e.g., 0–15 cm, 0–50 cm). The short horizontal gray lines indicate cases where only a single observation was available (N = 1), and therefore no box or whiskers could be displayed [21,31,40,41,42,45,46,48,49,50,51,52,53].

The effects of tillage practices and study duration on BD at varying soil depths are presented in Figure 4. In the topsoil layer (0–10 cm), BD was slightly lower under NT (1.32 ± 0.08 Mg/m³) compared with MP (1.33 ± 0.09 Mg/m³) and chisel tillage (1.39 ± 0.12 Mg/m³). However, two-way ANOVA indicated that tillage effects on BD were not statistically significant (F = 1.39, p = 0.272). Sample sizes (N) varied from 1 to 8 per group. The absence of whiskers reflects either limited sample size or lack of variability, while groups represented by a single value, such as chisel tillage at composite depth, do not have an associated standard deviation. The data were synthesized from published studies, where boxplots display the interquartile range and median, and whiskers represent the overall data range. The absence of statistically significant differences may be attributed to the high variability among soils and study sites, which can obscure management effects. BD is particularly sensitive to soil texture, organic matter content, and inherent structural heterogeneity, reducing statistical power even when apparent mean differences exist. Moreover, the limited number of studies and unequal replication across tillage categories likely constrained the ability to detect clear treatment effects.

This lack of significance may reflect high variability across soils and sites, which can mask management effects. BD is strongly influenced by soil texture, organic matter content, and natural structural heterogeneity, which can reduce statistical power even when mean differences appear evident. Additionally, the relatively small number of studies and unequal replication among tillage categories may have limited detection of clear treatment effects.

In contrast, soil depth exhibited a significant effect on BD (F = 12.49, p = 0.002), with greater compaction observed at deeper or composite layers. BD at composite depths (>10 cm) was higher under NT (1.56 ± 0.09 Mg/m³) and chisel systems (1.56 Mg/m³, based on a single composite-depth observation), compared with MP (1.41 Mg/m³, single reported value without standard deviation). Although single data points were used for some composite depths, they were retained to represent existing literature trends rather than for inferential comparison. These values provide descriptive context for depth-wise compaction under reduced soil disturbance. The interaction between tillage and depth was not significant (p = 0.391), indicating similar BD patterns across systems when comparing surface and subsurface layers.

Analysis of NT study duration revealed that BD in the topsoil layer tended to be higher in the 4–30-year group (1.34 ± 0.09 Mg/m³) than in the 31–60-year group (1.21 ± 0.13 Mg/m³), although the difference was not significant (F = 1.50, p = 0.252). For composite layers, BD was slightly higher in the 4–30-year group (1.54 ± 0.12 Mg/m³) than in the 31–60-year group (1.49 Mg/m³), the latter derived from a single reported value. As before, these single data points were included descriptively to illustrate the long-term trend of gradual BD reduction with extended NT duration. The interaction between study duration and soil depth was also non-significant (F = 0.30, p = 0.596), suggesting consistent BD variation across depths regardless of NT duration. However, the main effect of soil depth remained significant (F = 10.18, p = 0.011), confirming that compaction generally increases with depth, independent of management duration.

These findings suggest that depth is the dominant factor influencing BD, rather than tillage system or duration alone. While NT shows potential for maintaining or slightly lowering surface BD over time, its effect is inconsistent and may not be sufficient to alleviate subsoil compaction. These results align with previous findings [54], emphasizing the need for integrated strategies, including deep-rooted cover crops, to mitigate subsoil compaction in long-term NT systems.

The broader implications of these findings are profound, indicating that while NT is generally beneficial for reducing BD and enhancing soil structure, it is not universally applicable. Specific conditions such as soil type, climatic conditions, and crop rotation must be considered. For instance, Fiorini et al. [19] observed a temporal decrease in BD under NT, which suggests that the benefits of NT accrue over time, enhancing soil’s physical properties progressively.

However, the adoption of NT should be carefully managed. Wander et al. [55] and Weninger et al. [56] noted instances where NT induced higher BD compared to CvT, particularly in silt-dominated soils, potentially leading to increased soil compaction. This indicates that NT can have counterintuitive effects depending on the soil texture and environmental conditions. Moreover, Fornara and Higgins [57] demonstrated a positive correlation between BD and the frequency of tillage and reseeding events, which suggests that not all NT systems automatically reduce soil compaction, and strategic tillage might be necessary to mitigate some of the compaction issues associated with continuous NT.

3.2.2. Variations in Saturated Hydraulic Conductivity Across Tillage Systems

The adoption of CT practices such as NT and RT is generally associated with improved soil hydraulic properties that are critical for effective water management (Table 2). Across studies, NT consistently enhances Ks relative to CvT, reflecting improved soil structure, greater pore continuity, and reduced compaction in surface soils [21,58]. Reported increases in Ks under NT indicate more efficient water transmission and aeration within the soil profile, which are key functions of well-developed macropore networks. However, the magnitude of Ks improvement varies among studies and is influenced by soil texture, residue management, and the duration of CT implementation. While some studies report substantial increases in Ks under NT, others show more moderate responses, suggesting that hydraulic benefits are conditional rather than universal. Overall, these patterns indicate that Ks responses to CT are governed more by the preservation of soil pore structure and biological activity than by tillage category alone.

Table 2. Tillage effects on saturated hydraulic conductivity (Ks) under different soil types, climates, soil sampling depth, and management durations. MAP = mean annual precipitation; MAT = mean annual temperature; NT = no-tillage; RT = reduced tillage; CvT = conventional tillage; MP = moldboard plow; NIT = Non-inversion tillage, NSE = No Significant Effect.

Location	Texture	MAP (mm)	MAT (°C)	Tillage	Time (yr)	Depth (cm)	Major Findings	References
North Dakota, USA	Sandy loam	366	5.4	NT	10	0–40	NSE	[40]
Ohio, USA	Silt loam	1039	11.5	NT, Chisel	Since 1994	0–60	NT had higher Ks	[39]
Minnesota, USA	Silt loam	652	5.3	NT, CvT	Since 2007	0–5, 10–15	NT had higher Ks than CvT	[24]
Iowa and Ohio, USA	Loam to clay loam	886–1019	8–10	NT, Chisel, MP	6 to 28	0–7.5	NT had higher Ks	[59]
Wisconsin, USA	Sandy	832	6.7	NT, MP	5	Surface	MP had higher Ks	[60]
Ohio, USA	Silt loam, clay loam	1083	11.2	NT	Since 2004	0–20	Reduced Ks	[29]
Germany	Silt loam	700	9.9	RT, CvT	10	Surface	Reduced Ks for RT, CvT	[61]
The Netherlands	Clay loam	825	9.7	MP, NIT	5	0–5, 10–15	MP had higher Ks	[23]
Minnesota	Silt loam	887	4.4	NT, MP	10	surface	NT had higher Ks	[60]

However, the benefits of NT on soil hydraulic properties are not uniform and can be influenced by management practices such as residue management. Blanco-Canqui et al. [28] highlighted a significant reduction in Ks from 4.2 to 0.6 mm/h with complete stover removal under NT, showcasing a potential downside to inappropriate residue management that can negate the benefits of conservation practices by impairing the soil’s ability to transmit water.

RT systems also contribute positively to soil hydraulic functions, although the extent can vary depending on specific practices and environmental conditions. Crittenden et al. [23] noted that non-inversion tillage (NIT), a form of RT, improved Ks in organic farming settings, particularly evident during autumn when soil compaction is less pronounced. This improvement is likely due to less soil disturbance compared to CvT, which preserves natural soil architecture and enhances pore connectivity.

Conversely, CvT often degrades these beneficial structures, leading to decreased Ks. Rasmussen [62] documented increased bulk density and reduced macroporosity under CvT, which adversely affects the soil’s hydraulic capabilities. This degradation underscores the critical need for strategic management of tillage practices to avoid counterproductive outcomes on SPQ. Analogous challenges of pore blockage and hydraulic decline have been documented in engineered water systems, where maintaining pore continuity is critical for long-term functionality, reinforcing the importance of managing soil pore networks to sustain hydraulic conductivity under CT systems [63].

The implications of these findings are substantial for promoting the adoption of CT. They highlight the necessity for careful management of tillage depth and residue to optimize the hydraulic benefits of NT and RT systems. Such practices not only enhance the soil’s water handling characteristics but also contribute to broader environmental conservation goals by improving water quality and reducing erosion. The integration of CT into modern agricultural practices offers a sustainable approach to managing soil and water resources effectively. However, the variable effects documented in different studies call for a nuanced application of these practices, tailored to specific soil types, climatic conditions, and cropping systems to maximize their benefits and mitigate potential drawbacks.

3.2.3. Comparative Analysis of Available Water Capacity

Tillage practices exert complex and context-dependent effects on AWC (Table 3). Across studies, NT generally enhances AWC through improvements in soil structure and increased SOC, which promote favorable pore size distribution and greater water retention [31]. Similar improvements in AWC have also been reported under RT, where enhanced soil structure and higher SOC contribute to improved water holding capacity (WHC) relative to more intensive tillage systems [64]. Evidence from controlled incubation studies further indicates that optimized pore structure and surface charge can enhance WHC even under CvT conditions, as demonstrated by acid-modified pineapple biochar application in saline soils [65]. In contrast, intensive tillage practices often reduce AWC by degrading soil structure and lowering SOC. CvT has been associated with increased BD and reduced air capacity, which constrain both soil aeration and water retention, particularly in silt-dominated soils susceptible to compaction and erosion [56]. Collectively, these patterns indicate that AWC responses are governed by interactions among soil structure, SOC dynamics, and soil texture rather than tillage intensity alone.

Table 3. Tillage effects on available water capacity (AWC) under different soil types, climates, soil sampling depth, and management durations. MAP = mean annual precipitation; MAT = mean annual temperature; NT = no-tillage; RT = reduced tillage; CvT = conventional tillage; MP = moldboard plow; NSE = No Significant Effect.

Location	Texture	MAP (mm)	MAT (°C)	Tillage	Time (yr)	Depth (cm)	Major Findings	References
Ohio, USA	Silt loam	1016	11.1	NT, Chisel	13	0–10	NSE	[42]
Spain	Sandy loam	869	16	NT, CvT	8	0–5	NT had higher AWC	[66]
Belgium, Czech Republic, Hungary, Italy, UK	Varies	Varies	Varies	NT, CvT, RT	8 to 54	0–15	Minimal effect on AWC	[11]
Illinois, USA	Silt loam	949	11.7	NT, Chisel, MP	8	0–75	NSE	[67]
Spain	Silt loam	448	15.6	NT, CvT	8	0–30	NT had higher AWC	[68]

Panagea et al. [11] noted that while SOC increases generally enhance water retention, the effects are more pronounced in coarser-textured soils with lower initial SOC content and less significant in finer-textured soils. CT practices, such as NT and RT, have frequently demonstrated measurable benefits by significantly increasing AWC. Similarly, long-term studies in Ohio showed that NT practices resulted in higher AWC in well-drained silt loam soils, providing evidence of its sustainable benefits in moisture retention and availability [31].

Variations in AWC among tillage systems arise from differences in soil structure, pore distribution, and organic carbon stabilization. NT enhances aggregation and mesoporosity, increasing water retention and reducing evaporative loss through improved structural stability [31,68]. In contrast, intensive tillage destroys aggregates and macropores, leading to reduced pore continuity and limited plant-available water [56]. RT exerts intermediate effects by loosening soil while maintaining SOC protection [63]. These findings collectively demonstrate that practices preserving soil structure and carbon are key to sustaining AWC in temperate agroecosystems.

3.2.4. Evaluating Aggregate Stability for Assessing Soil Health

Different tillage practices exert pronounced effects on soil WAS, with responses reflecting both management intensity and soil structural preservation (Table 4). Across studies, conservation practices such as NT consistently enhance WAS by maintaining aggregate integrity and minimizing mechanical disruption. Improved WAS under NT is commonly attributed to greater aggregate cohesion driven by residue retention and increased SOC, resulting in higher proportions of stable aggregates compared to CvT systems [31,34]. RT systems further demonstrate that partial disturbance can still support aggregate stability when soil structure is largely preserved. Higher WAS and increased aggregate MWD under RT indicate improved soil structural condition relative to more intensive tillage, particularly in surface soils [69]. Similarly, combinations of organic management and RT have been shown to promote the formation of large macroaggregates and higher MWD in the upper soil profile, reinforcing the role of reduced disturbance and organic inputs in stabilizing soil aggregates [70]. Collectively, these patterns indicate that WAS responses are governed primarily by the degree of structural disturbance and organic matter inputs rather than tillage category alone.

Table 4. Tillage effects on wet aggregate stability (WAS) under different soil types, climates, soil sampling depth, and management durations. MAP = mean annual precipitation; MAT = mean annual temperature; NT = no-tillage; RT = reduced tillage; CvT = conventional tillage; MP = moldboard plow; NSE = No Significant Effect.

Location	Texture	MAP (mm)	MAT (°C)	Tillage	Time (yr)	Depth (cm)	Major Findings	References
Wisconsin, USA	Silt loam	889	8.3	CvT	18	0–20	Higher in pasture and alfalfa-based systems	[30]
Spain	Sandy loam	389	14.7	NT, Chisel, MP	16	0–7.5	Higher in NT	[71]
Illinois, USA	Silty clay loam	965	11.5	NT, CvT	15	0–60	Higher in NT	[20]
South Dakota, USA	Loam	654	7.8	NT, Chisel, MP	2–3	0–15	Higher in NT	[72]
Ohio, USA	Silt loam	940	10.6	NT, Disk plow	10	0–12	Higher in continuous NT	[26]
Kansas, USA	Silt loam	580	26.2	NT, CvT	45	0–2.5	Higher in NT	[73]
Northern Great Plains, USA	Silt loam	425	7.2	NT, CvT	17 and 8 years	0–30	Higher in NT	[34]
Denmark	Sandy loam	558	8.5	NT, MP	12	0–20	NSE	[27]
Germany	Clay loam	700	9	CvT, RT	10	10–240	Higher in RT	[69]
Spain	Clayey	525	13.5	NT, CvT	10	0–30	NSE with stubble burning	[32]
Ohio, USA	Silt loam	1016	11	NT	22	0–10	Higher WSA in NT, 68.7%	[52]

Long-term NT practices, coupled with diversified crop rotations, also showed significant WAS improvements [38]. However, RT may increase soil BD and induce soil consolidation, as Bilibio et al. [69] noted at a 0.10–0.24 m depth range, where CvT systems had lower total pore space and higher BD compared to conventionally plowed treatments. Büchi et al. [74] highlighted substantial intra-system heterogeneity in soil properties, sometimes surpassing differences between tillage regimes. Moreover, Stavi et al. [26] found that even sporadic soil disturbance in long-term NT systems negatively impacted soil quality indicators, including a decrease in WAS and MWD. This suggests that while NT practices generally benefit WAS, the degree of improvement is strongly influenced by soil texture, initial organic carbon content, and baseline aggregation, with finer-textured, carbon-rich soils responding more positively than coarse or degraded soils. Climatic conditions, such as precipitation regime and freeze–thaw intensity, also shape outcomes: humid temperate regions tend to favor macroaggregate stabilization, whereas semi-arid or drought-prone environments may limit WAS gains due to moisture deficits. Occasional disturbance can further offset these benefits by disrupting aggregate stability and reducing MWD.

3.2.5. Long-Term Variations in Soil Penetration Resistance

The effects of tillage practices on SPQ, particularly PR, show strong depth- and management-dependent responses with important implications for soil function (Table 5). PR is a key indicator of soil compaction and directly influences root growth and crop productivity. Across studies, NT frequently reduces PR in the topsoil, especially in long-term systems with residue retention and soil organic matter (SOM) accumulation. These reductions are commonly linked to minimal mechanical disturbance, improved soil structure, and increased biological activity in surface layers [19,29,31].

Table 5. Tillage effects on penetration resistance (PR) under different soil types, climates, soil sampling depth, and management durations. MAP = mean annual precipitation; MAT = mean annual temperature; NT = no-tillage; ST = striptillage; CvT = conventional tillage; MP = moldboard plow; NIT = Non-inversion tillage.

Location	Texture	MAP (mm)	MAT (°C)	Tillage	Time (yr)	Depth (cm)	Major Findings	References
Illinois, USA	Silt loam	890–914	10.6–11.1	NT, Chisel plow	7	0–30	Higher PR in NT with residue removal	[35]
Ohio, USA	Silt loam, Clay loam	845–905	9.1–9.9	NT, MP, Chisel plow	47–49	0–20	Higher PR in NT	[31]
New Mexico, USA	Sandy	250	17	NT, CvT, ST	2	0–20	Higher PR in NT	[29]
Ohio, USA	Silt loam	940	10.6	NT, Disk plow	10	0–18	Higher PR in NT	[26]
Iowa, USA	Silty clay loam	733	10	NT, Chisel plow	13	0–15	Higher PR in CP	[25]
Wisconsin, USA	Silt loam	889	8.3	CvT	18	0–20	Higher PR in alfalfa-based systems	[30]
The Netherlands	Clay loam	825	9.7	MP, NIT	3 to 4	0–5, 10–15	Higher PR under NIT	[23]
Denmark	Sandy loam	626	7.3	NT, MP	10	0–20	Higher PR in NT	[27]
Spain	Clay loam	525	13.5	NT, MP	10	0–10	Higher PR in NT	[32]
Italy	Silty clay loam	890	12.2	NT, CvT	3	0–60	Higher PR in NT	[19]

In contrast, PR responses at greater soil depths are more variable. Several studies report higher PR under NT in subsoil layers, reflecting the persistence or accumulation of compaction in the absence of periodic mechanical loosening [25,31]. Elevated subsoil PR under NT has been associated with soil texture, historical compaction, and management duration. During the transition from CvT to NT, soils may initially exhibit increased PR due to residual compaction from previous tillage operations, with gradual structural adjustment occurring over time [23]. Collectively, these findings indicate that PR responses to NT are governed by interactions among soil depth, management history, and SOM dynamics rather than being uniformly beneficial.

CvT methods such as moldboard plow effectively reduce PR, particularly in the subsoil, by mechanically disrupting compacted layers, which facilitates root growth and water infiltration. While this immediate reduction in PR is advantageous for crop establishment and root penetration, it is not devoid of long-term disadvantages. Frequent use of CvT can lead to increased soil erosion and decreased SOM, presenting a trade-off between immediate benefits and sustainable soil health [75,76]. Therefore, the choice of tillage system should be a strategic decision influenced by specific soil conditions, crop requirements, and long-term sustainability goals. The varying impacts of NT and CvT on soil PR exemplify the intricate relationship between tillage practices and soil health. To optimize agricultural productivity and environmental sustainability, management strategies must carefully consider both the immediate and extended consequences of tillage on soil structure and function [77].

3.2.6. Dynamics of Soil Organic Carbon Storage and Distribution

CT methods, particularly NT and RT, consistently promote SOC accumulation, which plays a critical role in soil fertility and climate change mitigation (Table 6). Across studies, higher SOC concentrations are commonly reported in surface soils under NT relative to CvT, reflecting the combined effects of reduced soil disturbance, residue retention, and enhanced organic matter stabilization [39,78]. These patterns indicate that minimal mechanical disruption under NT favors the preservation and accumulation of SOC, particularly in the upper soil layers. In addition to increasing SOC, long-term NT management is closely linked with improvements in soil’s physical structure. Enhanced SOC under NT is frequently accompanied by lower BD and higher WSA, indicating stronger aggregation and improved structural stability [21]. Evidence from temperate agroecosystems further demonstrates that sustained organic inputs under NT support coupled gains in SOC and nitrogen sequestration while simultaneously improving aggregation and reducing BD over time [79]. Collectively, these findings highlight that SOC responses to CT are governed by interactions between organic matter inputs, disturbance intensity, and soil structural development, rather than tillage category alone.

Table 6. Tillage effects on soil organic carbon (SOC) under different soil types, climates, soil sampling depth, and management durations. MAP = mean annual precipitation; MAT = mean annual temperature; NT = no-tillage; RT = reduced tillage; CvT = conventional tillage.

Location	Texture	MAP (mm)	MAT (°C)	Tillage	Time (yr)	Depth (cm)	Major Findings	References
South Dakota, USA	Silty	508	8.3	NT	14–24	0–60	4-year rotation increased SOC	[38]
Kansas, USA	Silt loam	440	17.2	NT, RT	19	0–5	NT increased SOC	[80]
Illinois, USA	Silty clay loam	965	11.7	NT, CvT	15	0–60	NT increased SOC	[20]
Alabama, Indiana, Ohio, USA	Varies	991–1405	10.9–17.8	NT	4	0–30	NT increased SOC	[33]

The efficacy of NT in increasing SOC is, however, variable and may diminish as SOC levels begin to stabilize over time, as noted by VandenBygaart et al. [81]. This variability underscores the complex interaction between tillage practices and soil carbon dynamics. Additionally, the adoption of NT can occasionally lead to soil compaction and reduced water infiltration, potentially impacting crop yields adversely over time [82]. Such negative outcomes highlight the need for careful management and consideration of local soil conditions when implementing NT practices. Additionally, the integration of biochar as a soil amendment within CT systems has been suggested to address challenges like soil compaction, though environmental and health considerations related to biochar production and application must be carefully managed [83].

Despite these challenges, the long-term benefits of NT, particularly when combined with diverse crop rotations and organic amendments, have been demonstrated to significantly enhance SOC, microbial biomass, and overall soil health. Maiga et al. [38] reported improvements in these parameters, reinforcing the potential of NT to enhance agricultural sustainability. In similar findings, Krauss et al. [84] observed a 25% increase in topsoil SOC under reduced tillage coupled with organic amendments over a 15-year period, suggesting that a combination of reduced tillage and organic matter addition can synergistically boost SOC levels.

Moreover, Büchi et al. [74] have further refined our understanding of how tillage impacts SOC. They noted that NT, especially when integrated with cover cropping in soybean systems, resulted in significantly higher SOC levels compared to RT, illustrating the added benefits of cover crops in carbon sequestration strategies. They emphasized that pedoclimatic factors alongside management practices significantly dictate the extent of SOC improvement, with NT and organic systems showing higher SOC at the surface compared to conventionally tilled fields.

Given these findings, it is clear that while CT practices like NT and RT can enhance SOC levels and improve soil health, the outcomes are dependent on a multitude of factors that require careful consideration and management. Continuous monitoring and adaptive management strategies are essential to optimize the benefits of CT for SOC enhancement, ensuring that agricultural practices align with sustainability goals while adapting to specific local conditions.

3.2.7. Cross-Indicator Integration and Trade-Offs

Across the reviewed literature, tillage-induced changes in soil’s physical and hydraulic indicators are closely interlinked rather than independent (Figure 5). Improvements in SOC under CT, particularly NT and RT, are consistently associated with enhanced WAS and reduced BD in surface soils, which collectively support improved pore continuity and higher Ks [21,31,34,39,78]. Increased aggregation and lower BD under NT further contribute to improved AWC by promoting a favorable balance of storage pores and stable soil structure [31,64]. These synergistic responses highlight the central role of SOC in coupling structural stability with hydraulic functioning under reduced disturbance systems.

Figure 5. Conceptual framework showing soil’s physical responses to tillage intensity across soil depths. Tillage systems range from conventional tillage (CvT) to reduced tillage (RT) and no-tillage (NT). Arrows indicate direction of change in soil properties across depths. (BD = bulk density; PR = penetration resistance; Ks = saturated hydraulic conductivity; WAS = wet aggregate stability; AWC = available water capacity; SOC = soil organic carbon). Arrows indicate the direction of change in soil properties: ↑ increase, ↓ decrease, ↔ variable or no change, and ⚠ trade-off or constraint.

Clear trade-offs emerge across indicators between the surface soil and composite depth layers (Figure 5), highlighting the depth-dependent nature of tillage effects on soil’s physical functioning. While NT frequently improves SOC, WAS, Ks, and AWC in the topsoil, several studies report elevated PR at greater depths, indicating persistent or accumulated subsoil compaction in the absence of periodic mechanical loosening [23,25,31]. This depth-dependent divergence suggests that gains in surface soil hydraulic and structural quality may coexist with mechanical constraints in the subsoil. Consequently, SPQ under CT reflects a balance between structural stabilization and compaction dynamics that varies with soil depth, management duration, and soil texture. These findings underscore the importance of evaluating tillage effects through integrated indicator responses rather than relying on single-property assessments.

4. Future Research Directions

Despite extensive research on the impacts of diverse tillage methods on soil’s physical properties, several critical knowledge gaps remain. Long-term effects of CT practices, such as NT and RT, on soil structure and hydraulic properties across diverse soil types and climates need further study [9]. While CT and organic amendments have demonstrated clear benefits for SPQ, their long-term impacts under varying climatic and soil conditions require further investigation. Munna and Lal [85] highlight the need for region-specific management strategies that integrate organic inputs with reduced tillage to optimize soil water retention and structure. Future research should focus on multi-year trials to assess the interactive effects of organic amendments, tillage intensity, and residue management on soil hydraulic properties. Short-term studies show promising results in improved WAS and water infiltration rates, but the long-term sustainability and potential limitations, especially in the context of climate change, require more thorough evaluation [12]. Policies that promote sustainable tillage practices are essential for their widespread adoption. Kremen and Miles [86] argue that regulatory frameworks and incentive-based approaches can drive farmer behavior toward conservation practices. Further research is needed to evaluate the effectiveness of existing policies and design innovative approaches that combine financial, educational, and environmental incentives.

Long-term studies are essential for assessing the sustained effects of tillage practices on soil’s physical properties. Short-term studies often fail to capture cumulative impacts on SOM, crop yields, and profitability [13]. Similar time-dependent trade-offs have been observed in land restoration systems, where vegetation introduction initially altered soil’s physical and hydrological functioning but led to long-term recovery of soil structure and ecosystem services, underscoring the importance of temporal scale in evaluating soil–water management interventions [87]. Longitudinal research across diverse climatic and soil conditions is necessary to develop region-specific sustainable practices. Given climate change, tillage must adapt, integrating advanced models that incorporate climate variables to predict soil responses. Such models facilitate understanding interactions between tillage, precipitation, temperature fluctuations, and extreme weather [16], offering data-driven insights for resilient agricultural systems.

Emerging technologies such as remote sensing, AI, and PA provide high-resolution, real-time soil data, optimizing management strategies [88]. IoT-enabled soil sensors enhance predictive capabilities, improving on-farm decision-making. Comparative studies across ecological zones are crucial for identifying regional adaptations to tillage practices, considering variations in soil, climate, and cropping systems [89]. Such studies reveal global trends and localized solutions for enhancing SPQ.

Economic analyses of tillage should consider both direct and indirect costs. Evaluating long-term benefits of improved SPQ against short-term adoption costs can guide policy and decision-making [90]. Additionally, subsoil characteristics such as compaction and porosity are often overlooked despite their role in water movement and root development [10]. Depth-specific studies can enhance soil health management strategies. These research priorities highlight the need for an integrated, interdisciplinary approach to tillage, addressing agricultural sustainability and broader environmental challenges.

5. Conclusions

This review advances a synthesis-level understanding of how CT practices, particularly NT and RT, influence soil’s physical and hydraulic functioning in temperate agroecosystems. Rather than indicating uniform benefits across all indicators, the evidence highlights depth-dependent and indicator-specific responses that reflect trade-offs between structural stabilization and compaction dynamics. Conceptually, this review integrates BD, Ks, WAS, AWC, PR, and SOC within a unified framework that emphasizes coupled physical processes in soil rather than isolated responses. Across studies, NT was associated with reduced BD in the topsoil and enhanced Ks, particularly under residue retention, although evidence for hydraulic responses remains more limited and variable than for structural indicators. Improvements in WAS under continuous NT reached 33.4%, while long-term RT practices incorporating organic amendments increased topsoil SOC by approximately 25%. These surface soil benefits are closely linked through SOC-driven aggregation and pore development. However, interpretations of SOC and AWC responses should be considered tentative, as these properties are supported by comparatively few studies. Despite these benefits, BD remained high at composite depths under NT, reflecting limited subsoil disturbance and ongoing compaction. Increased PR in deeper soil layers further indicates that NT systems may experience persistent physical constraints in the subsoil. From a practical perspective, these findings suggest that CT should be implemented with explicit consideration of soil depth, management duration, and complementary practices. The inclusion of deep-rooted cover crops may help alleviate subsoil PR and improve vertical soil structure under long-term NT. At the same time, this synthesis reveals clear knowledge gaps related to subsoil responses, regional variability, and the integration of structural and hydraulic indicators. Future studies should prioritize longer-term field experiments, standardized depth classifications, and improved reporting of variability and uncertainty. The integration of emerging tools such as artificial intelligence and precision agriculture may further support adaptive soil management strategies. When applied with contextual understanding, CT has strong potential to promote sustainable soil health and agricultural productivity under changing climatic conditions.