Soil λ is a fundamental property that governs heat transfer within the soil matrix, significantly influencing agro-environmental systems (A-ES). It is defined as the rate of heat flow per unit area under a unit temperature gradient, typically expressed in watts per meter per degree Celsius (W/(m °C)) (Wu et al. 2025b). Heat transfer in soil occurs through three primary mechanisms: conduction, convection, and radiation (Fig. 2) (Najafian Jazi et al. 2024; Romio et al. 2022; Zimmer et al. 2023). Among these, conduction is the dominant process, strongly affected by soil composition, moisture content, structure, and organic matter levels.

Fig. 2

Principles, mechanisms, and measurements of soil λ

Soil λ is a critical factor in A-ES, influencing various physical, chemical, and biological processes essential for agricultural productivity and soil health (Ding et al. 2021; Hu et al. 2022; Wang et al. 2023b). It affects root development, microbial activity, nutrient cycling, and water dynamics, all of which play vital roles in crop growth and soil sustainability. Effective soil management practices (SMP) such as tillage systems, organic matter incorporation, mulching, and irrigation strategies directly modify soil λ, thereby regulating soil temperature, moisture retention, and overall thermal stability.

Accurate assessment of soil λ is crucial for optimizing agricultural systems. Measurement techniques include steady-state and transient methods, along with advanced sensor-based approaches (Al-Shammary et al. 2022; Fu et al. 2024a; Kashyap & Kumar 2021). Additionally, empirical, numerical, and mixing models are used to simulate and predict soil heat transfer under varying environmental conditions (Sepaskhah & Mazaheri-Tehrani 2024; Song et al. 2024b; Xia et al. 2025). Understanding soil λ dynamics and its interaction with SMP is essential for enhancing agricultural resilience, improving productivity, and promoting sustainable land management in the face of climate change.

3.1 Influence of soil management practices (SMP) on soil thermal conductivity (λ)

Soil management practices significantly influence soil λ by altering key soil properties such as structure, µ, OMC, and ρb. These factors collectively determine the soil’s ability to transfer heat efficiently.

3.1.1 Tillage Systems (Ts)

Tillage systems are crucial in determining soil TCs by altering soil physical characteristics that govern heat transfer. The effect of tillage on soil λ is complex, as it depends on the type of tillage system used and the depth at which tillage is applied (Al-Shammary et al. 2022; Liebhard et al. 2022; Thotakuri et al. 2024). Figure 3 illustrates how different tillage methods affect soil λ by influencing soil structure, moisture retention, and temperature regulation (Al-Shammary et al. 2024; Song et al. 2024a; Yin et al. 2023; Tschanz et al. 2024).

Fig. 3

Soil λ effect by tillage practices

Conventional tillage (Tillage trad) and conservation tillage (Tillage cons) have distinct impacts on soil λ. Conventional tillage typically results in reduced ρb and increased porosity (Φ), enhancing the soil’s ability to transfer heat (Gatea Al-Shammary et al. 2023; Wang et al. 2023c). This increase in porosity allows for more efficient heat conduction, improving λ. However, this also leads to greater temperature fluctuations because the soil is more exposed to air, which has a lower thermal capacity than water. Therefore, while conventional tillage increases heat transfer, it also makes the soil more susceptible to rapid temperature changes, which may adversely affect plant growth and microbial activity (Song et al. 2024a).

In contrast, conservation tillage preserves soil structure by minimizing soil disruption. This results in better moisture retention and higher organic matter content, which increases the soil’s heat storage capacity (Cárceles Rodríguez et al. 2022; Haque et al. 2024). Because water has a higher thermal capacity than air, maintaining moisture in the soil increases λ. At the same time, conservation tillage reduces the rate of temperature fluctuations in the soil. This enhanced thermal stability is beneficial for maintaining optimal growing conditions for plants and supporting consistent microbial activity.

The depth of tillage also affects λ. Deeper soil layers generally have lower λ due to increased compaction and reduced porosity (Al-Shammary et al. 2020a; Liu et al. 2024a). Shallow tillage primarily influences the upper soil layers, where temperature fluctuations are more pronounced. As a result, shallow tillage practices often alter λ at the soil surface, affecting the heat dynamics and influencing soil temperature regulation.

In addition to tillage systems, the composition of the soil itself plays a significant role in determining λ. For example, soils rich in quartz tend to have higher λ, while higher clay content and increased porosity generally reduce λ (Xiuling et al. 2024). Extrinsic factors such as seepage velocity and salinity also influence λ. Increased seepage velocity tends to increase heat transfer, while lower salinity levels generally reduce λ (Cheng et al. 2024; Malek et al. 2021). Soil moisture content, in particular, is a major determinant of λ; saturated soils, for instance, exhibit higher λ because water conducts heat more effectively than air (Wu et al. 2025b).

Understanding the relationship between soil λ and tillage systems is crucial for optimizing agricultural practices. By selecting appropriate tillage methods, farmers can improve soil structure, moisture retention, and thermal stability, leading to more efficient soil heat transfer. Advanced soil monitoring techniques allow for precise measurements of λ, helping farmers to manage soil properties better and adapt to changing climatic conditions. Ultimately, incorporating effective SMP can enhance crop yields, improve soil health, and contribute to sustainable agricultural practices.

3.1.2 Soil organic matter (SOM) management

Soil organic matter (SOM) plays a crucial role in regulating soil λ, as it directly affects soil structure, Φ, water retention, and nutrient availability (Nutri av), all of which influence agricultural productivity. As shown in Fig. 4, the relationship between SOM and λ is complex, with SOM influencing several physical properties of the soil that ultimately affect heat transfer (Allende-Montalbán et al. 2024; Chen et al. 2024c; Fu et al. 2024b; Tian et al. 2025). While SOM can improve soil structure by improving water retention and nutrient cycling, it also tends to decrease the soil’s ability to transfer heat due to its inherently lower λ compared to mineral soil components (Xiuling et al. 2024).

Fig. 4

Soil λ effect on soil organic matter (SOM) with its influence on environmental and agricultural processes

Studies have shown that soil λ typically decreases as the conditional nature of SOM’s concentration increases (He et al. 2021; Pan et al. 2024; Usowicz and Lipiec 2020; Wessolek et al. 2023; Zhu et al. 2019). This is primarily because organic matter, being less thermally conductive than mineral particles, reduces the overall λ of the soil (He et al. 2021). As SOM concentration rises, particularly in saturated soils, the reduction in λ becomes more pronounced. While SOM provides numerous benefits for soil health, such as enhancing microbial activity and supporting nutrient cycling, it also limits the heat transfer efficiency of the soil, which can influence crop growth and soil temperature regulation.

Nevertheless, the presence of SOM in soil contributes to improved agricultural outcomes when managed optimally. Optimal λ levels can support healthy microbial communities that are essential for nutrient cycling and soil fertility (Xu et al. 2024a). Furthermore, SOM plays a key role in carbon sequestration, which is vital for mitigating the effects of climate change. While SOM generally reduces λ, it also helps the soil retain moisture, which can improve thermal stability by reducing rapid temperature fluctuations and maintaining more consistent conditions for plants and microbes.

The relationship between SOM and λ is also influenced by µ. As moisture content increases, λ tends to increase as well, since water has a much higher thermal conductivity than air (Abu-Hamdeh and Reeder 2000). However, when SOM content rises, the rate at which λ increases with moisture diminishes. This is due to the higher water retention capacity of organic matter, which holds more moisture but does not significantly improve the heat conductivity as much as the mineral components of the soil would (Xiuling et al. 2024).

The λ of soils rich in organic matter is further influenced by temperature. In frozen conditions, organic-rich soils typically exhibit higher λ due to the presence of ice, which conducts heat more efficiently than liquid water. However, as temperatures rise and the soil thaws, the moisture content in SOM-rich soils tends to decrease, which lowers λ. The porous and loose nature of organic matter also leads to increased air content within the soil matrix, further reducing heat transfer, since air is a poor conductor of heat (Wang et al. 2024c).

3.1.3 Irrigation practices (IP)

Irrigation practices (IP) play a critical role in influencing soil λ, and by extension, they affect key factors such as soil µ, soil temperature, root growth, and overall crop performance (Lunt et al. 2023; Parlak et al. 2022; Pascoal et al. 2024; Quan et al. 2024a; Tan et al. 2025). As depicted in Fig. 5, the interaction between IP and soil λ is essential for optimizing agricultural productivity and promoting soil health. The addition of water through irrigation increases the moisture content of the soil, which directly influences λ. Water, being a better conductor of heat than air, replaces air in soil pores, thereby enhancing the soil’s ability to conduct heat (Fu et al. 2024a; Sepaskhah and Mazaheri-Tehrani 2024).

Fig. 5

Soil λ effect on irrigation practices (IP), with its influence on environmental and agricultural processes

This relationship is particularly evident in sandy soils, where water saturation can increase soil λ by orders of magnitude, given the significant contrast between water and air’s thermal conductivity. Various irrigation methods, such as surface irrigation, sprinkler irrigation, and drip irrigation, impact soil temperature profiles in different ways. For example, surface irrigation tends to elevate soil moisture levels, which increases soil λ since water retains heat more efficiently than air (Fig. 5). The influx of water through surface irrigation leads to a more uniform distribution of moisture throughout the soil profile, thus improving λ.

In contrast, drip irrigation, which delivers water directly to the soil at specific points, can reduce surface soil temperatures and lower soil λ. The frequent, localized watering associated with drip irrigation generally results in lower moisture content in the surrounding soil areas, which reduces the overall heat retention ability of the soil (Wen et al. 2023). This decrease in λ can influence soil temperature dynamics, particularly at the surface, where heat fluctuations are more pronounced.

The effect of irrigation practices on soil λ is also affected by several extrinsic factors, including seasonal variations, soil type, climate conditions, and crop type (Parajuli et al. 2024; Pascoal et al. 2024). For instance, in dry conditions or during hot seasons, irrigation can significantly modify soil temperature profiles by enhancing moisture retention, which in turn improves λ and helps to moderate extreme temperature variations that could otherwise stress crops. Conversely, during cooler seasons or in regions with high rainfall, irrigation might have less of an effect on λ, as soil moisture levels are typically already high.

Given these factors, understanding the interactions between irrigation practices and soil λ is essential for farmers aiming to optimize irrigation methods. By carefully selecting and managing irrigation techniques, farmers can enhance soil health, as well as crop growth, and maximize water use efficiency. This, in turn, can lead to more sustainable agricultural practices, particularly in regions affected by water scarcity or erratic climatic conditions. Optimizing irrigation not only boosts λ but also contributes to better soil structure, more efficient nutrient cycling, and enhanced crop resilience to environmental stressors.

3.1.4 Crop rotation (CR)

Crop rotation (CR) is a key agricultural practice that can significantly influence soil λ, as shown in Fig. 6. CR enhances soil structure, increases organic matter content, improves moisture retention, and fosters the development of diverse root systems, all of which contribute to the stabilization of soil and its thermal properties. These changes ultimately benefit both crop growth and overall soil health (Haque et al. 2024; Haruna et al. 2017; Malek et al. 2021; Yang et al. 2024). Specifically, the inclusion of cover crops in CR systems can increase soil organic carbon (SOC), which is essential for controlling soil properties, including λ (Cerecetto et al. 2024).

Fig. 6

Soil λ effect on crop rotation (CR), with its influence on environmental and agricultural processes

While organic matter is known to generally reduce λ due to its effect on soil porosity, which decreases the packing density of soil particles (He et al. 2022; Zhu et al. 2019), the influence of CR on λ can be more complex. Higher levels of SOC contribute to the loosening of soil, leading to increased porosity, particularly in the upper layers. This can lower λ because the increased air-filled pore spaces hinder heat conduction. However, CR can also have an inverse effect on soil pb, which is typically negatively correlated with λ (He et al. 2021). For example, the practice of no-till cover crop management has been shown to increase pb compared to conventional tillage, which results in higher λ values (Haque et al. 2024; Saha et al. 2024).

Furthermore, CR can modify soil µ by influencing soil structure and organic matter content, which in turn affects water retention. As water has a higher thermal conductivity than air, increased moisture content generally leads to higher λ (Bayat et al. 2021). Cover crops, through their root systems and organic matter inputs, can also affect the distribution and size of soil pores. By increasing total pore space and water-filled pore spaces, cover crops help to increase moisture retention, thus promoting higher λ values (Schjønning 2021). However, the increase in organic matter may also lead to more air-filled pores, reducing λ due to air’s relatively low thermal conductivity.

Understanding the effects of CR on soil λ is crucial for optimizing soil temperature regulation, which has a direct impact on crop development, microbial activity, and overall soil health. A reduction in λ, for instance, could help to mitigate extreme temperature fluctuations, which could be advantageous for crops that are sensitive to temperature stress. By carefully planning and implementing CR strategies, farmers can improve soil health, optimize water use, and increase crop productivity, leading to more sustainable agricultural practices and greater resilience to climate variability.

3.1.5 Nutrient availability (Nutri av)

Soil λ has a profound impact on nutrient availability (Nutri av) by influencing various factors such as soil temperature, µ, microbial activity, and root growth, which together govern the solubility and mobility of nutrients in the soil matrix (Al-Shammary et al. 2020a). As depicted in Fig. 7, these interconnected processes directly influence crop growth and yield by determining how nutrients are mobilized and accessed by plants.

Fig. 7

Soil λ effect on nutrient availability (Nutri av), with its influence on environmental and agricultural processes

Soil temperature is one of the most important factors affecting nutrient solubility and mobility. Temperature regulates the rate of chemical reactions and microbial processes, such as organic matter decomposition and nutrient mineralization. As soil temperature increases, microbial activity generally intensifies, leading to a higher Nutri av. However, excessively high temperatures can cause the volatilization of specific nutrients, such as nitrogen, which reduces their bioavailability. Temperature fluctuations also influence root growth and exudation patterns, essential processes for nutrient uptake. Different plant species have optimal temperature ranges for growth, and deviations from these thresholds can impede nutrient absorption, leading to reduced plant health and growth.

The relationship between λ and µ is integral to nutrient transport within the soil. Higher λ is generally associated with higher moisture content, which enhances nutrient solubility and availability (Wu et al. 2025b). However, excessive moisture can lead to nutrient leaching, especially in systems where fertilizers are regularly applied, which could reduce the availability of essential nutrients. Soil texture further influences λ, and consequently Nutri av. For example, sandy soils tend to have higher λ compared to clay-rich soils, but they also experience faster drainage, which can result in reduced nutrient retention. On the other hand, clay soils have better moisture retention but lower λ, which can limit nutrient diffusion within the soil.

Agricultural practices such as tillage, irrigation, and crop spacing play a critical role in altering soil thermal behaviour, directly affecting nutrient availability. Conservation tillage and no-till farming practices, for instance, can improve soil λ by enhancing water retention and, subsequently, nutrient availability. These methods are particularly beneficial in comparison to conventional tillage systems, which may disrupt soil structure and reduce nutrient retention (Haque et al. 2024). However, soil compaction, which increases pb, can impede root growth while enhancing nutrient diffusion rates, which ultimately restricts nutrient uptake.

Organic matter (OM) content in soil is another critical determinant of both TCs and nutrient availability. While higher OM levels can improve nutrient retention, it can also lower λ, potentially slowing the rate at which nutrients are released. Soil pH and land management strategies are also vital factors influencing nutrient cycling and availability. For example, the use of organic amendments can significantly improve the soil’s nutrient-holding capacity, but this may come at the cost of reduced λ due to the changes in soil structure that accompany organic matter buildup.

Given the complexity of these interactions, effective soil management requires a comprehensive understanding of how TCs, moisture dynamics, and nutrient availability are linked. Further research into the mechanisms by which TCs influence nutrient cycling is needed, particularly in light of changing climate conditions and the development of advanced agronomic technologies. A deeper understanding of these processes will be crucial for developing precision agriculture strategies that optimize nutrient use efficiency, ensuring both sustainable crop production and long-term soil fertility.

3.1.6 Soil textures (Soil tex)

The texture of soil (Soil tex) plays a significant role in determining its λ, with the characteristics of particle size, porosity, and water retention capacity having a profound influence (Klamerus-Iwan et al. 2024). These factors are crucial for understanding the behaviour of soils within agro-environmental systems, as soil texture directly impacts various soil properties that are essential for agricultural productivity and ecosystem health (Liu et al. 2024a; Różański 2022). As illustrated in Fig. 8, different soil textures, including sandy, silty, and clayey soils, exhibit distinct λ characteristics, largely due to differences in their particle size and µ (Song et al. 2024b; Xia et al. 2025).

Fig. 8