Soil Ecological Functions Research Articles

Factors of biologization of farming in the forest-steppe zone of Volga region

The modern development of world farming was announced at the UN Conference on Environment and Development, and is connected with the biosphere paradigm of nature management (1992), which implies the priority of maintaining the ecological functions of soils and landscapes (ecologization). In agriculture, ecologization is known as “organic farming” (ecological, biological, etc.), but in Russia, “organic farming”, in its pure form (without pesticides and chemical fertilizers), has not gained momentum yet. The legislative base for this was developed only in 2019 and in the coming years it is unlikely to receive widespread distribution among representatives of agribusiness for economic, social and cultural reasons. Further development of modern agribusiness is possible due to technological modernization through the technological upgrading by means of a system of biologization. In this article, we have revealed the main factors and practical methods of biologization of modern farming under the conditions of the forest-steppe zone of the Volga region.

Soil pH Responses to Simulated Acid Rain Leaching in Three Agricultural Soils

Soil has the nature of acidity and alkalinity, mostly indicated by soil pH that could greatly affect soil ecological processes and functions. With exogenous inputs of acidic materials (such as acid rain), soils may more or less resist to maintain their pH levels within specific thresholds by various buffering processes. It has been well established that soil properties such as cation exchange capacity (CEC), soil organic matter (SOM), and clay content play important roles in mitigating the effects of acid inputs, but the factors varied across soils. This microcosm experiment was conducted to investigate changes in the soil pH and quantitatively estimate the critical pH threshold of simulated acid rain for three highly weathered soils (red soil, lateritic red soil, and latosol) that are typical soil types widely distributed across the world’s subtropical and tropical climatic zones, as well as important influential factors, after continuously adding different levels of simulated acid rain on the surface of soil cores. The results showed that the change in the soil pH was not significantly different among the three soils, although it was exponentially related to soil CEC and clay content. Resultantly, the latosol that had high soil CEC and clay content was more resistant to simulated acid rain, especially when relatively weak simulated acid rain treatments were applied. The lateritic red soil that contained the lowest soil CEC and clay content showed the greatest decline in the soil pH under the strongest simulated acid rain treatment of pH being 2.5. Furthermore, we estimated the critical pH threshold of simulated acid rain for the three soils and observed that it was considerably different among the soils. Surprisingly, the pH threshold of simulated acid rain was also positively related to the soil CEC and clay content, therefore making the highest pH threshold in the latosol. Our results imply that soil CEC and clay content may play critical roles in the soil acid-buffering processes from two aspects; it could not only contribute to the soil acid-buffering capacity, but also affect the threshold of acidity of acid rain below which abrupt soil acidification may occur.

Soil Maps in the New Ecological Atlas of Russia

A series of maps in the second edition of the Ecological Atlas (2017) characterizes several aspects of the ecological situation in Russia and prerequisites of its formation; the maps were compiled basing on the soil map and other thematic maps. In terms of the methods of their compilation, the maps may be grouped into factual and interpretational, the former being directly based on cartographic and analytical data, while the latter were compiled by means of targeted interpretation of information obtained from other maps (primarily, from the soil map). This information concerns soil profiles and particular properties of soil units in the legend of the basic soil map, which is also included in the atlas. The experience in compilation of the series of maps in the atlas enabled us to introduce new elements in the methodology of creating interpretational maps, which is being developed within the framework of the soil-landscape-geochemical approach suggested by M.A. Glazovskaya. The innovative maps in the series are the following: Ecological Functions of Soils, Red Data Soil Book, and Soil and Landscape-Geochemical Processes. As compared to the National Soil Atlas of Russia, the set of soil maps and their contents are rather different owing to the ecological orientation of the atlas.

Arbuscular mycorrhizal fungal community differentiation along a post-coal mining reclamation chronosequence in South Africa: A potential indicator of ecosystem recovery

Arbuscular mycorrhizal (AM) fungi contribute to the restoration of soil ecological functions and processes during ecosystem development. Here, diversity and differentiation of AM fungi in rhizosphere soils and roots of the dominant vegetation along a post-coal mining reclamation soil chronosequence of 3, 11, 15, 19 and 24 years after reclamation were investigated. High-throughput sequence analysis of partial Glomeromycotan 18S rRNA in soils and roots revealed a high number of core operational taxonomic units (OTUs) across chronosequence. Arbuscular mycorrhizal fungal (AMF) OTU richness, Shannon-Weiner index and species dominance were not significantly different across soil and root but were significantly (P < 0.05) correlated with ammonium, nitrate, silt fraction, litter, pH, foliar and/or basal covers. AMF community structure was significantly different (P < 0.05) across unmined and reclamation chronosequence soils, with differentiation between younger reclaimed areas (3 and 11 years) and older reclamation ages (19 and 24 years) in multivariate space. In contrast, structural differentiation in the AMF community colonising the single plant-host across the chronosequence was not significant (PERMANOVA, P > 0.05), although community composition and structure were heterogeneous within 3–11 years but similar within 15–24 years. Seven Glomeromycotan genera were detected in soil and roots, including the relatively dominant Glomus genus, and the differentially abundant Acaulospora, Diversispora, Paraglomus and Scutellospora in either earlier or later years since post-mining reclamation. Canonical correspondence analysis revealed that nitrates (NO3-N), clay content and bulk density significantly influenced (P < 0.05) the AMF community structure in soil, whereas, the AMF community in root was not significantly influenced (P > 0.05) by environmental variables. Overall, the study suggests that AMF community differentiation reflect ecosystem development over chronological space-time. Thus, AMF species differentiation may be included as part of a minimum dataset for monitoring ecosystem restoration following post-mining reclamation.

Mixing effect of polylactic acid microplastic and straw residue on soil property and ecological function.

Microplastics have become a contaminant of increasing concern in soils. Although biodegradable plastics were considered as alternatives of traditional plastics, some evidence showed that biodegradable plastics might produce more microplastics. Until now, the effect of biodegradable microplastics on soil functions and processes, as well as microbial communities is uncertain. Based on high throughput sequencing, enzymatic activity assay and dynamic analysis of soil carbon and nitrogen, we investigated the effects of biodegradable polylactic acid microplastics (PLA MPs) on soil microbiota and related ecological processes under conditions of high or low carbon content. The results showed that PLA MPs had no significant effect on the overall diversity and composition of bacterial communities or related ecosystem functions and processes. However, co-occurrence network analysis revealed that PLA MPs impacted the interactions between constituent species, which might have legacy effect on soil bacterial communities and functions. Our data also revealed that PLA MPs could trade off the priming effect of carbon source. Our results provided an integrated picture in understanding the effects of PLA MPs on soil microbes, properties and ecological functions, which will help to further understand the effects of MPs on terrestrial ecosystems.

Ecological functions of soils and criteria for their assessment

In modern soil ecology, there is a need to develop a unified approach to assessing the ecological functions of the soil cover. Analysis of publications on this topic shows that this question is open. There are many criteria for evaluation individual soil properties. However, there is no general approach to assessing the eco-functions of the soil. The purpose of the work is the development of universal criteria for evaluation the ecological functions of soils. In this paper, it is proposed to use 2 criteria for assessing the ecological functions of the soil cover. These criteria are based on the fixation of changes in properties and their favorableness to the ecosystem. The proposed criteria were used to evaluate 5 biogeocenotic soil functions. This assessment approach is acceptable for agricultural soils.

Long-term phytomanagement with compost and a sunflower – Tobacco rotation influences the structural microbial diversity of a Cu-contaminated soil

At a former wood preservation site contaminated with Cu, various phytomanagement options have been assessed in the last decade through physicochemical, ecotoxicological and biological assays. In a field trial at this site, phytomanagement with a crop rotation based on tobacco and sunflower, combined with the incorporation of compost and dolomitic limestone, has proved to be efficient in Cu-associated risk mitigation, ecological soil functions recovery and net gain of economic and social benefits. To demonstrate the long-term effectiveness and sustainability of phytomanagement, we assessed here the influence of this remediation option on the diversity, composition and structure of microbial communities over time, through a metabarcoding approach. After 9 years of phytomanagement, no overall effect was identified on microbial diversity; the soil amendments, notably the repeated compost application, led to shifts in soil microbial populations. This phytomanagement option induced changes in the composition of soil microbial communities, promoting the growth of microbial groups belonging to Alphaproteobacteria, many being involved in N cycling. Populations of Nitrososphaeria, which are crucial in nitrification, as well as taxa from phyla Planctomycetacia, Chloroflexi and Gemmatimonadetes, which are tolerant to metal contamination and adapted to oligotrophic soil conditions, decreased in amended phytomanaged plots. Our study provides an insight into population dynamics within soil microbial communities under long-term phytomanagement, in line with the assessment of soil ecological functions and their recovery.

Significant Impacts of Both Total Amount and Availability of Heavy Metals on the Functions and Assembly of Soil Microbial Communities in Different Land Use Patterns.

Land use change alters the accumulation of heavy metals (HMs) in soils and might have significant influence on the assembly and functions of soil microbial community. Although numerous studies have discussed the impacts of either total amounts or availability of metals on soil microbes in land change, there is still limited understanding on which one is more critical. In the present study, soils from three land use types (forest, mining field, and operating factory) located in Shaoguan city (Guangdong Province, China) were collected to investigate the impacts of soil HMs on soil enzyme activities and bacterial community structures. Mining activities remarkably increased the concentrations of HMs in soils, and land use patterns changed soil properties and nutrition level. Soil pH, total and available HMs (Cu, Pb, Zn, and Cd) and organic matters (SOM) were identified as the key influential factors shaping soil ecological functions (soil enzyme activities) and community assembly (bacterial community composition), explained by HMs accumulation and soil acidification caused by human activities. In addition, total amount and availability of some metals (Zn, Pb, Cu, and Cd) showed similar and significant effects on soil bacterial communities. Our findings provide new clues for reassessing the environmental risks of HMs in soils with different land use.

Analyzing the influence of landscape pattern change on ecological water requirements in an arid/semiarid region of China

With climate change and the intensification of human activities, landscape patterns have undergone important changes. These changes can have multiple impact on hydrology, nutrient transport between soil and vegetation and ecological function and health in vegetative ecosystems. Dynamic changes in landscape patterns may affect the ecological water requirements (EWRs) of vegetation. Based on meteorological data, soil data and 6 years of land use data (from 1990 to 2015), the EWRs were obtained through the Penman–Monteith formula. eight suitable landscape indices (Patch Density (PD), Connectivity Index (COHESION), Largest Patch Index (LPI), Aggregation Index (AI), Shannon Diversity Index (SHDI), Contagion Index (CONTAG), Separation Index (SPLIT), and Landscape Shape Index (LSI)) were used to explore the spatial and temporal characteristics of landscape patterns. Furthermore, the influences of landscape pattern changes on the EWRs of the middle main reaches of the Yellow River, China, were investigated. From 1990 to 2015, the total number of patches in the landscape pattern of the watershed increased, and the patch shape became more complex; the EWRs decreased from 392.7 mm to 276.5 mm, and the annual volume of the EWRs in the study area decreased from 124.8 × 108 m3 to 89.6 × 108 m3. The EWRs had a positive correlation with the LPI, indicating that the changes in the largest patch had a great impact on the EWRs. The EWRs also had a negative correlation with the SPLIT, showing that the more fragmented the landscape patches, the smaller the EWRs. With an increase in SHDI, the EWRs showed a downward trend. Furthermore, the EWRs showed a downward trend with decreasing CONTAG and COHESION. These results provide useful information for ecological restoration and provide an important reference for ecological environmental protection and the optimal allocation of water resources in arid/semiarid regions around the world. In the future, the EWRs can be regulated, and the utilization rate of water resources can be improved, by combining the current ecological environmental protection policies of the Yellow River Basin and managing future trends in landscape patterns.

Potential Indicators of Soil Health Degradation in Different Land Use-Based Ecosystems in the Shiwaliks of Northwestern India

Identifying the importance of soil biology in different land use systems is critical to assess the present conditions of declining soil (C) and global land degradation while regulating soil health and biogeochemical nutrient cycling. A study was undertaken in a mixed watershed comprising of different land use systems (agricultural, grassland, agroforestry, and eroded); situated in the Shiwalik region in the foot hills of the lower Himalayas in India, a fragile ecosystem susceptible to land degradation. Soil samples from 0–15 and 15–30 cm depths were collected from these land use systems and analyzed for a suite of different soil health indicators, including physio-chemical soil properties, aggregate stability, soil microflora, and the enzymatic activities that are critical for nutrient cycling. Principal component analysis was used to group different land uses and understand their association with soil microflora, enzyme activities, and soil physio-chemical properties. We found that a greater number of soil microflora and enzymatic activities were associated with grassland and agroforestry land use systems. Aggregate-associated soil C correlated well with the soil microflora under different land use systems studied. The biplots revealed that the fungal:bacterial ratio (2 × 103–0.1 × 103) was a robust indicator of C accumulation and soil health, and was in greater association with the agroforestry land use system. Random forest, a non-parametric statistical test, on average explained that 68% to 92% of the variability in soil microbial population was due to land use and other soil health properties. Overall, the biological soil health indicators used in this study demonstrated the fact that land use management systems that employ constant crop cover with minimal disturbance have the potential to improve soil sustainability and ecological functioning.

Identification of phytotoxic metabolites released from Rehmannia glutinosa suggest their importance in the formation of its replant problem

The yield and quality of medicinal tubers of Rehmannia glutinosa are seriously restricted by replanting problems. However, the origin and identification of the potential allelochemicals associated with this issue have not been well described. Therefore, in a series of related studies, we aimed to identify the key phytotoxic metabolites released from R. glutinosa. R. glutinosa residues were harvested and extracted for metabolic profiling and bioassay-directed identification. Metabolites in the leaf, tuber, and soil surrounding R. glutinosa roots were profiled using high pressure liquid chromatography coupled to a quadrupole/time of flight mass spectormeter. A Petri dish-filter paper and modified Parker bioassay were used to evaluate the phytotoxicity of plant residues and candidate allelochemicals. Seventeen metabolites specific to R. glutinosa were identified/annotated using non-targeted metabolic profiling combined with known standards. Assay results suggested an iridoid glycoside and several phenylethanoid glycosides as key allelochemicals originating from R. glutinosa. Identification of bioactive metabolites in planta and in the rhizosphere has increased our understanding of the phytochemistry of R. glutinosa. Further evaluation of the soil persistence and ecological functions of these bioactive compounds will be important for determination of the specific mechanisms associated with R. glutinosa replanting issues.

Impact of Leptospermone, a Natural β-Triketone Herbicide, on the Fungal Composition and Diversity of Two Arable Soils.

Impact of leptospermone, a β-triketone bioherbicide, was investigated on the fungal community which supports important soil ecological functions such as decomposition of organic matter and nutrients recycling. This study was done in a microcosm experiment using two French soils, Perpignan (P) and Saint-Jean-de-Fos (SJF), differing in their physicochemical properties and history treatment with synthetic β-triketones. Soil microcosms were treated with leptospermone at recommended dose and incubated under controlled conditions for 45 days. Untreated microcosms were used as control. Illumina MiSeq sequencing of the internal transcribed spacer region of the fungal rRNA revealed significant changes in fungal community structure and diversity in both soils. Xylariales, Hypocreales, Pleosporales and Capnodiales (Ascomycota phyla) fungi and those belonging to Sebacinales, Cantharellales, Agaricales, Polyporales, Filobasidiales and Tremellales orders (Basidiomycota phyla) were well represented in treated soil microcosms compared to control. Nevertheless, while for the treated SJF a complete recovery of the fungal community was observed at the end of the experiment, this was not the case for the P treated soil, although no more bioherbicide remained. Indeed, the relative abundance of most of the saprophytic fungi were lower in treated soil compared to control microcosms whereas fungi from parasitic fungi included in Spizellomycetales and Pezizales orders increased. To the best of our knowledge, this is the only study assessing the effect of the bioherbicide leptospermone on the composition and diversity of the fungal community in soil. This study showed that leptospermone has an impact on α- and β-diversity of the fungal community. It underlines the possible interest of microbial endpoints for environmental risk assessment of biopesticide.

Using reservoir deposits to quantify the source contributions to the sediment yield in the Black Soil Region, Northeast China, based on the fingerprinting technique

Identifying patterns of sediment dynamics is an important aspect of understanding soil erosion processes and developing reasonable management strategies to address environmental problems and assess the ecological functions of soil and water conservation measures. In this study, the sediment fingerprinting technique was applied in order to quantify the relative contributions of sediment to the Hebei catchment in the black soil region of Northeast China, with the aim of determining the response of soil erosion to recent changes in land management. Within an area of approximately 28 km2, three potential sediment sources were identified based on land use types. They included cultivated topsoil, uncultivated topsoil, and gullies. A total of 69 sediment source samples were collected from potential sediment sources from 27 sampling sites for cultivated topsoil, 18 sampling sites for uncultivated topsoil, and 24 sampling sites for gullies. Six uniformly spatially distributed sediment cores were sampled from the Liudui reservoir. The Walling–Collins model was optimized using a genetic algorithm combined with the Latin hypercube sampling procedure. The results indicated that cultivated topsoil and gullies were the primary sediment provenances and that gully erosion is as important as rill and interrill erosion. According to the mean sediment contributions of the six deposited sediment cores, the sediment contribution from cultivated topsoil was 50.6%, ranging from 34.4% to 63.7%, whereas gullies contributed 42.9%, ranging from 30.1% to 57.8%. However, the sediment from uncultivated topsoil (mainly containing forest and grassland) contributed only 6.5%, with a range of 5.0% to 7.8% over the last few decades with a mean absolute fit of 0.95. This indicated that caution is needed in when using only a single core to provide results for a reservoir. Over the 1976–2016 period, rill and interrill erosion showed a general decreasing trend, whereas gully erosion showed an increasing trend. According to the sedimentation depth and time marks based on the 137Cs and D50 peak horizon and decayed vegetation layer in the six sediment cores, sedimentation rates during 1976–1998 and 1999–2016 were 1.6 cm yr−1 (14.4 kg m−2 yr−1) and 0.9 cm yr−1 (7.6 kg m−2 yr−1), respectively. For the entire time series (1976–2016), the sedimentation rate was 1.2 cm yr−1 (10.7 kg m−2 yr−1). A good correlation exists between the distance from the reservoir entrance and sediment contribution/mean annual sedimentation rate (r2 > 0.68, except uncultivated topsoil).

Soil Structure - the elusive and fragile scaffolding for soil ecological functioning

Soil Structure - the elusive and fragile scaffolding for soil ecological functioning

A method for estimating nematode body lengths for use in the calculation of biomass via a simplified formula

Soil nematode biomass is related to a number of soil ecological processes and functions. Nematode shape is simple, i.e., they have elongate cylindrical bodies that taper towards both ends. Consequently, the weight of an individual nematode can be estimated from its greatest body diameter (D) and body length (L), using a simple formula developed by Andrássy. Because heat-killed and fixed nematodes often have non-linear, irregular shapes, however, it is easier to measure D than L. To reduce the time required to assess an individual nematode's weight, we propose a new method of calculating nematode weight with D as the single measure. Our formula was based on the recognition of a strong linear correlation between D and L. The performance of our formula was compared with Andrássy's formula for the whole nematode community and for nematode trophic groups in an area with four land use types. The nematode weights calculated with these two formulas were positively correlated, and the slopes of the regressions between the two biomass estimates were close to 1 for the whole nematode community and the five trophic groups. In addition, there was no difference in the outcome due to land use type, indicating that the proposed formula may be generally useful for assessing nematode weights in terrestrial ecosystems. We also propose to include five trophic group-specific factors in the new formula for more accurate assessments.

Intensive tropical land use massively shifts soil fungal communities

Soil fungi are key players in nutrient cycles as decomposers, mutualists and pathogens, but the impact of tropical rain forest transformation into rubber or oil palm plantations on fungal community structures and their ecological functions are unknown. We hypothesized that increasing land use intensity and habitat loss due to the replacement of the hyperdiverse forest flora by nonendemic cash crops drives a drastic loss of diversity of soil fungal taxa and impairs the ecological soil functions. Unexpectedly, rain forest conversion was not associated with strong diversity loss but with massive shifts in soil fungal community composition. Fungal communities clustered according to land use system and loss of plant species. Network analysis revealed characteristic fungal genera significantly associated with different land use systems. Shifts in soil fungal community structure were particularly distinct among different trophic groups, with substantial decreases in symbiotrophic fungi and increases in saprotrophic and pathotrophic fungi in oil palm and rubber plantations in comparison with rain forests. In conclusion, conversion of rain forests and current land use systems restructure soil fungal communities towards enhanced pathogen pressure and, thus, threaten ecosystem health functions.

Effect of biogas slurry addition on soil properties, yields, and bacterial composition in the rice-rape rotation ecosystem over 3 years

Organic treatments may improve soil nutrient availability and ecological functions. This study aimed to determine the effect of biogas slurry (BS) on soil properties, yields, and bacterial community activity and to examine the main environmental factors impacting bacterial compositions in the ecosystem. A 3-year field experiment was conducted in yellow soil under a rice-rape rotation to understand the effect of BS originating from anaerobically digested pig waste on soil chemical and bacterial compositions. Compared with an inorganic nutrient treatment and a control, adding BS at a moderate dose (BS6, 165.1 t ha−1) positively affected the rice and rape yields, soil fertility, and bacterial diversity. The BS was more suitable than chemical fertilizer for maintaining agricultural soil sustainability, especially the BS6 and BS7 treatments (165.1 and 182.1 t ha−1, respectively), by improving nutrient content, increasing soil pH, and promoting soil crumb structure formation. The relative abundance of Actinobacteria in BS6 was decreased by 37.9% compared with the untreated soil and 27.7% compared with the fertilizer treatment, while the relative abundance of Nitrospirae in BS6 increased by 41.2% and 43.5% compared with these treatments, respectively. Redundancy analyses (RDA) showed that pH, rape yield, cation exchange capacity (CEC), and total nitrogen (TN) were significantly correlated with soil bacterial community composition and explained 56.0%, 46.4%, 43.2%, and 34.9% of the total community variability, respectively. The soil bacterial diversity depended mainly on soil pH, and crop rotation played an important role in changing the bacterial community. The soil bacterial composition was clearly altered after 3 years of BS treatments. These increases in bacterial diversity could be of ecological significance in maintaining soil fertility and functionality.

A Review of Geophysical Methods for Soil Structure Characterization

AbstractThe growing interest in the maintenance of favorable soil structure is largely motivated by its central role in plant growth, soil ecological functioning, and impacts on surface water and energy fluxes. Soil structure pertains to the spatial arrangement of voids and solid constituents, their aggregation, and mechanical state. As a fragile product of soil biological activity that includes invisible ingredients (mechanical and ecological states), soil structure is difficult to define rigorously, and measurements of relevant metrics often rely on core samples or on episodic point measurements. The presence of soil structure has not yet been explicitly incorporated in climate and Earth systems models, partially due to incomplete methodological means to characterize it at relevant scales and to parameterize it in spatially extensive models. We seek to review the potential of harnessing geophysical methods to fill the scale gap in characterization of soil structure directly (via impact of soil pores, transport, and mechanical properties on geophysical signals) or indirectly by measurement of surrogate variables (wetness and rates of drainage). We review basic aspects of soil structure and challenges of characterization across spatial and temporal scales and how geophysical methods could be used for the task. Additionally, we propose the use of geophysical models, inversion techniques, and combination of geophysical methods for extracting soil structure information at previously unexplored spatial and temporal scales.

Responses of biological soil crusts to rehabilitation strategies

Biological soil crusts (biocrusts) are common to dryland ecosystems and can influence a broad suite of soil ecological functions including stability and surface hydrology. Due to long recovery times following disturbance, there is a clear need for rehabilitation strategies to enhance the recovery of biocrust communities. Essential to biocrust recovery are exopolysaccharides (EPS): secretions comprised mainly of high molecular weight polymers that protect cyanobacteria and other biocrust organisms from harsh environmental conditions. We examined whether biocrust rehabilitation strategies (combinations of inoculation with surface shading and artificial soil stabilization) promote EPS production. To test if responses varied by soil texture, we measured biocrust recovery on two fine-textured soils (clay and sandy clay loam) in a cool desert ecosystem. Shade coupled with inoculum addition resulted in the highest biocrust recovery, especially on clay soils. Independent of rehabilitation strategies, natural recovery of biocrusts occurred more rapidly on clay soils, reflected by greater increases in chlorophyll a (chl a). Chl a, a proxy for cyanobacterial biomass, was correlated to EPS amounts, suggesting that cyanobacteria are significant contributors to EPS production in biocrust development. Despite the role of EPS in biocrust establishment, EPS amounts had negligible effects on soil stability on the fine soil texture.

Effects of orchard floor management on the peach rhizosphere

A preliminary study examining soil microbiology and nutrient dynamics in year three of a peach orchard at the Sandhills Research Station‎, North Carolina, USA found that maintaining a 3.6-m vegetation-free strip in the tree row reduced microbial biomass and associated activities in the soil, compared with a 0 m strip, and that the use of under tree micro-sprinkler irrigation increased peach root colonization by endomycorrhizal fungi as well as microbial biomass and associated activities. The current study was conducted in years four and five of that orchard and examined vegetation-free strip widths of 0, 1.2, 2.4, and 3.6 m, with and without irrigation, to determine their effects on endomycorrhizal fungal colonization of peach roots, soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), soil microbial respiration (SMR), and net nitrogen mineralization (NNM). There were no significant differences between treatments for endomycorrhizal fungal colonization or MBC by year four. The 3.6 m vegetation-free strip had the lowest MBN and SMR in year four with no significant difference between strip treatments in year five. NNM decreased with greater vegetation-free strip widths in years four and five. Irrigated plots had significantly higher MBN and lower SMR in the spring of year five with no other significant differences due to irrigation. These important findings show that under standard commercial management of a bearing peach orchard there is little impairment of soil ecological function in the rhizosphere, allowing for maximum peach yield and quality while supporting the health of trees and soil.