Soil Health Indicators Research Articles

Status of Soil Health Indicators after 18 Years of Systematic Tillage in a Long-Term Experiment

Long-term cultivation experiments are gaining more attention due to the possibility of following the changes in soil parameters (e.g., soil organic carbon (SOC), stock and soil health indicators, etc.). Our objective was to assess the status of soil in an 18-year-old tillage experiment after almost two decades of systematic tillage. In this research, soil physical (bulk density, moisture content), chemical (pH, SOC), and biological properties (soil microbial respiration, abundance, biomass, species composition of earthworms, yield) were used as indicators in three soil cultivation methods representing different degrees of disturbance (no-till—NT; shallow cultivation—SC; and ploughing—P). Based on our results, there were significant differences in bulk density (NT > SC, P) in 0–10 cm, and NT > P in deeper layers (10–20, 20–30, 30–40 cm), while the SOC content in 0–10 cm was the highest in NT (2.5%), followed by SC (2.4%) and P (2.0%). Soil microbial respiration was significantly greater in NT than in SC and P. The abundance and biomass of earthworms was the highest in NT (189 ind m−2, 41.26 g m−2), followed by SC (125 ind m−2, 36.9 g m−2) and P (48 ind m−2, 7.4 g m−2). We concluded that NT offered a beneficial habitat for earthworms and microorganisms and a high SOC storage capacity; however, bulk density was less convenient due to soil compaction in our experiment. Therefore, SC can be used as an alternative approach for sustainable soil tillage.

Impact of stockpile depth and storage time on soil microbial communities

Soil removal and stockpiling prior to mining activities have adverse effects on soil health, which raises concerns about the suitability of stockpiled soils as a reclamation substrate. Due to the fundamental roles microbes play in ecosystem function and services, they can be used as indicators of soil health and quality. We analyzed the prokaryotic microbial communities in a chronosequence of 0.5–28-year-old stockpiles at increasing depths (0–300 cm), in two oil-extraction locations in northern Alberta. Our results indicate that the microbial communities of the seven stockpiles examined were more similar to each other than to the undisturbed soils used as reference, which might indicate that stockpiling shifts the microbial community composition outside the range of natural variability. Furthermore, while microbial communities in younger and older stockpiles were dissimilar to the reference soils, the communities of intermediate-age stockpiles were more similar to those in the reference soils. We interpret these divergences in similarity to indicate that initial disturbance leads to a shift in the microbial community, which then recovers following several years of storage, but eventually, long-term storage leads to a secondary divergence from the range of natural variability. Additionally, the bacterial diversity decreased significantly with increasing stockpile depth, which could be attributed to the harsh conditions of the deeper stockpile layers and the scarcity of nutrients. Our findings provide important insights into the impact of soil stockpiling on microbial communities and complement those of earlier studies highlighting the importance of stockpile depth and storage time as predictors of variability of soil microbial diversity and community composition. Furthermore, due to the crucial functions played by microbes in soils, our conclusions should serve for reclamation agencies to modify the stockpiling protocols in order to mitigate the impact of stockpiling on soil microbial communities.

Comparative Assessment of The Climatological Conditions on The Biological Activity of Ampelocenoses Soils Cultivated in The Wine-Growing Regions of The Southern Coast of Crimea and The Eastern Part of The National Park “Fruska Gora”

Over the last years, research interest in the use of soil biological activity indicator for predicting the state and sustainability of natural and agroecosystems has increased significantly due to climatic changes altering the location and boundaries of established agroclimatic belts. These changes are characterized by unprecedented speed, as well as spatial and temporal heterogeneity. In this regard, the identification of regularities of influence of regional agroclimatic factors on soil microbiota as an indicator of soil health under different types of land use is of great relevance. In this paper, we tried to determine the climatic factors limiting the activity of soil microbiome functioning on the basis of calculation of climatic indices in two regions of grape cultivation close in temperature regime, but contrasting in humidity, located in the Republic of Crimea and the Republic of Serbia.

Integrating pastured meat chickens into organic vegetable production increased nitrogen and microbial biomass with variability in presence of E. coli and Salmonella spp

Abstract Integrating animals into a farm supports a closed or semi-closed production system where nutrients are recycled and off-farm inputs are reduced. In comparison to other livestock, chickens can be a low-investment option for animal-crop integration of small-scale, diversified, vegetable farms. Although crop-animal integration poses many potential benefits to farms, soils, and the environment, there are significant food safety risks when considering the production of vegetables in close proximity to raw manure. The objectives of this study were to examine the effects of poultry integration with meat chickens (broilers) in two different seasons on soil health, food safety, vegetable yield, and poultry feed efficiency in organic vegetable cropping systems. We explored these effects in an open field study with three rotation treatments (two that integrated chickens and a no-chicken control): vegetables-cover crop (V-CC; control treatment), vegetables-cover crop-poultry (V-CC-P), and vegetables-poultry-cover crop (V-P-CC). In response to crop rotation, over three years, we monitored soil nutrient status, soil microbial biomass carbon (MBC), permanganate oxidizable carbon (POXC), and microbial catabolic potential and diversity using Biolog® microplates. The presence or absence of foodborne pathogens in soil and vegetables was also measured. Nitrate–nitrogen (NO3–N) was higher in V-P-CC in year 2 as compared to both V-CC and V-CC-P (P = 0.001 and <0.001, respectively). After poultry removal in the summer of year 2 and year 3 V-P-CC was on average two times higher in NO3–N as compared to V-CC and V-CC-P, respectively. After chicken removal in the autumn of year 3 V-CC-P was 2.1 and 1.8 times higher in NO3–N as compared to V-CC and V-P-CC, respectively. On average phosphorus (P) increased by 45% in year 2 and by 13.2% in year 3. Microbial biomass carbon (MBC) increased from after harvest (summer) in year 1 to the end of the season (autumn) of year 2 from 219.75 to 303.23 mg carbon (C) kg−1. Integrating poultry increased MBC by 25%, on average between both treatments across all sampling dates, compared to the V-CC (P = 0.042). The vegetable-cover crop control (V-CC) preferentially used carbohydrates, compared to V-P-CC which corresponded to greater amino acid usage. Escherichia coli O157:H7 was detected in all plots in the spring of year 3 and select replications of plots in the autumn of year 3. Salmonella spp. was found in one plot in year 2. No pathogens were detected on the spinach crop when leaf surfaces were tested. Integrating chickens into organic vegetable crop rotations increases NO3–N and has the potential for off-farm fertilizer reductions if time and stocking density are further examined. However, poultry feed is often an off-farm input and should be considered when determining the true N input of this system. Soil health may be improved, but MBC and other soil health indicators should be monitored with longer-term rotations. There are food safety risks that come with the integration of chickens into vegetable production and fields should be treated as if raw manure has been applied. Despite the potential benefits of integrating poultry into vegetable crop rotations, more research on these systems is required to determine optimum integration strategies that provide maximum benefit to the producer, the animals, and the environment.

Soil management affects soil C and N stocks but not overall soil health

Soil health describes a soil’s capacity to function as a vital ecosystem that sustains plants, animals, and humans. It can be assessed by measuring specific soil physical, chemical, and biological parameters combined into a soil health index (SHI). The objective of this study was to evaluate the effect of management, depth, and their interaction on soil health indicators. We evaluated long-term continuous tillage, horticultural crop rotation, which had an antecedent tropical pumpkin/bean rotation, and a no-till avocado orchard in a Cumulic Haplustolls at the Juana Díaz Agricultural Experiment Substation. Soil samples were taken at 0 to 15, 15 to 30, 30 to 50, 50 to 75, and 75 to 100 cm intervals using a hydraulic probe. Soil pH, electrical conductivity, bulk density, dry stable aggregates, mean weight diameter, tensile strength, carbon and nitrogen stocks, and water content were quantified. The data were analyzed in a multivariate ANOVA. Results were classified considering threshold values, and an SHI score was determined based on the simple additive method. Our findings show that the no-till avocado orchard had better soil physicochemical qualities, including higher C and N stocks, but this did not lead to an improved SHI score when compared with the continuous tillage crop rotation plot. Soil depth, management, and their interaction were significant effects in both management systems with a score of 0.55 on the SHI scale. These results imply that, although overall soil health is not affected, increased C concentration, no-till, and perennials have a favorable effect on SHI indicators in horticultural systems in the San Antón series.

Growth and Performance of Baby Spinach grown under different Organic Fertilizer

This study investigates the effects of several organic fertilizers on baby spinach (Spinacia oleracea L.) cultivation’s growth, productivity, and sustainability. A randomized complete block design was employed to assess six organic fertilizer treatments, including vermicompost, farm yard manure (FYM), poultry waste, Azotobacter + poultry waste + FYM, Azotobacter + vermicompost, and a control (no fertilizer application). Plant growthparameters, nutrient content, pest resistance, soil health indicators, and environmental implications were evaluated to understand the effectiveness of organic fertilizers in promoting sustainable spinach production. Results indicate that treatments incorporating Azotobacter inoculants, particularly those combined with poultry waste or vermicompost, demonstrated superior performance in terms of production, biomass accumulation, plant height, leaf area, and nutrient content. These findings underscore the potential of bioinoculants in organic farming to increase soil fertility and ecological resilience, decreasedependency on synthetic inputs, and increase crop output. Moreover, organic fertilizers significantly influenced soil health parameters, with treatments exhibiting higher soil pH, organic matter content, and microbial activity contributing to improved soil fertility. Environmental implications of organic fertilizer use were also assessed, revealing varyinglevels of nutrient runoff and greenhouse gas emissions across different treatments. While Azotobacter-inoculated treatments showed higher greenhouse gas emissions, they also exhibited greater nutrient retention, indicating complex trade-offs between nutrient cyclingand environmental impact

A 1 billion euro mission: A Soil Deal for Europe

AbstractSoils have achieved prominence in the political agenda of the European Commission with the proposal for a Soil Monitoring Law and the ambitious Soil Mission research framework. The EU Soil Observatory (EUSO) used the latest state‐of‐the‐art pan‐European datasets to propose a preliminary assessment of soil health in the EU based on 18 soil degradation proxy indicators. The body of knowledge will soon be enriched thanks to the investment of 1 billion euros towards the Mission ‘A Soil Deal for Europe’, which has the ambition to promote the development of new harmonized bottom‐up and top‐down soil health indicators. New data and knowledge are also anticipated through the national soil monitoring schemes to support the implementation of the Soil Monitoring Law. We present the Soil Mission roadmap towards assessing and achieving soil health in the EU by 2030 to meet Green Deal objectives. We introduce the EUSO Soil Health Dashboard, a soil degradation indicator tool using soil health indicators developed by the European Soil Data Centre (ESDAC) (2012–2023) that will contribute to Soil Monitoring Law assessments.

Comprehensive chemical passivation of active-state heavy metals in relation to soil biological activity in Taojia River basin

Rapid global industrialization has resulted in irreversible environmental degradation, with one pressing issue being the escalating problem of land contamination induced by heavy metals (HMs). This phenomenon not only inflicts lasting harm on plants and microorganisms within the affected regions but also imposes significant losses on various industrial chains, particularly in the realm of agriculture. A noteworthy illustration is the soil contamination in the Taojia River Basin, Hunan Province, China, attributed to mining activities. Therefore, this study is dedicated to examining the passivation of active-state lead (Pb) and cadmium (Cd) in the cultivated fields of the Taojia River Basin. To achieve this, two passivating agents, namely bentonite (referred to as passivator-P) and an acidifying soil agent known as “Shi Di Jia” (referred to as passivator-S), were employed, along with a control group (CK). The passivation of Pb primarily relies on cation exchange adsorbed on the passivator's surface, while the passivation of Cd is intricately linked to total nitrogen content (TN). Indoor incubation tests were conducted to assess Pb and Cd in the soil. Additionally, an analysis of various soil health indicators and their relationships with microbial dynamics and soil enzymes was undertaken. The findings revealed that passivator-P exhibited greater efficacy in the passivation of Pb at concentrations of 3% and 5%, while higher concentrations of passivator-S demonstrated increased effectiveness in passivating Cd. Concerning bacterial diversity, the soil pH post-passivation showed a positive correlation with the Observed_species index, whereas Pb and Cd exhibited negative associations with the Chao1 index. Regarding fungal diversity, soil TN post-passivation displayed a positive correlation with the Simpson index. It is concluded that adding passivator-P at a 3% concentration proved to be the optimal passivating agent for Pb-contaminated soils in the Taojia River Basin. Although passivator-S demonstrated lesser efficacy in passivating Pb, it proved to be suitable for Cd passivation. These findings offer a crucial reference for passivation passivation remediation in the Taojia River area and other sites with similar characteristics, shedding light on the impacts on soil organisms. The implications underscore the necessity for site-specific remediation strategies and a holistic approach to addressing HMs contamination.

Determinants of Field‐Saturated Soil Hydraulic Conductivity Across Sub‐Saharan Africa: Texture and Beyond

AbstractSoil infiltration is critical for water security and related ecosystem services. This infiltration, the ability of soils to absorb water at their surface, is controlled by the soil hydraulic conductivity. Despite recent efforts in assembling measurements of soil hydraulic conductivity, global databases and derived pedotransfer functions lack coverage in the tropics. Here, we present soil infiltration measurements and other indicators of soil and land health collected systematically in 3,573 plots from 83 100 km2 sites across 19 countries in sub‐Saharan Africa. We use these data to (a) determine field‐saturated hydraulic conductivity (K fs) and (b) explore which variables best predict variation in K fs. Our results show that sand content, soil organic carbon (SOC), and woody cover had a positive relationship with K fs, whereas grazing intensity and soil pH had a negative relationship. Our findings highlight that, despite soil texture being important, structure also plays a critical role. These results indicate considerable potential to improve soil hydrological functioning through management and restoration practices that target soil structure. Enhancing SOC content, limiting animal stocking, promoting trees, shrubs, and other vegetation cover, and preventing soil erosion can increase K fs and improve water security. This data set can contribute to improving Earth system and land surface models for applications in Africa.

Reduction of Nitrate Leaching and Threats to Surface Water Under Conservation Tillage

Highlights Conservation agriculture practice (NT) improved soil organic matter, a principal indicator of soil health, soil health score (SHS) and CO2 respiration, and other soil physical and chemical properties vs. conventional till (CT) practice. Conservation agriculture practice (NT) promoted soil health functions under sufficient precipitation distribution and ample temperature conditions and aided the soil's retention ability to resist nitrate leaching and loads in subsurface drainage discharge systems. Uneven weather conditions, drought, and other variable agronomic practices rendered soil conditions unfavorable to retain nitrate and induced adverse effects by increasing the nitrate leaching and loads in NT vs. CT. The limited experiment period presented significant challenges for the evaluation and synthesizing of soil health motivations and barriers in the NT vs. CT. Abstract. An edge-of-field subsurface drainage discharge system removes excess subsurface water from agricultural fields to improve the conditions of the soil system making them favorable for plant growth. Conversely, edge-of-fields can increase the nitrate (NO3 -) offsite movement to surface water bodies, which ultimately impacts water quality. In St. Johns, MI. Two on-farm large areas were initiated in 2013 for conservation (NT) and conventional till (CT) practices, of which two microscale fields, an area of 4 acres for each, were delineated in 2019 for NT and CT practices under a corn/soybean crop rotation. NT and CT fields were monitored and evaluated through full water years (WYs) 2019-2022. The objective was to use an innovative approach in coupling edge-of-field with soil health assessments to learn how improved soil health functions are influencing nitrate leaching and loads. NT practice enhanced SOM, other physical properties, and soil health parameters, promoting soil health functions compared to CT practice under conditions of adequate precipitation and favorable temperatures. Additionally, it improved the soil's ability to retain and resist nitrate loads in the 2020 water year, with reductions of 9.6 and 18.3 kg/ha, respectively. In 2021, WY nitrate loads reported nearly an equal value in NT vs. CT (4.8 and 4.4 kg/ha, respectively). Factors of uneven weather conditions and drought, variable agronomic practices, and residual nitrogen after corn, rendered soil conditions unfavorable to retain nitrate and induced adverse effects by increasing the nitrate leaching and loads in NT vs CT in 2022 WY (8.1 and 5.8 kg/h, respectively). Therefore, the limited evaluation period (2019-2022 WYs) presented significant challenges and revealed no affirmative evidence that the improved soil health functions under NT reduced the nitrate leaching loads in all WYs of this research. Further research is needed to prove the impact of NT on improving soil health functions to sustainably reduce nitrate leaching and loads in edge-of-fields. Keywords: Conservation no-till (NT), Conventional till (CT), Nitrate load, Soil health functions, Subsurface drainage discharge, Water quality.

Response of soil microbial community structure to temperature and nitrogen fertilizer in three different provenances of Pennisetum alopecuroides.

Soil microorganisms are key indicators of soil health, and it is crucial to investigate the structure and interactions of soil microbial communities among three different provenances of Pennisetum alopecuroides under varying nitrogen fertilizer and temperature levels in Northwest China. This study aims to provide theoretical support for the sustainable use of artificial grassland in this region. Employing a two-factor pot-control experiment with three nitrogen fertilizer treatments and three temperature treatments, a total of all treatments was utilized to examine the composition and abundance of soil microbial communities associated with Pennisetum alopecuroides using high-throughput sequencing, PCR technology, and molecular ecological network analysis. The results revealed that Proteobacteria was the dominant bacterial phylum while Ascomycota was the dominant fungal phylum in the soil samples from three provenances of Pennisetum. Specifically, Proteobacteria exhibited higher abundance in the N3T2 treatment compared to other treatments under N3T2 (25-30°C, 3 g/pot) treatment conditions in Shaanxi and Gansu provinces; similarly, Proteobacteria was more abundant in the N1T2 (25-30°C, 1 g/pot) treatment in Inner Mongolia under N1T2. Moreover, Ascomycota displayed higher abundance than other treatments in both Inner Mongolia and Gansu provinces. Additionally, Pennisetum Ascomycota demonstrated greater prevalence under (25-30°C, 3 g/pot) treatment compared to other treatments; furthermore, Shaanxi's Pennisetum Ascomycota exhibited increased prevalence under N3T1 (18-23°C, 3 g/pot) treatment compared to other treatments. The richness and diversity of soil microbial communities were significantly influenced by nitrogen fertilizer and temperature changes, leading to notable alterations in their structure. Molecular ecological network analyses revealed strong collaborative relationships among microbial species in Shaanxi Pennisetum and Inner Mongolia Pennisetum under high nitrogen and high temperature treatments, while competitive relationships were observed among microbial species in Gansu Pennisetum under similar conditions. Redundancy analysis indicated that soil pH, total potassium, and total phosphorus were the primary environmental factors influencing microorganisms. In summary, this study offers a theoretical foundation for assessing the sustainable utilization of Pennisetum artificial grasslands in Northwest China by investigating the shifts in soil microbial communities and the driving factors under varying nitrogen fertilizer and temperature levels.

Influence of herbicide on rhizospheric microbial communities and soil properties in irrigated tropical rice field

Microbial diversity is an essential biological indicator of soil health as well as crop productivity and helps in maintaining the ecosystem dynamics. In land management, Nature based Solutions (NbS) are not mainstream management, however, for sustaining the balanced ecosystem, integrity in the structural and functional diversity of microbes via NbS is imperative. Direct seeded rice (DSR) cultivation is a promising technique for efficient rice production, but weed infestation can lead to yield loss, requiring extensive herbicide use like pendimethalin (PND) and pretilachlor (PRT). The results revealed that with a reduction in PND and PRT residues (0.93–0.01 µg g−1 soil), values of soil microbial biomass C (132.3–112.6 mg kg−1 soil) and MBN (12.6–8.5 mg kg−1 soil), and enzyme activities increased. Negative correlations were observed between herbicide residues and microbial parameters. In control soils, higher population sizes of archaea, bacteria, and fungi were obtained compared to herbicide-treated soils. High-throughput amplicon sequencing (16S rRNA, ITS genes) detected dominant archaea, atronorbrum_4312, MethanothrixX_B, and Methanosarcina_2619 in herbicide treated whereas Nitrosocosmicus, Methanoregula, in control. Bacillus, Methyloceanibacter, Azospira, and Nitrospira bacterial genera were present in both groups. Control soil showed the dominance of Humicola, Nigrospora, and Paramyrothecium fungi, while treated one exhibited Mariannaea, Ceratobasidium, Funneliformis (PND), Aspergillus, Pseudorhypophila, and Lecythophora (PRT). Overall, herbicides had a detrimental impact on microbial dynamics, and their residues correlated negatively with soil variables and microbial diversity. The research outcomes revealed the dramatic variations in microbial communities under the influence of herbicides. This will further aid in a better understanding of the development of NbS solutions for effectively managing herbicide application in direct-seeded rice for enhancing soil health and ecosystem services while supporting sustained productivity.

Higher improvement in soil health by animal-sourced than plant-sourced organic materials through optimized substitution

Organic material input can improve soil health and mitigate adverse environmental consequences; however, there is controversy regarding the promoting effects of organic material inputs on soil health due to a lack of quantitative information on the effects of different organic materials from agricultural sources on soil health. This study proposed a novel soil health evaluation method using tree-structured machine learning algorithms to quantitatively assess the effects of animal-sourced (AS) and plant-sourced organic materials (PS) on soil health. The results demonstrated that in the testing set, the two ensemble models, random forest regressor (RFR) and light gradient boosting machine regressor (LightGBMR), showed high coefficient of determination (R2) of 0.879 and 0.877, respectively, and relative percent deviation (RPD) of 2.83 and 2.84, respectively (P < 0.001). Our findings indicated that the application of AS resulted in superior improvement of soil health for rice, wheat, and maize in comparison to PS. Compared with chemical fertilizer (CF), AS improved soil health indices (SHIs) for rice, wheat, and maize by 23.8–39.8%, PS improved SHIs for rice, wheat, and maize by 13.4–24.4%, and AS + PS improved SHIs for rice, wheat, and maize by 16.0–35.4% (P < 0.001). In addition, the positive effect of AS on SHIs was greater than that of PS. Compared with PS, the SHIs for rice, wheat, and maize increased by 7.34–14.9% for AS (P < 0.001). The reasonable nitrogen (N) application rates for rice, wheat, and maize were 262–290, 235–259, and 299–331 kg ha−1 year−1, respectively. Based on the positive feedback effects on soil health, the reasonable AS substitution rates for rice, wheat, and maize were 26.4–29.2%, 27.0–29.8%, and 29.6–32.8%, respectively. This study confirmed that organic materials improve soil health through optimized substitution, thus contributing to sustainable agricultural management and reducing adverse environmental impacts.

Сравнительный анализ лимитирующих функционирование почвенного микробиома факторов при культивировании винограда в условиях Южного берега Крыма и Автономного края Воеводина Республики Сербия

Research interest in the use of soil biological activity indicator for predicting the state and sustainability of natural and agroecosystems has increased significantly in recent years due to climatic changes changing the location and boundaries of established agroclimatic belts. Distinctive features of these changes are unprecedented speed, as well as spatial and temporal heterogeneity. In this regard, the identification of regularities of influence of regional agroclimatic factors on soil microbiota as an indicator of soil health under different types of land use is of great relevance. In this work, an attempt was made to determine the climatic factors limiting the activity of soil microbiome functioning on the basis of calculation of climatic indices in two regions of grape cultivation close in temperature regime but contrasting in humidity. The results of the research showed that the value of basal respiration in the soils of ampelocenoses of the Autonomous Province of Vojvodina of the Republic of Serbia was 6-11 times higher than in the soils of ampelocenoses of the South Coast of Crimea, which is probably due to a sharp deficit of moisture in the latter (moisture coefficient 0.39 vs. 1.13 in Vojvodina). Regardless of the geographical location of wineries, basal respiration of soils in organic vineyards was twice as high as in soils of farms practicing the traditional system of grape cultivation, indicating more favorable conditions for the functioning of the soil microbial community. Keywords: BASAL RESPIRATION, BIOCLIMATIC INDICES, VINEYARDS, AMPELOCENOSIS, WINKLER THERMAL INDEX, HUGLIN HELIOTHERMAL INDEX, SELYANINOV HYDROTHERMAL HUMIDIFICATION COEFFICIENT, HUMIDIFICATION COEFFICIENT

Effects of soil physico-chemical parameters on Sclerotium rolfsii suppressiveness

The relationship of soil physico-chemical parameters with disease suppressiveness property of soil is not well understood phenomenon. In this regard, the surveys were conducted on the occurrence of collar rot disease caused by Sclerotium rolfsii in two districts (North 24 Parganas and Nadia) of West Bengal Gangetic new alluvial region of India from February to March, 2016. Soil samples were screened through the disease conduciveness and suppressiveness. The physicochemical properties of soils showed that the clay loam soil dominated in new the alluvial region of West Bengal. It was found that soil suppressiveness against S. rolfsii significantly positively correlated with soil aggregate ratio (AR). PCA explained the closeness of the parameters with soil suppressive index (SI) and aggregate stability (AS). Mostly the exponential relationship has been observed among the selected physico-chemical parameters. From this study we found AR, AS and bulk density were most determining parameters for S. rolfsii soil suppressiveness. Such indicators of soil health would be very beneficial for forecasting potential risks and providing guidance on appropriate farming techniques for specific geographic areas or microclimates. However, further investigation is required to fully comprehend the impact of physical and chemical properties on soil suppressiveness.

A full-length SSU rRNA-based workflow for high-resolution monitoring of nematode communities reveals direct and indirect responses to plant-based manipulations

Agricultural intensification has resulted in a decline in soil biodiversity, and concerns about the deterioration of the biological condition of soils prompted the development of measures to restore soil life. Due to the overwhelming biodiversity of soils, evaluation of such measures is not straightforward, and proxies are used to assess soil health. Because of their trophic diversity, high abundance, and relatively well-characterized ecologies, nematodes are often used as soil health indicators. However, the scarcity of informative morphological characters hampers the upscaling of this proxy. Here we present a community analysis approach that uses nanopore sequencing to generate full-length sequences of small subunit ribosomal DNAs (SSU rDNA). Cover cropping is a common agricultural practice that stimulates soil life, and we mapped the effects of ten cover crop treatments on nematode communities in a field experiment. These analyses included the monitoring of a high-impact plant-parasite, Meloidogyne chitwoodi. In total, 132 nematode samples were analyzed, and 65 nematode taxa were detected, mostly at the species level, including representatives of all trophic groups. As a validation, all samples were analyzed microscopically for M. chitwoodi, and a comparison of count and DNA read data revealed highly similar results. Treatments did not only affect plant-parasitic nematodes but also free-living nematodes in a cover crop-specific manner. Free-living nematodes from the same trophic group, and even congeneric species, responded differentially to plant-mediated manipulations of the soil microbiome. Hence, nanopore-based SSU rDNA sequencing could facilitate a substantial refinement of the use of nematodes as indicators for soil health.

Crop diversification promotes soil aggregation and carbon accumulation in global agroecosystems: A meta-analysis

Soil aggregation contributes to the stability of soil structure and the sequestration of soil organic carbon (SOC), making it an important indicator of soil health in agroecosystems. Crop diversification is considered a rational management practice for promoting sustainable agriculture. However, the complexity of cropping systems and crop species across different regions limits our comprehensive understanding of soil aggregation and associated carbon (C) content under crop diversification. Therefore, we conducted a meta-analysis by integrating 1924 observations from three diversification strategies (cover crops, crop rotation, and intercropping) in global agroecosystems to explore the effects of crop diversification on soil aggregates and associated C content. The results showed that compared to monoculture, crop diversification significantly increased the mean weight diameter and bulk soil C by 7.5% and 3.3%, respectively. Furthermore, there was a significant increase in the proportion of macroaggregates and their associated C content by 5.0% and 12.5%, while there was a significant decrease in the proportion of microaggregates as well as silt-clay fractions along with their associated C under crop diversification. Through further analysis, we identified several important factors that influence changes in soil aggregation and C content induced by crop diversification including climatic conditions, soil properties, crop species, and agronomic practices at the experimental sites. Interestingly, no significant differences were found among the three cropping systems (cover crops, crop rotation, and intercropping), while the effects induced by crop diversifications showed relatively consistent results for monoculture crops as well as additive crops and crop diversity. Moreover, the impact of crop diversification on soil aggregates and associated C content is influenced by soil properties such as pH and SOC. In general, our findings demonstrate that crop diversification promotes soil aggregation and enhances SOC levels in agroecosystems worldwide.

Soil health benefits associated with urban horticulture

As the global population grows and is increasingly concentrated in urban environments, the quality of urban horticultural soils is of mounting importance. Until now, most urban horticultural soil assessments have been applied in nations and continents outside North America, and none have been conducted in Canada—an important agricultural region. Here, we present the first Canadian study to evaluate soil health in urban horticultural soil (gardens producing fruit and vegetables), benchmarked against conventional agricultural soil in surrounding rural areas (producing cereals, oilseeds, and legumes). We assessed a range of soil health indicators (total C, soil organic C [SOC], active C, CO2 evolution, wet aggregate stability [WAS], total N, autoclave citrate extractable [ACE] protein, potentially mineralizable N [PMN], and N2O production), soil fertility indicators (inorganic N, available P, and available K), and inherent soil properties (texture, electrical conductivity [EC], and pH). We found that carbon- and nitrogen-based soil attributes in urban horticultural soils were 200 % that of the agricultural soils, indicating superior soil health—which had significant implications for interpreting soil health scores. As for soil fertility, inorganic N and available K did not differ between the two systems, but available P was 400 % higher in urban horticulture than agriculture soils, indicating that management practices which build soil health might risk also building excessive soil P levels. Our findings suggest that urban horticulture soils may provide superior ecosystem services and function as a reservoir for SOC, likely due to the soil health management practices implemented by gardeners—but care should be taken to manage soil health alongside managing soil fertility. Urban horticulture soil is an ideal platform for expanding research and governance not only for food production but for valuable ecosystem services.

Soil Health in an Integrated Production System in a Brazilian Semiarid Region

Soil health is directly related to sustainable development goals (SDGs) and can be affected by inadequate management practices. In this work, soil edaphic respiration and changes in microbial biomass promoted by cover crops in an integrated crop–livestock system (ICLS) were evaluated using soil health indicators with the respirometry method. The design was completely randomized in a 3 × 6 factorial arrangement, and multivariate principal components analysis (PCA) was performed according to MANOVA. Edaphic respiration was determined based on the respirometry technique. The results showed that edaphic soil respiration was significant in the nine evaluation periods, demonstrating the importance of grass cover in edaphic respiration arising from the biological activity of microorganisms, which is directly related to the amount of soil organic carbon. The cover crops increased soil organic matter and consequently microbial respiratory activity.

Cover crop-mediated soil carbon storage and soil health in semi-arid irrigated cropping systems

Cover cropping is considered a climate-smart strategy to regenerate low-fertility soils in arid and semi-arid regions. However, the mechanisms of soil organic carbon (SOC) storage and soil health improvement in semi-arid irrigated cropping systems are poorly understood. The main goal of this study was to evaluate cover crop effects on various physical, chemical, and biological indicators of soil health in an irrigated silage corn (Zea mays L.)–sorghum [Sorghum bicolor (L.) Moench] rotation and understanding how changes in soil health contribute to SOC storage. We evaluated various SOC and nitrogen (N) pools, and microbial community structure under cover crop mixture of grasses, brassicas, and legumes (GBL), grasses and brassicas (GB), grasses and legumes (GL), and no cover crops (NCC) control for four years. Grasses included annual ryegrass (Lolium multiflorum Lam.) and winter triticale (× Triticosecale Wittmack), brassicas included turnip (Brassica rapa subsp. rapa L.) and daikon radish (Raphanus sativus var. Longipinnatus Bailey), and legumes included pea (Pisum sativum subsp. arvense L.) and berseem clover (Trifolium alexandrinum L.). Soil C pools: SOC, potentially mineralizable C, microbial biomass C, mineral-associated organic C (MAOC), and particulate organic C (POC) were greater with cover crops than without, but the effects were not consistent in all study years. Soil organic N was also greater under cover crops than under NCC. Soil C-to-N (C:N) ratio increased over the years but was similar among treatments. Cover crops used N and soil water to grow, significantly reducing soil inorganic N content and water-filled pore spaces in the first two years. However, fungal and bacterial communities grew better under cover crops with a high fungi-to-bacteria ratio than under NCC. The soil MAOC content was related to microbial community and enzyme activity while POC was affected by soil physicochemical conditions, specifically soil pH and mineral N availability, highlighting two major pathways of SOC sequestration in semi-arid cropping systems. This study showed how cover crops enhance SOC storage and soil health in semi-arid cropping systems.