Relating indicators to soil health functions in conventional and organic Mediterranean cropping systems

Soil is one of the most diverse and complex natural systems at global scale and is involved in several reactions of formation, development, and breakdown of chemicals, many of these depending on soil microorganisms.According to the combination of soil forming factors, soil properties show a large horizontal and vertical variability, which can have a huge impact on soil microbial communities. However, relatively few investigations have been carried out to associate the changes in soil microbial community with the variations of soil properties across the genetic horizons and along depth.In Italy, chestnut groves used to be key sources of products in mountain regions. Recent socio-economic changes have led to the progressive abandonment of this land use, producing degradation of the landscape and increased hydrogeologic risk. Now, programs for the restoration of this activity collide with outbreaks of illnesses such as ink disease, which is caused by Oomycetes present in the soil. In this framework, the physicochemical and biological features of soils play a crucial role in the distribution and assessment of the risk and severity of this disease.The objective of this study was to correlate the diversity and eco-functionality of the microbial communities with soil properties and health indicators along depth and across a transect including chestnut trees with and without symptoms of ink disease.The study area was a fruit chestnut grove located in the Apennine mountains south of Bologna, Italy. Soil profiles were opened along a transect ranging from a chestnut tree showing ink disease symptoms (INK1) to two subsequent chestnut trees with no visible symptoms (INK2 and INK3). In each profile, the horizons were described and sampled; to assess spatial variability, three minipits were opened around each profile, and their horizons were also described and sampled. Each horizon was also sampled in sterility. The samples were then analyzed for physicochemical and biological parameters, and total DNA was extracted to perform a taxonomic analysis.Results showed that some physicochemical parameters, while presenting a trend with depth, also presented a trend with distance from the diseased tree: pH and base saturation decreased near this tree, while C:N and C:P increased, as well as water-extractable organic carbon. The taxonomic analysis showed that, while no substantial variation was detected in the bacterial composition of INK2 and INK3, INK1 showed a higher prevalence of phyla involved in the organic matter cycle (Acidobacteriota and Proteobacteria). Regarding the fungal population, in INK2 and INK3 the main trophic group was soil saprotrophs, while in INK1 the most frequent were short- and medium-distance ectomycorrhizae, which often indicate plant stress. Shannon index showed that bacterial diversity increased with depth while fungal diversity decreased. In both cases the profile near the diseased tree presented the least diversity. No difference was detected between the profiles in soil health indicators, such as organic matter content and microbial biomass and its activity, and these were not correlated with microbial diversity. These results suggest that taxonomic analysis of soil microorganisms could integrate traditional indicators in assessing soil and ecosystem health. 

Landfill leachate has multiple negative impacts on soil health indicators in Hyrcanian forest, northern Iran

Since soil health is impacted by inherent soil properties, it is, therefore, challenging to apply the same soil health frameworks across multiple regions and soil types. Here, we examined the effect of soil textural group (coarse, medium, and fine) on four soil health indicators of soils sampled from diverse agricultural systems across Ontario. Scoring functions were developed by calculating cumulative normal distributions, using the mean and standard deviation of each soil health indicator, for three or five soil textural groups. For each soil health indicator, soil health scoring values were provided using the “more is better” approach, where greater soil health scores implied better soil health. Soil health indicators were significantly affected by three but not all five soil textural groups. Evolved NH3 and CO2, and potentially mineralizable N had stronger associations with each other as revealed by correlation and principal component analysis. Our results also suggested that mean separation of the tested soil health indicators was more consistent with three soil textural groups (coarse, medium, and fine) than five soil textural groups (clays, clay loams, loams, sandy loams, and sand); therefore, we recommend using three soil textural groups to develop soil health scoring functions. The findings of this study lay a groundwork for future soil health assessment involving a larger number of samples across Ontario and more soil indicators, which will facilitate the regional interpretation of soil health.

Soil health assessment uses a combination of potential indicators affecting soil processes to comprehensively monitor soil change, caused by cropping systems and soil management. The objectives of the study were to assess the effects of selected cropping systems, soil management and landscape slope positions on the soil health characteristics of the Sanborn Field long-term experimental study in Columbia, Missouri, United States. Soil samples were collected on each of four dates over two years (8 th May 2014, 4th September 2014, 1st April 2016, and 18th August 2016) from selected plots to address each objective, and these time samples were used as replications. Soil physical, chemical, and biological characteristics were analyzed in the laboratory for these samples to assess soil health using the Cornell Comprehensive Assessment of Soil Health (CASH) method. To assess soil health in this study, soil health scoring was determined used R-studio version 1.1.149 to relate the interaction of cropping systems, soil management, and slope positions. Most soil resources on Sanborn Field are a poorly-drained claypan soil classified as a Mexico silt loam (fine, smectitic, mesic Vertic Epiaqualf). In addition, soil samples collected from Tucker Prairie was used as a proxy for the original state of Sanborn Field soils. The first study was conducted to evaluate the effects of long-term cropping systems on soil health properties. The results from the characterization indicated that continuous timothy (Phleum pretense L.) and warm season grass treatments were classified with very high soil health scores, and the lowest score was found for continuous corn (Zea mays L.). In addition, results showed strong positive linear associations between soil organic carbon, total nitrogen, potentially mineralizable nitrogen, active carbon, microbial biomass, and water stable aggregates; while a strong negative linear correlation existed between each of these properties and bulk density. The second study was conducted to evaluate the effects of long-term annual applications of no fertilizer, full fertilizer, and manure on soil health measurements of selected cropping systems. Different cropping systems, including continuous corn, continuous wheat (Triticum aestivum L.), corn-wheat-red clover (Trifolium pretense L.) rotation, and corn-soybean (Glycine max L.)-wheat rotation treatments were used in this study. Results showed that annual dairy cow (Bos Taurus) manure applications had the greatest effect on all soil health indicators and had the largest overall soil health score compared to full fertility and no fertilizer treatments. Moreover, continuous wheat with manure application presented the best combination of effects on soil properties with the largest score for most soil health indicators and an overall health score of 82 out of 100 classified as very high which is the best. The last study evaluated the effects of landscape slope positions on soil health properties of the long-term experiment. Results showed that the summit position had the highest overall soil health score while the lowest score was found on the shoulder position. However, there were no significant differences along the transect slope for water-stable aggregates and bulk density. There were significant differences along the transect for the biological properties such as soil organic carbon, active carbon, potentially mineralizable nitrogen, and microbial biomass. Results of this study illustrate the effect of selected variables on soil health and provide the recent addition of using biological characteristics to account for soil health properties. It is important to remember that this study of the long-term Sanborn Field experiment is just for a small-sized plot area. Future studies of soil management effects on soil health need to account for their own field conditions and their own unique environment.

Impacts of biodegradable plastic mulches on soil health

The dataset presented here supports the research paper entitled “A calculator to quantify cover crop effects on soil health and productivity”. Soil health (sometimes used synonymously with soil quality) is a concept that describes soil as a living system to sustain plants, animals, and human. Soil physical, chemical, and biological properties, along with their interactions, are required to quantify soil health. The use of cover crops in agricultural rotations may enhance soil health, yet there has been little progress in understanding how external factors such as climate, soil type, and agronomic practices affect soil and cash crop responses. In response, this dataset compiles measurements from 281 studies and provides an analysis of field-measured changes in 38 soil health indicators due to cover crop usage. Environmental and background indicators were also compiled to assess how climatic and management practices affect soil and cash crop responses to cover crops, with specific categories including climate type (tropical, arid, temperate, and continental), soil texture (coarse, medium, and fine), cover crop type (legume, grass, multi-species mixture, and other), and cash crop type (corn, soybean, wheat, vegetable, corn-soybean rotation, corn-soybean-wheat rotation, and other). An unbalanced analysis of variation was used to determine the hierarchy of most to least important factors that affected responsiveness of each soil health indicator. Based on the hierarchy structure, a soil health calculator was then developed to quantify the response of 13 parameters – erosion, runoff, weed suppression, soil aggregate stability, leaching, infiltration, microbial biomass carbon, soil bulk density, soil organic carbon, soil nitrogen, microbial biomass nitrogen, cash crop yield, and saturated hydraulic conductivity – to cover crops. The presented data in the calculator report the mean change in parameter values based on all combinations of climate, soil texture, cover crop type, and cash crop type.

Soil health and global sustainability: translating science into practice

Long-term biosolids land application influences soil health

Soil health in agricultural ecosystems: Current status and future perspectives

Monitoring soil nitrogen (N) dynamics in agroecosystems is foundational to soil health management and is critical for maximizing crop productivity in contrasting management systems. The newly established soil health indicator, autoclaved‐citrate extractable (ACE) protein, measures an organically bound pool of N. However, the relationship between ACE protein and other N‐related soil health indicators is poorly understood. In this study, ACE protein is investigated in relation to other soil N measures at four timepoints across a single growing season along a 33‐year‐old replicated eight‐system management intensity gradient located in southwest Michigan, USA. On average, polyculture perennial systems that promote soil health had two to four times higher (2–12 g kg −1 higher) ACE protein concentrations compared to annual cropping and monoculture perennial systems. In addition, ACE protein fluctuated less than total soil N, NH 4 + ‐N, and NO 3 − ‐N across the growing season, which shows the potential for ACE protein to serve as a reliable indicator of soil health and soil organic N status. Furthermore, ACE protein was positively correlated with total soil N and NH 4 + ‐N and negatively correlated with NO 3 − ‐N at individual sampling timepoints across the management intensity gradient. In addition, ACE protein, measured toward the end of the growing season, showed a consistent and positive trend with yield across different systems. This study highlights the potential for ACE protein as an indicator of sustainable management practices, SOM cycling, and soil health and calls for more studies investigating its relationship with crop productivity.

Manuring improves soil health by sustaining multifunction at relatively high levels in subtropical area

Soil health (SH) indicators, such as organic matter (OM) content and enzymatic activity (EA), are critical for assessing the sustainability of mineral soils in integrated and cover cropping systems. Taking into account the following objectives: (i) to assess the relationship between OM and other SH indicators, (ii) to evaluate the evolution of SH using two models (SH indicators (SHI) scoring approach and A Modified Comprehensive Assessment of Soil Health scoring system developed for Florida soils (A modified CASH method)), and (iii) present their effectiveness in Brazil and the USA, a medium-term study (2019–2023) in Brazil and a short-term seasonal study (2022–2023) in the USA were conducted in diverse agroecosystems. In Brazil, four agricultural systems were analyzed: Cerrado (Cer), Conventional (Conv), Integrated Crop-Livestock (ICL), and Integrated Crop-Livestock-Forestry (ICLF). In the USA, two cover cropping systems in South Florida were assessed: double cover cropping system (DCCS) and multiple cover cropping system (MCCS). Soil samples were collected for analysis of key soil properties. Results in Brazil showed higher OM in the Cer (1.08 dag kg-1) and ICL (1.12 dag kg-1) systems, and increased enzymatic activity in 2023, particularly in ICL (AS = 33.85 mg de p-nitrofenol kg-1 soil h-1 and BG = 54.65 mg de p-nitrofenol kg-1 soil h-1) and ICLF (AS = 21.07 mg de p-nitrofenol kg-1 soil h-1 and BG = 48.90 mg de p-nitrofenol kg-1 soil h-1). Enzyme activity was more responsive to management practices than OM. Principal Component Analysis revealed stronger correlations between OM, EA, and macronutrients in more sustainable systems like ICL and ICLF. The SHI scoring approach better captured changes in Brazil. In the USA short-term cover cropping systems showed no significant changes in OM or EA, but CASH method suggested slight improvements in MCCS. This study highlights the importance of OM and EA as key indicators for assessing and improving SH and suggests that while integrated and cover cropping systems offer potential benefits, longer-term management and organic amendments are necessary to achieve sustained improvements in soil health.

Measuring Soil Respiration with a Gas Chromatograph

The challenges of soil degradation and climate change have led to the emergence of Conservation Agriculture (CA) as a sustainable alternative to tillage-based agriculture systems. Despite the recognition of positive impacts on soil health, CA adoption in Africa has remained low. Previous soil health studies have mainly focused on ‘scientific’ measurements, without consideration of local knowledge, which influences how farmers interpret CA impacts and future land management decisions. This study, based in Malawi, aims to 1) combine local knowledge and conventional soil science approaches to develop a contextualised understanding of the impact of CA on soil health; and 2) understand how an integrated approach can contribute to explaining farmer decision-making on land management. Key farmers' indicators of soil health were crop performance, soil consistence, moisture content, erosion, colour, and structure. These local indicators were consistent with conventional soil health indicators. By combining farmers' observations with soil measurements, we observed that CA improved soil structure, moisture (Mwansambo 7.54%–38.15% lower for CP; Lemu 1.57%–47.39% lower for CP) and infiltration (Lemu CAM/CAML 0.15 cms−1, CP 0.09 cms−1; Mwansambo CP/CAM 0.14 cms−1, CAML 0.18 cms−1). In the conventional practice, farmers perceived ridges to redistribute nutrients, which corresponded with recorded higher exchangeable ammonium (Lemu CP 76.0 mgkg −1, CAM 49.4 mgkg −1, CAML 51.7 mgkg −1), nitrate/nitrite values (Mwansambo CP 200.7 mgkg −1, CAM 171.9 mgkg −1, CAML 103.3 mgkg −1). This perception contributes to the popularity of ridges, despite the higher yield measurements under CA (Mwansambo CP 3225 kgha-1, CAML 5067 kgha-1, CAM 5160 kgha-1; Lemu CP 2886 kgha-1, CAM 2872 kgha-1, CAML 3454 kgha-1 ). The perceived carbon benefits of residues and ridge preference has promoted burying residues in ridges. Integrated approaches contribute to more nuanced and localized perceptions about land management. We propose that the stepwise integrated soil assessment framework developed in this study can be applied more widely in understanding the role of soil health in farmer-decision making, providing a learning process for downscaling technologies and widening the evidence base on sustainable land management practices.

Soil health is pivotal to agricultural sustainability. Promoting and sustaining soil health management is challenging since it involves many interdependent components and steps and is an iterative process. Herein, the soil health cycle (SHC) is proposed as a soil health management cycle encompassing human dimensions, management practices, and their effects on soil health indicators (SHIs), leading to subsequent impacts on soil functions. The SHC provides a structure for an iterative testing of changes to improve soil health. A systematic review of research publications was also conducted using the Web of Science database supplemented by Elicit AI and Scopus API searches to determine the status of research reports connecting SHIs to soil function outcomes, a critical component in the SHC. The review focused on publications from 2000 to 2022 and highlighted that most soil health studies separately report the potential roles of soil health practices such as cover cropping, no‐tillage or reduced tillage, crop rotation, and crop–livestock integration in improving SHIs or soil function outcomes such as productivity and sustainability. The confidence in the causality of improved SHIs due to practices can be increased by demonstrably linking them to soil function outcomes such as productivity, environmental quality, and profitability. Presenting such evidence might allow us to tease confounding factors apart and present and contextually recommend soil health practices. It will also affect the human dimension in the SHC through informed and beneficial policies and incentives.