Changes In Soil Quality Research Articles

Nitrogen flow in livestock waste system towards an efficient circular economy in agriculture.

The race is on to achieve an important level of efficiency in the attainment of a circular economy in agriculture especially with the aim of sustainable nitrogen management. This cycle in the agricultural sector cuts across livestock farming, agriculture-induced waste generation, recycling and utilization, energy generation, crop production, ecosystem protection and environmental management through the mitigation of climate changes. In this work, we assess the process and functionalities of livestock waste generated from the piggery farm and their combinations with other by-products such as biochar and ash in comparison with mineral fertilization as sources of nitrogen applied in agricultural soil. The experiment was performed in a controlled environment with wheat (Triticum aestivum L.) grown in a neutral and an acidic soil. Pig manure was used as the primary feedstock, fed and processed to biogas and nutrient-rich digestate by the anaerobic digestion process. The results revealed that the co-amendments of pig manure digestate with biochar and ash had complimentary positive effect on measured indices such as mobile potassium, phosphorus, biomass yield and nitrogen use efficiency. The mineral nitrogen fertilizer significantly induced carbon dioxide emissions from day 35 when compared to emissions from the organic amendments. In contrast, the organic amendments influenced nitrous oxide emissions from the onset till day 30 before flattening out. The individual combination of pig manure digestate with biochar and ash had a negative influence on enzymatic activity (dehydrogenase). Soil microbial biomass carbon was induced across all treatments in both soil types. Pig manure digestate + ash and pig manure digestate had 32.1 and 48.8% soil microbial biomass increase in neutral soil and acidic soil, respectively. Overall, the processing and application of single-use amendment or in combination with biochar and ash holds huge potential in the optimization of nitrogen and carbon efficiency towards sustainable soil management via improving soil quality, carbon sequestration and climate change.

Unravelling the carbon pools and carbon stocks under different land uses of Conoor region in Western Ghats of India

Land uses are pivotal in global carbon cycles. The native forest lands possess a greater potential to sequester higher carbon, which can directly address soil quality and climate change problems. Unfortunately, the rapid conversion of forests to other land use over the past few decades has significantly declined the concentration of carbon in the soils. Therefore, in order to estimate the impact of land-use change (LUC) on soil carbon status, this present study was attempted under major ecosystems (Forest (FOR), cropland (CRP), tea plantation (TEA)) of Conoor. Results from findings revealed that total organic carbon (TOC) concentration and carbon pools were significantly (p<0.05) higher in FOR than in CRP and TEA. TOC (0-45 cm) recorded in FOR, CRP and TEA was 32.88, 11.87 and 18.84 g kg-1 and it decreased along the depth increment. Carbon stock (t ha-1) in FOR, CRP and TEA (0-45cm) was 68.10, 26.04, 42.42. Microbial biomass carbon (MBC) was higher in FOR (283.08 mg kg-1) followed by TEA (94.64 mg kg-1) and CRP (76.22 mg kg-1). The microbial biomass nitrogen (MBN) followed; FOR > TEA > CRP. These results clearly indicate that the LUC has inflicted a greater impact on soil carbon status and its extent was quantified using the land degradation index (LDI). The LDI (0-45 cm) recorded in CRP (-38.65) and TEA (-61.75) signals the need for immediate implementation of carbon management strategies in the CRP and TEA ecosystem to keep the soils of Conoor alive and prevent land degradation.

Variation Characteristics of Particle Surface Electrochemical Properties during the Improvement of Reclaimed Soil from Hollow Village in Loess Area

Soil surface electrochemical properties, such as specific surface area and surface charge number, are important indexes to evaluate the agricultural soil quality change. However, there is not enough focus on the effect of different improved materials on the reclaimed soil surface electrochemical characteristics. Therefore, we selected maturing agent (TM), fly ash (TF), organic fertilizer (TO), maturing agent + organic fertilizer (TMO), fly ash + organic fertilizer (TFO), and no modified material (CK) treatment for 5 years of field location experiments to study the effects of different improved materials on the surface electrochemical properties of reclaimed soil from abandoned homestead. The results showed that, compared with CK treatment, the specific surface area, surface charge number, and surface charge density of reclaimed soil increased to 11.36–14.05 m2 g−1, 13.49–18.58 cmol kg−1, and 1.14–1.76 C m−2 after five years of application of different improved materials, respectively, and the number of surface charge under TFO, TMO, and TO treatment increased by 28.9%, 25.2%, and 37.7% compared with CK, respectively. Meanwhile, the specific surface area increased significantly (p < 0.05), showing an order of TFO > TMO > TO > TF > TM > CK. The surface electric field strength can reach the order of 108 V m−1. The statistical analysis results suggest that the contents of soil organic matter (SOM), silt, and clay were positively correlated with the soil surface electrochemical properties, which were the main factors for the changes of reclaimed soil surface electrochemical properties. Our research conclusion shows that in the process of reclamation of abandoned homestead in Loess Plateau, the application of different materials is helpful to improve the soil surface electrochemical properties, among which the organic–inorganic TFO treatment was a suitable improved material treatment for improving the surface electrochemical properties and fertility of reclaimed soil.

Restoring soil carbon in marginal land of Indian Himalayas: Impact of crop intensification and conservation tillage.

Soil carbon (C) loss is the prime sign of land degradation, and C pools have a great impact on soil quality and climate change mitigation. Hence, a field experiment was conducted for three consecutive years to assess the impact of crop intensification and conservation tillage practices on changes in the C pool at different soil depths of marginal land of the Indian Himalayas. The experiment consisted of two intensified cropping systems viz., CS1-Summer maize (Zea mays L.) -rainy season maize-lentil (Lens esculenta L.) and CS2-Summer maize-rainy season maize-mustard (Brassica juncea (L.) Czern) and five tillage practices viz., No-till (NT); NT+live mulch of cowpea (NT+LMC); reduced tillage (RT); RT+LMC and conventional tillage (CT). Results revealed that CS2 produced significantly higher biomass, C retention efficiency (9.85%), and sequestrated greater C (0.42Mgha-1 yr-1) in the soil system than CS1. Of the various tillage practices, RT+LMC registered higher biomass and recycled greater biomass and C than those under other tillage practices. However, the highest soil organic carbon (SOC) content (7.03gkg-1) and pool (9.62Mgha-1) in 0-10cm depth were observed under NT+LMC. The non-labile C pool size under NT in 0-10cm and 10-20cm depths was significantly greater than those under CT. The NT+LMC sequestrated significantly higher SOC (0.57Mgha-1 yr-1) than other tillage practices. Thus, the study indicated that the adoption of an intensified maize-based system under RT+LMC or NT+LMC would increase SOC storage and C sequestration in marginal lands of the Indian Himalayas.

Commercial organic fertilizer substitution increases wheat yield by improving soil quality

Traditional organic fertilizer substitution is an effective measure for increasing crop yield and soil quality while reducing chemical fertilizer input. However, the effects of commercial organic fertilizer substitution (COFS) on soil quality and wheat yield, and the underlying mechanisms, are unknown. In this study, agricultural fields with low fertility (LF) and high (HF) fertility soils were selected for a two-year (2018–2019) field experiment in the oasis region of Northwest China. Three fertilization treatments with three replications (no fertilization, CK; local conventional chemical fertilizer application, LCF; and 20 % of inorganic nitrogen (N) was substituted by commercial organic fertilizer, COFS) were established to study the effects of COFS on wheat growth, yield, nutrient-use efficiency and soil quality. The results showed that compared with LCF in 2018 and 2019, COFS in LF and HF promoted wheat growth, improved nitrogen use efficiency (NUE) and phosphorus use efficiency (PUE), and increased yield (by 1.52 %–3.05 % and 1.16 %–1.39 %) and soil quality (by 15.09 %–28.63 % and 22.53 %–64.82 %) by improving most soil indicators (e.g., soil organic matter (SOM) and available nutrients). Moreover, SOM and available nutrients significantly affect soil quality and wheat yield, which can monitor changes in soil quality and wheat yield. In conclusion, our study revealed that the mechanism of COFS in HF and LF increased wheat yield by improving soil quality. COFS is recommended for agricultural production, but its continuous application requires monitoring changes in SOM and available nutrients to adjust fertilization to guarantee soil quality and crop yield. This study provides guidance for the scientific application of COFS to improve farmland productivity and soil quality and helps to promote healthy and sustainable agricultural development.

Changes in soil quality over time focusing on organic acid content in restoration areas following coal mining

Coal extraction is associated with the creation of waste dumps, in which the soils are extremely depleted owing to dilution of the existing topsoil by mixing with the subsoil; however, the evolution mechanism of such soils remains unclear. Here, we investigated the changes in the soil properties over time, focusing on organic acid content in restoration areas following coal mining. The soil of three soil depths (0–10, 10–20, and 20–30 cm) from natural land and three waste dumps with primary succession ages of 5 (R5), 10 (R10), and 20 (R20) years in the Heidaigou open-pit coal mine of Northwest China, were analyzed to examine changes in the soil properties and to highlight relationships between these properties. Results showed soil pH, total nitrogen, alkali-hydrolyzable nitrogen, available phosphorus, soil organic matter, and organic acid increased with increasing restoration age. However, only soil organic matter and organic acid were influenced by soil depth and the interaction of restoration age and soil depth. Moreover, the total phosphorus content did not alter with the restoration age, soil depth, or their interactions. In contrast, the N:P ratio increased with increasing restoration age, indicating that the total phosphorus content might restrict restoration. The alkali-hydrolyzable nitrogen was significantly correlated to available phosphorus, acetic acid, soil organic matter, and pH. The available phosphorus was significantly correlated to the oxalic acid, while the pH and soil organic matter significantly influenced the acetic acid. Our findings provide theoretical support to improve the soil quality and may assist in restoration in coal dam areas.

Spatial distribution of soil quality under different vegetation types in the Yellow River Delta wetland

The soils from four typical natural wetlands, namely, Phragmites australis, Tamarix chinensis, Suaeda salsa, and tidal flat, as well as reclaimed wetland, were selected to evaluate the soil quality in the Yellow River Delta. Fourteen soil physicochemical property indexes were employed to build a minimum data set (MDS). Combined with vegetation type and soil depth, the soil quality index (SQI) was conducted. A fuzzy logic model was applied for data normalization. The contrast test was conducted to verify the accuracy of the MDS. The results showed that the MDS consists of TOC, NO3--N, soil salinity, TS, TP, Mg, C/N and pH. The soil quality decreased from the inland to the coastline and from reclaimed wetland to tidal flat with the change of vegetation type. The soil quality of 0–10 cm soil depth was better than that of 20–30 cm soil depth. The soil qualities of reclaimed land were significantly better than those of natural wetlands at the same soil depth. Correlation analysis results showed that agricultural reclamation has become an important factor of soil quality change in the study area. Comparative results of two methods of MDS and the total data set (TDS) testified that the method of MDS was credible and accurate for soil quality assessment of the study area. Our results indicated that wetland protection and agricultural reclamation in coastal areas should keep a rational balance.

Changes in Soil Quality through Conservation Agriculture in North-Eastern Italy

Conservation Agriculture includes practices focused on the conservation and the restoration of main soil features, such as organic carbon content, structure, and biological diversity and activity. Our study was conducted in three farms in North-Eastern Italy in pairs of closely located fields to compare conservation agriculture (no tillage, cover cropping) with conventional agriculture. Differences in terms of soil enzymatic activity, such as FDA and β-glucosidase through spectrophotometric analyses, microbial biomass carbon and nitrogen contents, total organic carbon, and nitrogen contents with CNS Elemental Analyzer and soil arthropod community via the QBS-ar index were investigated. Enzymatic activities resulted to be readily and positively affected by conservation agriculture whereas total and microbial carbon, nitrogen contents, and microarthropod community seemed to be more dependent on the time factor. The responses to conservation agriculture differed between the three farms, pointing out that differences in soil features may drive the effectiveness of conservation management. N stock, maybe dependent on previous soil management, might be the key characteristic able to influence soil evolution in the studied conditions. The present results could be helpful to predict soil reaction to sustainable agriculture in short periods.

Field-Scale Evaluation of the Soil Quality Index as Influenced by Dairy Manure and Inorganic Fertilizers

Long-term addition of manure increases soil organic carbon (SOC), provides nutrient supply, enhances soil quality and crop yield (CY), but may also increase global warming potential (GWP). In this study, a long-term experiment was conducted to investigate impacts of organic dairy manure and inorganic fertilizer on the spatial distribution of soil quality indicators in field scale. The experiment was initiated in 2008 (seven years), and includes three manure and two inorganic fertilizer treatments along with a control (no manure or no inorganic fertilizer addition). The study was set into a randomized complete block design with six treatments and four replications in a total of 24 plots with an equal size each of 6 × 18 m (108 m2). Soil physical, chemical and biological properties (total 26 properties) were considered as the total data set and principal component analysis (PCA) was used to determine long-term organic and inorganic fertilizer-induced changes in soil quality. Ordinary kriging interpolation methods were used to predict the spatial distributions of soil quality index (SQI) and mean soil quality values were compared with fertilization treatments by using Duncan’s test. Results showed that most measured soil quality index parameters showed significant differences (p < 0.05). The long-term dairy manure applications had positive impacts on soil quality index parameters where overall SQI scores were higher under high manure (HM) compared to medium manure (MM), low manure (LM), medium fertilizer (MF), high fertilizer (HF), control (CK) by 25%, 27%, 47%, 55% and 92%. A similar trend was observed for CY and GWP. This indicates that long-term dairy manure can be an option to increase SQI values and provide higher CY, however, this may lead to greater GWP.

Response of Soil Enzyme Activities to Natural Vegetation Restorations and Plantation Schemes in a Landslide-Prone Region

Soil enzyme activities in different plantation types and land use patterns could indicate changes in soil quality. This research was aimed at exploring the dynamics of soil enzyme activities involved in carbon, nitrogen and phosphorus cycling, and their responses to changes in soil physicochemical properties resulting from natural vegetation restorations and plantation schemes. Knowing about the effects of soil physicochemical properties on soil enzyme patterns is crucial for understanding ecosystem functions and processes. The study selected four main land-use types (natural forestland, natural grassland, artificial forestland, and artificial grassland) and one control plot (bare land) in the West Qinling Mountains, China, which is a typical landslide region. We collected the soil samples from each land use type and tested their physicochemical properties and enzyme activities compared with control land. The results showed that both natural vegetation restoration and artificial plantation schemes have significant effects on enzyme activities. Soil physicochemical properties explained 92.2% of the variation in soil enzyme activities for natural vegetation restoration, while it only explained 77.8% of the variation in soil enzyme activities for plantation schemes. Furthermore, natural vegetation had a greater effect than the plantation schemes on soil enzyme activities.

Soil quality both increases crop production and improves resilience to climate change

Interactions between soil quality and climate change may influence the capacity of croplands to produce sufficient food. Here, we address this issue by using a new dataset of soil, climate and associated yield observations for 12,115 site-years representing 90% of total cereal production in China. Across crops and environmental conditions, we show that high-quality soils reduced the sensitivity of crop yield to climate variability leading to both higher mean crop yield (10.3 ± 6.7%) and higher yield stability (decreasing variability by 15.6 ± 14.4%). High-quality soils improve the outcome for yields under climate change by 1.7% (0.5–4.0%), compared to low-quality soils. Climate-driven yield change could result in reductions of national cereal production of 11.4 Mt annually under representative concentration pathway RCP 8.5 by 2080–2099. While this production reduction was exacerbated by 14% due to soil degradation, it can be reduced by 21% through soil improvement. This study emphasizes the vital role of soil quality in agriculture under climate change. Food demand is increasing, while climate change is impacting the magnitude and stability of crop yields. High-quality soils are able to buffer the negative impacts of climate change and lead to smaller yield reduction and higher yield stability, indicating a potential adaptation strategy.

Impact of Long Term Nutrient Management on Soil Quality Indices in Rice-Wheat System of Lower Indo-Gangetic Plain

Globally, soil degradation is an important issue for sustainable crop production. Soil quality indicators are the soil attributes that address the ecological functions of soil. Therefore, indicator-based soil quality assessment has been emphasized for quantifying the relative soil quality changes in different nutrient management systems. Soil quality underthe rice (Oryza sativa L.) and wheat (Triticum aestivam L.) cropping system was assessed using a modified “Soil Management Assessment Framework (SMAF)” model. Soil’s physical, chemical, nutritional, and biological indices were analyzed for different nutrient management strategies, viz., inorganic fertilizer (NPK), NPK + 7.5 Mg ha−1 farmyard manure (NPKF), NPK + 10.0 Mg ha−1 paddy straw (NPKP) and NPK + 8.0 Mg ha−1 Sesbania sesban L. green manure (NPKG). Nutrient management strategies significantly influenced soil quality indices. NPKF showed the highest SMAF score for soil physical quality index followed by NPKP > NPKG > NPK and control; whereas the score of soil chemical quality was greater in NPKP followed by NPKF/NPKG > NPK > control (p > 0.05). Overall, the soil nutritional quality index was greater in NPKF (0.96) followed by NPKG > NPKP > NPK, and the least was in control. The SMAF score of soil biological quality index was highest in NPKF compared to NPKG > NPKP > NPK > control. The wholesome index of SMAF (SQI) was developed withthehighest score in NPKF (0.94) followed by NPKG (0.90) > NPKP (0.89) > NPK (0.79) > control (0.71). The β-glucosidase activity, mineralizable C, KMnO4 oxidizable N, microbial biomass C, and total water-stable aggregates explained 82% variability in the dataset and represented a good agreement with system yield (R2 = 0.89, p < 0.05). This study concludes that the conjunctive application of NPK with manures restores the overall soil quality more than other management practices, and thatthe SQ indices can be utilized for screening the best management practices for rice-wheat and other similar cropping systems.

Impact of Paper Board Industry Effluent Irrigation to Agroforestry System on Changes in Soil Quality

The study assessed the impact of paper board industry effluent irrigation on soil quality under agroforestry system. The agroforestry system was maintained at the Tamil Nadu Newsprint and Paper Limited (TNPL) - Unit II located at Mondipatti Village, Manaparai Taluk, Trichy district, Tamil Nadu. The site is situated at the intersection of latitude 10º 41' N and longitude 78º 26" E. The soil analysis were carried out for various quality parameter as per standard procedure. The results reveals that application paper board industry effluent were significantly influenced the organic carbon, Available P, and K. Hydraulic conductivity of surface soils was ranged from 2.02 to 4.39 cm h-1 with the mean value of 3.27 cm h-1. Infiltration rate was ranged from 6.6 to 52.5 cm h-1 with the mean value of 23.0 cm h-1. Among the micronutrients status zinc was recorded below the critical level whereas cupper, iron and manganese were recorded above the critical level. Microbial biomass carbon (MBC), Soil microbial population (Bacteria, Fungi and Actinomycetes) and enzyme activities (Urease and Phosphatase) were significantly higher when application with paper board industry effluents under agroforestry system. The activity of soil enzymes and MBC showed significant positive correlation with organic carbon, available water and pH. These findings reveal that paper board industry effluent act as an irrigation source and fertigation under agroforestry system.

Impacts from Topsoil Stockpile Height on Soil Geochemical Properties in Two Mining Operations in British Columbia: Implications for Restoration Practices

Mining activities are often severely disruptive to the landscape, and a major barrier to reclamation after mining is lack of quality topsoil. This research addresses knowledge gaps in the industry by exploring the compositional nature of topsoil stockpiles and their ability to facilitate post-mining revegetation after long-term storage. To do this, we conducted an extensive profile characterization of two topsoil stockpiles at two mining operations in the interior of British Columbia, where soil geochemical properties were investigated. Both stockpiles showed reduced soil quality and significant changes compared to reference soils. Importantly, there was an accumulation of metals and a reduction in soil nutrients with increasing stockpile depth in one or both stockpiles. These results highlight the important influence of topsoil-stockpile height on soil geochemical properties, which ultimately influences the success of restoration. This research provides insights into the response of soil geochemistry across a depth gradient in severely disturbed mining soils.

Arsenic-induced response in roots of arsenic-hyperaccumulator fern and soil enzymatic activity changes

In a pot experiment, arsenic-hyperaccumulating Pteris cretica cv. Albo-lineata plant ferns were cultivated and exposed to low and high doses of arsenate (20 and 100 mg As/kg, respectively) for six months. Physiological and morphological changes of roots, as well as changes in soil quality of the root zone and bulk soil (water-soluble fraction of elements and activity of soil enzymes), were determined. The results showed that the accumulation of inorganic As, mainly in the form of As3+, did not significantly affect the yield of roots, but caused changes in root morphology (deformation of root cell walls due to lignification) and metabolism (decrease of auxin indole-3-acetic acid and 2-oxoindole-3-acetic acid contents). Although the soil quality results varied according to the As dose, there was a clear difference between the root zone and the bulk soil. The activities of enzymes in the root zone were greater that those in the bulk soil. The results showed a significant influence of the high dose of As (100 mg As/kg), which decreased the activity of arylsulfatase, nitrate reductase, and urease in the root zone, while a decrease in acid phosphatase and nitrate reductase was observed in the bulk soil. The water-soluble fractions of As, organic nitrogen, nitrate nitrogen and organic carbon were significantly affected by the high dose of As.

Tolerance of Berberis thunbergii DC. to greywater irrigation and changes in soil quality

Climate changes that lead to an increasing shortage of drinking water (DW) dictate the use of alternative water sources for irrigation. Therefore the aim of this research was to determine the tolerance of plant growth and development of Berberis thunbergii DC. (Japanese barberry) to irrigation with greywater (GW) and to examine changes in chemical properties of soil. The two-year experiment, conducted during vegetation season, was comprised of the following treatments: K (control, 100% DW), T1 (diluted GW containing 50% DW and 50% GW), T2 (100% GW) and T3 (alternating watering with 100% DW and 100% GW). After statistical analyses the results indicate the similarity between the K and T3 treatments in terms of the plant growth and development of new shoots. T1 treatment leads to slower plant growth, whereas T2 treatment leads to slower development of new shoots, but the vitality of the plants was not observed. Application of T1, T2 and T3 treatments resulted in slight salinization of the soil. In general, the results of this research indicated that GW can be used for irrigation of B. thunbergii, preferably with the application of alternating watering T3 treatment.

Soil characteristic changes and quality evaluation of degraded desert steppe in arid windy sandy areas.

Grassland degradation has become a serious problem in some areas, making it necessary to quantitatively evaluate this process and its related factors. The study area was the arid windy sandy area in eastern Ningxia. The purpose of this study was to explore how soil properties and quality change during the process of grassland degradation in arid windy sandy areas. We looked at undegraded, lightly degraded, moderately degraded, and severely degraded desert steppe to study the physical, chemical, and biological changes at 0–5 cm, 5–15 cm, and 15–30 cm soil depths at different degradation degrees. We also analyzed the correlations across soil factors, established the minimum data set, and used the soil quality index (SQI) to evaluate the soil quality of grassland at different degradation degrees. The results showed that with grassland degradation, the soil bulk density increased; the soil clay, moisture, organic matter, total nitrogen, and available potassium content decreased; and the number of soil bacteria, actinomycetes, and fungi, as well as the activity of urease, polyphenol oxidase, protease, phosphatase, and sucrase, decreased. As soil depth increased, soil bulk density increased; the soil moisture, organic matter, available potassium, and available phosphorus content decreased; and soil microorganisms accumulated in the upper soil of undegraded, lightly, and moderately degraded grassland. There was also a positive correlation among the soil clay content, moisture content, organic matter content, total nitrogen content, available potassium content, microorganism quantity, and enzyme activity, while soil bulk density was negatively correlated with the above factors. The minimum data set for the soil quality evaluation of the degraded desert steppe was comprised of soil organic matter content, soil total nitrogen content, soil available phosphorus content, and phosphatase activity. Based on the minimum data set, we calculated the SQI of the grassland at different degradation degrees and found that the ranking based on overall soil quality was undegraded >lightly degraded >moderately degraded >severely degraded grassland. The results showed that the degradation of desert steppe in arid windy sandy areas had relatively consistent effects on the physical, chemical, and biological traits of the soil. The minimum data set can be used to replace the total data set when evaluating the soil quality of the desert steppe at different degrees of degradation.

Biochar from food waste: a sustainable amendment to reduce water stress and improve the growth of chickpea plants

The application of biochar in agriculture is a developing means to improve soil water retention, fertility, and crop yield. The present work focuses on biochar preparation from mixed vegetable and fruit wastes, using cauliflower, cabbage, banana peels, corn leaves, and corn cobs. The biochar produced at 400 °C was applied to the soil as an amendment to observe the qualitative changes of soil quality, plant growth, and water retention capacity of the soil based on screening in a previous study. Pot experiments were conducted at a laboratory scale having 0%, 2%, and 6% biochar mixed with sand. Each pot was sown with seeds of chickpeas (Cicer arietinum L.) and monitored over 60 days. Two biochar application rates improved soil quality by increasing soil porosity from 49.3 to ≥ 53.4%, more than doubling cation exchange capacity to ≥ 21.1 cmolc.kg−1, providing a small reduction in bulk density of approximately 10% and decreasing electrical conductivity of the extract by at least 40% in comparison to control condition. The biochar application also increased key soil nutrients K, Mn, S, and P by a factor of 2–9 times. Application of biochar at 2% and 6% improved water retention from 55 to 77 and 91 mL respectively over the study and, more importantly, more than doubled the biomass yield for the same water application. The lower biochar application rate of 2% led to more germinated seeds (p = 0.0001), leaves (p = 0.0001), flowers, and fruiting chickpeas than the control condition. The 6% biochar application rate slightly improved plant height (p = 0.01) and provided a small reduction in water loss compared with the 2% biochar. Both biochar loadings increased the root and shoot biomass (p = 0.005) and nutrient content of the shoot and root biomass, particularly K, P, and S (p = 0.0001). This study demonstrates that biochar application at 2–6% is an effective means to increase chickpea yield and reduce water stress. Given small differences in performance within this application range, 2% application is recommended. The study establishes valorization of cellulose rich food waste in the form of biochar as a potential method for positive soil management and increased agricultural productivity in arid environments.

Assessing changes in soil quality between protected and degraded forests using digital soil mapping for semiarid oak forests, Iran

Soil quality, defined as the capacity of a soil to function, is one of the most important characteristics of soil. Methods for modelling and monitoring soil quality are needed for sustainable soil management and evaluating soil degradation. In Iran, resource demands have led to the deforestation of the mixed semiarid oak forests; however, the impacts of these activities on the spatial patterns of soil quality remains unclear. This study calculates a soil quality index (SQI) from an integrated suite of soil biological, physical, and chemical properties and compares the SQI between a paired degraded/deforested area and a protected forested area in Iran using a digital soil mapping (DSM) approach via geostatistical and machine learning techniques. Here, 50 soil samples were acquired for each of the degraded/deforested and protected forested areas, whereby 14 soil attributes were measured. Results showed that the soil organic carbon, total nitrogen, available potassium, cation exchange capacity, pH, clay, saturated water content, and basal respiration in the protected area were significantly higher than the degraded forest area. Furthermore, the soil quality in the protected area was substantially higher than the degraded area. To select the best modelling approach for mapping SQI, machine learning approaches using regression tree (RT), artificial neural networks (ANN), and Random Forest (RF) models were compared against geostatistical approaches using inverse distance weighted interpolation, global polynomial interpolation, radial basis function interpolation, local polynomial interpolation, and kriging (ordinary, simple, and universal). Of the machine learning techniques, the RF model (R2 = 0.66) outperformed ANN and RT, while Universal Kriging outperformed all geostatistical approaches (R2 = 0.71). By comparing the SQI maps between the degraded/deforested and protected forested areas, the soil quality was substantially higher for the protected areas. This study demonstrates a framework for assessing the impacts of deforestation on the spatial patterns of soils using DSM techniques, which will facilitate effective land use planning and sustainable forest resource management strategies.

Changes in Soil Quality of an Urban Wetland as a Result of Anthropogenic Disturbance

Urban wetland soil provides ecosystem services (ES) through their functions. Changes in soil properties due to anthropogenic disturbances lead to a loss of soil quality. The aim of this research was to evaluate the effect of nearby anthropic disturbance on the chemical, physical and biological properties of the urban wetland soil. Soil samples were collected from four sites (P1, P2, P3 and P4) located in the Angachilla urban wetland, Chile, according to the magnitude of anthropogenic disturbance. An assessment of the physical and chemical properties of the soil profile was carried out in two sites, P1 and P4. Additionally, chemical and biological properties of the soil were evaluated in the four sites selected. Results from the soil profiles showed that Hz1 of P4 had a higher levels of soil fertility as a result of low anthropogenic disturbance in contrast to Hz1 of P1 (p < 0.05). Relevant differences among sites were observed for P-Olsen, pH NaF, nosZ gene, Nitrate and Na (PC1: 50.5%). Composition of the soil bacterial community in P1 and P4 showed higher richness and diversity. Anthropogenic disturbance on the urban wetland soil leads to a loss of the soil’s organic horizon, as well as its soil quality and, subsequently, its capacity to provide ES through its functions.