Soil Chemical Indicators Research Articles

Effect of long-term liquid dairy manure application on activity and structure of bacteria and archaea in no-till soils depends on plant in development.

This study aimed to evaluate the impact of long-term liquid dairy manure (LDM) application on the activity and structure of soil bacterial and archaea communities in two cropping seasons over 1year of a no-till crop rotation system. The experiment was run in a sandy clay loam texture Oxisol, in Brazil, including LDM doses of 60, 120, and 180 m3ha-1year-1, installed in 2005. Soil sampling was conducted during spring 2018 and autumn 2019 at 0-10-cm depth. Microbial biomass carbon and nitrogen, 16S rRNA gene sequencing, microbial respiration and quotient were performed. Over the 14-year period, LDM application increased soil microbial community activity. Analysis of 16S rRNA gene sequencing revealed dominance by Proteobacteria, Acidobacteria, and Actinobacteria phyla (67% in spring and 70% in autumn). Genera Pirulla and Nitrososphaera showed enrichment at LDM doses of 120 and 180 m3ha-1year-1 doses, respectively. During spring, following black oat cropping, shifts in the relative abundance of Bacteroidetes, Proteobacteria, Firmicutes, Gemmatimonadetes, Verrucomicrobia, Chloroflexi, Actinobacteria, and AD3 phyla were observed due to LDM application, correlating with soil chemical indicators such as pH, K, Ca, Mn, and Zn. Our findings indicate that plant development strongly influences microbial community composition, potentially outweighing the impact of LDM. Our findings indicate that the application of liquid dairy manure alters the soil bacterial activity and community; however, this effect depends on the developing plant.

Assessing the Impact of King Coconut Husk Ash and Biochar, Combined with Chemical Fertilizer Application, on Enhancing Soil Fertility in Coconut Plantations

Sustainable soil fertility management is crucial for enhancing productivity in coconut plantations. This study investigated the synergistic effects of king coconut husk (KCH) ash, biochar, and chemical fertilizers on soil properties in a coconut plantation over a short period (4 months). Six treatments were applied: control, chemical fertilizers alone (F), fertilizers with ash (FA), fertilizers with biochar (FB), fertilizers with both ash and biochar (FAB), and fertilizers with half ash and biochar (FA1/2B). Strongly alkaline KCH ash contained significantly higher total and available potassium content levels than mildly alkaline biochar. Data indicated that KCH ash significantly enhanced soil available potassium, electrical conductivity, and organic carbon content compared to the control and F treatments over a short-term period. Even though biochar application demonstrated initial improvements in soil moisture content, a longer study duration may be required to evaluate its influence on other soil parameters comprehensively. Highlighting the synergistic benefits of KCH ash and biochar, FA1/2B treatment exhibited the highest combined index score based on physical, biological, and chemical soil indicators, suggesting its potential for optimizing agricultural outcomes. It emerged as the most promising approach, underscoring the value of exploring sustainable soil amendments derived from agricultural waste streams to promote soil fertility and sustainable coconut production.

Mixing with native broadleaf trees modified soil microbial communities of Cunninghamia lanceolata monocultures in South China.

Mixing with different broadleaf trees into the monocultures of Cunninghamia lanceolata is widely adopted as an efficient transformation of the pure C. lanceolata forest. However, it is unclear how native broad-leaved trees influence the belowground ecological environment of the pure C. lanceolata culture plantation in nutrient-poor soil of South China. Herein, we aimed to investigate how a long-time mixing with native broadleaf trees shape soil microbial community of the pure C. lanceolata forest across different soil depth (0-20 cm and 20-40 cm) and to clarify relationships between the modified soil microbial community and those affected soil chemical properties. Using high-throughput sequencing technology, microbial compositions from the mixed C. lanceolata-broadleaf forest and the pure C. lanceolata forest were analyzed. Network analysis was utilized to investigate correlations among microorganisms, and network robustness was assessed by calculating network natural connectivity. Results demonstrated that the content of soil microbial biomass carbon and nitrogen, total phosphorus and pH in mixed forest stand were significantly higher than those in pure forest stand, except for available phosphorus in topsoil (0-20 cm). Simultaneously, the mixed C. lanceolata-broadleaf forest has a more homogeneous bacterial and fungal communities across different soil depth compared with the pure C. lanceolata forest, wherein the mixed forest recruited more diverse bacterial community in subsoil (20-40 cm) and reduced the diversity of fungal community in topsoil. Meanwhile, the mixed forest showed higher bacterial community stability while the pure forest showed higher fungal community stability. Moreover, bacterial communities showed significant correlations with various soil chemical indicators, whereas fungal communities exhibited correlations with only TP and pH. Therefore, the mixed C. lanceolata-broadleaf forest rely on their recruiting bacterial community to enhance and maintain the higher nutrient status of soil while the pure C. lanceolata forest rely on some specific fungi to satisfy their phosphorus requirement for survive strategy.

Soil quality evaluation of different land use modes in small watersheds in the hilly region of southern Jiangsu

The Yixing Yuantianjian small watershed is a provincial soil erosion key management area in the hilly region of southern Jiangsu. It has been implemented key national soil erosion control project for small watershed management, which is typical and representative in the region. It is important to quantitatively evaluate the soil quality of the area under different land use modes and then select suitable ecological restoration measures to promote the ecological and economic construction of small watersheds in the hilly region of southern Jiangsu. Used four types of land use (forest land, garden land, arable land and abandoned land) in the Yixing Yuantianjian small watershed as the research object, 13 soil physical and chemical property indicators were screened based on principal component analysis, correlation analysis and Norm value calculation to construct a minimum data set (MDS) for soil quality evaluation. The results showed that the variability of soil chemical indicators of land use modes was higher than that of soil physical indicators in the study area. The MDS indicators affected by soil quality in the small watershed are sand content (Sand), total nitrogen (TN), available nitrogen (AN), available potassium (AK), total soil porosity (TSP) and bulk density (BD), which provide valid information on soil quality in the area with high accuracy. The soil quality index for different land use modes in the small watershed in the hilly areas of southern Jiangsu was SQI forest land (0.83) > SQI cultivated land (0.74) > SQI garden land (0.66) > SQI abandoned land (0.46), with soil quality at a medium to high level. AN was the key factor limiting the soil quality of this watershed. This study can provide a scientific basis for soil quality enhancement and ecological restoration in the small watersheds of the southern Jiangsu hilly region.

Biological soil health indicators are sensitive to shade tree management in a young cacao (Theobroma cacao L.) production system

Cacao agroforestry systems can offer important benefits, such as greenhouse gas mitigation, microclimate regulation and improved soil health. The selection of tree species for cacao agroforestry systems is a critical step impacting cacao yields, as well as the environmental and economic sustainability of the production system. However, the effects of different tree species on soil processes and functions have been poorly studied. We assessed a series of soil health indicators in a five-year-old agroforestry trial located in the Ecuadorian Amazon. The following treatments: “control” (cacao monoculture), “timber” (cacao with Cedrelinga cateniformis Ducke; a leguminous tree), “fruit” (cacao with Bactris gasipaes), “N-fix” (cacao with Erythrina velutina Wild) and “mixed” (cacao with C. cateniformis + E. velutina) were replicated 3 times in randomized blocks. The experiment was managed organically with low levels of external inputs. We collected soil, litter and leaf samples of cacao trees at two different distances (∼2 m and ∼ 6 m) from the shade tree. Biological (potential soil respiration, and macrofauna abundance, richness and Shannon diversity), chemical (pH, CEC, total C and N, macro and micronutrients and Cd), and physical (bulk density and water holding capacity) soil health indicators were measured. Additionally, we analysed nutrients and Cd in cacao leaves and litter. Results showed positive effects of the “timber” and “mixed” treatments on biological soil health indicators, primarily earthworm abundance and potential respiration, as compared to cacao monocultures. Treatment effects on potential respiration showed different trends in litter versus soil, indicating that effects of shade trees on litter respiration do not transfer directly to soil respiration. Physical and chemical soil indicators, including available Cd which is irrelevant in the context of food safety regulations, did not show any differences among the treatments. Five years after establishment, no significant differences in yields were found among the control and any of the shade tree treatments.

Impact of agrochemicals application on soil quality indicators and trace elements level of wetlands under different uses

An attempt to boost agricultural production has led to increased agrochemical usage. Continuous agrochemical usage for decades has brought changes to soil properties. The study assessed the impact of agrochemicals (fertilizers and pesticides) on wetland characteristics in Abeokuta, Nigeria. Five wetlands under maize, plantain, rice, vegetable productions, and control site were studied. Profiles were dug on each wetland, and soil samples were collected from pedogenic horizons and analysed using appropriate techniques. The morphological properties like colour, texture, structure, and consistency differ across the wetlands. The particle size fraction showed that the sand content was higher than silt and clay contents. Soil chemical indicators like pH, OM, TN, and K were lower in agrochemicals applied fields than in the control site, whereas available P was increased in these fields. The total trace element contents were highly affected and their levels have almost reached the permissible limit of WHO standards for agricultural purposes. Nutrient depletion and trace element build-up were more prominent in agrochemicals applied fields as against the control field. Information gathered from this study can help the policymakers on the proper usage and management of these wetlands on a productive and sustainable basis. To reduce agrochemicals impact which majorly contributed to the differences in the soil quality indicators and trace elements level, it is our opinion that planning to shift toward organic agriculture with no or minimal use of agrochemicals are to be considered.

Evaluating the Soil Quality of Forest, Broom Grass and Cultivated Land Uses in Hilly Agro-ecosystem, Meghalaya Plateau, North East India

Soil quality can be inferred from selected chemical soil indicators and it may be altered under the impact of changes in land uses (LUS). For achieving sustainable management practices the soil quality indicators (SQI) should be measured. The objective of this study was to compare the soil quality index in forest, Broom and cultivated land use systems in some areas of Meghalaya, using a completely randomized design at nine different land uses containing Mixed-Forest, Pine-Forest, Broom-Grass, Rice-Potato, Rice-Cabbage, Upland Rice-Monocrop, Lowland Rice-Monocrop, upland pineapple crop and slash-burn cropping system with three replications and two depths. 54 soil samples were collected from the surface and subsurface soil depth of diverse LUS and 9 soil chemical attributes was selected for SQI. Values of SQI deduced using the average factorial deviation from the values of soil quality indicators of diverse LUS site relative to their value of the mixed forest as a (reference) scaled to 100 per cent. The results showed that the pine forest land use had the premier value of SQI (98.99) and poorest in the rice-potato (70.00) land use system in both the depth compared to mixed forest land. It can be concluded that cultivated land use decreases soil quality index such as rice-potato system.

SOYBEAN BASE FERTILIZATION: CHEMICAL AND MICROBIOLOGICAL SOIL INDICATORS AND CROP YIELD

Recent research suggests that soybean yield could be doubled in Brazilian conditions, implying that the base fertilization is pivotal, as it might influence chemical and microbiological soil indicators and, hence, the crop grain yield. The current study had the goal of assessing alterations in the chemical and microbiological soil indicators, in the short term, as well as the soybean biometric and grain yield performance as a function of different fertilizers for base fertilization, in two sowing periods. An experiment comprised of two sowing periods was carried out in the 2019/2020 season on a dystrophic Red Latosol, in north Parana state. Five treatments were assessed, comprising: 1) control; 2) mineral fertilizer; 3) organomineral fertilizer; 4) mineral fertilizer mixed with granulated gypsum; and 5) slow release mineral fertilizer. A randomized block design with four replicates was adopted. The following variables were assessed: chemical and microbiological soil indicators; final stand; first pod insertion height; plant height; stem diameter; number of pods per plant; number of grains per plant; number of grains per pod; grain mass per plant; and one thousand grain mass and grain yield. There is no base fertilization effect on the chemical soil indicators in the short term, however, there is an effect on the microbiological soil indicators. Soybean biometric and grain yield performance is decreased with the delayed sowing period, regardless of the type of fertilizer utilized for base fertilization. Analyzing a set of soil quality indicators enables precise and judicious results to be gathered on management practices in the soil environment.

Utilization of Mustard Seed Meal Extract for Improving Soil Health in a Small-Scale Organic Potato Cropping System

ABSTRACT Maintaining and improving soil health is one of the top priorities in organic agriculture to ensure crop production sustainability. Mustard seed meal extracts are promising organic soil amendments that can reduce pesticide pressure and improve crop yields. In this study, we investigated the potential of mustard seed meal extract developed in our laboratory, to improve soil health in organic potato systems. Field trials were conducted on two certified organic farms in Northern Idaho to 1) assess the changes in soil chemical indicators after mustard seed meal extract application; 2) evaluate the effect of mustard seed meal extract on microbial biomass carbon; and 3) measure plant-available nutrients levels in soil after mustard seed meal extract application. To the best of our knowledge, this is the first report studying the effect of mustard seed meal extract on soil quality in organic potato systems. Out of 27 soil chemical and biological indicators measured, 19 indicators were sensitive to the addition of mustard seed meal extract. The data obtained for organic and inorganic soil constituents indicate a positive impact of mustard seed meal extract on soil quality. Addition of mustard seed meal extract to soil increases Haney soil health score up to 1.5 times demonstrating the benefit of application for improving soil quality in organic production.

The influence of rhizosphere soil fungal diversity and complex community structure on wheat root rot disease.

Wheat root rot disease due to soil-borne fungal pathogens leads to tremendous yield losses worth billions of dollars worldwide every year. It is very important to study the relationship between rhizosphere soil fungal diversity and wheat roots to understand the occurrence and development of wheat root rot disease. A significant difference in fungal diversity was observed in the rhizosphere soil of healthy and diseased wheat roots in the heading stage, but the trend was the opposite in the filling stage. The abundance of most genera with high richness decreased significantly from the heading to the filling stage in the diseased groups; the richness of approximately one-third of all genera remained unchanged, and only a few low-richness genera, such as Fusarium and Ceratobasidium, had a very significant increase from the heading to the filling stage. In the healthy groups, the abundance of most genera increased significantly from the heading to filling stage; the abundance of some genera did not change markedly, or the abundance of very few genera increased significantly. Physical and chemical soil indicators showed that low soil pH and density, increases in ammonium nitrogen, nitrate nitrogen and total nitrogen contributed to the occurrence of wheat root rot disease. Our results revealed that in the early stages of disease, highly diverse rhizosphere soil fungi and a complex community structure can easily cause wheat root rot disease. The existence of pathogenic fungi is a necessary condition for wheat root rot disease, but the richness of pathogenic fungi is not necessarily important. The increases in ammonium nitrogen, nitrate nitrogen and total nitrogen contributed to the occurrence of wheat root rot disease. Low soil pH and soil density are beneficial to the occurrence of wheat root rot disease.

Key gaps in soil monitoring during forest restoration in Colombia

The knowledge of soil indicators during forest restoration is essential for understanding the recovery of ecosystem functions such as biomass production and water regulation. Despite this importance, in most restoration programs over the world, the soil remains under‐investigated. Here, we conducted a systematic literature review in order to determine: (1) the extent to which soil indicators are monitored during forest restoration in Colombia; (2) the type of soil indicators (e.g. physical, chemical, or biological) that are used for the monitoring; and (3) the regions where soil indicators are measured. We found 34 studies that report soil indicators. The most frequently studied restoration sites were 0–5 years old (36%). The majority (71%) of the studies only measured the soil characteristics at the topsoil. Soil sodium (Na) and phosphorus (P) concentrations were the most common chemical soil indicators reported by the studies. Soil biological indicators were the least frequently reported indicators. The studies rarely reported soil indicators that affect water movement directly. Of the retrieved studies, most included information about old‐growth forests (63%) or degraded sites (56%) for comparisons with forests undergoing restoration. Based on these results we provide recommendations for monitoring soil characteristics to assess the effectiveness of forest restoration projects in Colombia, and other tropical countries.

Alluvial Soil Quality Indicators As Affected By Different Land-Uses. مؤشرات جودة التربة الطمييه تحت تأثير الاستخدامات المختلفة للأراضي.

Soil deterioration and yield decline are the main factors affecting the environmental sustainability of long-term irrigated sugarcane monoculture. This research was conducted to detect changes of soil physical, chemical and physicochemical quality parameters associated with intensive irrigated sugarcane monoculture with groundwater for long term. Sugarcane monoculture resulted in a severe impact on some soil physical indicators of soil quality as increased the soil bulk density and reduced soil clay content, decreased soil aggregate stability and the water content at the field capacity causing decreases in soil porosity and decline in soil fertility. Significant impacts on some soil chemical indicators of soil quality were also recorded as reduced soil organic matter content and increased soil pH and EC producing soil salinity. Fields under long-term irrigated sugarcane monoculture had low OM values ranged from 2.09 to 2.61% while areas under crop rotation had the highest OM values ranged from 2.62 to 3.39%. Fields under sugarcane monoculture system had higher pH, EC and SAR values ranged from 7.96 to 8.41, from 2.98 to 4.22 dS m-1 and from 7.75 to 11%, while fields under crop rotation system had the lowest pH, EC and SAR values ranged from 7.64 to 7.92, 1.41 to 2.42 dS m-1 and from 4.51 to 5.86%, respectively. From these results, it could be concluded that long term sugarcane monoculture has significantly deteriorated soil physical and chemical properties indicating the urgent demand for more sustainable management practices to preserve soil quality.

Spatial heterogeneity of soil fertility in coastal zones: a case study of the Yellow River Delta, China

At the intersection of land and sea, coastal zones are unstable areas that can suffer intensive coastal erosion or sedimentation. The Yellow River Delta, which has experienced rapid land growth, is of great significance in soil fertility research. To qualitatively and quantitatively analyse the basic soil fertility characteristics of coastal zones, we sampled six soil chemical indicators obtained from the Yellow River Delta in July 2019. Principal component analysis (PCA) and the Nemoro quality index (NQI) were integrated for the geostatistical analysis of soil fertility by using the ArcGIS and SPSS software. The NQI, modified NQI (mNQI) and PCA results significantly represented soil fertility, and the mNQI performed better than the NQI. The soil fertility met the classification of ‘III, generally fertile’. The main factors affecting soil fertility were total potassium, total nitrogen and organic matter. The soil fertility indexes declined consistently from west to east. Increasing distance from the sea significantly negatively affected soil fertility, while soil fertility positively impacted land productivity. Therefore, future agricultural planning should focus on soil total nitrogen, total potassium and organic matter and control salinization to improve land productivity. The eastern coastal zone, especially the south-eastern region, should be the first area of focus.

Reference states of forest ecosystem types and feasibility of biocenotic indication of ecological soil condition as part of ecosystem integrity and services assessment

BackgroundStructures and functions of ecosystems and, subsequently, their services for human societies may be influenced by climate change and atmospheric deposition. Jenssen et al. (UBA Texte 87/2013: 1–381, 2013) developed a spatially explicit evaluation system enabling the evaluation of ecosystems’ integrity. This methodology is based on a spatially explicit ecosystem classification of forests. Based on the six ecological functions, the methodology enables to compare the ecosystem type-specific integrity at different levels of ecological hierarchy for a reference state (1961–1990) with the further development of the forest ecosystem types as measured for the years 1991–2010 and as modelled for the period 2011–2070. The present study aimed at deepening the methodology and developing it into a practical system for assessing and mapping forest ecosystem integrity and services. The objectives of this advanced investigation were: (1) to quantify the reference conditions for a total of 61 forest ecosystem types; (2) to test the possibility of supplementing the quantification of ecosystem integrity by information on soil biocenoses as yielded by soil monitoring; (3) to model chemical soil indicators and to compare the respective results with those derived by Ellenberg’s indicator values for nutrient state; and (4) to verify the indicator modelling.ResultsReference states related to the time prior to 1991 have been quantified for a total of 61 forest ecosystem types covering 85% (81,577 km2) of the mapped forest area of Germany. The reference states comprise statistical indicators for the plant-species diversity (habitat function), for nutrient and water balances and further ecological information as net-primary production and carbon storage. The assignment of lumbricide communities as soil biocenosis indicators was attempted but not succeeded because of insufficient data availability. The nutrient cycle types of the elaborated reference states were characterized by humus form, C/N ratio in topsoil and N indicator values according to Ellenberg et al. (Scr Geobot 18:1–262, 2001). Applying the developed methodology, for 83 out of 105 study plots the reference states prior to 1991 could be determined.ConclusionsFor complementing forest ecosystem reference states by soil biocenosis indicators it is necessary to further evaluate the primary literature looking for missing observation data. The W.I.E. indicator value applied in this paper to determine topsoil C/N ratios in forests is well suited for area-covering mapping of both near-natural forest–soil states and deposition-induced disharmonic state changes, in which C/N value and base saturation are no longer correlated.

Efecto de tres condiciones agronómicas diferentes sobre el perfil bioquímico y la diversidad en la rizosfera de plantaciones de banano con Fusarium oxysporum Raza 1

Soil microorganisms play an important role as a link in the transfer of nutrients from the rhizosphere. The physical and chemical properties of soil, the metabolic profiles of microbial communities and different crop management practices can enhance our understanding of hizospheric interactions. This study aimed to establish differences in microbial communities associated with banana crops and the biochemical profile in farms under different agronomic conditions. Seven farms with different levels of intervention, management, and fusariosis severity were analyzed. The biochemical profile of the microbial community was determined using EcoPlates and the main substrates consumed by the microbial communities were identified through multivariate principal component analysis (PCA). Seven microorganisms were selected as indicators of nutrient cycles, pathogenicity and soil health. Also, soil chemical indicators were determined through a complete mineral analysis. For the physiological profile of soil microbial populations, it was observed that farms with the same management tend to be metabolically very similar. In the PCA, two principal components explained 90 % of the variance in the data. It was also determined that the genus Bacillus is predominant in all farms and that farm 4 (medium intervention) presented the most favorable values in all factors analyzed. The effective cation exchange capacity values are highlighted in the chemical analyses, which determined that all farms have a high fertility level. The metabolic profile, diversity and richness of each of the different farms were affected by the type of agronomic management used.

Effect of feather compost on soil chemical indicators in CCN-51 cocoa plantation (Theobroma cacao L.)

Introduction. Organic management of cocoa accounts for 60% of production in Peru and large amounts of compost prepared with different inputs are used, in order to improve the quality of the soil and cocoa yields. Objective. Evaluated the effect of the application of chicken feather compost on the main soil chemical indicators in a cocoa plantation CCN-51 un the Town of Nuevo Progreso, province of Padre Abad in the Ucayali-Peru region was evaluated. Materials and methods. A randomized complete block design was used, with four treatments and four repetitions where: FC1 was an absolute witness, FC2 feather compost at a rate of 2,000 kg. ha-1, FC3 feather compost at a rate of 4,000 kg. ha-1 and FC4 feather compost at a rate of 6 000 kg. ha-1. The main chemical indicators of soil quality were evaluated: hydrogen potential (pH), organic matter (OM), total nitrogen (N), available phosphorus (P), potassium (K+), calcium (Ca2+), magnesium (Mg2+) , aluminum (Al3+), available cadmium (Cd2+), changeable acids (AC) and cation exchange capacity (CEC). Results. The results showed a decrease in exchangeable aluminum and changeable acidity and increases in organic matter, nitrogen, phosphorus, and potassium, depending on the proportion of compost applied, these indicators presented significant differences (p <0.05); The pH, calcium and cadmium available did not show significant differences (p <0.05). Conclusion. Feather compost (FC) significantly improved the levels of OM, N, P and K+, indicators that define soil quality and reduce aluminum levels, the latter of utmost importance in acidic soils.

Enzyme Activity, Glomalin, and Soil Organic Carbon in Agroforestry Systems

Abstract This study aimed to evaluate enzyme activity, glomalin-related soil proteins (GRSP), soil chemical attributes, and total organic carbon (TOC) in two Agroforestry systems (AFS) (AFS-1 and AFS-2), in a traditional agriculture area (TA), and secondary forest (SF) area in Paraty (RJ). Soil samples (from 0 to 5 cm depth) were collected during the rainy and dry seasons. AFS improves and/or maintains soil chemical indicators based on pH increase, reduces aluminum saturation and maintains soil nutrient content (Ca, Mg and K), when compared with SF. The contribution of organic material and the biodiversity of the AFS provide the maintenance of the total organic carbon content of the soil. AFS maintain the activity of the enzymes protease, β-glucosidase, acid phosphatase, and total enzyme activity (FDA), and the production of glomalin-related soil protein at levels similar to those observed in SF, especially during the rainy season.

How does tillage intensity affect chemical soil health indicators? A United States meta‐analysis

AbstractTillage intensity can affect chemical soil health indicators either positively or negatively depending on inherent soil properties and management practices. Soil chemical data (total N, P, K, Ca, Mg, and pH) from four depth increments within 196 published studies were compiled and subjected to a meta‐analysis comparing chisel plow (CP), no‐till (NT), and perennial systems (PER) with moldboard plowing (MP). Overall, CP did not affect soil chemical indicators when compared to MP, but converting from MP to NT increased total N, P, and K concentrations within the top 15 cm. Below that depth, Ca and Mg concentrations were lower under NT than MP but total N, P, and K were not significantly different. Topsoil total N response to NT was moderated by soil order and cropping system, with the largest increase in total N found in Ultisols, Inceptisols, Alfisols, and Mollisols under more diversified cropping systems including those with cover crops. The greatest topsoil P increase in response to NT was found under long‐term experiments (>5‐yr) and on fine‐textured soils. Phosphorus changes in studies on coarse‐textured soils, with short‐term duration, and manure applications were generally neutral. Perennial systems had lower soil P and K but higher total N content in the surface layer as compared to MP. The positive response to PER systems was most notable in Alfisols, Mollisols, and Ultisols and under long‐term PER management. Finally, we demonstrate that these chemical indicators respond to tillage and cropping systems over a wide range of conditions, showing utility for soil health assessment.

Revegetation process increases the diversity of total and arbuscular mycorrhizal fungi in areas affected by the Fundão dam failure in Mariana, Brazil

Mining activities have environmental impacts. The rupture of the Fundão tailing dam ejected a significant volume of iron ore mining waste (IOMW) and was characterized as the greatest disaster in mining history. The use of microorganisms to monitor the affected soils is ideal due to their sensitivity to environmental changes and their capacity for soil remediation, as they can promote plant growth under stressed conditions. This study aimed to evaluate the total fungi diversity and arbuscular mycorrhizal fungi (AMF) community structure of the area affected by IOMW that is currently under rehabilitation. Soil and root samples were collected from an impacted site without rehabilitation (REC1), two revegetated areas with grass and leguminous species (REC2 and REC3), and one reference area in the undisturbed forest (UND) during two seasons (rainy and dry). The total fungal diversity was analyzed by next generation sequencing. The AMF was identified morphologically and the number of spores, colonization, and denaturing gradient gel electrophoresis (DGGE) were identified for this group of fungi. Total fungi diversity, AMF community structure, and soil chemical indicators differed among areas and between seasons. UND exhibited the highest organic matter content whereas rehabilitated areas were more affected by pH and presented higher values. The total fungal diversity and AMF community structure in REC areas showed that spore number and species richness increased along with the revegetation process. Glomus and Rhizophagus comprised the most abundant genera. In both climate seasons, AMF diversity in UND was higher than in REC areas but increased diversity in REC was observed in subsequent sampling. The fungal community diversity in affected areas was altered by the revegetation process—which increased the total fungal diversity—as well as AMF helping the recovery of this area.

COMPORTAMIENTO DEL CADMIO Y OTROS INDICADORES EN SUELO Y ALMENDRA DE CACAO (Theobroma cacao L.), BAJO APLICACIÓN DE COMPOST Y NPK

En la última década, las investigaciones advierten elevados niveles de cadmio (Cd2+) en suelos y almendra en determinadas zonas del Perú. También, la relación que presenta el Cd2+ con algunos indicadores físicos y químicos del suelo. Por ello, el objetivo fue valuar el efecto del compost y NPK en el Cd2+ del suelo, almendras y la relación con otros indicadores del suelo, en una plantación de cacao CCN-51 (Theobroma cacao L.) en la provincia Padre Abad, región Ucayali-Perú. La investigación utilizó un diseño de bloques completamente aleatorizado (DBCA) con cuatro tratamientos y cuatro repeticiones, donde T1: tratamiento control, T2: compost a razón de 3 000 Kg. ha-1, T3: NPK en dosis de 84-35-161, y T4 compost a razón de 1500 kg. ha-1 + NPK 42-18-80. Se evaluó Cd2+ disponible en suelo y almendras, el % de arcilla, % de materia orgánica (MO), pH, Capacidad de intercambio de cationes (CICe) y Mg2+ intercambiable. Los resultados muestran medias entre 18.5 a 22% de arcilla, 4.11 a 4.42 de pH, 2.32 a 4.41% de MO, 7.87 a 9.45 Cmol/kg de CICe, 0.17 a 0.23 µg g-1 de Cd2+ en el suelo y 0.31 a 0.43 µg. g-1 en almendras. Se encontró correlación positiva significativa entre los tratamientos y los indicadores pH, MO y Cd en almendras y negativa significativa para CICe. Se concluye que la aplicación del compost y NPK presento efecto significativo sobre los indicadores pH, MO, CICe y Cd2+ en almendras; encontrándose correlación significativa entre la CICe, MO, y Cd2+ en almendra, entre Mg2+ y Cd2+ en suelo y altamente significativo entre la CICe y Cd2+ en suelo. Siendo, T2 (compost) el tratamiento con menores valores de Cd2+ en suelo y almendras.