Soil Biological Characteristics Research Articles

Soil Quality Index as Affected by Integrated Nutrient Management in the Himalayan Foothills

Soil quality assessment serves as an index for appraising soil sustainability under varied soil management approaches. Our current investigation was oriented to establish a minimum data set (MDS) of soil quality indicators through the selection of apt scoring functions for each indicator, thus evaluating soil quality in the Himalayan foothills. The experiment was conducted during two consecutive years, viz. 2016 and 2017, and comprised of 13 treatments encompassing different combinations of chemical fertilizers, organic manure, and biofertilizers, viz. (i) the control, (ii) 20 kg P + PSB (Phosphorus solubilizing bacteria), (iii) 20 kg P + PSB + Rhizobium, (iv) 20 kg P + PSB + Rhizobium+ FYM, (v) 20 kg P + 0.5 kg Mo + PSB, (vi) 20 kg P + 0.5 kg Mo + PSB + Rhizobium, (vii) 20 kg P + 0.5 kg Mo + PSB + Rhizobium + FYM, (viii) 40 kg@ P + PSB, (ix) 40 kg P + PSB + Rhizobium, (x) 40 kg P + PSB + Rhizobium+ FYM, (xi) 40 kg P + 0.5 kg Mo + PSB, (xii) 40 kg P + 0.5 kg Mo + PSB + Rhizobium, and (xiii) 40 kg P + 0.5 kg Mo + PSB + Rhizobium + FYM. Evaluating the physical, chemical, and biological indicators, the integrated module of organic and inorganic fertilization reflected a significant improvement in soil characteristics such as the water holding capacity, available nitrogen, phosphorus, potassium, and molybdenum, different carbon fractions and soil biological characteristics encircling microbial biomass carbon (MBC), and total bacterial and fungal count. A principal component analysis (PCA) was executed for the reduction of multidimensional data ensued by scoring through the transformation of selected indicators. The soil quality index (SQI) established for different treatments exhibited a variation of 0.105 to 0.398, while the magnitude of share pertaining to key soil quality indicators for influencing soil quality index encircled the water holding capacity (WHC), the dehydrogenase activity (DHA), the total bacteria count, and the available P. The treatments that received an integrated nutrient package exhibited a higher SQI (T10—0.398; T13—0.372; T7—0.307) in comparison to the control treatment (T1—0.105). An enhanced soil quality index put forth for all organic treatments reflected an edge of any conjunctive package of reduced synthetic fertilizers with prime involvement of organic fertilizers over the sole application of inorganic fertilizers.

Potential effects of soil chemical and biological properties on wood volume in Eucalyptus urophylla × Eucalyptus grandis hybrid plantations and their responses to different intensity applications of inorganic fertilizer.

Long-term and high-intensity application of inorganic fertilizer leads to a strong variation of soil characteristics. The changes in soil chemical and biological properties can significantly affect the yield of Eucalyptus plantation. However, the mechanism of soil chemical properties affecting wood volume mediated by biological factors is not clear. The purpose of this study was to identify which soil properties were affected by different fertilization intensities and to disentangle the dominant factors affecting Eucalyptus volume. After clear felling evergreen broad-leaved forest, a Eucalyptus plantation was established that was coppiced every 5 years and fertilized every year. Within this plantation, areas with different treatments were established. These treatments were a 5-year growth period (low); two times 5-year growth period (medium); and three times 5-year growth period (high). In each treatment area and in a nearby evergreen broad-leaved forest (EBLF Control), five sample plots per treatment were set up. Various biological and chemistry analyses (18 in total) were related to determining the most important path and index for optimizing Eucalyptus plantation. The analysis of variance of enzyme activity and microbial biomass showed that the soil biological characteristics decreased over 10 years of plantation, and the enzyme activity was close to the state of EBLF control in medium, while the microbial biomass failed to return to its original state during continuous planting. Redundancy analysis results show that there was a strong correlation in chemical indicators and biological characteristics. Partial least square structural equation model showed that total phosphorus, nitrate nitrogen, urease, catalase, and microbial biomass nitrogen and phosphorus were the most influential soil biochemical factors, and the indirect effect of chemical properties on volume was achieved by microorganisms through enzyme activity. Continuous planting and large-scale application of inorganic fertilizer would lead to a decrease in plantation yield and fertilizer utilization efficiency and would affect the microbial biomass and enzyme activity by destroying the stability of soil chemical properties.

Studying the Effect of Straw Returning on the Interspecific Symbiosis of Soil Microbes Based on Carbon Source Utilization

Heilongjiang province has made great contributions to ensuring the food security of China. Grain production has increased year by year, followed by a large amount of straw—especially the production of corn straw. Straw returning is the best treatment method from the perspective of ecology. This study simulated modern mechanized operation conditions from the field of soil biological characteristics to explore the impact of straw decomposition on the changes in the soil microbial community. In this study, in the black soil region of Northeast China (45°45′27″~45°46′33″ N, 126°35′44″~126°55′54″ E), the orthogonal experimental design was used to experiment for two years (2019–2020), using straw length, amount, and buried depth as returning factors. The carbon source utilization intensity algorithm that was developed by our team was used to extract a single carbon source. A compound mathematical model was constructed based on path analysis and grey relation analysis. This study analyzed the interspecific symbiotic relationship of soil microbes in the process of straw returning and explored the regulatory methods and schemes with which to promote straw decomposition. The results showed that in the first year after straw returning, the cumulative decomposition rate of straw could reach 55.000%; the supplement of the carbon source was glycyl-l-glutamic acid, which was helpful for the decomposition of straw. It was found that cyclodextrin should be added within 90–120 days after straw returning to promote decomposition. In the second year of straw returning, the cumulative decomposition rate of straw can reach 73.523% and the carbon sources α-d-lactose and d-galactonic acid γ-lactone should be supplemented appropriately to promote straw decomposition. This study provides an experimental basis for corn straw returning to the black soil of the cold regions, along with the scientific and technological support for the sustainable development of agriculture and a guarantee of national food security.

Rhizobacteria modify soil biological indices and induce tolerance to osmotic stress in tomato depending on the salinity level and bacteria species.

Salinity is a major abiotic stress that impacts crop productivity globally. Plant growth-promoting rhizobacteria (PGPRs) exploit several mechanisms to not only decrease soil salinity but also improve the systemic tolerance of plants to osmotic stress. In this work, the effect of five PGPR strains was investigated on the growth and physiological responses of tomato plants, including stomatal closure, proline, and K+ and Na+ content under a range of salt stress, 0, 2.5, 5, 7.5, and 10 dS m-1. The effect of PGPR strains and salinity levels on the soil biological characteristics was also investigated. Salt stress affected the plant growth and physiological factors and soil biological factors in a dose-dependent manner. The highest saline stress, 10 dS m-1, reduced shoot and root dry weight and root volume up to 51.3, 41.5, and 51.8%, respectively. It also increased stomatal resistance and proline content 2.01- and 3.66-folds and decreased K+/Na+ ratio 4.16-folds, respectively. It also reduced basal respiration, substrate-induced respiration, and microbial biomass carbon up to 2.25-, 4.83-, and 6.7-folds and increased qCO2 3.18-folds, respectively. PGPR strains were able to modulate salt tolerance mechanisms, improve plant growth factors, and improve soil biological indicators. Bacillus megaterium P2 was the best strain in the balancing K+/Na+ uptake at least at 10 dS m-1. However, the efficiency of strains was dependent on the magnitude of salt stress. Therefore, it is possible to introduce PGPR strains based on soil salt level or exploit rhizobacteria consortia to manage salt stress in different conditions.

The Analysis Of Peat Soil Biological Characteristics After Being Incubated Using Vermicompost From A Mixture Of Chicken Dung, Banana Hump, And Tofu Waste

Peatlands are formed from piles of trapped plant residues, obstructing their decomposition process. The organic matter decomposition process certainly involves soil microbes. This study aims to determine the biological characteristics of peat soil after incubation with vermicompost. This research was conducted at Kampung Perlabian Village, Kampung Rakyat Sub-district, South Labuhanbatu Regency, North Sumatra. Soil biological analysis was conducted in the soil biology laboratory, Faculty of Agriculture, University of North Sumatra. This study used a non-factorial Randomized Block Design (RAK) with three treatments: P0 (control), P1 (1 kg peat soil + 500-gram vermicompost), and P2 (1 kg peat soil + 1 kg vermicompost). The results showed that adding vermicompost fertilizer to peat soil with treatment two could increase the total bacteria by 6.17 x 106 cfu/ml and the total fungus by 8.8 x 105cfu/ml, and CO2 respiration by 4.125 (mg CO/day). As a result, the soil's microorganism's activity is a process in which microorganisms live and do activities in a soil mass.

The Clean Water Act and biosolids: A 45‐year chronological review of biosolids land application research in Colorado

The 1972 U.S. Clean Water Act set forth the generation of biosolids. In Colorado, biosolids land application research began in 1976 and continues today. Pastureland research suggested that sewage effluent could effectively be land applied to benefit aboveground plant growth and to polish water prior to reaching receiving waters. Forest wildfire-affected ecosystems can also benefit from biosolids applications; application rates of up to 80 Mg ha-1 can lead to greater plant establishment, soil microbial activity, and nutrient turnover and reduced nutrient and heavy metal concentrations in runoff below livestock and USEPA drinking water standards. Long-term (24-yr) observations in oil shale-mined lands showed that biosolids (up to 224 Mg ha-1 ) can have a positive effect on microbial-mediated nutrient cycling and, in turn, on aboveground plant community structure. Biosolids applications of up to 40 Mg ha-1 in high-elevation shrubland ecosystems, dominated by Mo-containing shale deposits, can aid in reducing imbalances between Mo and Cu in soils and plants; excessive plant Mo, when consumed by ruminants, can lead to molybdenosis. Biosolids and lime applications (both at 224 Mg ha-1 ) have been shown to improve long-term reclamation success on acid-generating, heavy metal-containing fluvial mine tailings. Thirty years of grazing land research, focused on soil and aboveground plant benefits, illustrate that soil health and plant productivity can be improved to the greatest extent at biosolids application rates close to 10 Mg ha-1 . Finally, 40 yr of dryland agroecosystem research (a) have helped identify biosolids N fertilizer equivalency (∼8kg N Mg-1 ) and thus dryland winter wheat application rates (e.g., 4.5-6.7 dry Mg ha-1 ); (b) have identified first-year mineralization rates of 25-32%; (c) dispute the "time bomb" theory by showing that plant metal uptake follows an exponential rise to a maximum; (d) showcase economic return to producers via increased wheat grain protein content; (e) suggest that biosolids-borne proteins and their degradation products are labile C and N sources; (f) have led to long-term tracking of micronutrients and heavy metals in soils and revealed that plants-soil concentrations will not lead to groundwater degradation and that plants are safe for human consumption; and (g) have shown that biosolids provide Zn, helping to overcome soil deficiencies and enhancing Zn biofortification in wheat grain. This latter point is important because ∼2 billion people globally suffer from Zn deficiencies. Forty-five years of research in Colorado have proven that biosolids can enhance environmental quality, improve soil health, and produce healthy food products.

Methane Emission Reduction and Biological Characteristics of Landfill Cover Soil Amended With Hydrophobic Biochar.

Biochar-amended landfill cover soil (BLCS) can promote CH4 and O2 diffusion, but it increases rainwater entry in the rainy season, which is not conducive to CH4 emission reduction. Hydrophobic biochar–amended landfill cover soil (HLCS) was prepared to investigate the changes in CH4 emission reduction and biological characteristics, and BLCS was prepared as control. Results showed that rainwater retention time in HLCS was reduced by half. HLCS had a higher CH4 reduction potential, achieving 100% CH4 removal at 25% CH4 content of landfill gas, and its main contributors to CH4 reduction were found to be at depths of 10–30 cm (upper layer) and 50–60 cm (lower layer). The relative abundances of methane-oxidizing bacteria (MOB) in the upper and lower layers of HLCS were 55.93% and 46.93%, respectively, higher than those of BLCS (50.80% and 31.40%, respectively). Hydrophobic biochar amended to the landfill cover soil can realize waterproofing, ventilation, MOB growth promotion, and efficient CH4 reduction.

Effect of Polymer Mixtures on Physical-Chemical Properties of Sandy Soil and Plant Growth

Serious desertification problems were found in alpine grassland of the Qinghai-Tibet Plateau, China. The rehabilitation progress of degraded grassland is slow under natural conditions that have low rainfall and large evaporation. Organic agent-solidified soil is one of the most important measurements that limit desertification and grassland conservation-restoration. However, the characteristics of vegetation growth and development in solidified soil need to be studied in depth. This research is based on the modified carboxymethyl cellulose (MCMC) of independent development. Based on the sand soil taken from moving sandy land of Zoige, potted plants were tested in the environmental chamber at the laboratory. The physical, chemical, and biological characteristics of root soil were monitored for more than 7 months. As a result, the plant biomass in the experimental group increased, lodging rate decreased, drought tolerance and survival rate increased, and the number of plant roots and root surface area index, root cross-sectional area ratio, and root volume ratio increased compared with the matched group. It is shown that MCMC can effectively promote plant root development and improve plant drought tolerance and lodging resistance. We also found that, compared with the matched group, the values of the rhizosphere soil mass, root soil mass, and soil crust layer thickness of the experimental group were much higher, meaning that MCMC has strengthened the root soil-fixation ability and soil-crusting ability of plants. The soil nutrient indexes and bioactivity of the experimental group were higher than the matched group, indicating that MCMC has a positive influence on soil maturation. The quantitative description model of soil aging enhancement of MCMC material during root growth and development was established to explore the soil-fixation mechanism of MCMC plant root succession and provided an important scientific basis and technical support for the conservation and restoration of alpine grassland desertification grassland.

Soil Amended With Organic Matter Increases Fluvial Erosion Resistance of Cohesive Streambank Soil

AbstractFluvial erosion of cohesive soil is mediated by interactions between soil physical, biological, and chemical characteristics such as soil aggregate stability and extracellular polymeric substances (EPS). While labile organic matter (OM) stimulates microbial EPS production and significantly improves soil aggregate stability in agricultural soils, these interactions remain unexplored in streambank soils. The study goal was to quantify the impact of OM on aggregate stability, EPS, and fluvial erosion rates of cohesive streambank soil. Increasing amounts of 1‐mm sieved dry grass were incorporated at rates of 0, 1, and 4 g per 100 g of 2‐mm sieved silt‐loam soil (treatments T0, T1, and T4, respectively). Samples (eight replicates per treatment) were matured in a greenhouse for 50 days prior to flume erosion testing. EPS carbohydrates were significantly (p < 0.05) lower in T1 (324 ± 63 μg/g) compared to T0 (388 ± 37 μg/g) and T4 (376 ± 44 μg/g). EPS proteins were significantly higher in T1 (194 ± 15 μg/g) and T4 (223 ± 61 μg/g) compared to T0 (101 ± 20 μg/g) and positively correlated with mean weight diameter (MWD), a measure of soil stability against slaking. MWD was 16% and over 100% higher for T1 and T4, respectively, than for T0. Similarly, the average soil erodibility coefficient of T1 and T4 was 25% and 61% lower than the erodibility of T0; however, only the reduction for T4 was significant. The data presented here underscore the important role labile OM plays in improving soil physical stability and increasing the resistance of cohesive soil to fluvial erosion of streambanks.

Biological make-up of soil and seed infection by the root rot pathogen (Bipolaris sorokiniana) of barley in the Southeastern Region of Kazakhstan

One of the important factors for the sustainable development of the agricultural industry in Kazakhstan is the prevention of crop losses due to plant diseases. The purpose of the paper is to study the biological characteristics of soil and seed infection by the common root rot pathogen (Bipolaris sorokiniana) in barley in the Southeastern Region of Kazakhstan. The scientific novelty of the study is due to the fact that the plant protection systems, existing in the region, in most cases based on the use of chemicals, even with high efficiency, are not able to provide long-term stabilisation of the phytosanitary situation in the cereal crops agrocenoses and their compliance with modern environmental requirements. Within the framework of this study, the dependence of the temperature conditions on the time and quality of rot development was found. The practical significance of the study lies in the fact that in the modern strategy and tactics of plant protection, great importance is attached to the design of agrocenosis, optimised by phytosanitary characteristics, where the number of pests is reduced to economic thresholds of harmfulness. It was concluded that the main pathogen of barley root rot is the Bipolaris sorokiniana Shoem. fungus, the parasitic frequency of which reached 65%.

Soil Environments Influence Gut Prokaryotic Communities in the Larvae of the Invasive Japanese Beetle Popillia japonica Newman.

Invasive scarab beetles, like the Japanese beetle Popillia japonica Newman (JB), spend most of their lives as larvae feeding in the soil matrix. Despite the potential importance of the larval gut microbial community in driving the behavior, physiology, and nutritional ecology of this invasive insect, the role of soil biological and physicochemical characteristics in shaping this community are relatively unknown. Our objectives were to (1) characterize the degree to which larval gut microbial communities are environmentally acquired, (2) examine the combined effects of the gut region (i.e., midgut, hindgut) and local soil environments on gut microbial communities, and (3) search for soil physicochemical correlates that could be useful in future studies aimed at characterizing gut microbial community variation in soil-dwelling scarabs. Gut communities from neonates that were never in contact with the soil were different from gut communities of third instar larvae collected from the field, with neonate gut communities being significantly less rich and diverse. The influence of compartment (soil, midgut, or hindgut) on prokaryotic α- and β-diversity varied with location, suggesting that JB larval gut communities are at least partially shaped by the local environment even though the influence of compartment was more pronounced. Midgut microbiota contained transient communities that varied with the surrounding soil environment whereas hindgut microbiota was more conserved. Prokaryotic communities in the hindgut clustered separately from those of soil and midgut, which displayed greater interspersion in ordination space. Soil cation exchange capacity, organic matter, water holding capacity, and texture were moderately correlated (≥29%) with gut prokaryotic microbial composition, especially within the midgut. Findings suggest that microbial communities associated with the JB gut are partially a function of adaptation to local soil environments. However, conditions within each gut compartment appear to shape those communities in transit through the alimentary canal.

Understanding the Role of Humic Acids on Crop Performance and Soil Health

Humic acids (HA) are organic molecules that play essential roles in improving soil properties, plant growth, and agronomic parameters. The sources of HA include coal, lignite, soils, and organic materials. Humic acid-based products have been used in crop production in recent years to ensure the sustainability of agriculture production. Reviewed literature shows that HA can positively affect soil physical, chemical, and biological characteristics, including texture, structure, water holding capacity, cation exchange capacity, pH, soil carbon, enzymes, nitrogen cycling, and nutrient availability. This review highlights the relevance of HA on crop growth, plant hormone production, nutrient uptake and assimilation, yield, and protein synthesis. The effect of HA on soil properties and crops is influenced by the HA type, HA application rate, HA application mode, soil type, solubility, molecular size, and functional group. This review also identifies some knowledge gaps in HA studies. HA and its application rate have not been tested in field experiments under different crops in rotation, nitrogen fertilizer forms, sites and climatic conditions. Furthermore, HA chemical and molecular structures, their water and alkaline soluble fractions have not been tested under field experiments to evaluate their effects on crop yield, quality, and soil health. The relationship between soil-plant nutrient availability and plant nutrient uptake following HA application should also be further studied.

Plant-Mycorrhizal Fungi Interactions in Phytoremediation of Geogenic Contaminated Soils.

Soil contamination by geogenic contaminants (GCs) represents an imperative environmental problem. Various soil remediation methods have been successfully employed to ameliorate the health risks associated with GCs. Phytoremediation is considered as an eco-friendly and economical approach to revegetate GC-contaminated soils. However, it is a very slow process, as plants take a considerable amount of time to gain biomass. Also, the process is limited only to the depth and surface area of the root. Inoculation of arbuscular mycorrhizal fungi (AMF) with remediating plants has been found to accelerate the phytoremediation process by enhancing plant biomass and their metal accumulation potential while improving the soil physicochemical and biological characteristics. Progress in the field application is hindered by a lack of understanding of complex interactions between host plant and AMF that contribute to metal detoxification/(im)mobilization/accumulation/translocation. Thus, this review is an attempt to reveal the underlying mechanisms of plant-AMF interactions in phytoremediation.

Nano-biochar: A novel solution for sustainable agriculture and environmental remediation

Currently, the applications of biochar (BC) in agricultural practices and for environmental remediation purposes have demonstrated multifaceted advantages despite a few limitations. Nano-BC offers considerable opportunities especially for the remediation of hazardous contaminants as well as the improvement of crop productivity. Positive outcomes of nano-BC on soil physico-chemical and biological characteristics have indicated its suitability for agricultural applications. Nano-BC may effectively regulate the mobilization and sorption of important micro- and macro-nutrients, along with the hazardous contaminants including potentially toxic metals, pesticides, etc. Additionally, the sorption characteristics of nano-BC depends substantially on feedstock materials and pyrolysis temperatures. Nevertheless, the conducted investigations regarding nano-BC are in infant stages, requiring extensive field investigations. The nano-enhanced properties of BC on one hand dramatically improve its effectiveness and sustainability, on the other hand, there may be associated with toxicity development in diverse aquatic and/or terrestrial environments. Therefore, risk assessment on soil organisms and its indirect impact on human health is another area of concern linked with the field application of nano-BC. The present review delineates the potentiality of nano-BC as an emerging sorbent for sustainable agriculture and environmental applications.

Integrated production systems in a Plinthosol: greenhouse gas emissions and soil quality

Integrated systems (crops, livestock, and forest) are tools to avoid increases in greenhouse gas (GHG) emissions, such as CO2, CH4, and N2O. The objective of this study was to evaluate the GHG emissions and soil biological and chemical characteristics in an integrated system. The experiment was carried out in an area with crop-livestock-forest integration systems (CLFI), in Pindaré-Mirim, state of Maranhão, Brazil. The treatments consisted of maize (Zea mays) intercropped with forage (Urochloa brizantha cv. Marandú) between eucalyptus trees (Eucalyptus urophylla × Eucalyptus tereticornis) (S1); maize intercropped with forage (Megathyrsus maximus cv. Massai) (S2); and degraded pasture areas with no soil or forage management for more than 14 years (S3), which was used as reference treatment. The experiment was conducted with four replications of four trenches for soil collection or four static chambers for gas flow assessments. The GHG emissions were collected by static chambers and analyzed by gas chromatography, and the soil quality was determined by chemical analysis. The interaction between GHG emissions and soil characteristics was assessed for each treatment, using multivariate analysis and PCA. The soil of the degraded pasture presented higher GHG emissions. The integrated systems presented negative methane fluxes, which denote their mitigating effect on GHG emissions. The CLFI system with eucalyptus and maize intercropped with U. brizantha cv. Marandú was the best option to improve the soil biological characteristics and mitigate GHG emissions. Crop-livestock-forest integration with Eucalyptus, maize, and U. brizantha cv. Marandú is indicated to improve soil biological characteristics and mitigate GHG emissions in the Amazonian region of the state of Maranhão, Brazil.

Application of cotton straw biochar and compound Bacillus biofertilizer decrease the bioavailability of soil cd through impacting soil bacteria

BackgroundCd seriously threatens soil environment, remedying Cd in farmland and clearing the response of soil environment to modifiers in Cd-contaminated soils is necessary. In this study, the effects of cotton straw biochar and compound Bacillus biofertilizer used as modifiers on the biochemical properties, enzyme activity, and microbial diversity in Cd-contaminated soils (1, 2, and 4 mg·kg−1) were investigated.ResultsThe results showed that both cotton straw biochar and compound Bacillus biofertilizer could improve the soil chemical characteristics, including the increase of soil C/N ratio, electrical conductance (EC) and pH, and the most important decrease of soil available Cd content by 60.24% and 74.34%, respectively (P < 0.05). On the other hand, adding cotton straw biochar and compound Bacillus biofertilizer in Cd stressed soil also improved soil biological characteristics. Among them, cotton straw biochar mainly through increasing soil alkaline phosphatase activity and improve bacteria abundance, compound Bacillus biofertilizer by increasing soil invertase, alkaline phosphatase, catalase, and urease activity increased bacterial community diversity. On the whole, the decrease of soil available Cd was mainly caused by the increase of soil pH, C/N, urease and alkaline phosphatase activities, and the relative abundance of Acidobacteria and Proteobacteria.ConclusionsIn summary, the applications of cotton straw biochar and compound Bacillus biofertilizer could decrease soil available Cd concentration, increase soil bacterial community diversity and functions metabolism, and reduce the damage of Cd stress, compared with cotton straw biochar, compound Bacillus biofertilizer was more effective in immobilizing Cd and improving soil environmental quality.

Empower Innovations in Routine Soil Testing

Conventional soil tests are commonly used to assess single soil characteristics. Thus, many different tests are needed for a full soil fertility/soil quality assessment, which is laborious and expensive. New broad-spectrum soil tests offer the potential to assess many soil characteristics quickly, but often face challenges with calibration, validation, and acceptance in practice. Here, we describe the results of a 20 year research program aimed at overcoming the aforementioned challenges. A three-step approach was applied: (1) selecting and establishing two contrasting rapid broad-spectrum soil tests, (2) relating the results of these new tests to the results of conventional soil tests for a wide variety of soils, and (3) validating the results of the new soil tests through field trials and communicating the results. We selected Near Infrared Spectroscopy (NIRS) and multi-nutrient 0.01 M CaCl2 extraction (1:10 soil to solution ratio; w/v) as broad-spectrum techniques. NIRS was extensively calibrated and validated for the physical, chemical, and biological characteristics of soil. The CaCl2 extraction technique was extensively calibrated and validated for ‘plant available’ nutrients, often in combination with the results of NIRS. The results indicate that the accuracy of NIRS determinations is high for SOM, clay, SOC, ECEC, Ca-CEC, N-total, sand, and inorganic-C (R2 ≥ 0.95) and good for pH, Mg-CEC, and S-total (R2 ≥ 0.90). The combination of the CaCl2 extraction technique and NIRS gave results that related well (R2 &gt; 0.80) to the results of conventional soil tests for P, K, Mg, Na, Mn, Cu, Co, and pH. In conclusion, the three-step approach has revolutionized soil testing in The Netherlands. These two broad-spectrum soil tests have improved soil testing; have contributed to increased insights into the physical, chemical, and biological characteristics of soil; and have thereby led to more sustainable soil management and cropping systems.

Effects of Soil Quality on the Microbial Community Structure of Poorly Evolved Mediterranean Soils.

Physical and chemical alterations may affect the microbiota of soils as much as the specific presence of toxic pollutants. The relationship between the microbial diversity patterns and the soil quality in a Mediterranean context is studied here to test the hypothesis that soil microbiota is strongly affected by the level of anthropogenic soil alteration. Our aim has been to determine the potential effect of organic matter loss and associated changes in soil microbiota of poorly evolved Mediterranean soils (Leptosols and Regosols) suffering anthropogenic stress (i.e., cropping and deforestation). The studied soils correspond to nine different sites which differed in some features, such as the parent material, vegetation cover, or soil use and types. A methodological approach has been used that combines the classical physical and chemical study of soils with molecular characterization of the microbial assemblages using specific primers for Bacteria, Archaea and ectomycorrhizal Fungi. In agreement with previous studies within the region, physical, chemical and biological characteristics of soils varied notably depending on these factors. Microbial biomass, soil organic matter, and moisture, decreased in soils as deforestation increased, even in those partially degraded to substitution shrubland. Major differences were observed in the microbial community structure between the mollic and rendzic Leptosols found in forest soils, and the skeletic and dolomitic Leptosols in substitute shrublands, as well as with the skeletic and dolomitic Leptosols and calcaric Regosols in dry croplands. Forest soils displayed a higher microbial richness (OTU’s number) and biomass, as well as more stable and connected ecological networks. Here, we point out how human activities such as agriculture and other effects of deforestation led to changes in soil properties, thus affecting its quality driving changes in their microbial diversity and biomass patterns. Our findings demonstrate the potential risk that the replacement of forest areas may have in the conservation of the soil’s microbiota pool, both active and passive, which are basic for the maintenance of biogeochemical processes.

Quality of Soil in Gossaigaon Sub-Division and Its Impact on Environmental Degradation

People on Earth are under tremendous threat due to undesired changes in the physical, chemical and biological characteristics of water and soil. Due to increased human population, industrialization, use of unwanted amounts of fertilizers and man-made activities, water and soil is highly polluted with different harmful contaminants. Natural water and soil contaminates due to weathering of rocks and leaching of soils, mining processing etc. It is necessary that the quality of drinking water and soil should be checked at regular time interval, because due to use of contaminated drinking water, human population suffers from variety of water borne diseases. The study area, Gossaigaon sub-division of Kokrajhar district, Assam lies on the north bank of the Brahmaputra river and is slowly sloping towards south from the foothills of Bhutan upto an average height of 42 MSL. The tributaries of the Brahmaputra- Sankosh, Ripu, Dambra, Bura chara, Gadadhar, Gurufella, Madati, Hel, Gongea are flowing southward which have their sources in the Himalayas. In this paper an attempt has been made to assess the quality of soil of 10 different stations by considering the parameters like Colour, Temperature, pH value, Conductance, Alkalinity, Dissolved Oxygen, Hardness, TS, TDS, Chlorine, Fluorine, Sulphur, Nitrogen, Phosphorous, Iron, Calcium and Magnesium, Sodium, Potassium, Zinc, Nickel, Lead and Copper which have direct correlation with human health.

Effects of Crop Residues and Tillage Operations on Soil Quality Indices

Tillage and plant residues influence soil attributes and, consequently, soil quality. Therefore, suitable management and maintaining the stability of soil structure is important. This study was performed to evaluate the effects of tillage systems on soil quality during a 4-year crop rotation (wheat, canola, wheat and tomato) at the Agricultural Research Center of Khorasan Razavi province (Iran) from 2011 to 2015. The study was conducted as a randomized complete block design in a factorial arrangement with 3 replications. For this purpose, conventional tillage (CT), minimum tillage (MT) and no-tillage (NT) systems together with three rates of plant residues (0, 1,500, and 3,000 kg ha-1) were applied annually after harvesting. Soil quality was determined by using the integrated quality index (IQI) and Nemoro quality index (NQI) based on total data set (TDS) and minimum data set (MDS). In total, 23 physical, chemical, and biological soil characteristics were considered as TDS and 7 out of these were selected as MDS for use in the principal component analysis (PCA). Soil quality in different tillage treatments was determined and the most appropriate indices and effective characteristics for soil quality assessment were selected. Correlation coefficients between IQITDS and IQIMDS (r = 0.69) and between NQITDS and NQIMDS (r = 0.76) showed that NQI was a better indicator for assessing soil quality. The NQITDS provided a more accurate and comprehensive assessment of soil quality. However, using MDS reduced the cost and time with proper precision. Soil quality in MT and NT treatments was more desirable than the CT system, and the addition of plant residues improved the soil quality. According to the results of NQITDS, IQITDS, and IQIMDS, soil quality in the NT system with 3,000 kg ha-1 of plant residues and the MT system with 1,500 and 3,000 kg ha-1 of plant residues were more favorable than other soil tillage treatments. Soil characteristics that decreased soil quality in the conventional tillage were soil structure, macro and micronutrients, while in conservation tillage it was micronutrients, especially Zn.