Soil Health Parameters Research Articles

Nitrogen Fertilizer Effects on Microbial Respiration, Microbial Biomass, and Carbon Sequestration in a Mediterranean Grassland Ecosystem

Natural grasslands represent the second largest ecosystem in Turkey. However, the impact of varying nitrogen (N) fertilization rates on overall soil health indicators have not been reported in the country. A 2-year study was conducted in the Kahramnmaras Plateau region in Turkey to evaluate the impacts of seven N application rates [i.e., 0 (N0), 50 (N50), 100 (N100), 150 (N150), 200 (N200), 250 (N250), and 350 (N350) kg N ha−1] on physical, chemical, and biological parameters of soil health. Nitrogen addition decreased bulk density by 8–12%, and increased aggregate stability by 3–5% and EC up to 110%. Application of ≥ 100 kg N ha−1 increased soil porosity up to 6.7%. Soil pH and C:N ratios were not affected by N addition. The lowest plant available water occurred with the N0 and N50 treatments, decreasing around 24% and 17% compared to N300. Soil organic carbon, total nitrogen, and C and N stocks increased with increasing N addition. Application of N300 rates increased C stocks between 4 and 34%, and N stocks between 15 and 22% compared to all other treatments. Compared to control, N250 increased microbial biomass carbon by 349% and nitrogen by 250%. Microbial respiration in the N250 and the N300 treatments was 97% and 129% greater than control. Addition of N fertilization for a first time in a grassland ecosystem with a previous history of long-term overgrazing, even at low rates, positively impacted several parameters of soil health, a positive impact that could ensure a greater sustainability of these fragil systems over the long-term.

On-farm assessment of cover cropping effects on soil C and N pools, enzyme activities, and microbial community structure

AbstractIntroducing cover crops (CC) in annual cropping systems can promote nutrient cycling and improve soil health. However, impacts of CC on soil health indicators vary and depend on the duration of CC, cropping systems, and other environmental conditions. We performed an on-farm assessment of cover cropping impacts on soil health indicators including C and N pools, enzyme activities, and microbial community structure under different no-till maize-based cropping systems (maize (Zea mays L.)–soybean (Glycine max L.) [CS], CS-winter wheat (Triticum aestivum L.) [CSWw], and maize-oats (Avena sativa L.) [CO]). At five farms, fields with different durations of CC were compared to adjacent no CC (NCC) fields. In general, long-term CC enhanced the soil health parameters compared to NCC. Long-term (20-year) winter rye CC had higher water-extractable C and N content, enzyme activities (β-glucosidase (1.2 times greater), urease (5.5 times greater), acid (1.5 times greater) and alkaline (4 times greater) phosphatase, arylsulfatase (0.8 times greater) and fluorescein diacetate (FDA) (0.7 times greater)) and soil bacterial community abundance (1.2 times greater). Short-term (3–6 years) legume and grass CC mixtures increased β-glucosidase (0.9 times), acid (0.7 times) and alkaline (1.5 times) phosphatase, arylsulfatase (3 times), FDA (0.8 times) activities and total phospholipid fatty acid (1.6 times) concentration. However, short-term (3–6 years) winter rye, legume and brassica mixtures did not significantly alter soil microbial community structure. This study showed that implementation of CC for >6 years promoted C, N, S, and P cycling that are beneficial to soil health in maize-based cropping systems.

Response of soil health indicators to organic matter removal and compaction manipulations at six LTSP sites in the Western US

Forest soils control many ecosystem services that enable and support primary forest productivity. Therefore, maintaining the health of the soil is critical to sustainable forest management. The long-term soil productivity (LTSP) experiment was initiated to increase our understanding of how the soil responds to pulse harvest disturbance and experiments have enabled tracking of soil health parameters across many diverse forest types. The purpose of this study was to investigate the effect of organic matter (OM) removal and compaction manipulations on soil health indicators at six long-term LTSP sites (study durations 16–25 years) in the Pacific Northwest and Northern California, USA.We hypothesized that only the most severe OM removal treatment would exhibit decreased soil nutrient pools and reduced biological processes and compaction would have less detrimental impact on soil properties than OM removal treatments. We collected mineral soil samples at six LTSP sites and measured soil health properties related to nutrient pools (total soil carbon (C) and nitrogen (N), active C) and biological processes (C and N mineralization and enzymatic potential activity). Our results indicate that the effects of OM removal treatments are more prominent than those effects of compaction treatments. Despite variation in inherent site properties, we did find consistent evidence that severe harvesting treatments may disrupt mineral soil functions and remain detrimental to most soil health measurements, even after 16–25 years. In contrast, bole-only and whole-tree removal treatments did not have this effect on soil parameters indicating these practices may not incur such long-lasting or deleterious effects. These results indicate the importance of reducing soil disruption due to harvesting in order to maintain ecosystem functions and highlights the importance of understanding the range of impact harvesting practices may have on forest soil health.

In situ decomposition of crop residues using lignocellulolytic microbial consortia: a viable alternative to residue burning.

Open field burning of crop residue causes severe air pollution and greenhouse gas emission contributing to global warming. In order to seek an alternative, the current study was initiated to explore the prospective of lignocellulolytic microbes to expedite in situ decomposition of crop residues. Field trials on farmers' field were conducted in the state of Haryana and Maharashtra, to target the burning of rice and wheat residue and sugarcane trash, respectively. A comparative study among crop residue removal (CRR), crop residue burning (CRB) and in situ decomposition of crop residues (IND) revealed that IND of rice and wheat residues took 30days whereas IND of sugarcane trash took 45days. The decomposition status was assessed by determining the initial and final lignin to cellulose ratio which increased significantly from 0.23 to 0.25, 0.21 to 0.23 and 0.24 to 0.27 for rice, wheat residues and sugarcane trash, respectively. No yield loss was noticed in IND for both rice-wheat system and sugarcane-based system; rather IND showed relatively better crop yield as well as soil health parameters than CRB and CRR. Furthermore, the environmental impact assessment of residue burning indicated a substantial loss of nutrients (28-31, 23-25 and 51-77kgha-1 of N+P2O5+K2O for rice, wheat and sugarcane residue) as well as the emission of pollutants to the atmosphere. However, more field trials, as well as refinement of the technology, are warranted to validate and establish the positive potential of in situ decomposition of crop residue to make it a successful solution against the crop residue burning.

Effects of conservation agriculture on physicochemical soil health in 20 maize‐based trials in different agro‐ecological regions across Mexico

AbstractMaize (Zea mays L.) is Mexico's primary staple food, but the Country's degrading soils and climate variability limit its productivity. Conservation agriculture (CA), a management technique that combines minimal tillage, permanent soil cover, and crop diversification, could reduce soil degradation and help improve soil health. There is however a lack of information about the effects of CA on soil health in the diverse agroecological conditions in Mexico. This study reports results of a field trial network established to adapt CA to Mexico's diverse cropping systems and local conditions. Physicochemical soil health, also referred to as soil quality, was studied in 20 trials in agro‐ecologies ranging from handplanted traditional systems to intensive irrigated systems, initiated between 1991 and 2016. Soil in CA was compared to the local conventional practice (CP), which commonly involves tillage, residue removal, and continuous maize production. Across the sites, organic matter and nitrates were higher in the top (0–5 cm) layer of soil and soil aggregate stability was greater under CA than under CPs. For other soil health parameters, such as nutrient content, pH or penetration resistance, the effects of management varied widely across sites and soil types and most were determined more by local soil type than by management. CA increased maize yields at most sites and on average by 0.85 ± 1.80 t ha−1. Given the significant variation across agro‐ecologies, local adaptive trials are important to assess the effects of CA on soil health and fit the practice to local conditions.

Can yield, soil C and aggregation be improved under long-term conservation agriculture in the eastern Indo-Gangetic plain of India?

Deteriorating soil health, diminishing soil organic carbon (SOC), development of subsurface hard compact layer and declining system productivity are barriers to achieving sustainable production in the traditional rice–wheat cropping system (TA) in the eastern Indo‐Gangetic Plain of India. Conservation agriculture (CA), which favours minimum soil disturbance, crop residue retention and crop diversification could be a viable alternative to the TA to address most of those major problems. With that in mind, a long‐term experiment is being implemented at ICAR‐RCER, Patna, Bihar, India, with four treatments: (a) TA, (b) full CA (fCA) and (c and d) partial CA (pCA1 and pCA2), differing in crop establishment methods, cropping system and crop residue management in a randomized complete block design. Measurement of soil health parameters was carried out in the 11th year of the experiment. The results revealed a beneficial effect of CA and 46 and 40% increase in SOC concentration and stock, respectively, under fCA over TA in the 0–7.5‐cm soil layer. The effect of partial CA (pCA1 and pCA2) was variable, but an increasing trend was always observed under pCA compared to TA. There was an enrichment in SOC content of aggregates under CA irrespective of size class; however, no relation was found between SOC content and aggregate diameter. The contribution of macroaggregates to SOC stock was larger (36–66%) under CA in the 0–7.5‐cm soil layer. Adoption of CA improved the macroaggregate content, MWD and GMD of aggregates, and aggregation ratio. Soil macropore content was greater under fCA, whereas other parameters were similar among treatments. The impact of CA was mostly limited to 0–7.5 cm soil layer and a maximum up to 15 cm soil depth while evaluation until 60 cm soil depth was realized. The yield of rice in CA was comparable to or higher than in TA, whereas the system rice equivalent yield was always higher (38–53%) under CA than under the conventional practices. Therefore, a CA‐based cropping system must be encouraged, to increase SOC status, improve aggregation stability and, consequently, sustain or increase system productivity, in order to achieve food and nutritional security in the eastern Indo‐Gangetic Plain of India.Highlights Effects of long‐term conservation agriculture (CA) on soil C, aggregation and yield were evaluated.CA improved SOC concentration and stock by 46 and 40%, as well as macroaggregate SOC stock by 36–66%.Macro‐aggregation and mean weight diameter improved in CA but was mostly limited to a shallow soil depth.CA can be promoted for sustainability of a rice–wheat system due to higher productivity (38–53%).

In-Field Corn Residue Management for Bioenergy Use: Potential Effects on Selected Soil Health Parameters

In the U.S. biofuel industry is using corn (Zea mays L.) residue mix (CRM) consisting of corncob and stover for cellulosic ethanol and biogas production. The field storage method left different depths of CRM on the field after its removal, where negative effects on plant growth were observed. The objective of this study is to evaluate the CRM effect on selected soil health indicators. The field study conducted with four different depths of CRM, two tillage systems (no-till (NT) and chisel plow (CP), and three nitrogen (N) rates (0, 180, and 270 kg⋅N⋅ha−1) in a randomized complete block design with split-split arrangements in three replications in a continuous corn system from 2010 to 2012 at the Agronomy Research Farm at Iowa State University. The findings of this study showed a negative effect on soil organic carbon (SOC) change across all treatments at 0 - 15 cm (−0.35 to −0.03 Mg⋅ha−1⋅yr−1), while at 15 - 30 cm there was an increase in SOC rate (0.13 to 0.40 Mg⋅ha−1⋅yr−1) after 2-yr. In addition, soil aggregate-associated C of macro-aggregates decreased by 8%, while micro-aggregates increased by 2%. Soil microbial biomass carbon (MBC) across tillage and N rates for 2.5 & 7.5 CRM treatments increased by 14% in June to July 2011, while in 2012 increased by 9%. However, at the 15 cm soil depth, soil bulk density (ρb), soil penetration resistance (SPR), and soil pH showed no significant differences among CRM treatments. The findings of this study showed that in-field CRM management can affect certain soil health parameters in the short term.

Quality parameters of potato varieties (Solanum tuberosum L.) and soil health under peach-based agroforestry system in northern hills zone of Chhattisgarh

Quality parameters of potato varieties (Solanum tuberosum L.) and soil health under peach-based agroforestry system in northern hills zone of Chhattisgarh

The Role of Microbial Communities in Soil Formation and Soil Ecosystem Health

The concept of the microbial community (MC) current at the time of writing, its structure, and the theories that reflect and generalize the progress in MC research are considered. Contemporary knowledge is used as the basis to discuss the role and functions of microbial communities in the emergence and maintenance of what is traditionally referred to by the brief and capacious term “soil”, even though soil is essentially a product of the interaction of diverse biological communities and materials, and is a substance of infinite complexity and diversity, which can be regarded as an ecosystem; namely, the soil ecosystem (SE). A novel concept of soil health (SH), which integrates current knowledge of MCs and their functions, and can be used to understand their role in the soil ecosystem, is discussed. Methods for assessment of soil health parameters are briefly presented.

Assessment of soil health parameters and application of the sustainability index to fields under conservation agriculture for 3, 6, and 9 years in India

The effect of duration of conservation agriculture adoption on soil carbon dynamics and system sustainability was evaluated on farms of 30 villages in the Nilokheri block of Karnal district, Haryana, India. Sustainability was evaluated, in which a number of soil physical, chemical, and biological parameters were measured and a Sustainability Index (SI) was applied. Soil samples were collected from existing conservation agriculture (CA) and conventional tillage (CT) farms. Villages under CA practices were subdivided as CA3, CA6, and CA9 based on the number of years of CA practice adoption. Results showed that bulk density (BD) of 0-15 cm soil depth was 7% greater in CA3 plots, whereas in CA6 and CA9 plots BD values were only 2% and 3% higher than CT. Soil organic carbon (SOC) in 0-15 cm soil depth was found to be greater by 16.32% in CA3 than CT plots, whereas SOC was higher by 38.77% and 61.22% in CA6 and CA9. In CA, for the 0–15 and 15-30 cm soil depths, labile pools were 36% and 22% greater than CT, respectively. For both the soil depths in CA, the recalcitrant pool was 12% and 9% more than CT, respectively. Microbial biomass carbon (MBC) values of the 0-15 cm soil depth were increased over CT by 18.57%, 47.08%, and 71.5% for CA3, CA6, and CA9 respectively. In CA plots, the SI of 0-15 cm soil depth ranged between cumulative ratings (CR) of 18–21, which indicates that CA practice is “sustainable” for both soil depths. For CT, CR ranged from 25 to 30 for both soil depths resulting in a SI of “sustainability with high input”. Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) scores showed that SOC had the maximum weight (0.96) towards sustainability, giving it a rank of 1. Effective rooting depth (ERD), BD, texture, and wilting point (WP) ranked 2, 3, 4 and 5, respectively, indicating their corresponding weight of contribution towards the SI. Farmers in the Karnal district should be encouraged to adopt CA practices as they can increase SOC and move the systems from “sustainable with high input” to “sustainable”.

Impact of levels of residue retention on soil properties under conservation agriculture in Vertisols of central India

ABSTRACT Residue management is one of the most difficult tasks in the modern-mechanized agriculture with the intensification of cropping systems, which leads to reduced sowing window between two crops and farmers prefer in-situ burning of crop residues. Therefore, the present study was conducted to assess the effect of zero tillage (ZT) based residue management on soil health parameters in maize (Zea mays L.)–chickpea (Cicer arietinum L.) rotation in black soils of central India. After 4 years of study, the soil bulk density was reduced by 3.0–10.2% and volumetric moisture content was improved by 10.2–19.3% at 0–10 cm soil depth in ZT with residue over conventional tillage (CT). The soil organic carbon and labile carbon were increased by 13.6–61.7% and 6.0–22.0%, respectively, at 0–10 cm soil depths. Similarly, ZT with residue increased the KMnO4-N, Olsen-P and NH4OAc-K, and total fungal and actinomycetes density in surface soil as compared to CT. Thus, our study advocates that ZT with residue retention (1.8–5.4 Mg ha–1 maize and 0.8–2.4 Mg ha–1 chickpea residue) should be implemented for sustainable soil health in Vertisols (Typic Haplustert) of central India and other similar agro-ecological systems.

The effects of dryland cropping system intensity on soil function and associated changes in macrofauna communities

AbstractCrop production in water‐limited environments may be enhanced through improved soil function by facilitating precipitation capture and erosion control. Soil macrofauna are known to support improved soil structure and water dynamics through ecosystem engineering activities, and their populations can be influenced by management. We examined the effect of bare summer fallow frequency on soil macrofauna communities and soil physical properties in a long‐term (32‐yr) dryland no‐till agroecosystem experiment at two sites in eastern Colorado, USA. Treatments represented a gradient of fallow frequency and organic matter inputs, which included wheat (Triticum aestivum L.)–fallow, wheat–corn (Zea mays L.)–fallow, and continuously cropped with no planned summer fallow. The design also included a perennial grass treatment with minimal management consisting of six native grasses. We observed links between soil macrofauna and soil functional metrics, particularly related to soil aggregation and water infiltration. There was a trend toward higher macrofauna populations and soil function with increased cropping system intensity, and perennial grass outperformed the cropped treatments significantly for most soil health parameters. Multivariate analyses revealed that different treatments support relatively distinct macrofauna communities. Our results suggest that soil macrofauna populations may be important facilitators of soil structure and associated water dynamics in dryland no‐till agroecosystems and respond positively to reduced fallow and higher organic inputs.

Nutrient management options modulating soil physico-chemical and biological properties under direct-seeded rice-based cropping systems

ABSTRACT To achieve higher system productivity and better soil health under rice‒based cropping systems, this study was conducted to ascertain the best agricultural and nutrient management strategies. The study involved four cropping systems (CS) comprising direct seeded basmati rice (DSBR)‒wheat (CS1), DSBR‒wheat‒greengram (CS2), DSBR‒cabbage‒greengram (CS3) and DSBR‒cabbage‒onion (CS4) under different nutrient management strategies (NMS) comprising of control (NS0), 100% recommended dose of N, P and K fertilizers (RDF-NPK) (NS1), 50% RDF + 25% recommended dose of nitrogen (RDN) through leaf compost (LC) + biofertilizer (NS2), 50% RDF + 25% RDN through vermicompost (VC) + biofertilizer (NS3) and was carried out for two consecutive years. At the end of study, soil carbon fractions, bulk density and water stable aggregates were significantly (p < 0.05) higher under integrated NMS as compared to control and RDF alone. Soil biological parameters such as dehydrogenase, alkaline phosphatase and microbial biomass carbon increased significantly (p < 0.05) in all three seasons (rainy, winter and summer) under integrated NMS (NS2 and NS3) plots, as compared to NS0 and NS1. Inclusion of greengram in rice–based cropping systems and combined use of inorganic and organic nutrient sources resulted in positive influence on soil health parameters and sustaining system productivity.

Soil Health Impacts of Rubber Farming: The Implication of Conversion of Degraded Natural Forests into Monoculture Plantations

High revenues from rubber latex exports have led to a rapid expansion of commercial rubber cultivation and, as a consequence, the conversion of different land use types (e.g., natural forests) into rubber plantations, which may lead to a decrease in soil health. In this study in Quang Tri Province, Vietnam, we determined: (1) the variation of soil health parameters along a chronosequence of rubber tree stands and natural forests and (2) the relationships and potential feedback between vegetation types, vegetation structures and soil health. Our results revealed that: (1) soil health was higher in natural forests than in rubber plantations with a higher values in higher biomass forests; (2) soil health was lower in younger rubber plantations; (3) soil health depends on vegetation structure (with significantly positive relationships found between soil health and canopy cover, litter biomass, dry litter cover and ground vegetation cover). This study highlights the need for more rigorous land management practices and land use conversion policies in order to ensure the long-term conservation of soil health in rubber plantations.

Soil microbial community, enzyme activity, C and N stocks and soil aggregation as affected by land use and soil depth in a tropical climate region of Brazil.

The impact of agricultural land-use on soil microbial community composition and enzyme activity has not been extensively investigated in Ultisols. We investigated soil health parameters by analyzing phospholipid fatty acids (PLFAs), extracellular enzyme activity, C and N stocks, and soil structure. Four land uses were established in a tropical climate region of Brazil: native Cerrado (savanna), monoculture pasture [Urochloa brizantha (Hochst. Ex A. Rich.) R. Webster 'Marandu'], an integrated crop-livestock system (ICLS), and maize (Zea mays)-fallow in a no-tillage system. Soil microbial biomass was 40% higher in the native Cerrado than in the monoculture pasture, ICLS, and no-tillage maize. Soil organic carbon was positively correlated with microbial community composition (MB; gram-; AC; AMF; Fungi; F: B ratio) and enzyme activity (bG, AP, NAG). Large macroaggregates were positively correlated with bG, AP, and AMF. In summary, the native Cerrado had a higher level of carbon at the soil surface and greater soil structure with increased microbial biomass, gram+ bacteria, AMF, fungi, and F:B ratio in a tropical region of Brazil. However, bG and AP enzyme activities were lower in the ICLS and no-till maize at the soil surface (0-5cm) compared to the native Cerrado. The conversion of native Cerrado to agricultural systems shifted the soil microbial community composition, enzyme activity, C and N, and soil structure of this sandy soil of the Brazilian Cerrado.

Influence of nanosilicon dioxide along with bioinoculants on Zea mays and its rhizospheric soil.

Application of nanocompounds along with plant growth promoting rhizobacteria is gaining attention to improve agriculture productivity. In the present study, attempts have been made to observe the impact of nanosilicon dioxide (10mg L-1) and two plant growth promotory bacteria (PC1-MK106029) and (PC4-MK106024) on the growth of Zea mays and its rhizosphere in a pot experiment. Combined treatment of bacterial consortium and nanosilicon dioxide enhanced average plant height and number of leaves over control in maize after 30days of sowing. Similarly, percent enhancement of total chlorophyll, carotenoid, sugar, soluble protein, phenol and flavonoid content was 106, 307,116, 57, 159 and 132 respectively over control in maize leaves in the same treatment. Treated plants showed significant increase of 29.4 and 73.9% in catalase and peroxidase activities respectively over control. Physicochemical and biochemical parameters of soil health were also improved in the soil treated with PGPR and nanosilicon dioxide. An increase of 1.5-2 fold in the activities of fluorescein diacetate, dehydrogenase and alkaline phosphatase was observed in the treated soil as compared to control. Our results revealed that inoculation of beneficial microorganisms in combination with nanosilicon dioxide is an effective method for enhancing physicochemical and biochemical parameters of the soil which are responsible for increased plant growth and soil fertility by increasing enzyme activities of microbes. This approach presents an alternative to pesticides, fertilizers and GM crops to enhance crop productivity.

Coordination of Mesorhizobium sp. and endophytic bacteria as elicitor of biocontrol against Fusarium wilt in chickpea

Antagonistic Plant growth promoting rhizobacteria can contribute to disease management by induction of host defenses and biological control of pathogens. The present study was thus planned to develop a bio-inoculant with the ability to promote plant growth and reduce disease incidence due to Fusarium oxysporum sp. ciceris in chickpea. Isolates of Mesorhizobium sp. (6) and endophytic bacteria (5) were screened as potential antagonists exhibiting 50–93.7% growth inhibition of Fusarium wilt (in vitro). Selected Mesorhizobium sp. and endophytic bacteria were assessed for their compatibility to develop dual combinations with no mutual inhibition. Dual inoculants significantly enhanced in vitro plant growth promoting traits viz., Indole Acetic Acid, siderophores, phosphate solubilization and 1-aminocyclopropane-1-carboxylate-deaminase enzyme activity. Dual mesorhizobia and endophytic bio-inoculants (able to grow with recommended fungicide captan @ 3 g/kg seed) were further assessed in wilt-sick field conditions for growth, symbiosis, soil health, yield and bio-control parameters in two chickpea varieties (PBG-7 and PBG-1). Seed priming with dual inoculants significantly enhanced growth, symbiosis, soil quality parameters and antioxidant enzymes viz., catalase, peroxidase and total phenols over control. Dual bio-inoculant LGR2 + LCNE8 improved the grain yield by 6.5% over captan as the control. These results suggest that bio-inoculants of Mesorhizobium sp. and endophytic bacteria under a competitive environment can be explored as bio-fertilizers/bio-protectants for improving productivity and suppression of Fusarium wilt in chickpea.

Role of textile effluent fertilization with biosurfactant to sustain soil quality and nutrient availability

The textile industry is one of the world's most pollution generating industries, and management of its toxic effluent has become a global issue. However, the use of textile effluent as source of nutrients can be a viable option due to the presence of some essential minerals, although the presence of several toxic elements can deteriorate soil health. Therefore, experiments were conducted to identify the potential of textile effluent fertilization together with biosurfactant amendment to increase the soil health and nutrient status for agricultural sustainability. In this study, soil fertilized with different concentrations of textile effluent treatments (i.e. T1A, T2A and T3A) was treated with two different concentrations of biosurfactants to accurately appraise the suitability of a set of soil quality parameters including, physical, chemical, biochemical, and biological activities. A thorough analysis of all soil health parameters was undertaken before sowing the seeds and after cultivation of either Triticum aestivum (cv. LOK-1 and GW-496) or Capsicum annum (cv. GVC-101 and GVC-121). The results indicated that lower concentrations of textile effluent are a good source of nutrients while biosurfactants served as good solubilizers of metals and made it more available at the higher effluent concentration (T2C). Under these conditions, not only did fertilizers significantly increased, but also the microbial population as well as the enzymatic activity of soil was enhanced. Lower concentrations of micronutrients in the soil after crop cultivation is attributed to the higher level of their availability to the plants during their growth and development. This study provides new insight into the biosurfactants application to enhance soil micronutrients availability and increase crop productivity using textile effluents as a source of nutrients.

Impacts of metallic nanoparticles and transformed products on soil health

Widespread usage of nanotechnology has increased the release of metallic nanoparticles (MNPs) into the environment, which are mostly engineered. Agricultural soil is one of the most important sinks for MNPs. While numerous studies have focused on understanding the phytotoxicity of MNPs, and the extent and pathways of their accumulation in plants, the impacts of MNPs on soil health are only gaining attention recently. A comprehensive review summarizing the interactions of MNPs with soil is yet available. This review aims to fill the gap by evaluating the impacts of common MNPs on soil properties. Specifically, we examined the effects of MNPs on soil physical properties, the availability of plant nutrients and heavy metals from the perspective of food safety and security, as well as soil microbial ecology and microbial community associated with nutrient and carbon cycling. We underscored the impacts of environmental transformation of MNPs on soil health. Compared with soil physical and chemical properties, biological parameters of soil health are more susceptible to the impact of MNPs. Overall, the effects of MNPs and their transformed products on soil health vary with soils, MNPs, and exposure duration and dosage.

Reusing oil and gas produced water for agricultural irrigation: Effects on soil health and the soil microbiome

Produced water (PW) is a major waste-product of oil and gas production that some consider a viable agricultural irrigation water source. However, the presence of petroleum hydrocarbons, toxic metals and potentially high salinity of PW may be deleterious for soil health. Thus, we irrigated wheat with minimally treated PW to investigate effects on soil health, wheat growth, and the soil microbiome. Irrigation treatments included control irrigation water (IW), 1% and 5% PW dilutions (1% PW, 5% PW), and a saltwater solution with salinity equivalent to the 5% PW dilution (SW). Wheat was irrigated three times a week, for a total of 2.1 L per pot by harvest. During wheat growth, we measured plant physiological parameters, soil electrical conductivity, as well as profiled soil microbial diversity by performing 16S ribosomal ribonucleic acid (rRNA) gene analysis. Soil health parameters were measured after harvest, including chemical, biological, physical, and nutrient properties that were used to calculate an overall soil health index (SQI). SQI analysis revealed that the SW and 5% PW treatments had significantly reduced soil health as compared to the control. Furthermore, the 16S rRNA gene analysis showed that the microbial community membership and structure was significantly different between irrigation treatments, highlighting shifts in the soil microbiome which may impact soil biochemical cycling. Both the SW- and 5% PW-treated wheat had reduced yields as compared to the control. Our results indicate that irrigating wheat with minimally treated PW may result in yield decreases, as well as reducing both overall soil health and soil microbial community diversity. Future large-scale field studies are needed to determine the long-term soil health effects of PW on different soil types and crops.