Soil Nutrient Enrichment Research Articles

Biochar as a strategy to manage stem rot disease of groundnut incited by Sclerotium rolfsii

Due to the pathogen’s ability to survive in the soil for longer durations, soil-borne diseases are often difficult to control. This study investigates the multifaceted impacts of biochar on the management of stem rot disease in groundnut and its influence on soil properties and microbial communities. The effects of biochar at different concentrations, such as 0%, 1%, 3%, and 5% on groundnut stem rot disease incited by Sclerotium rolfsii were evaluated thoroughly. Under laboratory conditions, biochar exhibited no direct inhibitory effects on S. rolfsii at varying concentrations but revealed an indirect suppression of sclerotial body production, suggesting a concentration-dependent influence on pathogen resting structures. Further, it was observed that biochar treatments effectively delayed symptom onset and reduced disease progression in groundnut plants, with significant variation observed among genotypes and biochar concentrations. Notably, interactions involving genotypes ICGV 171002 and ICGV 181035 with BC2 + Sr (3% conc. of biochar + S. rolfsii) and BC3 + Sr (5% conc. of biochar + S. rolfsii) treatments showed superior efficacy in disease reduction under controlled conditions. Field evaluations confirmed these findings, highlighting genotype-specific responses to biochar treatments. However, no significant difference was observed between BC2 + Sr (3%) and BC3 + Sr (5%) treatments in managing stem rot disease compared to controls. Biochar application significantly increased soil nutrient levels, including nitrogen, phosphorus, and potassium, and increased soil organic matter content, EC, pH, emphasizing its potential to improve soil fertility. Overall, these findings highlight the potential benefits of biochar for sustainable agriculture through disease management, soil nutrient enrichment, and microbial modulation, warranting further investigation into optimal application strategies across different agricultural contexts.

SOIL NUTRIENT ENRICHMENT IN THE INDIAN SUBCONTINENT WITH MATHEMATICAL INTERPRETATIONS: MISTRAL ALGORITHM

Soil consists of particulate matter like loose earth, minerals, and essential nutrients, all required to cultivate botanical species carefully. The varying presence of soil attributes like alkalinity, humus, topsoil, Farm Yard Manure (FYM), organic matter, and Phyto-nutrients is an active area of research. Macro-nutrients and micro-nutrients present in soil overlook the amount of water consumed or produced as part of an agricultural process. Specific standard measures of soil attributes have been considered in past research. Forestation is also necessary to sustain agricultural land by providing rain-fed irrigation while ensuring low soil erosion levels. It is ascertained that a certain amount of the earth’s well-being is linked to crop cycles and agricultural production levels. In this research work, an algorithm called MISTRAL (Soil nutrient enrichment in the Indian Subcontinent with Mathematical Interpretations) is presented, which can be utilized to enrich soil nutrients and soil well-being levels leading to an overall increase in the net agricultural output in the Indian subcontinent.

Fertile island variation depends on species differences in the deserts of Northwest China

Desert ecosystems are extremely arid and nutrient poor. “Fertile islands” formed by mobile sand dunes and perennial desert plants are crucial for maintaining the structure and function of these ecosystems. However, the impacts of fertile islands created by different plant species at various spatial locations on soil physicochemical properties such as soil nutrients remain unclear. This study focused on the legumes (Astragalus flexus Fisch.), and non-legume (Eremurus inderiensis (M. Bieb.) Regel) plants widely distributed in the Gurbantunggut Desert in northwestern China. We analyzed the soil physicochemical properties of fertile islands formed by these two desert plants at different horizontal distances (0–140 cm) and vertical depths (0–15 cm). In addition, we investigated the relationship between plant functional shape and soil physicochemical properties. This study yielded the following results. (1) The fertile island was observed within the 0–140 cm soil layer of Astragalus flexus and Eremurus inderiensis and gradually weakened with increasing horizontal distance and soil depth. (2) The two plants had different nutrient enrichment rates. Eremurus inderiensis had higher TP and AK enrichment rates than Astragalus flexus. In contrast, Astragalus flexus demonstrated significantly higher enrichment rates for TN, NH4+-N, and NO3−-N, especially NH4+-N, highlighting the ability of legumes to fix and uptake N. (3) The correlation between plant height, crown width, and soil nutrient enrichment rate was more significant for Eremurus inderiensis than for Astragalus flexus. In general, both plants formed the fertile islands that gradually decreased with the increasing distance (both horizontal and vertical). Different plants exhibited varying abilities to enrich soil nutrients and form fertile islands, which presented a clear species effect. Therefore, protecting the diversity of desert plants to form stable fertile islands could be crucial for maintaining the soil fertility in desert ecosystems.

Arbuscular mycorrhizal communities respond to nutrient enrichment and plant invasion in phosphorus‐limited eucalypt woodlands

Abstract Arbuscular mycorrhizal fungi (AMF) facilitate ecosystem functioning through provision of plant hosts with phosphorus (P), especially where soil P is limiting. Changes in soil nutrient regimes are expected to impact AMF, but the direction of the impact may depend on context. We predicted that nitrogen (N)‐only enrichment promotes plant invasions and exacerbates their P limitation, increasing the utility of AMF and promoting AMF diversity. We expected that enrichment with N, P and other nutrients similarly promotes plant invasions, but decreases the benefit and diversity of AMF because P is readily available for both native and exotic plants. We tested these hypotheses in eucalypt woodlands of south‐western Australia, that occur on soils naturally low in P. We evaluated AMF communities within three modified ground‐layer states representing different types of nutrient enrichment and associated plant invasions. We compared these modified states to near‐natural reference woodlands. AMF richness varied across ground‐layer states. The moderately invaded/N‐enriched state showed the highest AMF richness, while the highly invaded/NP‐enriched state showed the lowest AMF richness. The reference state and the weakly invaded/enriched state were intermediate. AMF richness and colonisation were higher in roots of exotic than native plant species. AMF community composition differed among ground‐layer states, with the highly invaded/NP‐enriched state being most distinct. Distinctions among states were often driven by family‐level patterns. Reference and moderately invaded/N‐enriched states each supported distinct groups of zero‐radius operational taxonomic units (zOTUs) in Acaulosporaceae, Gigasporaceae and Glomeraceae, whereas Gigasporaceae and Glomeraceae were nearly absent from the highly invaded/NP‐enriched state. Further, Diversisporaceae and Glomeraceae were most diverse in the moderately invaded/N‐enriched state. Synthesis. Both the nature of soil nutrient enrichment and plant provenance matter for AMF. N‐only enrichment of low‐P soils increased AMF richness, likely due to the introduction of AMF‐dependent exotic plant species and exacerbation of their P limitation. In contrast, multi‐nutrient enrichment, decreased AMF richness potentially due to a decrease in host dependence on AMF, regardless of host provenance. The changes in AMF community composition with nutrient enrichment and plant invasion warrant further research into predicting the functional implications of these changes.

Effects of ant mounds construction on the carbon cycle in a drained peatland, Northeast China

Acting as ecosystem engineers, ant activities are significantly crucial in altering carbon (C) cycles by modifying the energy flows and nutrient cycles in soils. However, how ant mound constructions reshape soil organic carbon (SOC) pool heterogeneity and stability remains elusive. In this study, we compared differences in soil properties, vegetation biomass, greenhouse gas (GHG) emission, and molecular composition of SOC between ant mounds and nearby soils from a drained peatland, intending to decipher factors that govern carbon dynamics during ant excavates. Results indicated that ant mound construction simultaneously caused a decrease in SOC contents and an increase in nutrient level (total nitrogen and phosphorus), dissolved organic carbon (DOC), and its proportion to SOC (DOC/SOC) dramatically. The proportions of pyrolytic products derived from lignin, phenol, and aromatics decreased significantly from 31.70 % in nearby soils to 27.43 % in ant mounds. However, no significant difference in iron-bound organic carbon (OC-Fe) was found between ant mounds and nearby soils (p > 0.05). Ant mound building greatly accelerated SOC mineralization, with average CO2 emission fluxes 1–2 times higher than that in nearby soils. Notably, CH4 emissions from ant mounds was negative, meaning ant mounds acted as CH4 sinks. Meanwhile, net CH4 flux emission into the atmosphere from nearby soils were positive. Both plant biomass and SOC density (SOCd) in ant mounds were considerably lower than those observed in nearby soils. The structural equation model indicated that soil nutrient enrichment in ant mounds indirectly stimulated SOC decomposition by stimulating microbial abundance. Still, ant mounds construction had direct positive effects on labile carbon components accumulation and posed negative effects on resistant SOC compounds. Moreover, redundancy analysis and variation partitioning analysis confirmed that SOCd decline in ant mounds was primarily attributed to reduced soil moisture and elevated microbial abundance. The conceptual model implied that ants could effectively strengthen SOC content heterogeneity at the microscales, characterized by lower SOC storage and stability, and higher CO2 emission than those in nearby soils.

Artificial night‐time lighting and nutrient enrichment synergistically favour the growth of alien ornamental plant species over co‐occurring native plants

Abstract Insights into ecological drivers of alien plant invasions can be gained through comparative studies of growth and fecundity of invasive alien plants versus those of co‐occurring non‐invasive alien plants and native plants across environmental conditions in common garden settings. Habitats that harbour alien plant species in many ecosystems globally are presently experiencing light pollution resulting from artificial light at night (ALAN) and increased rates of nutrient enrichment of the soil. However, the potential interactive effects of ALAN and nutrient enrichment on invasiveness of alien plant species remain unknown. Here, we performed a common‐garden experiment to test the interactive effects of ALAN and soil nutrient enrichment on the growth of a random set of ten alien (five invasive and five non‐invasive naturalized) and seven co‐occurring native ornamental plant species that are commonly cultivated within urban and peri‐urban areas of Nairobi city in Kenya. We predicted that a simultaneous increase in photoperiod via ALAN and nutrient enrichment will favour growth of invasive alien plant species over that of non‐invasive alien and native plant species. We grew the 17 plant species under natural daylight (ALAN−) versus natural daylight followed by ALAN (ALAN+) and fully crossed with two levels of nutrient enrichment (low vs. high) and competition (competition vs. no‐competition against a native plant Ocimum gratissimum) treatments. Under simultaneous high‐nutrient and no‐competition treatments, ALAN enhanced mean total biomass of invasive and non‐invasive naturalized alien species by 61.1% and 131.4%, respectively but decreased that of native plant species by 34%. In contrast, under simultaneous high‐nutrient and competition treatments, ALAN enhanced mean total biomass of invasive alien plant species by 68.6% and that of non‐invasive naturalized alien species by 51.9% and native species by 35.4%. High‐nutrient treatment enhanced flower formation more strongly in invasive and non‐invasive naturalized alien plants than in native plants. The invasive and non‐invasive naturalized alien species grew taller than native species across the light, nutrient, and competition treatments. Synthesis: The present findings suggest that light pollution and nutrient enrichment may jointly confer growth advantage to invasive alien plant species over that of co‐occurring native plant species and enhance invasiveness of alien plant species.

Agroforestry systems in the mid-hills of the north-western Himalaya: A sustainable pathway to improved soil health and climate resilience

Identifying the new tree crop combinations plays an important function in transforming the low input agriculture into land units with high economic returns, increasing carbon (C) sink and nutrients storage capacity, and acting as a panacea to achieve Sustainability Development Goals (SDGs). The present study aims to evaluate various tree-crop combinations for (i) biomass production, (ii) carbon accumulation, and (iii) soil nutrient enrichment of traditional and commercially evolved eight agroforestry systems (AFSs), including agri-silvi-horticulture system, agri-silviculture system, silvi-pasture, fruit tree, fodder tree, bamboo, melia and poplar based AFSs with sole cropping system in the mid-hill zone of the north-western Himalaya. The results demonstrated that poplar based AFS accumulated a higher amount of biomass (130.87 Mg ha−1) and carbon (65.44 Mg ha−1) closely followed by melia-based AFS. The C stored in leaf litter was higher (0.66 Mg ha−1) in poplar-based AFS, however, soil C stock was maximum (114.69 Mg ha−1) under bamboo-based AFS. Overall, the Melia based AFS exhibited a higher rate of carbon dioxide mitigation (19.30 Mg ha−1 yr−1) and C-sequestration (5.26 Mg ha−1 yr−1) than other studied AFSs. Moreover, soil macro-nutrients (available N, P, K, S and Ca) were maximum under bamboo-based AFS, on the other hand, the fruit-based AFS had the higher concentrations of micro-nutrients i.e., Cu (3.05), Fe (31.10 mg g−1) and Mn (17.31 mg g−1). The soil microbial counts were higher in poplar-based AFS, whereas, the soil quality index improved significantly under bamboo based and fruit tree based AFSs. Hence, it can be concluded that the experimentally evolved AFSs represent an effective approach for boosting C-sequestration, soil fertility, regenerating the soil and sustainability of hill agriculture in the north-western Himalayas over traditional AFSs and sole cropping.

Glomalin-related soil proteins respond negatively to fertilization and fungicide application in China's arid grassland

Glomalin-related soil protein (GRSP) are a glycoprotein mainly produced by arbuscular mycorrhizal (AM) fungi. GRSP are deposited in the soil after being released from AM fungal hyphae, and they are believed to improve soil health and carbon (C) storage. However, it is unclear how fertilizer and mycorrhiza suppression affect the content of easily extractable (EE-GRSP) and total glomalin-related protein (T-GRSP) in arid grassland soil. We conducted a 3-yr in situ study to determine the main and interactive effects of nitrogen (N), phosphorus (P), and fungicide (benomyl) addition on EE-GRSP and T-GRSP content in the soil of desert steppe in Northwest China. To further explore the mechanisms influencing GRSP content, the plant community, soil fertility and the AM fungal traits were also identified. Following 3 years of fertilizer and fungicide application, P addition had a negative influence on EE-GRSP content (−12.50%), whereas N addition had no significant effect. Fungicide application reduced EE-GRSP (−18.47%) and T-GRSP content (−18.36%) regardless of N and P addition. By altering the extraradical hyphal length of AM fungi, P and fungicide application decreased the EE-GRSP and T-GRSP content without affecting the vegetation or soil characteristics. Overall, this study provides insights into the dynamics of GRSP in response to soil nutrient enrichment and fungicide application in a resource-limited grassland ecosystem.

Enrichment of soil nutrients and salt ions with different salinities under Tamarix chinensis shrubs in the Yellow River Delta

In this study, we investigated the characteristics of soil salt ions and soil nutrients at different locations around Tamarix chinensis and with different salinity levels on a coastal beach of the Yellow River Delta. The findings help clarify the effects of T. chinensis growth on the enrichment rates of soil nutrients and salt ions. T. chinensis shrublands with low salinity (0.25 %), moderate salinity (0.51 %), and high salinity (1.03 %) on the coastal beach of the Yellow River Delta were studied. The available nitrogen (AN), available phosphorus (AP), available potassium (AK), total organic carbon (SOC), and levels of eight major salt ions were measured and analyzed at different locations around the T. chinensis plants. The results showed that soil salinity significantly affected the contents of soil nutrients and salt ions. Soil salinity, soil location, and their interaction had significant effects on the following contents of soil: AN, AP, SOC, K+, Na+, Cl−, and SO42− (P < 0.01). The soil nutrient contents differed significantly at different locations around a T. chinensis plant (P < 0.05), and the highest nutrient content was found under the center of the canopy, followed by that at the roots. The soil nutrient enrichment rates under different salinity levels were all greater than 1, and T. chinensis shrubs had the strongest enrichment capacity for SOC. The enrichment rates of AN, AK, and SOC under the center and edge of the canopy of T. chinensis were higher under moderate salinity than under low or high salinity; thus, T. chinensis produced a stronger “fertile island” effect under moderate salinity. Soil salinity and location had a significant impact on the enrichment of salt ions. Under low and moderate salinity, the enrichment rates of soil K+, Ca2+, and Mg2+ were all greater than 1, forming “salt islands,” whereas under high salinity, “salt basin” formed. In soil at different locations and with different salinity levels, T. chinensis produced a “salt basin” effect on Na+ and Cl− but a “salt island” effect on soil SO42− and HCO3–. The Na+ enrichment rates under low and moderate salinity were significantly lower than those under high salinity. In summary, T. chinensis shrubs under different salinity levels in the coastal beaches all exhibited the fertile island effect, which was most significant under moderate salinity. In the saline–alkali land on coastal beaches mainly containing Na+ and Cl−, T. chinensis had a salt basin effect on both ions; thus, T. chinensis shrubs significantly reduced the overall soil salinity.

Negative effects of phosphorus addition outweigh effects of arbuscular mycorrhizal fungi and nitrogen addition on grassland temporal stability in the eastern Eurasian desert steppe.

The temporal stability of grassland plant communities is substantially affected by soil nutrient enrichment. However, the potential main and interactive effects of arbuscular mycorrhizal fungi (AMF) and soil nitrogen (N) and phosphorus (P) enrichment on the stability of plant productivity have not yet been clarified. We combined a three-year in situ field experiment to assess the impacts of soil fertilization and AMF on the stability of plant productivity. P addition decreased the stability of plant productivity by increasing the standard deviation relative to the mean of plant productivity. However, compared to species richness, the stability of C3 grasses and other functional groups asynchrony were the most important drivers changing the stability of plant productivity. The negative impacts of P addition overrode the impacts of AMF on the stability of plant productivity. Overall, our study suggests the importance of soil nutrient availability over AMF in terms of shaping the stability of plant productivity. Our results also suggest that three-year anthropogenic soil nutrient enrichment could reduce the stability of plant communities in grassland regardless of AMF in the P-limited grassland ecosystem.

The implication from six years of field experiment: the aging process induced lower rice production even with a high amount of biochar application

The single high-dose application of biochar to increase rice yield has been well reported. However, limited information is available about the long-term effects of increasing rice yield and soil fertility. This study was designed to perform a 6-year field experiment to unveil the rice yield with time due to various biochar application strategies. Moreover, an alternative strategy of the Annual Low dose biochar application (AL, 8 × 35% = 2.8 t ha−1) was also conducted to make a comparison with the High Single dose (HS, 22.5 t ha−1), and annual Rice Straw (RS, 8 t ha−1) amendment to investigate the effects on annual rice yield attributes and soil nutrient concentrations. Results showed that the rice yield in AL with a lower biochar application exceeded that of HS significantly (p < 0.05) in the 6th experimental year. The rice yield increased by 14.3% in RS, 10.9% in AL, and 4.2% in HS. The unexpectedly higher rice yield in AL than HS resulted from enhanced soil total carbon (TC), pH, and available Ca. However, compared to AL, liable carbon fraction increased by 33.7% in HS, while refractory carbon fraction dropped by 22.3%. Likewise, biochar characterization showed that more oxygen functional groups existed in HS than in AL. Decreasing inert organic carbon pools due to the constant degradation of the aromatic part of biochar in HS led to a lower soil TC than AL, even with a higher amount of biochar application. Likewise, the annual depletion lowered the soil pH and available Ca declination in HS. Based on the obtained results, this study suggested AL as a promising strategy to enhance rice productivity, soil nutrient enrichment, and carbon sequestration in the paddy ecosystem.Graphic abstract

A guideline for spatio‐temporal consistency in water quality modelling in rural areas

A guideline for spatio‐temporal consistency in water quality modelling in rural areas

Different adaptive strategies of three mangrove species to nutrient enrichment

Mangrove species are undergoing environmental changes from nutrient-poor to enrichment due to the large nutrient input. The potential difference in adaptive strategies between the slow- and fast-growing species may lead to great changes in species interaction and ecosystem stability. This study aims to test whether the slow-growing species Aegiceras corniculatum (L.) Blanco and Kandelia obovata Sheue, Liu & Yong sp. nov. are distinctly different from a fast-growing species Laguncularia racemosa (L.) Gaertn. f. in response to soil nutrient enrichment. With the increase of soil nutrients, L. racemosa shifted from a more conservative to a more acquisitive strategy. The potential causes included the increases in specific leaf area, nutrient resorption efficiency, and photosynthetic capacity as indicated by the increase of leaf δ13C and unchanged leaf succulence, as well as the relocation of photosynthetic products as indicated by the shift toward fast-growing at the cost of constructive and defense compounds. In contrast, A. corniculatum and K. obovata maintained conservative strategies at any soil nutrient levels with only a slight increase in growth. These findings implied that L. racemosa will be more competitive over the slow-growing species in nutrient-rich soils through altering adaptive strategies.

Nematode-based indices in soil ecology: Application, utility, and future directions

The health and functioning of soil ecosystems are the foundation of sustainable food production and land management. Of key importance in achieving sustainability, is the frequent measurement of soil health, and indices based on the community structure of nematodes are amongst the most widely used toolsets by soil ecologists. Thirty years after the development of the Maturity Index, we aimed to evaluate the application, utility, and future directions of nematode-based indices (NBIs). This review focused on NBIs that are calculated using the coloniser-persister classification of nematodes. Data from 672 empirical studies in terrestrial environments revealed that the NBIs presented a dissimilar usage trend. The Channel Index and Metabolic Footprints showed the strongest increase in application rates over time, thus indicating a greater interest in studying decomposition pathways and ecosystem functioning, respectively. Furthermore, nematode-based indices were mostly applied in agricultural systems associated with herbaceous crops and in studies investigating, for example, soil nutrient enrichment following manure and/or inorganic fertilizer application. We further provide a framework for selecting a focus-orientated subset of NBIs for testing hypotheses based on the underlying ecological mechanisms. Also, we highlight important considerations, including the unexpected behaviour of some nematode taxa, in the interpretation of NBIs. The improvement of NBIs relies on advancing our understanding of the autecology of nematodes. Finally, we deliver insight into the further development of NBIs considering recent methodological advancements. We highlight that NBIs have been and might become increasingly important in providing valuable information on soil ecosystem health and functioning, especially considering the urgent need for more sustainable land use.

Plant Growth Promoting (PGP) Activities of Rhizobial Isolates from Sesbania bispinosa in Response to Pesticides

The aim of this study was to investigate the impact of some pesticides on the plant growth promoting activities of Rhizobium spp. isolated from Sesbania bispinosa. Sustainability and environmental safety of agricultural production relies on eco-friendly approaches like use of biofertilizers, biopesticides and crop residue return. The plant growth promoters (PGP) emphasize the need for further strengthening the research and their use in modern agriculture. PGPs inhabit the rhizosphere for nutrients from plant root exudates. On return, they help to increase plant growth through soil nutrient enrichment by nitrogen fixation, phosphate solubilization, siderophore and phytohormone production, etc. Using pesticide/insecticide in the field may protect the plants from undesirable organisms, however, if accumulated in the habitat may adversely affect the growth and development of non-target lives like the rhizobacteria. The present study was performed to demonstrate the influence of pesticides on plant growth promoting activities of rhizobial isolates from Sesbania bispinosa known as green manure among farmers of Bangladesh. It was observed that two pesticides/insecticides (Imitaf 20SL and Tilt 250EC) in vitro shows variable effect on the plant growth promoting activities of the rhizobial isolates.&#x0D; Bangladesh J Microbiol, Volume 38, Number 2, December 2021, pp 31-37

Sewage Pollution Promotes the Invasion-Related Traits of Impatiens glandulifera in an Oligotrophic Habitat of the Sharr Mountain (Western Balkans)

An annual plant, Himalayan balsam (Impatiens glandulifera Royle) is globally widespread and one of Europe’s top invaders. We focused on two questions: does this species indeed not invade the southern areas and does the environment affect some of its key invisibility traits. In an isolated model mountainous valley, we jointly analyzed the soil (21 parameters), the life history traits of the invader (height, stem diameter, aboveground dw), and the resident vegetation (species composition and abundances, Ellenberg indicator values), and supplemented it with local knowledge (semi-structured interviews). Uncontrolled discharge of fecal wastewaters directly into the local dense hydrological network fostered mass infestation of an atypical habitat. The phenotypic plasticity of the measured invasion-related traits was very high in the surveyed early invasion (30–50% invader cover) stages. Different microhabitat conditions consistently correlated with its growth performance. The largest individuals were restricted to the deforested riparian habitats, with extreme soil nutrient enrichment (primarily by P and K) and low-competitive, species-poor resident vegetation. We showed that ecological context can modify invasion-related traits and what could affect a further invasion process. Finally, this species is likely underreported in the wider region; public attitude and loss of traditional ecological knowledge are further management risks.

Shotgun metagenomics evaluation of soil fertilization effect on the rhizosphere viral community of maize plants.

The need for sustainability in food supply has led to progressive increase in soil nutrient enrichment. Fertilizer application effects both biological and abiotic processes in the soil, of which the bacterial community that support viral multiplication are equally influenced. Nevertheless, little is known on the effect of soil fertilization on the Soil viral community composition and dynamics. In this study, we evaluated the influence of soil fertilization on the maize rhizosphere viral community growing in Luvisolic soil. The highest abundance of bacteriophages were detected in soil treated with 8 tons/ha compost manure (Cp8), 60kg/ha inorganic fertilizer (N1), 4 tons/ha compost manure (Cp4) and the unfertilized control (Cn0). Our result showed higher relative abundance of Myoviridae, Podoviridae and Siphoviridae in 8 tons/ha organic manure (Cp8) fertilized compared to others. While Inoviridae and Microviridae were the most relative abundant phage families in 4 tons/ha organic manure (Cp4) fertilized soil. This demonstrate that soil fertilization with organic manure increases the abundance and diversity of viruses in the soil due to its soil conditioning effects.

Assessing the profitability and sustainability of upland farming systems in Cambantoc subwatershed, Philippines

Deforestation, forest and land degradation affect the provision of ecosystem services in the watersheds of Laguna Lake. The study site, Cambantoc Subwatershed, experiences unsustainable upland farming practices that worsen the flooding situation in the downstream areas. This study analyzed rice monocropping and agroforestry farming systems upstream based on measures of profitability, sustainability, and soil quality using the Benefit-Cost Analysis and Soil Changes Under Agroforestry (SCUAF) model. Data on the costs and benefits of the farming systems and the parameters used in calibrating the model were acquired through interviews and secondary data collection. The study found that monocropping is more profitable while agroforestry has better environmental benefits because it can minimize soil erosion and soil nutrient loss through time. Agroforestry is an ideal example of Nature-Based Solution to achieve sustainable farming and enhance the delivery of ecosystem services such as soil nutrient enrichment in the upstream farms and flood mitigation in the downstream areas. The results of this study can serve as a decision support for the policy makers to consider developing and implementing market-based instruments to capture the total benefits of agroforestry to both upland farmers and downstream communities.

Effects of addition of nitrogen-enriched biochar on bacteria and fungi community structure and C, N, P, and Fe stoichiometry in subtropical paddy soils

Biochar can be a soil amendment that increases nutrient retention and carbon (C) sequestration in rice paddy systems. However, biochar can lose nutrient during its production processes so modifications such as coating with the nitrogen (N) that can slowly release nutrients to soil following application are necessary. Dynamic changes in paddy soil microbial communities affect the biogeochemical cycling of soil nutrients; however, the effects of addition of N-enriched biochar on paddy soil microorganisms and nutrient stoichiometry are unclear. Here, we investigated the effects of N-enriched biochar on soil bacteria and fungi community structure and on carbon (C), N, phosphorous (P), and iron (Fe) stoichiometry in subtropical paddy soils. The soil concentrations of TC, TN and TP increased by 0.27–18.55%, 1.31–18.15% and 10.35–54.24% respectively under the nitrogen rich biochar treatment. Under N-enriched biochar application, ratios of N/P and C/P decreased, while P-fixation capacity increased; the decrease in N/P ratio indicated that rice productivity was N-limited. The quantity of soil fungi increased by 42.07% and 10.89% in early and late rice, respectively in the treatment group applying 4t ha−1 of N-enriched biochar. Relative abundance of the bacteria Bacillus, Geobacter, and Sideroxydans decreased with N-enriched biochar, whereas that of Thiobacillus and Thermomonas increased; relative abundance of the fungi Spicellomyces and Crustoderma increased with biochar. Relative abundance of the bacteria Bacteroides was negatively correlated with TC and Fe3+ (P < 0.05) and Sideroxydans and Geoyhrx was negatively correlated with soil TP (P < 0.05). Relative abundance of the fungi genera Westerdykella, Synchytrium, Russula, and Orbilia was positively correlated with soil TC (P < 0.05), Trapelia, Leptosphaerulina, and Tremella was positively correlated with soil TN (P < 0.05), and relative abundance of Leucanium, Monoblepharis was positively correlated with soil TP (P < 0.05). Overall, application of N-enriched biochar to paddy soils affected the microbial community composition through changes in soil physicochemical properties that led to shifts in microbial community function and associated improvements in soil nutrient enrichment.

Halotolerant Microbial Consortia for Sustainable Mitigation of Salinity Stress, Growth Promotion, and Mineral Uptake in Tomato Plants and Soil Nutrient Enrichment

Salinity significantly impacts the growth, development, and reproductive biology of various crops such as vegetables. The cultivable area is reduced due to the accumulation of salts and chemicals currently in use and is not amenable to a large extent to avoid such abiotic stress factors. The addition of microbes enriches the soil without any adverse effects. The effects of microbial consortia comprising Bacillus sp., Delftia sp., Enterobacter sp., Achromobacter sp., was evaluated on the growth and mineral uptake in tomatoes (Solanum Lycopersicum L.) under salt stress and normal soil conditions. Salinity treatments comprising Ec 0, 2, 5, and 8 dS/m were established by mixing soil with seawater until the desired Ec was achieved. The seedlings were transplanted in the pots of the respective pH and were inoculated with microbial consortia. After sufficient growth, these seedlings were transplanted in soil seedling trays. The measurement of soil minerals such as Na, K, Ca, Mg, Cu, Mn, and pH and the Ec were evaluated and compared with the control 0 days, 15 days, and 35 days after inoculation. The results were found to be non-significant for the soil parameters. In the uninoculated seedlings’ (control) seedling trays, salt treatment significantly affected leaf, shoot, root dry weight, shoot height, number of secondary roots, chlorophyll, and mineral contents. While bacterized seedlings sown under saline soil significantly increased leaf (105.17%), shoot (105.62%), root (109.06%) dry weight, leaf number (75.68%), shoot length (92.95%), root length (146.14%), secondary roots (91.23%), and chlorophyll content (−61.49%) as compared to the control (without consortia). The Na and K intake were higher even in the presence of the microbes, but the beneficial effect of the microbe helps plants sustain in the saline environment. The inoculation of microbial consortia produced more secondary roots, which accumulate more minerals and transport substances to the different parts of the plant; thus, it produced higher biomass and growth. Results of the present study revealed that the treatment with microbial consortia could alleviate the deleterious effects of salinity stress and improve the growth of tomato plants under salinity stress. Microbial consortia appear to be the best alternative and cost-effective and sustainable approach for managing soil salinity and improving plant growth under salt stress conditions.