Organic Soil Fertility Research Articles

Effects of Alternate Wetting and Drying Irrigation on Methane and Nitrous Oxide Emissions From Rice Fields: A Meta-Analysis.

Reducing water input and promoting water productivity in rice field under alternate wetting and drying irrigation (AWD), instead of continuous flooding (CF), are vital due to increasing irrigation water scarcity. However, it is also important to understand how methane (CH4) and nitrous oxide (N2O) emissions and global warming potential ( of CH4 and N2O) respond to AWD under the influence of various factors. Here, we conducted a meta-analysis to investigate the impact of AWD on CH4 and N2O emissions and , and its modification by climate conditions, soil properties, and management practices. Overall, compared to CF, AWD significantly reduced CH4 emissions by 51.6% and by 46.9%, while increased N2O emissions by 44.0%. The effect of AWD on CH4 emissions was significantly modified by soil drying level, the number of drying events, mean annual precipitation (MAP), soil organic carbon content (SOC), growth cycle, and nitrogen fertilizer (N) application. Regarding N2O emissions, mean annual temperature (MAT), elevation, soil texture, and soil pH had significant impacts on the AWD effect. Consequently, the under AWD was altered by soil drying level, soil pH, and growth cycle. Additionally, we found that MAP or MAT can be used to accurately assess the changes of global or national CH4 and N2O emissions under mild AWD. Moreover, increasing SOC, but not N application, is a potential strategy to further reduce CH4 emissions under (mild) AWD, since no difference was found between application of 60-120 and > 120 kg N ha-1. Furthermore, the soil pH can serve as an indicator to assess the reduction of under (mild) AWD as indicated by a significant linear correlation between them. These findings can provide valuable data support for accurate evaluation of non-CO2 greenhouse gas emissions reduction in rice fields under large-scale promotion of AWD in the future.

Integrating isotope mixing and hydrologic models towards a more accurate riverine nitrate source apportionment

Nitrate (NO3–) is the major form of bioavailable nitrogen in most rivers, and its dramatic increase may lead to a number of serious environmental issues, such as eutrophication and biodiversity decline. Quantification of NO3– sources and fluxes in rivers is essential for effective management of NO3– pollution. Isotope mixing and hydrological models are proven practical tools for quantifying the sources of NO3– in rivers, yet both methods have severe limitations. To improve the accuracy and reliability of riverine NO3– source apportionment, this study proposed a protocol that integrates the strengths of both tools, capable of solving issues such as the calculation bias caused by isotope endmember overprinting in isotope mixing model and the lack of validation data for hydrological models. We applied the framework to a typical agricultural river, the Qihe River, and illustrated the effectiveness of the method in quantifying riverine NO3– sources. The proportional contribution of sewage simulated by the SWAT model approximated that estimated by the isotopic mixing model, yet the SWAT-based contributions of soil organic nitrogen and chemical fertilizer were 16.3 % lower and 14.0 % higher, respectively than the MCMC-based results. After integrating both models, we adopted the proportions of NO3– sources in the river from chemical fertilizer, sewage, and soil organic nitrogen as 45.1 %, 30.9 %, and 23.9 %, respectively. This study showed that coupling isotopic and hydrological models provided a new dimension for the accurate quantification of N sources in rivers.

Effects of Straw Addition on Soil Priming Effects Under Different Tillage and Straw Return Modes.

This study aims to investigate the impact of straw addition on soil activation effects under different tillage practices, providing a scientific basis for establishing reasonable straw return measures in the southern Northeast Plain, thus enhancing soil fertility, and mitigating greenhouse effects. Soil samples were collected from various straw return practices that were conducted continuously for two years as follows: rotary tillage without straw return (RTO), deep tillage combined with straw incorporation (PT), rotary tillage with straw incorporation (RT), and no-till with straw cover (NT). The samples were incubated in the dark at 25 °C for 70 days. We measured the CO2 release rate and cumulative release, apparent activation effect, soil organic carbon, active microbial biomass organic carbon, soluble organic carbon, and easily oxidizable organic carbon to clarify the effects of straw addition on soil activation under different tillage practices. The results indicate that a straw addition promotes the mineralization of soil organic carbon while also increasing the content of active organic carbon components. The CO2 release rates and cumulative release under different tillage practices were as follows: PT > NT > RT. The contents of the active microbial biomass organic carbon, soluble organic carbon, and easily oxidizable organic carbon increased by 16.62% to 131.88%, 4.36% to 57.59%, and 12.10% to 57.97%, respectively, compared to the control without the straw addition. Except for the RT practice, the addition of straw significantly enhanced the instability of soil organic carbon in the PT, NT, and RTO practices, with increases of 51.75%, 48.29%, and 27.90%, respectively. Different straw return practices altered the physical and chemical properties of the soil, resulting in significant differences in the strength of the apparent activation effect. Notably, the apparent activation effect of RT was reduced by 86.42% compared to RTO, while that of NT was reduced by 36.99% compared to PT. A highly significant positive correlation was observed between the apparent activation effect and the unstable carbon components in the soil, indicating that higher levels of easily decomposable organic carbon corresponded to stronger apparent activation effects. In conclusion, it is recommended that in this region, rotary tillage should be adopted for straw return in the first 2 to 3 years, as this practice is beneficial for the formation and stabilization of organic carbon in the short term. As the duration of straw return increases, adjustments can be made based on the degree of soil organic carbon retention and soil fertility status.

EFFECT OF MUNICIPAL SOLID WASTE COMPOST, GYPSUM AND MYCORRHIZA ON METALS CONTENT IN SOIL AND PEANUT GRAIN

Municipal solid waste compost (MSWC) is widely used as an organic soil amendment and fertilizer on agricultural land. However, applying MSWC can cause adverse effects due to the heavy metals contained. This study aimed to determine the heavy metal content of MSWCs in the presence of mycorrhizae and gypsum and their effects on soil and peanut grain. The field experiment was carried out in the split factorial design based on a completely randomized block in three replications as a field trial in 2018 and 2019, in Iran. The main factor includes two levels of gypsum (0 and 150 kg ha-1) and the sub-factors include the presence and absence of Arbuscular mycorrhizal fungi (AMF) and different levels of MSWC at five levels (0, 2, 4, 6, and 8 t ha-1). The findings showed that MSWC significantly increased the concentrations of manganese (Mn), lead (Pb), nickel (Ni), zinc (Zn), cobalt (Co), chromium (Cr), cadmium (Cd), and boron (B) in soil and grains. In addition, Co, Ni, and Zn concentrations in grain increased and Pb, Mn, Ni, and Zn concentrations in soil decreased with AMF application. Gypsum treatment also had no significant effect on metals in both grain and soil.

Long-term changes in soil biological activity and other properties of raised beds in Longan orchards

Introduction The Longan fruit tree of the Vietnam Mekong Delta is grown in raised beds to improve water drainage during the rainy season and can live as long as 100 years. Objective This research explores the extent to which the soil microorganisms as well as soil physical and chemical properties of these raised beds degrade over a period of 60 years under traditional management practices. Materials and Methods Raised bed topsoil samples at depths of 0–20 cm were obtained from four different Longan orchards raised bed age groups: group 1) 15–25 years (L1–L5); group 2) 26–37 years (L6–L10); group 3) 38–45 years (L11–L15); and group 4) 46–60 years. Soil biological properties were tested for nitrogen-fixing bacteria, phosphorus solubilizing bacteria, potassium solubilizing bacteria, calcium solubilizing bacteria and silicate solubilizing bacteria, β-glucosidase, urease, phosphomonoesterase, and phytase. Soil samples were also tested for moisture content, soil texture, soil porosity, and bulk density as well as soil chemical properties including pH, electrical conductivity (EC), soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (NH4+, NO3−), available phosphorus (AP), exchangeable potassium (K+), exchangeable calcium (Ca2 +), available silicate (SiO2), available copper (Cu), zinc (Zn), boron (B) and manganese (Mn). Key findings: The results showed that soil moisture, soil porosity, sand content, SOM, TP, TK, available P, exchangeable Ca2 +, available Si, nitrogen fixing bacteria number, β-glucosidase, urease, phosphomonoesterase, and phytase gradually and significantly decreased in the raised bed soil as the Longan orchard increased in age. Pearson correlation analysis between the ages of Longan orchards and soil properties revealed that raised bed ages were positively correlated with soil bulk density, but negatively correlated with soil moisture content, soil porosity, SOM, TN, β-glucosidase, urease, phosphomonoesterase, and phytase. Principal component analysis (PCA) showed Longan yields had a positive correlation with available NO3− but negative correlation with NFB, exchangeable Ca2 +, pH, and available B. These findings reveal that traditional long-term management of Longan trees in raised beds significantly reduce soil organic matter, moisture content, porosity, and soil fertility with impacts on soil microbial numbers and activity within raised bed soils. Future Directions This suggests that more sustainable management practices, such as mulch and cover crops that decrease soil compaction and increase soil organic matter, improve soil porosity, total N, and feed soil microorganisms that are critical to nutrient cycling are needed to improve raised bed soil quality.

Decomposition characteristics of woody peat and its mixtures with liable organic materials in a newly reclaimed saline-alkali soil: A one-year incubation experiment

The combined application of woody peat with labile organic materials has been shown to be an effective strategy for rapidly improving soil organic matter (SOM) and soil fertility in newly reclaimed lands. However, their decomposition dynamics, which can be greatly influenced by the residue-mixing effect, are not well understood. Therefore, this study investigated the decomposition characteristics and residue-mixing effect of woody peat, corn straw, organic manure and their binary mixtures in a newly reclaimed saline-sodic soil through a 360-day incubation experiment. The results revealed that both straw and organic manure contained large amount of O-alkyl C, leading to rapid degradation in mass and organic C (OC). In contrast, woody peat is rich in alkyl C and aromatic C, exhibiting the highest alkyl C/O-alkyl C (A/O-A) ratio and aromaticity. As a result, woody peat only lost less than 6.4% OC and showed minimal changes in mass and nitrogen content within a year, indicating strong degradation resistance in the saline-sodic soil. The combination of woody peat with straw or organic manure induced significant non-additive synergistic effects on mass and OC loss, aromatic C, carbonyl C, A/O-A ratio and aromaticity. This suggests that the addition of woody peat significantly slowed down the degradation of the mixtures and prolonged the retention of OC in soil. On the contrary, the mixing of straw and organic manure led to significant non-additive antagonistic effects on mass and OC loss, indicating that their combination accelerated the decomposition of the mixture. Consequently, this study suggests that, in contrast to the applicated of various labile organic materials, the combined application of recalcitrant woody peat with labile organic materials can extend the presence of organic matter in the soil, thereby promoting a sustained increase in active and passive SOM content and soil fertility.

Survey on Current Status, Challenges and Opportunities towards Integration of Traditional Smallholder Crop-livestock Systems in Kenya

The current study reports the results of a baseline survey conducted to establish current status of optimizing productivity of crop-livestock systems in Kenya. Results from the study showed that 74% and 18% of the household head and respondents were male and female respectively, indicating a male dominance of household headship. The household head (69%) and respondents (16%) reported to have completed classes for formal school. On average, farmers were walking 1.83 Km, 5.18 Km, 4.65 Km, and 12.79 Km to the nearest village market, town market, extension office and farmers’ training centers respectively. This shows that extension and communication services are still far apart from the farming communities, with a negative implication on technology adoption and household food and nutrition security. Majority of the farmers did not utilize organic nutrients for crop production (96%). Open heaping/piling, composting with other materials, use of solid and liquid manures was reported to be utilized on average 67 kg, 30 kg, 11 kg and 2 kg respectively. This implies a poor manure management, low adoption and utilization levels of organic manures, with subsequent impact on climate change, crop productivity and household food and nutrition security. The main constraint limiting the use of organic fertilizers were ranked as follows; ignorance of the technical aspects linked to the use of manure as an organic fertilizer (17.8%), low awareness of manure usefulness to improve soil fertility (16.4%), high affordability and timely accessibility of chemical fertilizers (16.3%). Results further show that majority of the respondent did not utilize Nitrogen fixing plants (66%), nutrient cycling (84%) and legume crops (75%). The main Nitrogen-fixing plants were faba bean (10%), Sesbania (9%), cowpea (5%), alfalfa (2%) and sunflower (1%) respectively. The survey recommends promotion of climate smart interventions and organic soil fertility management approaches, farmers capacity building and promotion of agribusiness.

Carbon Budgeting of a Long-term Rice-rice Cropping Sequence in the Typic ustipsamments of Kerala, India

A judicious management practice to improve the soil's organic carbon level and soil fertility is essential for agricultural and environmental sustainability. The present study was undertaken to assess the long-term effect of various management practices on soil carbon dynamics and agricultural sustainability by computation of indices like carbon pool index (CPI), carbon lability index (CLI), carbon management index (CMI), critical carbon input and carbon budgeting. CMI has been used as a more sensitive indicator to evaluate capacity of a management practice to promote soil quality. Sensitivity index was used to determine the degree of changes in each carbon fraction due to management practices. The study was carried out in a permanent manurial trial plot started in 1964 under a long term rice-rice cropping sequence in Kerala. Based on the results obtained, integrated application of NPK fertilizers along with FYM showed significantly higher carbon indices, increased soil carbon fractions, and carbon sequestration compared to other management practices. The study revealed that applying organics coupled with inorganic fertilizers will manage the SOC level and result in enhanced soil fertility, productivity, and agricultural sustainability.

Impact of Poultry Manure-Derived Biochar and Bio-Fertilizer Application to Boost Production of Black Cumin Plants (Nigella sativa L.) Grown on Sandy Loam Soil

Biochar derived from poultry manure increases nutrient availability and promotes plant growth. This study investigated the effect of biochar with mycorrhizal and/or plant growth-promoting rhizobacteria on soil fertility, chemical properties, oil, and seed yield of Black Cumin (Nigella sativa L.) plants. A split-plot design with three replicates was employed, with biochar derived from poultry litter (BC) applied at rates of 0, 5, and 10 t ha−1, with beneficial microbes such as arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) affecting the growth of Black Cumin plants, and some soil properties, such as pH, electrical conductivity (EC), soil organic matter (SOM) and fertility index (FI), showing significant differences (p ≤ 0.05) among biochar and/or bio-fertilizer treatments. All biochar treatments with or without bio-fertilizers significantly increased pH, EC, OM and FI in comparison to the control treatment. The results demonstrated that applying biochar at the highest rate (10 t ha−1) increased fresh and dry capsule weights by 94.51% and 63.34%, respectively, compared to the control treatment (C). These values were significantly increased by 53.05 and 18.37%, compared to untreated plants when combined with AMF and PGPR. Furthermore, when biochar was applied in conjunction with both AMF and PGPR, fresh and dry capsule weights saw significant increases of 208.84% and 91.18%, respectively, compared to the untreated control treatment. The interaction between biochar, AMF, and PGPR significantly improved plant growth, yield, soil properties, and the fixed and volatile oil content of Black Cumin. These findings suggest that the combined application of biochar, AMF, and PGPR enhances nutrient availability and uptake, leading to improved growth and higher yields in Black Cumin plants, resulting in increased yield production.

Response of N uptake, N-total and yield of sweet corn (Zea mays saccharata Sturt) due to fertilization with granulated solid organic fertilizer and NPK in Inceptisol soil

Sweet corn productivity is greatly influenced by proper cultivation techniques, of which fertilization is one of the main factors. Effective fertilization not only supports plant growth but also affects nutrient uptake and yield. This study aimed to evaluate the effect of granulated solid organic fertilizer and NPK fertilizer on nitrogen (N) uptake, soil N-total content, and sweet corn yield in Inceptisol soil. The research was conducted from February to June 2024 at the Experimental Field, Faculty of Agriculture, Padjadjaran University with treatments including control, NPK fertilizer, and various combinations of granular organic fertilizer and NPK. The results showed that the combination of granule organic fertilizer and NPK significantly increased nitrogen uptake and N-total content in the soil compared to the single NPK application. In addition, sweet corn yield, as measured by cob weight per plant, per plot, and per hectare, also increased significantly with the fertilizer combination treatment. This study supports the use of fertilization strategies that integrate organic and inorganic fertilizers as an effective way to increase sweet corn productivity on soils with limited fertility, such as Inceptisol. The application of a combination of 1 NPK + 1 granulated organic fertilizer was the best combination in increasing N uptake, N-total and sweet corn yield.

Soybean planting date affects the relationships between soil test values and grain yield

AbstractMany soybean [Glycine max (L.) Merr.] growers in the US Midwest rely on soil test values for evaluating the crop's fertilizer needs. However, threshold values for Illinois were calibrated to soybean yield in the 1960s when the production systems and yield potential were much different than today. The objective of this study was to determine which and how well soil test values predict yield of unfertilized soybean. Preplant soil samples, collected from 133 trials across Illinois from 2014 to 2021, were analyzed for 14 chemical attributes and compared to unfertilized soybean grain yields from those same studies. Pearson correlation coefficients (r), principal factor analysis, and latent variable regression models were used to determine those soil attributes most closely associated with grain yield and yield components. The association of planting date and yield (r = −0.56) led to dividing the data set into five planting date groups. Soil fertility levels resulted in a strong correlation with yield for Late or Very‐late planting groups, but not for the Early or Very‐early groups. A factor analysis of soil attributes largely resulted in retention of two factors, identified as Soil Organic Charge and Soil Fertility, across the planting‐date groups. Regression of these factors with yield confirmed that soil fertility had a greater influence on grain yield for late‐planted soybeans than early‐planted and that these differences were associated with average seed weight. Therefore, positioning late‐planted soybeans in higher fertility fields and early‐planted soybeans in lower‐fertility fields could reduce the need for supplemental fertilization.

Remote Sensing Inversion of Soil Organic Matter Content in Straw-Returned Fields in China’s Black Soil Region

China’s black earth region is the country’s corn golden belt, and returning corn straw to the field not only helps improve the Soil Organic Matter (SOM) content and soil fertility, but also resolves environmental pollution caused by straw burning. To study the effects of different years and amounts of straw returned to the field on SOM content, this study used soil sampling data from a conservation tillage experimental base in Gaojia Village, Lishu County, combined with indoor measurements of imaging spectral data, to establish a prediction model of SOM content by applying partial least squares regression, and inverting the SOM content in the study area. The results showed that the PLSR model accuracy using indoor measured soil imaging spectral data as the independent variable was high. The accuracy coefficients of samples with different field return and different field return amounts, R2, were 0.9176 and 0.8901, respectively, which better predicted SOM content. In the 0–50 cm tillage layer, the highest average SOM content of 39.73 g/kg was found under the NT-1 treatment with different no-tillage straw return year treatments. The depth of the tillage layer in the typical black soil region of Northeast China is around 0–20 cm, and the most significant increase in SOM content was observed in the experimental samples under the NT-1 treatment. SOM content in NT-1 treatment increased by 31.83% compared with CK-1, 68.24% compared with CK-2, 72.18% compared with NT-0, 699.48% compared with NT-2, and 311.44% compared with NT-3, respectively. The highest SOM content of 31.9 g/kg was found in NT-100 under the different treatments of different years of field return. At the 0–20 cm soil layer, the SOM content increases most significantly under NT-100 treatment, which is the most suitable treatment method for straw return to the field. And NT-100 is 22.09% higher than CK-1, 55.36% higher than CK-2, 58.99% higher than NC-0, 115.95% higher than NT-33, and 48.72% higher than NT-67, respectively. This study provides data that can support the conservation of soil ecosystem diversity and sustainable soil use, and it also enriches the application of the PLSR model application.

Rapid soil attribute evaluation for soil security assessments in data-poor environments in the Pacific region

Many global environments face increasing pressures on soil resources, and effective, scalable methods for assessment of soil condition and capital are essential to respond to tangible soil threats. This situation is common across Pacific Island Countries and Territories (PICTs), where high throughput soil analysis laboratories are limited, and issues such as soil organic carbon decline, acidification and fertility declines are present. Soil spectral inference presents an opportunity in such regions to provide rapid insights into soil capital and condition, though the need for robust calibration libraries remains a limiting factor. This work investigates the utility of a regionally appropriate spectral library, the New Zealand Soil Spectral Library (NZSSL) to support the development of soil spectral inference in data-poor environments, such as PICTs, through a case study on the island of Tongatapu in The Kingdom of Tonga. We contrast the performance of existing partial least squares regression (PLSR) models developed for New Zealand soils on soils from Tongatapu and explore the opportunities for enhancement of predictions formed through memory-based learning (MBL) supplemented with local data. Our work shows the potential for cost-effective and timely soil monitoring through soil spectral inference in PICTs. The work further underscores the importance of regional cooperation and data-sharing for addressing soil security.

Combinatory effects of pineapple peel liquid organic fertilizer and rice husk charcoal on melon (Cucumis melo L.) growth and yield

The intensive use of synthetic fertilizers in melon cultivation can reduce soil organic matter and fertility, ultimately decreasing productivity. This situation necessitates the improvement of growing media to achieve production targets through the use of rice husk charcoal and liquid organic fertilizer (LOF) from pineapple peel. This study aims to determine the combinatory effects of pineapple peel LOF and rice husk charcoal media on the growth and yield of melon plants. The research employed a factorial randomized block design (RBD) with 6 treatment levels, and data were analyzed using ANOVA followed by an HSD test at the 5% significance level. The results showed an interaction between pineapple peel POC and rice husk charcoal media on the number of leaves variable. The P0M1 treatment (NPK 16:16:16 at 3 g and 50% rice husk charcoal & 50% soil) at 52 days after planting (DAP) produced the highest number of leaves, totaling 26.12. However, this increase in leaf number was not accompanied by an increase in fruit weight or brix levels. These findings open opportunities for further research to understand why the increase in leaf number did not translate to higher fruit weight or Brix levels, and to identify treatment combinations that can enhance both growth and yield.

Heavy Metal Accumulation in Soil and Plants Using Municipal Solid Waste Compost in Variable pH Conditions

ABSTRACT Municipal solid waste composts (MSWC) are extensively utilized as organic soil conditioners and fertilizers in agricultural fields across many countries. However, the use of MSWC can lead to heavy metal pollution in soil and plants, which may adversely affect plant growth. This study examined the impact of MSWC on the heavy metal content in plants and soil across various pH levels. The experiment was conducted in a pot setting with three replications. The research findings indicated that MSWC application increased the levels of copper (Cu) and zinc (Zn) in soils but had no significant effect on lead (Pb), nickel (Ni), manganese (Mn), and iron (Fe) levels. Additionally, increases were observed in the Cu, Zn, and Fe content in plants, while Pb and Ni content remained unchanged. Cu, Zn, and Fe are essential for plant growth, and their enhancement in both soil and plants is a direct result of their relatively high presence in the MSWC used. The soil-plant transfer coefficients show that the transfer of heavy metals from soil to plants is highest under acidic conditions, indicating that the heavy metal content in MSWC can vary depending on soil pH and application rate. Therefore, it is crucial to carefully analyze and evaluate the heavy metal contents of soil and compost samples before employing MSWC in agricultural fields.

Adoption of organic soil fertility measures and their impact on farm outcomes: a case study of millet cultivators in India

This article investigated the economic impact of adopting organic soil fertility measures (OSFM) on millet farming outcomes in rainfed regions of rural India. Using survey data from 900 millet farmers, the analysis applied an endogenous switching regression model to correct for selection bias arising from both observable and unobservable factors. The results indicated that factors such as soil type, use of farmyard manure, crop diversification, gender of the household head, access to agricultural resources, proximity to residence and markets and education levels significantly influenced farmers’ adoption of OSFM. Notably, the adoption of OSFM had a positive and statistically significant impact on farm profits, with OSFM adopters gaining ₹5998 more than nonadopters. The average treatment effect on the treated for OSFM was 9.80% higher than for non-OSFM farmers. These findings reinforcing the importance of promoting OSFM practices in similar rainfed farming regions of the country.

Effects of Different Modified Materials on Soil Fungal Community Structure in Saline-Alkali Soil

Studying the effects of different modified materials on the physicochemical properties and fungal community structure of saline-alkali soil can provide theoretical basis for reasonable improvement of saline-alkali soil. High-throughput sequencing technology was used to explore the effects of five treatments, namely, control (CK), desulfurization gypsum (T1), soil ameliorant (T2), organic fertilizer (T3), and desulfurization gypsum compounds soil ameliorant and organic fertilizer (T4), on soil physicochemical properties and fungal community diversity, composition, and structure of saline-alkali soil in Hetao Plain, Inner Mongolia. The results showed that compared with those in CK, the contents of available phosphorus, available potassium, organic matter, and alkali hydrolysis nitrogen were significantly increased in modified material treatments, and the T4 treatment significantly decreased soil pH. Modified treatments increased the Simpson and Shannon indexes of fungi but decreased the Chao1 index. The dominant fungi were Ascomycota, Basidiomycota, and Mortierellomycota, and the dominant genera were Mortierella, Conocybe, Botryotrichum, Fusarium, and Pseudogymnoascus. The application of modified materials increased the relative abundance of Ascomycota, Basidiomycota, Fusarium, and Pseudogymnoascus, while decreasing the relative abundance of Mortierellomycota, Chytridiomycota, and Mortierella. LEfSe analysis showed that modified treatments altered the fungal community biomarkers. Correlation analysis showed that pH and available potassium were the main environmental factors affecting fungal community structure. The results can provide scientific basis for improving saline-alkali soil and increasing soil nutrients in Hetao Plain, Inner Mongolia.

Effects of reductive soil disinfestation and organic fertilizer application on microbial community stability in a facility vegetable soil

Reductive soil disinfestation (RSD) is an effective method for remediating degraded facility vegetable soils. However, the effectiveness of RSD using green manure as a carbon source in the field has not yet been clarified. We investigated the effects of RSD and organic fertilizer application on soil microbial community composition, diversity, and stability in a degraded facility vegetable soil. There were six treatments, including no fertilization (CK), no fertilization and soil flooded and mulched with plastic film (FF), soil amended with chicken manure (OM), soil amended with chicken manure and flooded and mulched with plastic film (OMR), soil amended with Sesbania cannabina (TF), and soil amended with S. cannabina and flooded and mulched with plastic film (TR). The results showed that the OMR and TR treatments significantly decreased bacterial Chao1 index, altered bacterial and fungal community structure, and increased the relative abundances of Bacillus, Rhodococcus, Clostridium, and Penicillium. The TR treatment significantly reduced the relative abundance of Fusarium. Results of redundancy analysis and Mantel test analysis suggested that soil ammonium nitrogen and dissolved organic carbon contents were the key factors influencing bacterial community composition, and soil pH was the key factor affecting fungal community composition. Results of cohesion analysis showed that the OMR and TR treatments significantly improved bacterial community stability, and that there was no difference between OMR and TR treatments. The TR treatment enhanced fungal community stability, which was significantly higher than the OMR treatment. Therefore, the RSD with green manure as carbon source could be effective remediation practice to improve soil health.

Unveiling the regulatory mechanism of poly-γ-glutamic acid on soil characteristics under drought stress through integrated metagenomics and metabolomics analysis.

It is of utmost importance to understand the characteristics and regulatory mechanisms of soil in order to optimize soil management and enhance crop yield. Poly-γ-glutamic acid (γ-PGA), a stress-resistant amino acid polymer, plays a crucial role in plant drought stress resistance. However, little is known about the effects of γ-PGA on soil characteristics during drought treatments. In this study, the effects of different forms of γ-PGA on soil texture and basic physical and chemical properties under short-term drought conditions were investigated. Furthermore, the impact of γ-PGA on the microbial community and metabolic function of maize was analyzed. Under drought conditions, the introduction of γ-PGA into the soil resulted in notable improvements in the mechanical composition ratio and infiltration capacity of the soil. Concurrently, this led to a reduction in soil bulk density and improved soil organic matter content and fertility. Additionally, metagenomic analysis revealed that under drought conditions, the incorporation of γ-PGA into the soil enhanced the soil microbiota structure. This shift led to the predominance of bacteria that are crucial for carbon, nitrogen, and phosphorus cycles in the soil. Metabolomics analysis revealed that under drought treatment, γ-PGA affected soil metabolic patterns, with a particular focus on alterations in amino acid and vitamin metabolism pathways. Correlation analysis between the soil metagenome and metabolites showed that microorganisms played a significant role in metabolite accumulation. These results demonstrated that γ-PGA could improve soil characteristics under drought conditions and play an important role in soil microorganisms and microbial metabolism, providing further insights into the changes in soil characteristics under drought conditions.

Short-term service crops affect the spatial organization of soil aggregates, microbial C[sbnd]N biomass, and microbial activities in a degraded monoculture system

Service crops are grown to provide ecosystem services, such as the ability to increase soil organic matter and fertility. Also, they reduce erosion processes, weed control, disease regulation, water purification, soil biodiversity, and physical restoration. The physical arrangement of elemental particles in soil aggregates controls many ecosystem functions such as soil stability and carbon sequestration. This study aimed to analyze the short-term effect of including different service crops on the soil aggregate dynamics in a degraded common bean monoculture system and how it influences the rhizospheric microbial activity, carbon, and nitrogen microbial biomass. Here, we measured soil water-stable aggregates, particulate and associated organic carbon, soil microbial biomass, microbial activity, service crop aerial biomass, and cash crop yield in bulk soils during the 2020/2021 and 2021/2022 agricultural cycles. Soil samples from depths of 0–10 cm from five management treatments (annual service crop/common bean) were analyzed under no-tillage: 1) Oat (O) = Avena sativa/common bean; 2) Wheat (W) = Triticale/common bean; 3) Vetch (V) = Vicia villosa/common bean; 4) Melilotus (Me) = Melilotus alba/common bean; 5) common bean monoculture (M) = common bean without service crop. Additionally, two controls were analyzed: 6) Brachiaria perennial (BP) = Brachiaria brizantha perennial; 7) Native vegetation (NV). Service crops significantly increased aggregate stability, mean weight diameter, particulate matter and associated organic carbon, promoting the formation of large macroaggregates (0.25–2 mm and > 2 mm). This led to an increase in carbon stocks. Microbial activity expressed as hydrolysis of fluorescein diacetate and acid phosphatase activity, increased in the largest fraction for all service crops. Vicia improved surface residues; on average all service crops increased the common bean yield by 107.25 %. In summary, Vicia represents the best alternative as a service crop to improve the quality and health of degraded monoculture soils.