Widely Targeted Metabolomics Reveals the Effects of Soil on the Metabolites in Dioscorea opposita Thunb.

Chinese yam (Dioscorea opposita Thunb. cv. Tiegun), a type of homologous medicinal plant, mainly grows in sandy soil (SCY) and loessial soil (LCY). However, the effects of the soil on the metabolites in SCY and LCY remain unclear. Herein, this study aims to comprehensively elucidate the metabolites in SCY and LCY. A UPLC-MS/MS-based, widely targeted metabolomics approach was adapted to compare the chemical composition of SCY and LCY. A total of 988 metabolites were detected, including 443 primary metabolites, 510 secondary metabolites, and 35 other compounds. Notably, 177 differential metabolites (classified into 12 categories) were identified between SCY and LCY; among them, 85.9% (152 differential metabolites) were upregulated in LCY. LCY significantly increased the contents of primary metabolites such as 38 lipids and 6 nucleotides and derivatives, as well as some secondary metabolites such as 36 flavonoids, 28 phenolic acids, 13 alkaloids, and 6 tannins. The results indicate that loessial soil can improve the nutritional and medicinal value of D. opposita.

A cleaner biocementation method of soil via microbially induced struvite precipitation: A experimental and numerical analysis.

Microbial-induced struvite precipitation (MISP) is a new biocementation method for soil improvement and hydraulic permeability reduction. Compared with traditional microbial-induced carbonate precipitation (MICP), MISP can significantly reduce the production of harmful ammonium ions during biochemical reactions and convert ammonium ions into struvite with promising mechanical strength. In this study, a series of experiments were conducted to compare the performance of the MICP and the MISP processes on sandy soils. Results showed that the average content of calcium carbonate in MISP cemented sand columns after 3 times of injection is similar to that in MICP cemented sand columns after 9 times of injection. The hydraulic permeability of MISP cemented sand columns after 3 times of injection is an order of magnitude lower than that of MICP cemented sand columns after 9 times of injection. To further investigate the physicochemical interactions during MISP and MICP processes, a one-dimensional finite element code considering the chemical reactions and the solute transportation was proposed. Results show that most of the MISP were formed in the early 3 h of the 6 h injection cycle, whereas most of the MICP were formed in the last 5 h of the injection cycle. The simulated total mass of the MISP precipitation, 11.3 g, was close to the experimental result of 9.6 g. The spatial distribution of MISP is more uneven as compared to MICP, as a result of the much faster reaction rate of struvite than calcium carbonate. The findings suggested that MISP could partially replace MICP in the applications of leakage mitigation and reinforcement of sandy soils.

Optimizing organic amendment applications to enhance carbon sequestration and economic benefits in an infertile sandy soil.

A thorough understanding of the agricultural, ecological, and economic benefits of organic amendment (OA) application in infertile soils is crucial for facilitating agricultural sustainability. We conducted a three-year field study to evaluate the effects of OA application on soil organic carbon (SOC) sequestration, crop yields, and the net ecosystem economic benefit (NEEB) in a typical infertile sandy soil (with an initial SOC content of 2.56 g kg-1) of the ancient Yellow River alluvial plain. In addition to the control (CK; non-OA application), two types of OAs, namely, manure-based organic fertilizer (M) and spent mushroom residue (MR), were each applied at 12, 24, and 36 Mg ha-1 yr-1. Two scenarios of OA application practices, namely, conventional manual OA application (AMA) and mechanical OA application (AME), were considered in the economic evaluation. An increase of 1 g kg-1 SOC content could improve the crop yield by 2.25 Mg ha-1 yr-1. Compared with the CK, the application of OAs enhanced the SOC content and SOC stock by 14.6%-39.8% and 8.5%-28.2%, respectively. However, the SOC sequestration efficiency of the OAs tended to decrease under high rates of OA application. MR was observed to have greater potential than M in sequestering SOC and promoting soil aggregates. OA-induced SOC sequestration could neutralize 36.6%-97.8% of greenhouse gas emissions, which resulted in a reduction in the global warming potential and its cost by 0.62-2.68 Mg CO2-eq ha-1 yr-1 and 15.46-65.78 CNY ha-1 yr-1, respectively. Nevertheless, in terms of the NEEB, the benefits of OA application on crop yield and SOC sequestration were largely offset by the increased material and labor costs. Compared with AMA, AME could save 10%-27% of agricultural costs. The AME of MR at a rate of 24 Mg ha-1 yr-1 achieved the highest NEEB. The results of this study suggest that a strategy involving the appropriate OA, optimal application rate, and cheapest incorporation cost for a specific individual soil should be adopted to achieve a sustainable solution for promoting crop productivity, enhancing SOC sequestration, and ensuring farmer income in infertile farming regions.

The status of heavy metals in arable soils of contrasting texture treated by biochar - an experiment from Slovakia.

Worldwide, many soils are impacted by degradation processes, which impose a risk to sustainable food production. There is a pressing need to limit these negative impact constraints to sustain the proper functioning of the soil-biota system and soil productivity. Biochar can be a nature-friendly solution for soil remediation; however, knowledge is incomplete in many aspects in this field, like the potential of biochar and biochar-based products as agents to immobilize toxic substances, including heavy metals (HMs) found in the soil. In this study, we investigated the effect of two biochar substrates (BSs) (1. biochar blended with farmyard manure as BS1, and 2. biochar blended with farmyard manure and digestate as BS2) at rates of 10 and 20 t ha-1 applied without or with fertilization (BS + F) on the immobilization of HMs in texturally different soils (1. sandy Arenosol, 2. loamy Chernozem, Slovakia). The results showed that application of BS had different effects in relation to soil textures. In sandy soil, BS improved soil properties, such as cation exchange capacity (an increase from 20 to 93%), soil organic carbon content (SOC) (an increase from 3 to 26%) and humic substances (HSs) stability (an increase from 12 to 20%). In loamy soil, SOC increased due to BS and BS + F in the range 3-19% and 12-55%, respectively. In both soils, the total content of HMs did not exceed the threshold limits for individual soils after BS and BS + F application. In sandy soil, the immobilization of HMs was due to a higher SOC content and a fulvic acids (FAs) content, while in loamy soil their elimination depended on a higher available phosphorus content.

Mesobacillus harenae sp. nov., isolated from the sandy soil of a cold desert.

A bacterial strain, designated Y40T, was isolated from sandy soil sampled on the Qinghai-Tibet Plateau. A polyphasic study confirmed the affiliation of the strain with the genus Mesobacillus. Strain Y40T was found to be an aerobic, Gram-stain-positive, motile and rod-shaped bacterium. The strain grew at 10-42 °C, pH 6-9 and with 0-2 % (w/v) NaCl. The diagnostic amino acid was meso-diaminopimeilic acid. MK7 was predominant menaquinone, and iso-C15:0, iso-C17:1 ω10c and anteiso-C15:0 were the major fatty acids. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified lipid. The DNA G+C content was 40.6 mol%. Based on he results of 16S rRNA gene sequence analysis, strain Y40T was phylogenetically closely related to Mesobacillus zeae JJ-247T and Mesobacillus foraminis CV53T, with similarities of 98.0 and 97.7 %, respectively. The average nucleotide identity (ANIb) values between strain Y40T and Mesobacillus zeae JJ-247T and Mesobacillus foraminis CV53T were 69.9 and 70.0 %, respectively. Based on the morphological, physiological, and chemotaxonomic data, it is proposed that strain Y40T (=CICC 24459T=JCM 32794T) should be classified into the genus Mesobacillus as Mesobacillus harenae sp. nov.

Managing fires in a changing world: Fuel and weather determine fire behavior and safety in the neotropical savannas.

Fire is an important ecological disturbance, but anthropogenic wildfires increasingly threaten native ecosystems and human lives. In fire-prone ecosystems, zero-fire policies have been replaced by active fire management to reduce the risk of wildfires and improve ecological outcomes. The environmental drivers of fire behavior are widely known, but climate change and deforestation are changing their roles, making fires less predictable. Thus, reassessing the main determinants of fire behavior is preeminent to allow for safe and adaptive uses of fire in protected areas (PA). We did this research in collaboration with PA managers during the initial implementation of a pilot Integrated Fire Management (IFM) program in the Brazilian savanna. The program mainly aimed to prevent large wildfires in the late-dry season and included prescribed burns during the rainy, early- and mid-dry seasons to create vegetation patch mosaics with different fire histories. We assessed fire behavior and its environmental drivers during prescribed fires in the mid-dry season (MF) and experimental late-dry season fires (LF) (emulating wildfires). We applied Linear Models to test for differences in fire intensity, heat released, combustion factor and flame height between fire seasons and to check the influence of meteorological and fuel conditions in these parameters. LF had a significantly higher fire intensity (3508 vs. 895 kW m-1), heat released (5537 vs. 3329 kW m-2), combustion factor (90 vs. 51%) and flame height (2.5 vs. 1.9 m) than MF. Relative humidity, air temperature, wind speed and fuel load were the best predictors of fire behavior, corroborating previous research. Air temperature and relative humidity pushed the seasonal differences in fire behavior while wind speed and fuel load showed similar effects across seasons. Our results emphasize the importance of considering primarily environmental variables during fire management planning, especially in the current climate changing world where extreme events and seasonal weather fluctuations are constantly defying our knowledge about fire behavior.

Recycling of sugar crop disposal to boost the adaptation of canola (Brassica napus L.) to abiotic stress through different climate zones.

We need to produce higher foods even under declining natural resources to feed the projected population of 9 billion by 2050 and to sustain food security and nutrition. Abiotic stress has adversely affected canola crop and oil quality especially in sandy soils. To combat this stress, adaptation at the farm level using new and cost-effective amendments are required. Field trials were conducted in two different climatic zones to determine the efficacy of cane molasses, bagasse ash, sugar beet factory lime, and their compost mixtures to improve soil quality and heat stress-adapting canola. The results showed a significant improvement in bulk density, hydraulic conductivity, organic matter content, and available macronutrients of sandy soil and subsequent canola growth, yield, quality and water productivity due to the application of the tested soil amendments, particularly those mixed with compost. Despite the estimated reduction of yield by 18.5% due to heat stress, application of sugar beet lime and compost mixture not only compensated for this reduction but also increased the seed yield by 27.0%. These findings highlight the value of recycling compost-based sugar crop disposal as a cost-effective technology to boost crop tolerance to abiotic stress, ensuring sustainable agriculture and food security in arid environments.

Effect of urea fertilization on growth of broad bean (Vicia faba L.) under various nickel (Ni) levels with or without acetic acid addition, using 15N-labeled fertilizer.

Although nickel (Ni) has direct relationship with nitrogen metabolism of plants, the high dose of Ni fertilizer in broad bean plants may affect the nitrogen use efficiency (NUE), impair plant development and even cause Ni pollution in soil. Thus, a pot experiment was set up to study the effect of urea fertilization on N-uptake, root and shoots' Ni content as well as growth of broad bean plants under different levels of Ni, using 15N tracer technique. 15N-labeled urea (5% 15N atom excess) was added at three doses (0, 30 and 60 mg N kg-1 soil). Nickel sulfate (NiSO4) was also applied at three levels (0, 50 and 100 mg Ni kg-1 soil). The experiment was laid out with or without acetic acid in randomized complete block design in three replicates. Treatment with the addition of 60 mg N + 50 mg Ni showed the highest values in dry weights of root and shoots, N-uptake by shoots, nitrogen derived from fertilizer (Ndff %) and NUE % by shoots in both with or without acetic acid solution. Higher rate of Ni addition can decrease shoot and root biomass by inhibiting the ability of the plant to uptake the nitrogen efficiently. However, addition of acetic acid solution induced the improvement of NUE % and Ndff % by shoot and root of broad bean plants. This study provides insight into how to improve plant yield without damaging the soil health and will be helpful to create a better world with sustainable agriculture.

The impact of pyrolysis conditions on orange peel biochar physicochemical properties for sandy soil.

The citrus industry is considered one of the main contributors to agricultural waste. Peels are commonly used in the food industry or as feedstock in biorefining. In this study, the potential of waste orange peel biochar for agricultural applications in sandy soil was investigated. This will not only increase the percentage of agricultural waste recycling, but also lead to more sustainable agriculture with environmental benefits such as carbon sequestration. Biochar was produced through slow pyrolysis in the temperature range 300-600°C and at two holding durations (10 min and 60 min). Both factors had a significant impact on the physicochemical characteristics of biochar in the heating region 300-450°C. However, varying the holding time for pyrolysis temperatures beyond 450°C had a diminishing effect on biochar properties compared with the impact of increasing pyrolysis temperature. The study also looked at certain properties that are specific to agricultural application not previously reported for orange peel. Very high cation exchange capacities of 70 cmol kg-1 were achieved at 300°C, whereas water holding capacity was not strongly influenced by pyrolysis conditions. Preliminary planting tests indicate potential for improving agricultural sustainability in sandy soils. The technoeconomic analysis of biochar showed that the pyrolysis process can be profitable with sufficient plant capacity.

Streptomyces harenosi sp. nov., a home for a gifted strain isolated from Indonesian sand dune soil.

A polyphasic study was undertaken to establish the position of a Streptomyces strain, isolate PRKS01-65T, recovered from sand dune soil collected at Parangkusumo, Yogyakarta Province, Java, Indonesia. A combination of chemotaxonomic, cultural and morphological properties confirmed its position in the genus of Streptomyces. Comparative 16S rRNA gene sequence analyses showed that the isolate was most closely related to Streptomyces leeuwenhoekii C34T (99.9 % similarity) and loosely associated with the type strains of Streptomyces chiangmaiensis (98.7 % similarity) and Streptomyces glomeratus (98.9 % similarity). Multilocus sequence analyses based on five conserved housekeeping gene alleles confirmed the close relationship between the isolate and S. leeuwenhoekii C34T, although both strains belonged to a well-supported clade that encompassed the type strains of S. glomeratus, Streptomyces griseomycini, Streptomyces griseostramineus, Streptomyces labedae, Streptomyces lomondensis and Streptomyces spinoverrucosus. A comparison of the draft genome sequence generated for the isolate with corresponding whole genome sequences of its closest phylogenomic neighbours showed that it formed a well-separated lineage with S. leeuwenhoekii C34T. These strains can also be distinguished using a combination of phenotypic properties and by average nucleotide identity and digital DNA-DNA hybridization similarities of 94.3 and 56 %, values consistent with their classification in different species. Based on this wealth of data it is proposed that isolate PRKS01-65T (=NCIMB 15211T=CCMM B1302T=ICEBB-03T) be classified as Streptomyces harenosi sp. nov. The genome of the isolate contains several biosynthetic gene clusters with the potential to produce new natural products.

The stimulatory effects of plant growth promoting rhizobacteria and plant growth regulators on wheat physiology grown in sandy soil.

The present study was aimed to investigate the effects of plant growth promoting rhizobacteria (PGPR) and plant growth regulators (PGRs) on the physiology and yield of wheat grown in less fertile sandy soil. The isolated PGPR strains were identified by 16S-rRNA gene sequencing as Planomicrobium chinense (P1), Bacillus cereus (P2) and Pseudomonas fluorescens (P3). Wheat varieties (Galaxy-13 and Pak-2013) differing in sensitivity to drought were soaked in fresh cultures of bacterial isolates and the PGRs (salicylic acid and putrescine) were sprayed at 150 mg/L on seedlings at three leaf stage. PGPR and PGRs treated plants showed significant increase in the contents of chlorophyll, sugar and protein even under harsh environmental conditions. Drought stress enhanced the production of proline, antioxidant enzymes and lipid peroxidation but a decrease was noted in the biochemical content (i.e. chlorophyll, protein and sugar) of inoculated plants. PGPR inoculation also significantly enhanced the yield parameters (i.e. plant height, spike length, grain yield and weight) and improved the fertility status of sandy soil. The accumulation of macronutrient, total NO3-N and P concentration and soil moisture content of rhizosphere soil was also enhanced by PGPRs inoculation. It is concluded that the combined effects of PGPR and PGRs have profound effects on the biochemical responses and drought tolerance of wheat grown in sandy soils.

Ahniella affigens gen. nov., sp. nov., a gammaproteobacterium isolated from sandy soil near a stream.

A bacterial strain, designated D13T, was isolated from sandy soil near a stream in Sinan-gun, Republic of Korea. Cells were Gram-stain-negative, aerobic, non-motile and flexible rod-shaped. Growth occurred at 15-35 °C (optimum 30 °C) and pH 6.5-8.0 (pH 7.0). NaCl was not obligatory for growth but could be tolerated at up to 0.5 % (w/v) NaCl. The DNA G+C content of the genomic DNA of strain D13T was 57.7 mol% and a phylogenetic analysis of the 16S rRNA gene sequence revealed that strain D13T formed a distinct evolutionary lineage within the family Rhodanobacteraceae of the order Lysobacterales. Strain D13T showed highest 16S rRNA sequence similarity to Lysobacter hankyongensis KTCe-2T (92.7 %), followed by Luteimonas cucumeris Y4T (92.7 %), Dyella japonica XD53T (92.6 %) and Aquimonas voraii GPTSA 20T (92.5 %). The major cellular fatty acids (>10 % of the total) were iso-C16 : 0, iso-C15 : 0 and summed feature 9 (iso-C17 : 1ω9с and/or C16 : 0 10-methyl). The respiratory quinone was ubiquinone-8 and the major polar lipids of the isolate consisted of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylmonomethylethanolamine. Based on polyphasic analysis, strain D13T could be differentiated from other genera in the family Rhodanobacteraceae, which suggests that strain D13T represents a novel species of a new genus in the family Rhodanobacteraceae, for which the name Ahniella affigens gen. nov., sp. nov. is proposed. The type strain is D13T (=KACC 19270T=JCM 31634T).

Actinomadura deserti sp. nov., isolated from desert soil.

A Gram-positive, strictly aerobic actinobacterium, designated BMP B8004T, was isolated from desert soil collected in Xinjiang Province, Northwest China. It produced an extensively branched non-fragmenting substrate mycelium, and very scanty aerial mycelium that formed a short hooked chain of arthrospores with a smooth surface. Optimum growth occurred at 28 °C, pH 7.0 and 0 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain BMP B8004T formed a distinct phyletic lineage within the genus Actinomadura. It shared the highest 16S rRNA gene sequence similarity to Actinomadura apis IM17-1T (99.2 %) and Actinomadura rifamycini NBRC 14183T (98.6 %). However, it could be distinguished from the two closest strains based on the low levels of DNA-DNA relatedness (52.7±0.7 and 45±1.8 %, respectively). Chemotaxonomic characteristics, including the main phospholipids, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannosides, the major menaquinones MK-9(H6) and MK-9(H8), the predominant fatty acids iso-C16 : 0, C16 : 0, C18 : 0 10-methyl and C18 : 1ω9c, were also consistent with the properties of the genus Actinomadura. The DNA G+C content of strain BMP B8004T was 71.9 mol%. Based on phenotypic and genotypic features, strain BMP B8004T is considered to represent a novel species of the genus Actinomadura, for which the name Actinomadura deserti sp. nov. is proposed. The type strain is BMP B8004T (=CGMCC 4.7432T=KCTC 39998T).

Pedobacter yulinensis sp. nov., isolated from sandy soil, and emended description of the genus Pedobacter.

A Gram-staining-negative, rod-shaped, strictly aerobic, non-motile, non-spore-forming, orange bacterium, which was designated strain YL28-9T, was isolated from sandy soil in the district of Yulin, Shaanxi province, PR China, and was characterized by using a polyphasic taxonomic approach. The optimal growth conditions of the strain were 30 °C, pH 7.0, 0 % (w/v) NaCl. Phylogenetic analysis, based on the 16S rRNA gene sequence, revealed that YL28-9T represented a member of the genus Pedobacter and showed the highest sequence similarity to Pedobacter rhizosphaeraeKACC 14938T (95.1 %). The genomic DNA G+C content of this strain was 50.4 mol%, which was out of the range reported for the other strains of members of the genus Pedobacter. The only respiratory quinone detected in YL28-9T was menaquinone-7 (MK-7). The predominant cellular fatty acids were identified as iso-C15 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and iso-C17 : 0 3-OH. The major polar lipid was phosphatidylethanolamine. On the basis of the results of phenotypic, genotypic, chemotaxonomic and phylogenetic analysis, YL28-9T could be distinguished from the most closely related species of the genus Pedobacter. It is evident from the derived data that YL28-9T represents a novel species of the genus Pedobacter,for which the name Pedobacter yulinensis sp. nov. is proposed. The type strain is YL28-9T (=CGMCC 1.16050T=KCTC 62104T). An emended description of the genus Pedobacteris proposed.

Bacterial polyextremotolerant bioemulsifiers from arid soils improve water retention capacity and humidity uptake in sandy soil.

BACKGROUND: Water stress is a critical issue for plant growth in arid sandy soils. Here, we aimed to select bacteria producing polyextremotolerant surface-active compounds capable of improving water retention and humidity uptake in sandy soils. RESULTS: From Tunisian desert and saline systems, we selected eleven isolates able to highly emulsify different organic solvents. The bioemulsifying activities were stable with 30% NaCl, at 4 and 120 °C and in a pH range 4-12. Applications to a sandy soil of the partially purified surface-active compounds improved soil water retention up to 314.3% compared to untreated soil. Similarly, after 36 h of incubation, the humidity uptake rate of treated sandy soil was up to 607.7% higher than untreated controls. CONCLUSIONS: Overall, results revealed that polyextremotolerant bioemulsifiers of bacteria from arid and desert soils represent potential sources to develop new natural soil-wetting agents for improving water retention in arid soils.

Effects of exogenously applied salicylic acid and putrescine alone and in combination with rhizobacteria on the phytoremediation of heavy metals and chickpea growth in sandy soil.

The present attempt was made to study the role of exogenously applied salicylic acid (SA) and putrescine (Put) on the phytoremediation of heavy metals and on the growth parameters of chickpea grown in sandy soil. The SA and Put were applied alone as well as in combination with plant growth promoting rhizobacteria (PGPR). The PGPRs, isolated from the rhizosphere of chickpea, were characterized on the basis of colony morphology and biochemical traits through gram staining, catalase and oxidase tests, and identified by 16S-rRNA gene sequencing as Bacillus subtilis, Bacillus thuringiensis and Bacillus megaterium. The chickpea seeds were soaked in 24 h old fresh cultures of isolates for 2-3 h prior to sowing. The growth regulators (PGRs), SA and Put (150 mg/L), were applied to the seedlings as foliar spray at three-leaf stage. The result revealed that plants treated with SA and Put alone or in combination with PGPRs, significantly enhanced the accumulation of heavy metals in plant shoot. PGPR induces Ni accumulation in sensitive variety and Pb in both the varieties, the PGR in combination augment the bioremediation effects of PGPR and both sensitive and tolerant variety showed significant accumulation of Ni, Cd, and Pb. SA was more effective in accumulating Ni and Cd whereas, significant accumulation of Pb was recorded in Put. PGPRs further augmented the PGRs induced accumulation of heavy metals and macronutrients in chickpea shoot and in rhizosphere. SA increased the proline content of tolerant variety while decreasing the lipid peroxidation and proline content of the sensitive variety but decreased the stimulating effect of PGPR in proline production. Interactive effects of PGPR and PGRs are recommended for inducing phytoremediation in chickpea plants under drought stress.

Analysis of water and nitrogen use efficiency for maize (Zea mays L.) grown on soft rock and sand compound soil.

BACKGROUND: Maize was grown on compound soils constituted from mixtures of soft rock and sand at different ratios, and water use efficiency (WUE), nitrogen use efficiency (NUE) and fertilizer nitrogen use efficiency (FNUE) were quantified. The data were used to assist in designing strategies for optimizing water and nitrogen management practices for maize on the substrates used. Maize was sown in composite soil prepared at three ratios of soft rock and sand (1:1, 1:2 and 1:5 v/v) in Mu Us Sandy Land, Yuyang district, Yulin city, China. Yields, amount of drainage, nitrogen (N) leaching, WUE and NUE were calculated. Then a water and nitrogen management model (WNMM) was calibrated and validated. RESULTS: No significant difference in evapotranspiration of maize was found among compound soils with soft rock/sand ratios of 1:1, 1:2 and 1:5, while water drainage increased significantly with increasing soft rock/sand ratio. WUE increased to 1.30 kg m-3 in compound soil with 1:2 soft rock/sand ratio. Nitrogen leaching and ammonia volatilization were the main reason for nitrogen loss, and N reduction mainly relied on crop uptake. NUE and FNUE could reach 33.1 and 24.9 kg kg-1 N respectively. Water drainage and nitrogen leaching occurred mostly during heavy rainfall or irrigation. Through a scenario analysis of different rainfall types, water and fertilizer management systems were formulated each year. CONCLUSION: This study shows that soft rock plays a key role in improving the WUE, NUE and FNUE of maize. © 2016 Society of Chemical Industry.

The effect of soil type on the bioremediation of petroleum contaminated soils.

In this research the bioremediation of four different types of contaminated soils was monitored as a function of time and moisture content. The soils were categorized as sandy soil containing 100% sand (type I), clay soil containing more than 95% clay (type II), coarse grained soil containing 68% gravel and 32% sand (type III), and coarse grained with high clay content containing 40% gravel, 20% sand, and 40% clay (type IV). The initially clean soils were contaminated with gasoil to the concentration of 100 g/kg, and left on the floor for the evaporation of light hydrocarbons. A full factorial experimental design with soil type (four levels), and moisture content (10 and 20%) as the factors was employed. The soils were inoculated with petroleum degrading microorganisms. Soil samples were taken on days 90, 180, and 270, and the residual total petroleum hydrocarbon (TPH) was extracted using soxhlet apparatus. The moisture content of the soils was kept almost constant during the process by intermittent addition of water. The results showed that the efficiency of bioremediation was affected significantly by the soil type (Pvalue < 0.05). The removal percentage was the highest (70%) for the sandy soil with the initial TPH content of 69.62 g/kg, and the lowest for the clay soil (23.5%) with the initial TPH content of 69.70 g/kg. The effect of moisture content on bioremediation was not statistically significant for the investigated levels. The removal percentage in the clay soil was improved to 57% (within a month) in a separate experiment by more frequent mixing of the soil, indicating low availability of oxygen as a reason for low degradation of hydrocarbons in the clay soil.

Calibration of contact parameters of sandy soil for planting tiger nut based on non-linear tools.

A methodology combining physical experiments with simulation was employed to acquire contact parameters of sandy soil precisely for planting tiger nuts in the desert area of Xinjiang. The stacking angle under different parameter combinations was applied as a response value. Through the Plackett-Burman test, several factors that have a significant influence were determined. The steepest ascent test was conducted to establish the finest scope of values for these parameters. The stacking angle was considered the response variable, and non-linear tools were used to optimize these parameters for simulation. The findings showed that applying response surface methodology (RSM) resulted in a relative error of 1.24%. In the case of BP-GA, the relative error compared to the physical test value was 0.34%, while for BP, it was 2.18%. After optimization using Wavelet Neural Network (WNN), the relative error was reduced to only 0.15%. Results suggest that WNN outperforms the RSM model, and the sandy soil model and parameters generated using WNN can be effectively utilized for discrete element simulation research.

Calcium-enriched biochar shifts negative effects of fluoride on the properties of arid sandy soil.

This study sheds light on the influence of fluoride on the changes in the properties of alkaline sandy soils and the efficiency of calcium-enriched biochar application. The investigation involved an incubation experiment with soil contaminated with varying NaF concentrations (0, 400, 800, and 1200 mg NaF kg-1 soil) and biochar (1% w/w). The data revealed that adding NaF to the soil resulted in significant increases in soil pH and decreases in total nitrogen (TN) content. Short-term fluoride pollution did not affect the microbial abundance due to certain factors such as increased soil pH and decreased microbial metabolism promoting the survival of cells under fluoride stress. However, a shift from bacterial to fungal-dominated microbial communities was observed at the highest NaF concentration. The nitrogen functional gene amoA was found to be highly sensitive to fluoride toxicity. The decrease in the abundance of amoA gene and the increase in soil pH can explain reduced nitrogen concentration. On the other hand, our findings indicated a significant decrease in enzyme activity in soil contaminated with mild to severe levels of NaF. This reduction in enzyme activity can be attributed to increased soil pH, decreased TN content, and the inhibition of microbial metabolism due to fluoride toxicity. Furthermore, the addition of calcium-rich biochar reduced fluoride solubility and adjusted pH, mitigating the negative effects of fluoride toxicity on soil properties. The use of biochar was also found to inhibit the accumulation of soil fluoride-resistant microbial genes.