Soil Total Nitrogen Content Research Articles

Effects of corn stalks returning on soil microbial carbon use efficiency and corn yield in semi-arid cropland

Soil microbial carbon use efficiency (CUE) is a key parameter controlling the short-term carbon (C) cycle in terrestrial ecosystems. The effect of urea application (156 kg N ha-1) and corn stalks returning (9.0 tons ha-1) on soil microbial CUE and corn yield in semi-arid cropland was studied using the 18O-labeled water approach during a one-year experiment. In semi-arid cropland, applying urea reduced soil microbial CUE by 44%, while the soil microbial CUE was increased significantly by 34% after returning corn stalks to the field. The application of urea increased the total nitrogen content of soil by 23%, and corn stalks returning further increased nitrate nitrogen (NO3–-N) by 45%, dissolved organic carbon (DOC) by 53%, and dissolved organic nitrogen (DON) by 122%. Compared with no fertilization, urea application increased the corn height by 4% and the corn yield by 21%. Corn stalks returning combined with urea reduced the corn stalks by 37% compared with no fertilizer. There was no significant difference in corn yield between corn stalks returning combined with urea and single urea application. Therefore, corn stalks returning combined with urea may be an effective agronomic measure to increase soil carbon sequestration, improve soil fertility, maintain corn yield, restore soil fertility, and improve production capacity.

Evaluation of Phytoremediation, Physicochemical and Heavy Metal Assessment of Crude Oil Polluted Soil Using Pseudomonas and Bacillus spp, Rivers State, Nigeria

Crude oil exploration has been beneficial to our economy but detrimental to our environment with the artisanal `refineries further compounding the challenge. This research was aimed at investigating the phytoremediation, physicochemical and heavy metal assessment of crude oil polluted soil using Peudomonas spp. and Bacillus spp. as augmenting microorganism, in Rivers state, Nigeria. This study was carried out in in south-south Nigeria (B-dere in Gokana Local government of `Rivers State). Contaminated Soil were collected and subjected to standard microbiological methods. Contaminated Soil samples were collected from two different area of Rivers state with sterilized soil auger at two depths of 0-15cm and 15-30cm. The contaminated soil sampled were analyzed for heavy metal (Cadium Chromium, Lead and Zinc) using Atomic Absorption spectrophotometric method. Microbiological analysis was carried out on the soil samples. Ten (10) treatments consisiting of contaminated soil (CS), uncontaminated soil (US), uncontaminated soil(US), Panicum subalbidum and Schoenoplectus senegalensis were setup for a period of 28 days. Physicochemical parameters were analyzed for uncontaminated soil and contaminated soil. The physicochemical parameters analyzed were pH, Temperature, Nitrogen, Phosphorus, Potassium and Total Hydrocarbon Content. The physiochemical parameters of the uncontaminated soil were pH (5.43), temperature (27oC), Electrical conductivity (9uS/cm), Moisture content (7.80%), Total organic carbon (0.93%), Soil organic matter (1.60%), total Nitrogen (56.695mg/kg), available phosphorus (0.621mg/kg), potassium (7.125mg/kg) and total hydrocarbon content (700mg/kg). Results revealed that the amount of hydrocarbon remediated and percentage (%) bioremediation in the soil after 28 days of monitoring from the initial THC value of (4050 mg/kg), is higher in set up with CS+PSE+SCH (3454mg/kg; 85.28%) and lowest in set up with US+SCH (434mg/kg: 62%) and the amount uptake of phytoremediation in the root after 28 days of monitoring to be higher in set up with CS+BAC+SCH (632Mg/kg; 15.6%) and lowest in set up with US+SCH (12.2mg/kg; 1.74%). The heavy metals assessed were cadium (Cd), chromium (Cr), lead (Pb) and zinc (Zn). This research revealed and recommend that Schoenoplectus senegalensis as a suitable plant species for phytoremediation of crude oil contaminated soil. Hydrocarbon utilizing bacteria identified in this study were; Pseudomonas and Bacilus spp.

Alpine Meadow Degradation Changed Soil Nitrogen Characteristics in the Eastern Qilian Mountains Area, Northwest China

ABSTRACT Nitrogen is the crucially sustainable element for most ecosystem including grassland. Fenced alpine meadow grassland (FG), lightly, moderately and heavily degraded (LD, MD and HD) alpine meadow in spring, summer and winter were studied to clear the effects of alpine meadow degradation on soil total nitrogen (TN), available nitrogen (AN), ammonium nitrogen (NH4 +-N), nitrate nitrogen (NO3 –-N), inorganic nitrogen (IN) content and the ratio of inorganic nitrogen to available nitrogen (IN/AN), and to find practical management strategies on the background of alpine meadow degradation and ecological environment restoration in the Eastern Qilian Mountains area, northwest China. The results showed that soil total nitrogen contents of the alpine meadow types were at a low level, ranged from 1.60 g·kg−1 to 5.15 g·kg−1, but soil available nitrogen contents was at a high level, ranged from 373.2 mg·kg−1 to 650.8 mg·kg−1in the study area. Alpine meadow degradation can seasonally change soil nitrogen status. Degraded alpine meadow had more inorganic nitrogen than fenced meadow in surface soil. Degradation only changed soil NO3 −-N profile distribution in winter and had no significant effect on profile distribution of TN, AN, NH4 +-N and IN. There were significant interactions of alpine meadow types, seasons and soil depth on soil available nitrogen, NH4 +-N, NO3 –-N and inorganic nitrogen content. Although soil available nitrogen increased under degradation, nitrogen input is needed in the restoration of heavily degraded alpine meadow during the summer growing season to improve vegetation coverage because of the low soil inorganic nitrogen and IN/AN ratio in summer growing season in 10–20 cm and 20–30 cm depth.

How applied reclamation treatments and vegetation type affect on soil fauna in a novel ecosystem developed on a spoil heap of carboniferous rocks

The restoration of soil fauna on a spoil heap is a strong indicator of successful reclamation. The studies were conducted on two types of materials: bare rock (BR) and BR with topsoil (TS) which were applied during coal spoil reclamation and three vegetation types. Four variants investigated included natural forest succession on BR (Succession_BR) and TS (Succession_TS), afforestation (Reclamation_TS) and afforestation with Robinia pseudoacacia (Robinia_TS). Soil pH, soil organic carbon (SOC) and total nitrogen (TN) content, and soil texture were measured in 0–10 cm layers. Earthworms were collected using hand sorting method, and enchytraeids were collected using wet extraction with the heating method.The investigated soil had varying pH values from 5.3 in a BR to 7.2 in Robinia_TS. The highest content of SOC and TN were in Successinon_BR, and the lowest was in Succession_TS. Enchytraeids density was in the following increasing order: 275, 2982, 3001 and 4548 ind m−2 for Succession_BR, Robinia_TS, Succession_TS and Reclamation_TS, respectively. Earthworm density ranged from 0 ind. m−2 in the Succession_BR through 116 ind m−2 and 120 ind m−2 in Reclamation_TS and Succession_TS, respectively up to 162 ind m−2 in the Robinia_TS.The reclamation treatment was a major driver for soil fauna development while vegetation type was of secondary importance. Investigated soil fauna was positively related to pH value and clay content. The most stimulating variant for the development of earthworms and enchytraeids was the application of reclamation with various tree species and the planting of Robinia pseudoacacia on the topsoil.

Biochar alleviates the crop failure of rice production induced by low-nitrogen cultivation mode by regulating the soil microbes taxa composition.

To improve the nitrogen utilization efficiency and a series of environmental problems caused by excessive application of nitrogen fertilizer, actual agricultural production often reduced the usage ratio of nitrogen fertilizer. However, the reduction in nitrogen fertilizer not only affects the soil microenvironment but also leads to adverse effects on rice yield. Due to its unique properties, biochar can regulate soil nutrient distribution and significantly affect soil microbial community structure/functions. To further understand the effects of different levels of biochar on soil nutrient indicators, soil microorganisms and crop growth under the nitrogen-reduction condition, our experiment with four groups was set up as followed: 0%, 2.5% and 5% biochar application rates with 99kg/hm2 nitrogen fertilizer and one control group (the actual fertilizer standard used in the field:110kg/hm2) without no exogenous biochar supplement. The rice yield and soil nutrient indexes were observed, and the differences between groups were analyzed based on multiple comparisons. 16S ribosomal RNA and ITS sequencing were used to analyze the community structure of soil bacteria and fungi. Redundancy analysis was performed to obtain the correlation relationships between microbial community marker species, soil nutrient indexes, and rice yield. Path analysis was used to determine the mechanism by which soil nutrient indexes affect rice yield. The results showed that a higher application rate of biochar led to a significant increased trend in the soil pH, organic matter and total nitrogen content. In addition, a high concentration of biochar under nitrogen-reduction condition decreased the soil bacterial diversity but elevated the fungal diversity. Different concentrations of biochar resulted in these changes in the relative abundance of soil bacteria/fungi but did not alter the dominant species taxa. Taken together, appropriate usage for biochar under the nitrogen-reduction background could induce alteration in soil nutrient indicators, microbial communities and crop yields. These results provide a theoretical basis for exploring scientific, green and efficient fertilization strategies in the rice cultivation industry. Notably, the interaction relationship between rhizosphere microorganisms in rice and soil microbial taxa are not yet clear, so further research on its detailed effects on rice production is needed. In addition, the Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis for the physiological functions of the soil microbes could only predict the potential metabolic pathways. Therefore, the next-generation metagenome techonology might be performed to explore detailed metabolic differences and accurate taxa alteration at the "species" level.

Soil Microbial Community and Their Relationship with Soil Properties across Various Landscapes in the Mu Us Desert

Soil microorganisms play crucial roles in maintaining material circulation and energy flow in desert ecosystems. However, the structure and function of soil microorganisms in different forestlands are currently unclear, restricting the use of sand-fixing plants and the understanding of forest ecosystem functions. In this study, Artemisia ordosica, Caragana korshinskii, and Salix psammophila, three types of sand-fixing forests widely distributed in the Mu Us Sandy Land, were used to explore the effects of sand-fixing forests on soil physicochemical properties, soil enzyme activity, soil microbial biomass, microbial community structure, and inter-microbial species relationships. Soils of forestlands showed higher soil organic carbon (SOC), total phosphorus (TP), and total nitrogen (TN) contents than bare sandy land. The SOC in bare sandy soil was only 0.84 g kg−1, while it remained 1.55–3.46 g kg−1 in forestland soils. The TN in bare sandy land soil was 0.07 g kg−1, which was significantly lower than that in forestland soils (0.35–0.51 g kg−1). The TP in bare sandy soil was 0.18 g kg−1, significantly lower than that in forestland soils (0.46–0.69 g kg−1). Afforestation of bare sandy land improved soil microbial carbon and nitrogen contents and increased microbial enzyme activities of acid phosphatase and N-acetyl-β-D-glucosaminidase. Significant differences were observed between the three forestlands and bare sandy land in terms of soil microorganisms and community composition. With the establishment of a sand-fixing forest, the alpha diversity of soil bacteria significantly improved, whereas that of soil fungi remained stable. The bacterial community comprised 33 phyla, 106 classes, 273 orders, 453 families, and 842 genera. While five fungal phyla were detected by OTUs at a similarity of 97%, bacterial and fungal community structures were affected by the organic carbon content, sand particle content, soil pH, total nitrogen, and total phosphorus contents of soils. This study is helpful for vegetation construction and protection on sandy lands from the perspective of plant-microbe interactions.

Synergistic effects of earthworms and cow manure under reduced chemical fertilization modified microbial community structure to mitigate continuous cropping effects on Chinese flowering cabbage.

The substitution of chemical fertilizers with organic fertilizers is a viable strategy to enhance crop yield and soil quality. In this study, the aim was to investigate the changes in soil microorganisms, soil chemical properties, and growth of Chinese flowering cabbage under different fertilization treatments involving earthworms and cow manure. Compared with the control (100% chemical fertilizer), CE (30% reduction in chemical fertilizer + earthworms) and CFE (30% reduction in chemical fertilizer + cow dung + earthworms) treatments at soil pH 8.14 and 8.07, respectively, and CFC (30% reduction in chemical fertilizer + cow manure) and CFE treatments increased soil organic matter (SOM), total nitrogen (TN), available nitrogen (AN), and available potassium (AK) contents. Earthworms and cow manure promoted the abundance of Bacillus and reduced that of the pathogens Plectosphaerella and Gibberella. The mantle test revealed that pH was not correlated with the microbial community. Random forest analysis verified that AN, SOM, and TN were important factors that jointly influenced bacterial and fungal diversity. Overall, the synergistic effect of earthworms and cow manure increased soil fertility and microbial diversity, thereby promoting the growth and development of Chinese flowering cabbage. This study enhanced the understanding of how bioregulation affects the growth and soil quality of Chinese flowering cabbage, and thus provided a guidance for the optimization of fertilization strategies to maximize the yield and quality of Chinese flowering cabbage while reducing environmental risks.

Effect of different biochar additions on the change of carbon nitrogen content and bacterial community in meadow soils

ABSTRACT Meadow soils are one of the important agricultural soil types, biochar is a good soil amendment, whereas the studies on the effects of biochar additions on carbon and nitrogen contents, as well as bacterial communities of meadow soils, were seldom carried out. The effects of one nitrogen addition rates (no addition, 0.2% addition) and two biochar addition patterns (no addition, 1% addition, 3% addition) on the carbon and nitrogen contents, as well as bacterial communities of meadow soils, were investigated by conducting a one-year indoor incubation experiment. Biochar addition increased the relative abundance of Proteobacteria, Chloroflexi and Bacteroidota. The combination of biochar and nitrogen source significantly increased the total organic carbon, ammonium nitrogen, nitrate nitrogen and total nitrogen content of the meadow soil. Therefore, the addition of moderate amounts of biochar to meadow soils can contribute to sustainable ecological agriculture as a form of soil improvement.

AM fungus promotes wheat grain filling via improving rhizospheric water & nutrient availability under drought and low density

Arbuscular mycorrhizal fungi (AMF) are widely considered as ecosystem engineers to positively affect the adaptation of plants to adverse environments, but whether AMF can commonly promote root-soil relationships and reproductive allocation is unclear in dryland crops. It is crucial to reveal if AMF can promote grain filling via mediating rhizosphere interactions regardless of soil water regimes and planting densities in dryland crops for the application of AMF regarding more precise management. To address this issue, Funneliformis mosseae was inoculated in pot-cultured wheat to examine the inoculation effects on wheat growth, yield formation, rhizospheric moisture and nutrient status across four planting densities under the drought and well-watered conditions. As expected, under drought stress, wheat grain filling, shoot biomass, rhizospheric soil water content (SWC), water use efficiency (WUE), soil organic carbon (SOC) content and the ratio of SOC to soil total nitrogen (TN) contents were significantly lowered in the soils without AMF inoculation across four planting densities. Under well-watered conditions, the SWC ranged from 10.30 % to 16.64 %, while under water stress conditions, the values ranged from 5.77 % to 9.61 %. Soil mineralized nitrogen (NO3−-N and NH4+-N) contents were decreased with AMF regardless of soil water status and planting densities. Under drought stress, AMF inoculation increased wheat productivity, WUE, SWC, SOC content, the ratio of SOC to TN, and promoted the absorption of mineralized nitrogen. Particularly, AMF inoculation substantially promoted the soil easily oxidizable organic carbon (EOC) content by 58.5 % and 55.6 % in the two highest densities, respectively. The soil microbial biomass carbon (MBC) content was totally >50 mg kg−1, whereas that of the non-AMF group was <40 mg kg−1. AMF inoculation significantly promoted grain yield up to 28.5 % under drought stress. Such a trend was tightly associated with higher WUE, rhizosphere C/N ratio and labile SOC (EOC and MBC) content owing to the enhanced absorption of soil mineralized nitrogen under drought stress with AMF. The above trend tended to become weaker with increasing densities. However, under a sufficient water supply, AMF inoculation had no such significant effect on the above parameters in low densities, and turned to generate negative effects under high densities (P < 0.05). For example, compared with well-watered, AMF inoculation reduced wheat grain yield and shoot weight by 9.78 % and 4.83 % in high planting density treatment (HC), respectively. Therefore, the inoculation effects of AMF were highly dependent on planting density and soil moisture, and the mechanism was that AMF optimized the rhizospheric interactions for better water and nutrient status under drought and low density. Our findings may provide novel insights into the application of AMF regarding agricultural sustainability under climate change.

Mulching cannot further amplify the improved effects of infiltration hole on soil environment in level ditch in semiarid loess plateau, northwestern China

Vegetation restoration is an important strategy for addressing global climate change challenges. Slope engineering measures are conducive to improve vegetation growth by improving soil environments. Infiltration hole is an effective supplement of existing measures to enhance the replenishment of deep soil water and nutrients in semi-arid area, but also increases shallow soil evaporation after rainfall. Can mulching further enhance the improved effects of infiltration hole on soil environments in slope measure via reducing ineffective evaporation under field conditions? In this study, the effects of different measures on soil environment and vegetation growth in level ditch were estimated, including control (LD) and infiltration hole (LD-IH), branch mulching (LD-BM), and their combination (LD-IH-BM). The results showed that the replenishment depth of rainfall was not variable under LD-BM after two rainy seasons, however, the one was increased by 40 cm and 30 cm under LD-IH and LD-IH-BM, respectively. The soil water storage (0–300 cm) under LD-IH and LD-IH-BM was obviously increased by 52.5/66.2 mm and 40.4/54.1 mm compared with LD/LD-BM, respectively. The increment of soil water storage (50–150 cm) was significantly higher under LD-IH and LD-IH-BM than LD and LD-BM. LD-BM just increased soil organic carbon and total nitrogen content of 0–10 cm soil layer and LD-IH and LD-IH-BM mainly increased that of 60–100 cm. The soil carbon/nitrogen storage (0–120 cm) was increased by 13.0/0.80 Mg hm−2, 29.8/2.81 Mg hm−2, and 20.3/2.54 Mg hm−2 under LD-BM, LD-IH, and LD-IH-BM, respectively. The contribution in the effects under LD-IH-BM was from infiltration hole rather than branch mulching, and even branch mulching had a negative effect. Overall, the combination of level ditch and infiltration hole is sufficient to promote the rehabilitation of slope in semi-arid areas by improving soil environment, but adding mulching would not continue to further amplify these effects. Despite these favorable changes, they were insufficient to promote the growth of C. korshinskii during the experimental period of less than two years. Based only on a short-term field trial, practitioners do not need to add mulching to the ecosystem of level ditch and infiltration hole in slope management. However, a longer-term trial is needed to evaluate the necessity for adding mulching because of its long-term effect on soil property improvement. Our findings provide the insight in selecting reasonably slope combined measures to successful vegetation restoration in semi-arid areas.

Response of soil nitrogen components and its vertical distribution to rainfall redistribution during Robinia pseudoacacia forest restoration on the Loess Plateau

The effects of vegetation restoration on soil moisture dynamics and nutrient content have been widely studied; however, the knowledge on variation in rainfall redistribution and soil nitrogen component characteristics remain limited, particularly with respect to their relationship in restored ecosystems. Therefore, the characteristics of plant community structure, rainfall redistribution, and soil nitrogen components from farmland and Robinia pseudoacacia (RP) plantations of four restoration ages (12, 20, 30, and 45 a) were investigated and measured in the Wuliwan watershed in the Loess Plateau, China. The results showed that changes in plant community structure affected the rainfall redistribution processes. The throughfall and moisture entering the soil (MES) had the largest proportions (79.50 % and 60.25 %) in the initial and second distributions of atmospheric rainfall, respectively. With the increase in restoration age, the content of soil total nitrogen (STN), soil nitrate nitrogen (SNN), soil soluble total nitrogen (SSTN), soil soluble organic nitrogen (SSON), and soil soluble inorganic nitrogen (SSIN) all increased with restoration age in the upper soil (0–40 cm), fluctuated in the middle soil (40–100 cm), and increased and then decreased in the deeper soil (100–200 cm). In addition, the vegetation restoration process can indirectly affect soil nitrogen content and distribution patterns by affecting the rainfall redistribution process. In the upper soil, litter interception (LI) had a significant effect on STN by affecting SSIN and SSON. In the middle soil, both LI and MES had significant effects on STN through SSIN and SSON, respectively. In the deeper soil, LI had no significant effect on any nitrogen component, whereas MES had a significant effect on STN by affecting SSIN. Overall, this study indicates that RP plantation restoration has the potential to transform rainfall redistribution and soil nitrogen distribution, providing an important reference for the reciprocal feedback relationship between water and nitrogen.

Effect of Multi-Walled Carbon Nanotubes on the Carbon and Nitrogen Cycling Processes in Saline Soil

Soil salinization is a pressing issue that needs to be addressed in current agricultural production. In this study, we utilized novel materials, unfunctionalized multi-walled carbon nanotubes (MWCNT) and functionalized multi-walled carbon nanotubes (MWCNT-OH), to explore the effects of soil carbon and nitrogen cycles in saline soil. We set up four treatments, which were exposed to two exposure doses of 1 g/kg and 1 μg/kg and two MWCNT types of functionalized MWCNT-OH and unfunctionalized MWCNT. Our results demonstrate that exposure of saline soil to 1 g/kg functionalized MWCNT-OH significantly increased the soil inorganic nitrogen (p &lt; 0.05), while also promoting the soil microbial biomass. This exposure can also potentially enhance greenhouse gas emissions from saline soil. Moreover, exposure to MWCNTs significantly increased the proportion of Actinobacteria and Proteobacteria, two dominant phyla (p &lt; 0.05), which in turn improved their contribution to the carbon and nitrogen cycling processes within saline soil. High exposure dose treatments (1 g/kg) significantly increased the abundance of functional genes associated with carbon metabolism, carbon fixation, methane metabolism, and nitrogen cycling processes within saline soil. In contrast, low exposure dose treatments (1 μg/kg) had no significant effect on the abundance of functional genes related to nitrogen cycling, but significantly increased the abundance of special functional genes related to carbon cycling. Redundancy analysis revealed that the microbial community composition within saline soil was significantly impacted by the soil total carbon, total nitrogen, and nitrate nitrogen content. Furthermore, it was observed that over 80% of the carbon and nitrogen cycling processes within the saline soil were contributed by the dominant phyla. In summary, our research confirms the potential applicability of MWCNTs within saline soil. Notably, exposure of saline soil to 1 g/kg functionalized MWCNT-OH exhibited the most significant promoting effect on the carbon and nitrogen cycles.

Long-term nitrogen fertilizer management for enhancing use efficiency and sustainable cotton (Gossypium hirsutum L.).

Optimal management of nitrogen fertilizer profoundly impacts sustainable development by influencing nitrogen use efficiency (NUE) and seed cotton yield. However, the effect of long-term gradient nitrogen application on the sandy loam soil is unclear. Therefore, we conducted an 8-year field study (2014-2021) using six nitrogen levels: 0 kg/hm2 (N0), 75 kg/hm2 (N1), 150 kg/hm2 (N2), 225 kg/hm2 (N3), 300 kg/hm2 (N4), and 375 kg/hm2 (N5). The experiment showed that 1) Although nitrogen application had insignificantly affected basic soil fertility, the soil total nitrogen (STN) content had decreased by 5.71%-19.67%, 6.67%-16.98%, and 13.64%-21.74% at 0-cm-20-cm, 20-cm-40-cm, and 40-cm-60-cm soil layers, respectively. 2) The reproductive organs of N3 plants showed the highest nitrogen accumulation and dry matter accumulation in both years. Increasing the nitrogen application rate gradually decreased the dry matter allocation ratio to the reproductive organs. 3) The boll number per unit area of N3 was the largest among all treatments in both years. On sandy loam, the most optional nitrogen rate was 190 kg/hm2-270 kg/hm2 for high seed cotton yield with minimal nitrogen loss and reduced soil environment pollution.

Coupling mechanism of C:N:P stoichiometry between plant and soil after long-term reclamation in the coastal area, eastern China

Human reclamation activity can significantly affect the balance of ecological processes and elements in the coastal wetland ecosystems. The coupling mechanism of C:N:P stoichiometry plays a vital role in exploring ecological processes and nutrient cycle in plant–soil systems which is still unclear in the coastal area after long-term reclamation. The carbon (C), nitrogen (N), and phosphorus (P) in plant and total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) content of the soil in a coastal reclamation area of Jiangsu Province, China were measured, and the coupling mechanism of plant and soil C:N:P stoichiometry were further analyzed with structural equation modeling (SEM). Results showed that the sediments in coastal wetland gradually transformed into arable soil and accumulated nutrition through the process of dehydration and desalination after reclamation. Soil TOC, TN, and TP content increased with the increasing reclamation time. Soil C:N ratio varied between 3.99 and 49.71, soil N:P ratios from a low of 0.11 to a high of 2.87, and soil C:P ratio fluctuated between 3.43 and 15.17. Plant C concentration decreased with the increasing reclamation time, while plant P and N content increased. Plant C:N ratios vary between 8.56 and 403.86, plant N:P ratios from a low of 0.72 to a high of 15.91, and plant C:P ratios vary between 65.60 and 1045.07. The growth of plants in the coastal reclamation area was supposed to be limited by the N element. Plant P element might be the medium between plant C and N. Soil WC significantly affected plant C:P, and soil EC had a significantly positive influence on plant N:P. This study highlighted that the coupling of C:N:P stoichiometry in plant and soil were tight and soil N:P could be a good predictor of plant C:P and N:P ratios.

Interactive effects between the invasive weed Stellera chamaejasme and grass: can arbuscular mycorrhizal fungi and fungal pathogens coregulate interspecific relationships?

The interaction between poisonous weeds and neighboring plants is complex. Poisonous weeds frequently have a competitive advantage in the interaction between poisonous weeds and neighboring plants. Arbuscular mycorrhizal fungi (AMF) and plant pathogenic fungi (PPF) are closely related to the interspecific relationships of plants. However, the role of AMF and PPF between poisonous weeds and neighboring grasses remains unclear. Here, we designed a pot experiment to determine the interspecific relationship between Leymus chinensis and Stellera chamaejasme and the regulation of AMF and PPF. The results showed that interactive effects between L. chinensis and S. chamaejasme significantly inhibited the aboveground growth of both but promoted the underground growth of L. chinensis. As the proportions of S. chamaejasme increased, the total nitrogen content and pH in the rhizosphere soil of L. chinensis were reduced, the soil pH of S. chamaejasme was reduced, and the relative abundance of AMF in the rhizosphere soil of L. chinensis significantly increased and that of S. chamaejasme decreased considerably. The relative abundances of PPF in the rhizosphere soil of both in the mono-cultures were significantly higher than those in the mixed cultures. Structural equation modeling indicated that soil abiotic (pH and N availability) and biotic (AMF and PPF) factors are major drivers explaining the interactive effects between L. chinensis and S. chamaejasme. We provided new evidence for the interspecific interactions between poisonous weeds and neighboring grasses and revealed the regulatory role of AMF and PPF in the interactive effects of both plants. This study will provide a scientific basis for the prevention and control of poisonous weeds and the vegetation restoration of degraded grasslands in the future.

The diversity and abundance of terrestrial snails in yankari game reserve, bauchi state, Nigeria

Land snails represent one of the most important groups of invertebrates in terrestrial ecosystems; this study was aimed at determining the distribution and abundance of land snails in Yankari Game Reserve Bauchi State, Nigeria. Land snails were investigated in Yankari using a combination of direct search and litter sieving techniques. 10 plots were sampled randomly within an area of 100m × 100m so as to have a good spread of each site. Soil sample were collected within each of the plots and analyzed for soil pH, total nitrogen, organic carbon, calcium and moisture content. A total of 103 specimens comprising of six species belonging to four molluscan families were collected from ten plots in Yankari Game Reserve. This showed that the molluscs were moderately diverse. The family, Achatinidae dominated the fauna in Yankari Game Reserve. This study has revealed that the land fauna in Yankari are moderately diverse with low densities. The result indicates that not all the sampling areas of the reserves had much species; it is therefore presumed that there may be richer areas of land snails which were not sampled in both sites.

Utilisation of Intrinsic and Extrinsic Soil Information to Derive Soil Nutrient Management Zones for Banana Production in a Smallholder Farm

In South Africa (SA), smallholder farmers contribute significantly to food production and play an essential role in the nation’s food and nutritional security. However, there is a lack of basic understanding of the spatial variability of soil nutrients and their controlling factors in these smallholdings, which subsequently hinders their agricultural production. In this work, we assessed the spatial variability and structure of key soil nutrients required by banana fruit, identified their factors of control, and delineated management zones in a smallholder farm. We used a regular grid (50 m × 50 m) to collect a total of 27 composite samples from the 0–30 cm depth interval and analysed for soil physicochemical properties. Our classical statistics results indicated that phosphorus (P), potassium (K), calcium (Ca) and zinc (Zn) varied highly, while magnesium (Mg) and total nitrogen (TN) varied moderately across the plantation. On the other hand, geostatistics revealed that P and K were strongly spatially dependent (implying a good structure), while Mg and Zn were moderately spatially dependent (indicating a moderate structure) across the banana plantation. Soil Ca and TN contents were found to be weakly spatially dependent (meaning there was no structure) across the farm. The spatial prediction maps showed that P, Mg and Zn contents were high in the northeast part (underlain by Valsrivier) and low in the northwest part (underlain by Westleigh) of the banana plantation farm. Similarly, K and Ca were low in the northwest part (underlain by Westleigh), but they were high in the south to southwest portion (underlain by Glenrosa) of the farm. Soil TN was high in the west part (underlain by Westleigh) and low in the east-northeast part (underlain by Valsrivier) across the plantation. Three management zones (MZs) were delineated for soil P, K and Ca, while for other nutrients (Mg, Zn and TN), two MZs were delineated. The results of this study provide baseline information for site-specific management of fertilisers to supplement soil nutrients in the field to improve banana productivity.

Soil Organic Carbon and Total Nitrogen Stocks and Interactions with Soil Metal Oxides in Different Climatic Zones

Studying both soil carbon (C) and nitrogen (N) storages in different climate zones and their relationship with climatic factors is of great significance for understanding soil fertility and predicting global climate change. Climate influences soil minerals, which are important for soil organic carbon (SOC) and N retention. However, there are few studies on SOC and soil total nitrogen (STN) storage in different climatic zones, and of the effects of soil oxidation minerals on SOC and STN storage. We measured the storage of SOC and STN and the content of oxidizable minerals in soils from different climatic regions, then obtained climate data from the China Meteorological Data Service Center, and finally investigated the effects of climate factors and soil oxides minerals on SOC and STN. The results showed that climatic factors (mean annual temperature—MAT, mean annual precipitation—MAP, and ≥10 °C mean annual cumulative temperature—MACT) had significant effects on SOC and STN content, and there was significant epistatic clustering of SOC and STN contents in different climatic zones. When MAT, MAP, and MACT increased, SOC and STN storage showed a trend of increasing and then decreasing, and both SOC and STN storages were largest in the middle temperate zone. The content of soil metal oxides (Al2O3, Fe2O3, Na2O, MgO, CaO, K2O, and TiO2) showed significant positive correlation with climatic factors (MAT, MAP, and MACT). The contents of Al2O3, Fe2O3, CaO, K2O, and TiO2 showed significant negative correlation with SOC and STN contents. In summary, our results showed that, although soil metal oxides (SMO) have a protective effect on SOC and STN to some extent, they do not change the influence of climatic factors on SOC and STN storage.

Soil and vegetation characteristics during the formation of typical Ligularia virgaurea degraded grassland.

To understand the formation process of typical poisonous plant degraded grassland, we studied the cha-racteristics of vegetation and soil during the gradual expansion of Ligularia virgaurea into the native grassland of Qinghai-Tibet Plateau. The results showed that population density, plant height, coverage, and biomass of L. virgaurea increased during the formation of L. virgaurea degraded grassland. In comparison with native grassland, the degraded grassland had higher total aboveground biomass (113.9%), soil total nitrogen concentration (61.0%), NH4+-N (77.9%), organic carbon concentration (45.3%), available phosphorus concentration (78.8%) as well as soil microbial biomass carbon (42.1%) and nitrogen (47.4%), but lower NO3--N (40.1%) and species richness (28.5%) and aboveground biomass (45.7%) of other species beyond L. virgaurea. The extremely strong abilities of interspecific inhibition and morphological plasticity of L. virgaurea, as well as efficient nutrient accumulation and utilization were the keys to its successful expansion, which facilitated the formation of typical L. virgaurea degraded grassland.

Deep Straw Burial Accelerates Straw Decomposition and Improves Soil Water Repellency

The continuous input, slow decomposition, and retention of straw can impede tillage and crop growth, and the decomposition process of the straw in soil is affected by its composition and the method of application. Experimental Station of Jilin Agricultural University, Changchun City, Jilin Province. The soil type was Argiudolls, the experimental field area was 30 m2, and the maize was planted continuously for 12 years without returning the straw to the field. There were four treatments: (1) control (CK), 10 g of straw was placed on the surface of a nylon mesh bag, and the nylon mesh bag was separated from the soil by polyethylene film without contacting with the soil; (2) straw mulching (CM), a nylon mesh bag with 10 g of straw was placed on the soil surface; (3) straw burying (CD), a nylon mesh bag with 10 g of straw was buried at a depth of 40 cm from the soil surface; (4) straw burying (CE), a nylon mesh bag with 40 cm of soil depth. Fifteen micro-zones were set up with a micro-zone area of 1 m2 and each micro-zone consisted of four treatments randomly grouped in three replicates per treatment. The on-site nylon bag burying trial started on 20 April 2021 and ended on 15 April 2022. Nylon bag and soil samples were collected on days 0, 30, 90, 180, 270, and 360. SOC, TN, straw component decomposition, and water droplet-soil contact angle were determined. Our results showed that the CE treatment increased soil organic carbon (SOC) and total nitrogen (TN) content compared to the CM and CD treatments. Compared with CK, straw decomposition rates increased by 13.3%, 30.8%, and 22.3% in the CM, CD, and CE treatments, respectively. Lignin decomposition rates increased by 7.8%, 27.3%, and 16.2%; cellulose decomposition rates increased by 14.6%, 35.4%, and 27.3%; and hemicellulose decomposition rates increased by 17.2%, 31.7% and 23.7% in the CD treatment, respectively. Compared with CK, the contact angle of droplets in the CD treatment was statistically significantly increased by 91.5% when the droplets remained on the soil surface for 5 s. The rate of decrease of droplet contact angle with time was statistically significantly decreased by 11.8%, and the penetration rate of droplets on the soil surface was slower. Overall, the CD treatment promoted straw decomposition and increased SWR compared to the CM and CE treatments. which are important attributes to enhance soil quality and improve soil structural stability.