Content Of Available Potassium Research Articles

Microenvironment created by Plantago lagopus L. may affect cover and diversity of coexisting species in urban vegetation

Some plant species may exhibit new microenvironments which lead to significant changes in the cover and diversity of the coexisting species. In this investigation, we evaluated the effects of Plantago lagopus L. on the cover and diversity of the associated plant species in the urban vegetation. A total of 70 plots were conducted in sites with- and without this species in urban gardens. Cover of the associated species and different diversity indices including species richness, Shannon-Wiener, evenness, and Simpson indices were measured. The allelopathic potential of P. lagopus was verified using its rhizosphere and non-rhizosphere soils on two target species existing within the same environment. Some soil criteria and seed sizes of the associated species were also determined. Most of the coexisting weeds were reduced in terms of their cover in plots with Plantago. The reduction of plant diversity depended on its cover. Besides, the aboveground biomass was reduced in sites comprising Plantago. The degree of inhibition was not related to the seed size of the species found. This species reduced the incident solar radiation and the local temperature over the soil surface. The locations exhibiting such species contained lower contents of available potassium and zinc. Rhizosphere soil of P. lagopus substantially inhibited germination and growth of Amaranthus viridis, but it didn't do so for Medicago lupulina. Reduction in cover, diversity, and biomass of the urban weeds associated with P. lagopus may be related to the reduction of received solar radiation, soil temperature, and nutrient availability. The allelopathic potential of P. lagopus may have a partial role in this reduction. These results suggest that P. lagopus may create a microenvironment of new conditions not favorable for most of the coexisting species.

Tobacco/Salvia miltiorrhiza Intercropping Improves Soil Quality and Increases Total Production Value

Unreasonable cultivation methods and management measures have led to widespread obstacles in tobacco continuous cropping in planting areas, resulting in reduced tobacco yield and soil degradation. Therefore, intercropping tobacco with other crops is an effective strategy to improve continuous cropping barriers. In this study, flue-cured tobacco NC102 and conventional planting varieties of Salvia miltiorrhiza were used as materials, and four treatments of flue-cured tobacco monoculture (CK), flue-cured tobacco, and Salvia miltiorrhiza at a ratio of 1:1 (TS11), 2:2 (TS22), and 2:3 (TS23), respectively, were set up to study their effects on soil microorganisms, physical and chemical properties, and yield and quality of flue-cured tobacco. The results showed that intercropping Salvia miltiorrhiza increased the number of soil bacteria and actinomycetes, decreased the number of fungi, and increased the activity of urease and sucrase. The content of available nitrogen and available phosphorus in intercropping Salvia miltiorrhiza soil was significantly higher than that of the flue-cured tobacco monoculture, while the content of available potassium was lower than that of the flue-cured tobacco monoculture. The soil environment was more conducive to the growth of flue-cured tobacco. Compared with the flue-cured tobacco monoculture, the proportion of superior tobacco in intercropping Salvia miltiorrhiza increased by 2.2–3.4%, and the ratio of potassium to chlorine in leaves of different parts of flue-cured tobacco increased by 12.3–75.0%. The content of total sugar and soluble sugar in middle and upper leaves of intercropping flue-cured tobacco was higher than that of the flue-cured tobacco monoculture, which improved the quality of flue-cured tobacco. From the analysis of the chemical composition of tobacco leaves, TS11 (flue-cured tobacco and Salvia miltiorrhiza intercropping row ratio of 1:1) had the best treatment effect, potassium content, total sugar, reducing sugar content, and potassium chloride ratio of flue-cured tobacco were the highest, the chlorine content was the lowest, and the quality was better than other treatments. From the analysis of total output value, the total output value of TS22 (flue-cured tobacco and Salvia miltiorrhiza intercropping row ratio of 2:2) was higher than that of other intercropping treatments. In 2018 and 2019, the total output value increased by 21.3% and 22.4%, respectively, compared with the flue-cured tobacco monoculture. The intercropping advantage was obvious, and the treatment effect was the best.

Ralstonia solanacearum differentially modulates soil physicochemical properties and rhizospheric bacteriome of resistant and susceptible tobacco cultivars

Ralstonia solanacearum is a devastating soilborne pathogen which poses significant yield and economic losses to tobacco production globally. The impact of R. solanacearum on rhizosphere bacteriome and soil physicochemical characteristics in resistant and susceptible tobacco cultivars is poorly understood. This study aims to determine the effect of R. solanacearum on soil physicochemical parameters and rhizosphere bacteriome of resistant (K326) and susceptible (Hongda) tobacco cultivars at various growth stages. Results demonstrated that the contents of available potassium and phosphorus, as well as soil pH were significantly increased in K326 soils (CK and T2) compared with Hongda (T1) after 21, 42, and 63 days post-inoculation (dpi) of R. solanacearum except for available nitrogen which showed an opposite trend. The qPCR results showed a significant decrease in R. solanacearum population in rhizosphere of K326 (T2) compared to the Hongda (T1) at 21 and 63 dpi than that after 42 dpi. The rhizosphere bacteriome analysis through 16S rRNA amplicon sequencing revealed that rhizosphere bacterial community composition was significantly different between two tobacco cultivars (Hongda and K326) and this effect was more prominent after 63 dpi (93 days after post-transplantation), suggesting that each cultivar recruits a unique set of bacterial communities. There was no obvious difference observed in the rhizosphere bacteriome of CK (K326) and T2 (K326), which might be attributed to the same genetic makeup and inherent resistance of K326 to bacterial wilt infection. Analysis of co-occurrence networks revealed that the microbial network in T1 (Hongda) was more complex than those in T2 (K326) and CK (K326), while the networks in CK and T2 were almost identical. The present research highlights the time-course relationship between environmental factors and rhizosphere bacteriome of tobacco cultivars showing different levels of resistance against R. solanacearum. Conclusively, studying the plant-soil-microbe interaction system in susceptible and resistant tobacco cultivars may enable us to develop effective integrated disease control plans for the healthy production of tobacco crops.

Effects of Microplastics on the Leaching of Nutrients and Cadmium from Soil

The environmental effects of microplastics, which are considered a type of emerging contaminants, have attracted increasing concern due to their small size, large specific surface area, strong adsorption capacity, and low degradability. Microplastics can change soil properties and affect the migration ability of nutrients and pollutants in soil, but their effects on the leaching of soil nutrients and heavy metals have not been sufficiently studied. A soil column leaching experiment was conducted to explore the effects of polystyrene (PS) and polylactic acid (PLA) microplastics at different mass fractions (0%, 0.2%, and 2%) on the leaching of nutrients and cadmium under simulated rainfall scenarios. The results showed that increasing rainfall intensity enhanced the leaching of nutrients and cadmium from soil. During downpour conditions, 2% PS significantly increased the leaching of total nitrogen and the content of available phosphorus in soil and reduced the leaching of inorganic phosphorus and the content of ammonium nitrogen in the soil, whereas it increased the content of available potassium during heavy rain. By comparison, 2% PLA reduced the leaching of nitrate nitrogen during heavy rain and intense rainfall and decreased the content of ammonium nitrogen in soil during intense rainfall and downpour conditions and the content of total nitrogen in soil during downpours. In addition, 0.2% PLA significantly increased cadmium leaching during downpours. To conclude, the effects of microplastics on the leaching of nutrients and cadmium were dependent on the type and concentration of microplastics, as well as the rainfall level. Our findings showed that the microplastics derived from both nondegradable PS and biodegradable PLA could affect the leaching of nutrients and heavy metals from soil.

Analysis on the Impact of Various Slope Ecological Restoration Techniques on Soil Fertility and Physicochemical Properties During the Summer Drought Period in Red Soil Area of Northeast Jiangxi Province

[Purpose] This study aims to investigate the impacts of three slope restoration techniques, namely, soil spray sowing, vegetation fiber, and vegetation concrete, on soil fertility, pH, and organic matter content during the summer drought period. The study also aims to explore the advantages of these three different restoration techniques, providing a basis for slope restoration in the Northeast Jiangxi region. [Methods] The study used experimental slopes established with three different restoration techniques: soil spray sowing, vegetation fiber, and vegetation concrete. Soil samples were collected during the rainy season in July 2022 and the drought season in September 2022. The changes in hydrolyzable nitrogen, available potassium, available phosphorus content, pH, and organic matter in the soil after restoration were comprehensively investigated. The study relies on the Qi-Wu expressway, and all the experiments are set on the slopes on both sides of the expressway. [Results]①For the soil restored using soil spray sowing during the drought season, the content of hydrolyzable nitrogen and available potassium was higher than that of the original soil, while the content of available phosphorus significantly decreased. The pH changed from acidic to weakly alkaline. ②For the soil restored using vegetation fiber during the drought season, although the content of available phosphorus increased, it was still relatively low. The content of available potassium decreased, but the total amount remained high. The content of hydrolyzable nitrogen was high and showed an increasing trend. The pH slightly decreased from weakly acidic to acidic. ③For the soil restored using vegetation concrete during the drought season, the content of hydrolyzable nitrogen, available potassium, and available phosphorus was high and showed an increasing trend. The pH slightly decreased, but it remained weakly alkaline before and after the drought. [Conclusion] Soil spray sowing, vegetation fiber, and vegetation concrete, all three restoration techniques, could demonstrate good performance during the drought period in the Northeastern Jiangxi region. In terms of their overall performance, the ranking from strong to weak is as follows: vegetation concrete > vegetation fiber > soil spray sowing. Soil spray sowing, as the most convenient and cost-effective slope restoration technique, could in the future incorporate additives that can improve local soil properties according to different regional characteristics. Vegetation fiber not only needs to improve soil acidity-alkalinity but should also appropriately incorporate phosphorus-containing additives. Vegetation concrete needs to address the issue of reducing soil acidity-alkalinity after restoration in the future.

Edaphic growth conditions of Prunus cerasifera Ehrh. in Nikitsky Botanical Garden

A soil survey was carried out under the collection plantings of Prunus cerasifera Ehrh., growing on the experimental site of the Nikitsky Botanical Garden. During the research, the morphological structure, granulometric composition, pH, content of carbonates, humus, exchangeable potassium, oxalate-soluble (amorphous) iron were studied using generally accepted methods of soil analysis. The content of mobile forms of micronutrients and heavy metals (Zn, Cu, Mn, Pb, Cd) was determined in ammonium acetate extract at pH=4.8. It was revealed that the soils of the experimental site are characterized by favorable physical, chemical properties and agrochemical parameters for cherry plum plants, including uniform distribution of humus along the profile, slightly alkaline reaction, low content of carbonates, high content of available potassium. Among the mobile forms of trace elements and heavy metals, exceeding of the maximum permissible concentration was found only for copper, the source of which is copper-containing fungicides. The slightly alkaline reaction of the soil contributes to a decrease in the mobility of micronutrients and heavy metals, therefore, even with their excessive content in the soil, there was no excess of maximum permissible concentration in cherry plum fruits.

Application of Poultry Manure Improves the Soil Sorption Capacity and Nutrient Regime of Vineyard Soils

ABSTRACT The sorption capacity and nutrient regime under different soil management practices (C – control, T – tillage and PM – tillage + poultry manure) in productive vineyard soil (Rendzic Leptosol) in the Nitra vineyard region (Nitra-Dražovce, Slovakia, Central Europe) were studied for the years 2013–2022. With T and PM, the soil pH was significantly lower than with C. The soil sorption capacity for both studied depths (0–30 and 30–60 cm) increased in the following order: T < PM < C. For all the soil management practices and soil depths, the soil sorption complex was fully saturated with basic cations. With T, in the 0–30 cm layer, the total nitrogen (Nt) content was lower by 218 and 292 mg kg−1, respectively, than with C and PM. However, in the period 2013–2022, the Nt increased statistically significantly, by 50.9, 87.6 and 97.8 mg kg−1 year−1 with T, C and PM, respectively. The application of PM had a positive effect on the increase in available phosphorus (P) – there was an increase with C and T of 96 and 112%, respectively. The content of available P increased linearly with all soil management practices. However, in the case of T, it was statistically significant (increase of 23.2 mg kg−1 year−1) over the period of 10 years. With PM, at 0–30 cm, the content of available potassium was significantly higher, by 29 and 91%, than with treatments C and T.

Daylily intercropping: Effects on soil nutrients, enzyme activities, and microbial community structure.

The daylily (Hemerocallis citrina Baroni)/other crop intercropping system can be a specific and efficient cropping pattern in a horticultural field. Intercropping systems contribute to the optimization of land use, fostering sustainable and efficient agriculture. In the present study, high-throughput sequencing was employed to explore the diversity in the root-soil microbial community in the intercropping of four daylily intercropping systems [watermelon (Citrullus lanatus)/daylily (WD), cabbage (Brassica pekinensis)/daylily (CD), kale (Brassica oleracea)/daylily (KD), watermelon/cabbage/kale/daylily (MI)], and determine the physicochemical traits and enzymatic activities of the soil. The results revealed that the contents of available potassium (2.03%-35.71%), available phosphorus (3.85%-62.56%), available nitrogen (12.90%-39.52%), and organic matter (19.08%-34.53%), and the urease (9.89%-31.02%) and sucrase (23.63%-50.60%) activities, and daylily yield (7.43%- 30.46%) in different intercropping soil systems were significantly higher compared to those in the daylily monocropping systems (CK). The bacterial Shannon index increased significantly in the CD and KD compared to the CK. In addition, the fungi Shannon index was also increased significantly in the MI, while the Shannon indices of the other intercropping modes were not significantly altered. Different intercropping systems also caused dramatic architectural and compositional alterations in the soil microbial community. A prominently higher relative richness of Bacteroidetes was noted in MI compared to that in CK, while Acidobacteria in WD and CD and Chloroflexi in WD were pronouncedly less abundant compared to those in CK. Furthermore, the association between soil bacteria taxa and soil characteristic parameters was stronger than that between fungi and soil. In conclusion, the present study demonstrated that the intercropping of daylily with other crops could significantly improve the nutrient levels of the soil and optimize the soil bacterial microflora composition and diversity.

The relationship between shifts in the rhizosphere microbial community and root rot disease in a continuous cropping American ginseng system.

The root rot disease causes a great economic loss, and the disease severity usually increases as ginseng ages. However, it is still unclear whether the disease severity is related to changes in microorganisms during the entire growing stage of American ginseng. The present study examined the microbial community in the rhizosphere and the chemical properties of the soil in 1-4-year-old ginseng plants grown in different seasons at two different sites. Additionally, the study investigated ginseng plants' root rot disease index (DI). The results showed that the DI of ginseng increased 2.2 times in one sampling site and 4.7 times in another during the 4 years. With respect to the microbial community, the bacterial diversity increased with the seasons in the first, third, and fourth years but remained steady in the second year. The seasonal changing of relative abundances of bacteria and fungi showed the same trend in the first, third, and fourth years but not in the second year. Linear models revealed that the relative abundances of Blastococcus, Symbiobacterium, Goffeauzyma, Entoloma, Staphylotrichum, Gymnomyces, Hirsutella, Penicillium and Suillus spp. were negatively correlated with DI, while the relative abundance of Pandoraea, Rhizomicrobium, Hebeloma, Elaphomyces, Pseudeurotium, Fusarium, Geomyces, Polyscytalum, Remersonia, Rhizopus, Acremonium, Paraphaeosphaeria, Mortierella, and Metarhizium spp. were positively correlated with DI (P < 0.05). The Mantel test showed that soil chemical properties, including available nitrogen, phosphorus, potassium, calcium, magnesium, organic matter, and pH, were significantly correlated to microbial composition. The contents of available potassium and nitrogen were positively correlated with DI, while pH and organic matter were negatively correlated with DI. In summary, we can deduce that the second year is the key period for the shift of the American ginseng rhizosphere microbial community. Disease aggravation after the third year is related to the deterioration of the rhizosphere microecosystem.

Warming changes the composition and diversity of fungal communities in permafrost

PurposeIt is the data support and theoretical basis for the response mechanism of soil fungi to climate warming in permafrost areas in the Greater Xing’an Mountains.MethodsWe collected permafrost from the Greater Xing’an Mountains for indoor simulation experiments and took the natural permafrost as the control (CK) and the test groups of 0 °C (T1), 2 °C (T2), and 4 °C (T3) were set. Illumina MiSeq high-throughput sequencing technology was used to understand the changes in characteristics of fungal communities, and the correlations were analyzed combined with the soil physicochemical properties.ResultsCompared with CK, the value of pH and the content of available potassium (AK) in the three warming treatment groups were significantly lower (P < 0.05), and the microbial biomass carbon (MBC) content was significantly higher (P < 0.05). The content of total nitrogen (TN) and available nitrogen (AN) in the T1 and T3 groups was significantly lower than that in the CK group (P < 0.05). A total of 11 phyla, 39 classes, 89 orders, 187 families, 361 genera, and 522 species were obtained through fungal sequencing and divided into 1463 amplicon sequence variants (ASVs). Ascomycota and Dimorphospora were the dominant phylum and genus, respectively, and there were differences in the response of relative abundance of various groups at the phylum and genus levels to warming. Warming significantly decreased the Sobs and ACE indexes of the treatment groups (P < 0.05), and the Shannon and Shannoneven indexes also showed a downward trend. Moreover, warming significantly changed the fungal beta diversity (P < 0.01), while the value of pH and the content of TN, MBC, and AK could significantly affect the community structure (P < 0.05), and the correlation between fungi at different phyla levels and soil physicochemical properties was different.ConclusionsThese results can provide a reference for further study on the changes in composition and structure of fungal communities and the influence factor in permafrost in the Greater Xing’an Mountains under the background of warming.

Effects of green manure intercropping on soil nutrient content and bacterial community structure in litchi orchards in China

Green manure intercropping is an agronomic management practice that effectively increases soil nutrients in understory and reduces weed population. However, the influence of different green manures on soil properties and soil bacterial community in litchi orchards in the tropical regions of China remains largely unknown. Here, we examined the effect of intercropping three leguminous green manure crops in litchi orchards of Hainan Province. No intercropping was used as the control. Different green manures increased the contents of different soil nutrients. For example, Desmodium ovalifolium increased the total nitrogen content by 7.93%; Grona heterocarpos increased the ammonium nitrogen content by 558.85%; and Stylosanthes guianensis increased the available phosphorus content by 1207.34%. However, intercropping with D. ovalifoliu and S. guianensis reduced the content of available potassium by 47.29% and 58.48%, respectively. The intercropping of green manure increased the abundance of several microbial genera, including Bradyrhizobium, Serratia, and Bacillus, which are known to facilitate soil nitrogen accumulation, plant growth, and phosphorus dissolution. Compared with no intercropping, the three intercropping treatments significantly improved the contents of soil ammonium nitrogen and soil available phosphorus in the litchi orchard. Therefore, intercropping with green manure crops in litchi orchards is an effective management measure; however, the choice of the green manure crop should be based on the soil conditions of litchi orchards.

Enhanced Root and Stem Growth and Physiological Changes in Pinus bungeana Zucc. Seedlings by Microbial Inoculant Application

Background and Objectives: As an extensively used tree species in landscaping and afforestation in China, lacebark pine (Pinus bungeana Zucc.) seedlings are in high demand. However, the small number of fine roots and the low growth rate of lacebark pine seedlings increase the risks encountered during transplant and extend the nursery time for outplanting. We aimed to find out whether a microbial inoculant would promote root growth and accordingly, shorten the nursery cultivation time. Materials and Methods: One-year-old lacebark pine seedlings were treated with the inoculant Bacillus subtilis 8–32 six times from June to September. At each application time, five treatments of undiluted microbial inoculants (UM), 30 times diluted microbial inoculants (30 DM), 40 times diluted microbial inoculants (40 DM), 50 times diluted microbial inoculants (50 DM), and distilled water as a control (CTRL) were administered to the seedlings. In the end, all the seedlings were harvested to measure the root growth, aboveground growth, and the physiological indices. Results: Root and stem growth was enhanced by the inoculants in terms of the increased number of root tips, the length and surface area of the roots, the biomass of the roots and stems, as well as the increase in height and basal stem diameter. The chlorophyll a/b of the needles was increased, in spite of the fact that the total chlorophyll content was decreased by the microbial inoculant treatments at the end of the growth phase. Meanwhile, the maximum photochemical efficiency (Fv/Fm) of the needles was increased by the inoculant treatments. The soluble sugar content was additionally translocated into the stems in the UM treatment, suggesting the change in carbon allocation. The content of available potassium, phosphorus, and ammonium nitrogen in the potting soil was increased in the 30 DM group, and the content of soil organic matter was increased in all the inoculant treatments. Conclusions: The microbial inoculant Bacillus subtilis 8–32, in appropriate concentrations, could be applied to promote root and shoot growth and improve the seedling quality of the lacebark pine during cultivation.

Synergic remediation of polycyclic aromatic hydrocarbon-contaminated soil by a combined system of persulfate oxidation activated by biochar and phytoremediation with basil: A compatible, robust, and sustainable approach

A new remediation strategy for polycyclic aromatic hydrocarbon (PAH)-contaminated soil was proposed using a combination of ammonium persulfate (APS) oxidation activated by iron-modified biochar (FBC) and phytoremediation with the aromatic plant, basil. After the 105-day pot experiment, the removal rates of soil total Σ16 PAHs by this combined system reached 61.6%–69.5%. In the combined system, basil grew the best among all treatment groups because the addition of FBC and APS increased the contents of available potassium and nitrogen in soil. The essential oils extracted from basil were deemed free of PAH contamination. High-throughput sequencing of soil bacteria and fungi after 105 days revealed that the advanced oxidation process substantially reduced the richness and diversity of soil microbes, which were restored to the original state by basil. Results indicate that the combined system can remediate the contaminated soil in a synergy by pronouncing the degradative capacity of FBC-APS while mitigating its adverse effects, which is suggested to be an effective, robust, and sustainable approach that holds promise for future site applications.

Effects of Biochar and Straw Returning on Soil Fungal Community Structure Diversity in Cotton Field with Long-term Brackish Water Irrigation

Brackish water irrigation increases soil salinity and changes the soil environment, which affects the structure and diversity of soil fungi. In this study, the effects of biochar and straw (3.7 t·hm-2 and 6 t·hm-2, respectively) on soil physical and chemical properties and fungal community structure diversity were investigated on the basis of long-term brackish water irrigation. The results showed that compared to the absence of biochar and straw application (control), biochar application significantly increased pH and the contents of total carbon, available potassium, and available phosphorus in soil but significantly decreased the soil conductivity by 20.71%. Straw treatment significantly increased the content of available potassium and phosphorus but significantly decreased the soil bulk density and conductivity by 4.17% and 64.50%, respectively. The biochar and straw treatment showed an increasing trend in the Chao1 index and ACE index of the fungal community but a decreasing trend in the Shannon index and Simpson index. The dominant fungal phyla in the soil were Ascomycota, Mortierellomycota, Basidiomycota, Chytridiomycota, and Glomeromycota. The dominant fungal genera were Chaetomium, Gibberella, Fusarium, Idriella, and Mortierella. Biochar and straw were applied to increase the relative abundance of Ascomycota, Mortierellomycota, Basidiomycota, Glomeromycota, and Chaetomium. However, the relative abundance of Chytridomycota, Gibberella, and Idriella decreased. LEfSe analysis showed that biochar application and straw returning decreased the number of potential biomarkers in fungal communities. RDA results showed that soil fungal community structure was significantly correlated with EC1:5 and TN. Brackish irrigation had adverse effects on soil, in which EC1:5and TN were the main factors driving the change in soil fungal community structure. The soil fungal community adapted to a salt-stress environment through the improvement of soil by biochar and straw.

Divergent Response of the Supply Capacity and Turnover of Inorganic Nitrogen to Pitaya Cultivation in the Subtropical Karst Region of Southwest China

Determining the availability and supply capacity of soil inorganic nitrogen (N) can effectively guide the appropriate application of N fertilizers during crop cultivation. However, the mechanism underlying soil inorganic N production remains unknown for cash crops in karst regions. In this study, the rates of organic N mineralization to ammonium (NH4+) and NH4+ nitrification to nitrate (NO3−) were determined using a 15N tracing technique to evaluate the supply capacity of inorganic N in soils from woodland and pitaya plantations with different cultivation years (3, 9, and 15 years) in the subtropical karst region of China. The conversion of woodland to pitaya plantations significantly decreased the content of soil organic carbon (SOC), total N, calcium (Ca), and magnesium (Mg), along with the soil pH and cation-exchange capacity (CEC), but significantly increased the content of available potassium, available phosphorus, iron, and aluminum, in a more pronounced fashion with the increasing length of pitaya cultivation. The conversion of woodland to pitaya plantations has not significantly changed soil NH4+ and NO3− content, but this land use has resulted in divergent effects on mineralization and nitrification rates. Compared to woodland (5.49 mg N kg−1 d−1), pitaya cultivation significantly reduced the mineralization rate to 0.62–2.38 mg N kg−1 d−1. Conversely, the nitrification rate significantly increased from 4.71 mg N kg−1 d−1 in soil under woodland to 9.32 mg N kg−1 d−1 in soil under 3-year pitaya cultivation, but this rate decreased to 1.74 mg N kg−1 d−1 under 15-year cultivation. Furthermore, the mean residence time of inorganic N was significantly higher in long-term than in short-term pitaya plantations, indicating the decline in inorganic N turnover with the increasing length of pitaya cultivation. Taken together, long-term pitaya cultivation could significantly decrease the supply capacity and turnover of inorganic N in soil. The Ca, Mg, SOC, and total N content, as well as CEC, were significantly and positively related to the mineralization rate, but negatively related to the mean residence time of NH4+ and NO3−, suggesting that the incorporation of organic matter can accelerate the soil inorganic N supply and turnover for long-term pitaya plantation in subtropical regions.

Intercropping Pinto Peanut in Litchi Orchard Effectively Improved Soil Available Potassium Content, Optimized Soil Bacterial Community Structure, and Advanced Bacterial Community Diversity

Intercropping is widely used in agricultural production due to its capability of raising land productivity and providing an opportunity to achieve sustainable intensification of agriculture. In this study, soil samples from 10 to 20 cm depth of intercropping Pinto peanut in litchi orchard and litchi monoculture mode were established to determine soil attributes, enzyme activities, as well as the effect on soil bacterial diversity. On this basis, 16S rRNA V4-V5 region of soil bacterial communities in litchi/Pinto peanut intercropping (LP) mode and litchi monoculture mode (CK) was detected by the Illumina MiSeq sequencing platform. The results showed that the content of available potassium (AK) in LP was significantly higher than that in CK by 138.9%, and the content of available nitrogen (AN) in LP was significantly lower than that in CK by 19.6%. The soil enzyme activities were higher in LP as a whole, especially sucrase (SC) and acid protease (PT) were significantly higher by 154.4 and 76.5%, respectively. The absolute abundance and alpha diversity of soil microbiota were significantly higher in the intercropping group. Most importantly, endemic species with a significant difference in LP was higher by ~60 times compared to CK treatment. In the aspect of soil bacterial community structure, the dominant phyla of the two groups were Acidobacteria, Proteobacteria, Chloroflexi, and Actinobacteria. At the genus level, the absolute abundance of Flavobacterium and Nitrososphaera was significantly higher by 79.20 and 72.93%, respectively, while that of Candidatus_Koribacter was significantly lower with an amplitude of 62.24% in LP than in CK. Furthermore, the redundancy analysis (RDA) suggested that AK, which was highly associated with the dominant genera and phyla, is the vitally dominating environmental factors in LP groups, while in CK groups, it is AN and pH. In addition, PICRUSt2 analysis indicated that intercropping improved the metabolic activity of bacteria which can be correlated to the resistance of litchi root systems to soil-borne diseases. Overall, this study is expected to provide a theoretical basis and technical support for the healthy intercropping cultivation of litchi.

Physico-chemical Characteristics and Nutrient Status of Guava (Psidium guajava L.) Orchards in North-Western India

One hundred eight soil samples were collected from 12 guava orchards existing at different locations as well as 108 soil samples from non-orchard soils adjoining in the vicinity of selected orchards spread over five blocks of district Rewari namely Bawal, Rewari, Jatusana, Khol and Nahar. The samples were collected from 3 depths (0-15, 15-30, 30-60 cm) and analyzed for physico-chemical properties and available nutrients viz., nitrogen, phosphorus and potassium. The composite leaf sample of guava plants was also collected from each orchard. Rewari district soils (orchard and non-orchard) were sandy loam to loamy sand in nature. The calcium carbonate content in soils showed an increasing trend with depth and it increased significantly with an increase in sand and pH. Soils were alkaline with low organic carbon and nearly one-third of samples were saline. Available nitrogen was low, available phosphorus was low to medium while available potassium was medium to high in soil samples. Despite the high content of available potassium in soils, the plant leaves were found deficient in potassium. Therefore, the use of balanced fertilizers is required for sustainable and enhanced productivity of the guava orchards.

Effects of different land consolidation methods on soil properties of cultivated land

As an important reserve cultivated land resource in my country, its development and utilization are of great significance to ensure food security. Aiming at the problems of bare gravel leakage and shallow soil layer in the barren rock beach area, through community simulation experiments, different covering soil structures were set up on the basis of the underlying gravel, and the effects of different covering soil structures on soil physical and chemical properties and crop yield were monitored to obtain Find suitable soil structures. The results show that: when the covering thickness is 60cm, the content of total nitrogen and available phosphorus in the soil reaches the maximum; when the soil bulk density is set to 1.5 g/cm3, the content of available phosphorus in the soil reaches the maximum. The content of available potassium increased with the increase of soil bulk density.

Early effects of crop tree management on undergrowth plant diversity and soil physicochemical properties in a Pinus massoniana plantation

BackgroundSoil and understory vegetation are vital components of forest ecosystems. Identifying the interaction of plantation management to vegetation and soil is crucial for developing sustainable plantation ecosystem management strategies. As one of the main measures of close-to-nature management of forest plantation, few studies have paid attention to the effect of crop tree management on the soil properties and understory vegetation.MethodsA 36-year-old Pinus massoniana plantation in Huaying city, Sichuan Province was taken as the research object to analyse the changes in undergrowth plant diversity and soil physicochemical properties under three different crop tree densities (100, 150, and 200 N/ha).ResultsOur results showed that the contents of available phosphorus, organic matter and hydrolysable nitrogen in the topsoil increased significantly after crop tree management, while content of available potassium decreased. The composition of shrub and herb layer was richer, and the dominant species were obviously replaced after crop tree management. The Shannon–Wiener index and Richness index of shrub layer, and the diversity of herb layer increased significantly after crop tree management. Herb layer diversity indexes and Richness index of shrub layer were closely related to soil organic matter, available phosphorus, hydrolysable nitrogen, available potassium, soil moisture and bulk density. As the main limiting factors for plant growth, nitrogen, phosphorus and potassium were closely related to plant diversity and to the distribution of the dominant species. At the initial stage of crop tree management, each treatment significantly improved the soil physicochemical properties and plant diversity of Pinus massoniana plantation, and the comprehensive evaluation was 200 N/ha >100 N/ha >150 N/ha >CK. Compared with other treatments, 200 N/ha had the best effect on improving the undergrowth environment of the Pinus massoniana plantation in the initial stage of crop tree management.

English

Myxobacteria can produce rich and varied biological active substances against bacteria, fungi and viruses, which have great development and research value in medicine and agriculture. In this study, the diversity of culturable myxobacteria in central Inner Mongolia in China was studied and the effects of soil utilization mode, soil type and environmental parameters on the distribution of myxobacteria in this region were analyzed. Furthermore, the activities of myxobacteria against potato late blight pathogen were tested. The results showed that Myxococcus, Corallococcus, Pyxidicoccus, Cystobacter, Archangium and Mellittangium were the dominant genera of myxobacteria in this region. Soil utilization mode and soil types have obvious influence on the distribution of myxobacteria. The populations of myxobacteria were abundant in grassland and cultivated land samples, but few in woodland and unused land samples. The diversity of myxobacteria in the soil samples from fuvo-aquic soils, grey-cinnamon soils, castanozems, and bog soils was relatively rich, while the richness of myxobacteria in aeolian soils, solonetzs, skeletol soils and castano-cinnamon soils was poor. There was no significant correlation between myxobacteria distribution and soil environmental parameters (including the water content, pH value, content of organic matter, content of available phosphorus, content of hydrolytic nitrogen and content of available potassium). Most of the myxobacterial strains isolated in this area (83%) showed the activity against P. infestans, among which the proportion of the disease-resistant strains belonging to Myxococcus and Corallococcus was high, the proportion of the strains belonging to Cystobacter and Mellittangium in the medium, and the proportion of the strains belonging to Pyxidicoccus and Archangium low. The completion of this work will enrich the myxobacteria resource bank in Inner Mongolia and lay a foundation for the further study on myxobacteria and the development of biological pesticide against potato late blight. © 2021 Friends Science Publishers