Resources and Environment
The study was conducted to investigate the effects of reduced nitrogen fertilization combined with the biostimulants of fulvic acid and chitosan on the growth and development, glycoside content, and nitrogen uptake of Stevia rebaudiana, aiming to provide a theoretical basis for optimizing fertilization practices and enhancing quality and efficiency in Stevia production. Stevia rebaudiana was used as the test material, and four nitrogen fertilization levels were set, including conventional nitrogen application (300 kg/hm2), 20% nitrogen reduction (240 kg/hm2), 40% nitrogen reduction (180 kg/hm2) and no nitrogen application (0 kg/hm2). These were supplemented with either the fulvic acid (F) or chitosan (C), with an equal amount of water (W) serving as the control. The impacts on Stevia rebaudiana growth characteristics, leaf enzyme activities, glycoside content, and nitrogen uptake were analyzed. The results showed that nitrogen application, as well as the combination with fulvic acid and chitosan, promoted Stevia rebaudiana growth, relative chlorophyll content, and nitrogen uptake. Specifically, the treatment with 20% nitrogen reduction supplemented with fulvic acid (N0.8F) resulted in a plant height of 97.0 cm, stem diameter of 9.19 mm, and leaf mass per plant of 18.70 g, which were approximately 12.30%, 13.05% and 9.76% higher than other treatments, respectively. Nitrogen uptake in both leaves and stems was higher than in other treatments. The average contents of rebaudioside A (RA) in the treatments supplemented with fulvic acid, chitosan, and the control were 10.93%, 10.13% and 10.80%, respectively; the average contents of stevioside (Stv) were 1.04%, 1.01% and 1.18%, respectively; and the average total glycoside contents were 13.62%, 13.38% and 13.38%, respectively. Among treatments supplemented with the same biostimulant, as nitrogen application decreased, the contents of superoxide dismutase (SOD) and peroxidase (POD) tended to decrease, with fulvic acid showing better effects than chitosan. In the chitosan-supplemented treatments, the 40% nitrogen reduction treatment (N0.6C) increased plant height, stem diameter, and leaf mass per plant by 11.92%, 9.57%, and 8.66%, respectively, compared to other nitrogen levels, and increased SOD and POD contents by 9.12% and 7.81%, respectively. A comprehensive analysis of the effects of reduced nitrogen fertilization combined with biostimulants on Stevia rebaudiana revealed that the treatment with 20% nitrogen reduction supplemented with fulvic acid (N0.8F) effectively promoted Stevia rebaudiana growth, enhanced leaf enzyme activity, increased the content of RA in leaves, decreased the content of Stv, and improved the ratio of RA to total glycosides, thereby enhancing Stevia rebaudiana quality. Additionally, a 20% reduction in nitrogen fertilization improved plant nitrogen uptake and nitrogen use efficiency.
In order to screen out new potato varieties suitable for field planting in Ningxia, two varieties of 'Jizhangshu 8' and 'Hutou' were planted by double ridge side hole sowing in the field environment, and 10 treatments such as different film colors and film mulching methods were set up. The results were analyzed by variance and repeated comparison. The results showed that the water content of black film was 5.1% higher than that of 0-20 cm open soil, and 2.3% higher than that of white film. The ground temperature was 0.6℃ higher than that in the open field and 1.5℃ lower than that in the white film field at 0-20 cm of autumn tuber swelling stage. The average yield of black film covered potato was 27000 kg/hm2, which was 4500 kg/hm2 higher than that of white film covered potato and 10500 kg/hm2 higher than that of open field, with the increases of 20% and 63.6% respectively. The yield of black film was significantly higher than that of white film, and the yield of full film significantly higher than that of half film. The yield of 'Jizhang Potato 8' was significantly higher than that of 'Hutou', in which the weight of a single plant with black full film was 488 g higher; the output was 16311 kg/hm2 higher, increasing by 306.5%, and the effect of increasing production was very significant. In terms of planting density, under the planting density of 30000 plants /hm2, the yield was the highest, and the increase rate reached 27.7%. It is suggested to popularize 'Jizhang Potato 8' in a large area, which increase yield by more than 3 times under black full film cultivation by drip irrigation.
Anaerobic digestion, a widely utilized technology for the treatment of organic waste, offers the dual benefits of emission reduction and energy recovery. Anaerobic digestion is susceptible to various factors due to the complex biochemical reactions involved in the process. Polycyclic aromatic hydrocarbons (PAHs) are a class of refractory organic pollutants, which mainly come from human activities such as industrial wastewater, incomplete combustion of fossil fuels and automobile exhaust emissions. PAHs possess toxicity and adsorptive. In anaerobic digestion systems, it is necessary to find methods to reduce the content of PAHs in the substrate since PAHs often mix with other materials, influencing hydrolysis, acidification and methanogenesis, which hinder degradation of substrate and methane production. Compared to physical and chemical methods such as heating, adsorption and photolysis, adding exogenous substances to promote the removal of PAHs has the advantages of simplicity, lower cost and reduced secondary pollution. The paper reviewed the influencing factors of anaerobic digestion, the inhibitory effects of PAHs on anaerobic digestion and strategies to alleviate the inhibitory effects of PAHs by introducing different exogenous substances, aiming to provide references for further improving the anaerobic digestion technology.
This study explores the effects of inoculating three types of arbuscular mycorrhizal (AM) fungi on the growth and development, and active compound production of mulberry trees in non-sterilized soil. Using the 'TeYou No. 2' mulberry variety as material and natural soil as the substrate, we conducted a pot experiment with four treatments: a control group (CK), and inoculations with Claroideoglomus etunicatum (CE), Funneliformis mosseae (FM), and Rhizophagus intraradices (RI). After 120 days, data on mulberry biomass, leaf carotenoids, and flavonoids were collected. The results revealed that, compared to the control group, root fresh weights increased by 57.57%, 81.92%, and 90.03% for CE, FM, and RI inoculations, respectively, while root dry weights rose by 24.10%, 47.65%, and 72.58%. The net photosynthetic rates for CE, FM, and RI increased by 20.73%, 4.22%, and 25.41%, respectively, and carotenoid content grew by 28.57%, 28.57%, and 35.71%. The average flavonoid content in leaves for CE, FM, and RI was 4.23 mg/g, 3.31 mg/g, and 3.85 mg/g, all exceeding the control group’s 2.55 mg/g. Inoculation with AM fungi in non-sterilized soil positively impacted mulberry growth, enhanced root development, increased active compound accumulation in leaves, and fostered a beneficial symbiotic relationship with the mulberry trees.
To explore the potential of chemical nitrogen substitution by ploughing and returning Vicia villosa as the preceding crop of flue-cured tobacco in Lijiang tobacco-growing area of Yunnan Province, this study conducted a systematic analysis through three experiments: (1) measuring the degradation rate of Vicia villosa after ploughing; (2) using the δ15N isotope labeling technique to precisely quantify the amount of nitrogen transferred from Vicia villosa to tobacco plants; (3) verifying the substitution effect of chemical nitrogen by returning Vicia villosa to the field under field conditions. The research results showed that Vicia villosa could naturally decompose and release nutrients in the soil after ploughing, and the decomposition rate was the fastest within two weeks after ploughing. The appropriate ploughing time should be 90 to 100 days before tobacco transplanting. At this time, more than 50% of Vicia villosa could decompose, and nitrogen, phosphorus and potassium were released by approximately 48.75%, 52.00% and 83.65% respectively. The isotope tracking results showed that among the fertilizer nitrogen absorbed by tobacco, the nitrogen from Vicia villosa accounted for 10.15% of the total fertilizer nitrogen, and the nitrogen utilization rate of green manure in the current season was approximately 3.66%. Therefore, after returning Vicia villosa to the field, the application amount of chemical nitrogen fertilizer should be appropriately reduced, and the optimal nitrogen fertilizer dosage was 80% of the conventional dosage. The research indicated that planting Vicia villosa as the preceding crop of flue-cured tobacco and ploughing it over could not only increase the yield and economic value of tobacco leaves but also effectively reduce the usage amount of chemical fertilizers, achieving the goal of reducing fertilizer application and increasing efficiency.
Abundant crop straw production in our country makes anaerobic dry fermentation for biogas production an important way to utilize crop straw resources. However, the dense structure of lignocellulose in straw limits the hydrolysis and acidification of straw, making it difficult for anaerobic bacteria to degrade straw and produce biogas. Currently, pretreatment of straw is considered to be an effective way to enhance the rate of anaerobic digestion and improve biogas yield. The text elaborates on the mechanism of anaerobic dry fermentation, and reviews the common pretreatment methods that can increase the efficiency of biogas production in straw anaerobic dry fermentation, including physical, chemical, biological, and combined pretreatment methods, and provides a perspective on the technology of straw pretreatment.
This study comprehensively evaluated the preparation techniques of chitosan oligosaccharide (COS) and conducted an in-depth analysis of the effects of COS and microbial metabolites on plant growth, crop quality enhancement, and pest management, aiming to enhance agricultural production efficiency and promote environmental sustainability. The results revealed the importance of COS and microbial metabolites in improving agricultural yield and maintaining environmental stability. In response to the challenges posed to food security by climate and ecosystem changes caused by natural and human activities, we propose that future research should focus on the activities of organic nanoparticles such as COS and microbial metabolites, and emphasize the necessity of advancing emerging fertilizer research to provide scientific basis and technical support for the sustainable development of agricultural production.
This study aims to systematically understand the flowering biological characteristics of 16 citrus rootstock resources, including trifoliate orange and citrange, and to provide references for rootstock germplasm creation and new variety breeding. 16 collected trifoliate orange and citrange resources were used as materials. The phenological stages were observed, and the characteristics of floral organs, including bud color, petal number, petal length and width, anther number, filament number, filament color, and stigma number, were compared. Additionally, pollen quantity, pollen grain size, pollen viability, and pollen germination ability were measured using an optical microscope and in vitro pollen germination method. Finally, a comprehensive evaluation of flowering biological characteristics was conducted using the weighted membership function method. (1) The results showed that trifoliate oranges and most of citrange resources were deciduous trees. Citrange trees exhibited a more erect growth habits and reached phenological stages slightly later than trifoliate oranges. Both trifoliate oranges and citrange primarily exhibited pale purple filaments, with most specimens having 20-24 anthers and filaments. However, the petals of trifoliate oranges were generally smaller than those of citrange. (2) Significant differences existed between trifoliate oranges and citrange in terms of pollen viability, pollen quantity, and pollen grain size. Trifoliate oranges generally exhibited higher pollen staining vitality and pollen germination rates compared to citrange. (3) Utilizing the weighted membership function method, trifoliate oranges such as common small-leaf trifoliate orange, M-3 and citrange Dayong No.3 were identified as rootstocks with superior pollen fertility. These results provide reference for evaluating and utilizing rootstock resources, as well as for interspecific and intraspecific hybridization breeding within the citrus genus to create new citrus rootstock germplasm.
Organic material application is an important measure for agricultural soil fertility improvement and has a great effect on soil greenhouse gas emissions. To explore the effect of the addition of different organic materials on soil greenhouse gas emissions from typical open field vegetable and rice-rotated planting patterns in the Erhai Lake basin, the incubation experiment was conducted with four treatments, including no addition (CK), straw, biochar and cow manure addition for 15 days under constant temperature and humidity. The results showed that: (1) compared with CK treatment, the addition of three organic materials all had a reduction trend for vegetable soil N2O emissions, but an increase for rice-rotated soil, of which the straw addition had a significant increase effect. Compared with straw treatment, soil N2O emissions from rice-rotated soil under biochar and cow manure treatments declined by 64.9% and 68.3%, respectively (P<0.05). The N2O emission ratio of open field vegetable soil was reduced by all three organic materials (P<0.05), while only straw significantly increased the soil N2O emission ratio of rice-rotated soil. (2) The biochar and cow manure treatments had a slight inhibiting effect on soil CO2 emissions for two soils compared with CK treatment. Compared with straw treatment, the biochar and cow manure treatments significantly reduced soil CO2 emissions from open field vegetable and rice-rotated soil by 84.9%-85.1% and 41.7%-43.1%, respectively (P<0.05). (3) The addition of organic materials increased the soil CH4 emission from open field vegetable soil, while only straw addition increased the soil CH4 emission from rice-rotated soil (P<0.05). (4) Compared with CK treatment, soil nitrification rate of open field vegetable soil was significantly increased after organic material addition (P<0.05), and soil mineralization rate was also increased, but only straw and cow manure treatment had significant effects (P<0.05). However, the nitrification rate and mineralization rate of rice-rotated soil after organic material addition were both reduced compared with CK treatment, of which straw and biochar significantly decreased the two rates (P<0.05). The soil N2O and CO2 emissions of rice-rotated system with only organic fertilizer were significantly higher than those of open field vegetable system with organic and inorganic fertilizer application, and the soil N2O and CO2 emissions were significantly increased after the addition of straw. The global warming potential (GWP) of rice-rotated soil with long-term application of organic fertilizer was higher than that of open field vegetable soil, and the addition of straw significantly increased GWP of rice-rotated soil, while the addition of organic matter significantly reduced GWP of open field vegetable soil. This study provided a scientific basis for the appropriate addition of organic materials to farmland in the Erhai Lake basin to reduce greenhouse gas emissions and improve soil nitrogen supply capacity.
To understand the suitability of different preceding crops for flue-cured tobacco production in Dali tobacco planting areas, the soil samples of wheat, barley, broad bean, rape, pea, garlic and winter fallow for five years were collected from 12 tobacco planting areas in Dali, and the soil nutrient content was determined. The membership of each nutrient index was calculated by fuzzy mathematics, and the membership of soil nutrient was used to comprehensively evaluate the suitability of preceding crop for flue-cured tobacco planting in Dali. The results showed that distribution proportion and membership degree of alkali hydrolyzed nitrogen and water-soluble chlorine content in soil suitable for tobacco growth after planting wheat were high, while the distribution proportion and membership degree of available phosphorus and available potassium content were medium. The distribution proportion and membership degree of soil alkali hydrolyzed nitrogen, available potassium, and water-soluble chlorine content suitable for tobacco growth after winter fallow were high, while the distribution proportion and membership degree of available phosphorus content were medium. The most suitable rotation mode is flue-cured tobacco and wheat and winter fallow in the Dali tobacco planting areas.
Excessive or irrational application of nitrogen (N) fertilizer not only increases N losses, decreases N use efficiency (NUE) and affect yield improvement in cropland, but also causes some environmental problems. Nitrification inhibitors (NIs) can reduce N losses and improve NUE through inhibiting nitrification process. Although numerous studies about NIs focused on the reduction of nitrous oxide (N2O) emissions and promotion of yield in cropland in China, systematic analysis was still poor. In this paper, meta-analysis was used to study the effects of N fertilizer combined with NIs on the reduction of N2O emissions, major crop yield and NUE in cropland in China, so as to clarify the influences of soil pH, N application amounts and crop types on effects of NIs. The results showed that N fertilizer combined with NIs reduced the N2O emissions effect from cropland by 38.66% significantly (P<0.05), increase the effect of major crop yield by 7.31% (P>0.05), and enhance the effect of crop N uptake and NUE by 10.97% (P>0.05) and 25.64% (P>0.05), respectively. Among the different types of NIs, DMPP reduced the effect of N2O emissions to maximum extent (57.30%), followed by CP and DCD, which reduced the effect of N2O emissions by 35.07% and 32.28%. CP enhanced the effect of yield to maximum extent (12.76%), followed by DCD (5.65%) and DMPP (4.25%). The reduction size of NIs on N2O emissions in high N input cropland (≥300 kg/hm2) was greater than that in medium and low N input cropland (<300 kg/hm2). The increasing effect of NIs on yield of main crops in medium N input cropland (200-300 kg/hm2) was greater than that in high and low N input cropland. The effects of NIs on reducing N2O emissions and increasing crop yield in neutral soil were greater than those in acidic and alkaline soil. Principal component analysis (PCA) showed that soil pH was the main factor affecting crop yield and N2O emission under the condition of N fertilizer applied with NIs. To sum up, N fertilizer combined with NIs could reduce N2O emissions significantly, increase crop yield, improve N uptake and NUE to a certain extent, which was an effective path to decrease N losses and promote N utilization.
It is of great significance to grasp the occurrence and development law of wheat dry hot wind disaster and take targeted defensive measures to ensure food security. According to the meteorological industry standard of wheat dry-hot wind, using the daily meteorological observation data of 9 national meteorological stations and 114 regional automatic stations in agricultural areas in Bazhou from May to June from 1981 to 2023, the data of wheat development period and geographical basic information of agricultural meteorological observation stations, combined with ArcGIS10.8 technical mapping, the spatial and temporal variation characteristics of wheat dry-hot wind days and processes in Bazhou were analyzed, and the risk zoning and evaluation were carried out. The results showed that the number of dry hot wind days and weather process showed a trend of decreasing first and then increasing slowly, and then increasing obviously after decreasing slowly. The trend tendency rate was 2.2 d/10a and 1.2 meta/10 a, respectively in recent 43 years. In the 1980s, the decrease was more obvious, in the 1990s and 2010s, it showed an increasing trend, and after 2011, it increased significantly, which had the characteristics of time stages, and 2017 and 2022 were the years of high dry hot wind. From the proportion of three different degrees of dry-hot wind, the number of days and processes of light dry-hot wind are the most, and the trend of light process is significant; the number and process of medium and heavy dry-hot wind days did not change significantly. The number of dry hot wind days and the number of dry hot wind weather processes are similar in spatial distribution, that is, the desert oasis area in the southeast margin of the Taklimakan Desert is frequent and high occurrence area, the Bosten Lake waters and Yanqi Basin are less occurrence area, and other areas are secondary occurrence area, showing the spatial distribution characteristics of ‘more in the southeast and less in the northeast’ with obvious regionalism. The risk zoning results are divided into four levels of dry hot wind risk areas: heavy, heavier, moderate and mild (no), which can provide reference for disaster prevention in different risk planting areas.
To investigate the effects of different modified materials on the physical and chemical properties of saline-alkali soil and maize yield, the effects of desulfurized gypsum, new modifier and organic fertilizer on saline-alkali soil improvement and maize growth were studied on moderate saline-alkali soil in Tumote Right Banner, Inner Mongolia. The results showed that: (1) the application of the modified materials reduced the soil pH and the total salt content in 0-20 cm and 20-40 cm soil layers. Among them, T4 treatment had the best effect on soil pH reduction, and soil pH in different soil layers decreased significantly by 8.38% and 6.65%, respectively, compared with the control. T6 treatment had the best effect on salt inhibition in 0-20 cm soil layer, which was significantly decreased by 44.84% compared with the control. And T4 treatment had the best effect on salt inhibition in the 20-40 cm soil layer, with significant decreases of 44.84% compared with the control. (2) The application of modified materials increased the content of available phosphorus, available potassium and available nitrogen in 0-20 cm and 20-40 cm soil layers, with an average increase of 15.8%-65.48%, 3.06%-19.07% and 3.45%-20.24%, respectively. (3) The application of modified materials increased maize height and stem diameter at different growth stages, and increased maize yield and yield components. T7 treatment had better effect on maize growth and yield enhancement than other modified treatments, with maize plant height, stem diameter, 100-kernel weight, and yield significantly increased by 26.21%, 20.64%, 21.56% and 55.21%, respectively, compared with the control. In summary, the application of modified materials could improve the quality of saline-alkali soil, improve soil nutrients, promote maize growth and increase maize yield.
Various forage planting patterns are introduced to attempt to rehabilitate rocky desertification grassland so that suitable vegetation patterns can be selected for ecosystem functioning restoration. Six different planting modes were conducted experimentally at the typical rocky desertification areas with three different levels of degradation in Yanshan County, southeast of Yunnan Province. The six modes were Lolium perenne monoculture, Festuca ovina monoculture, Setaria anceps monoculture, intercropping of Festuca ovina and Crotalaria pallida, intercropping of Setaria anceps and Trifolium repens, and intercropping of Setaria anceps and Medicago sativa. The results showed that (1) a variety of vegetation and soil traits increased significantly after rehabilitation, which included above- and under- ground biomass, gross cover, soil organic matter, total phosphorus, available phosphorus and available potassium. (2) There were significant differences among six modes in soil water content, water utilization efficiency, gross cover, above-ground biomass, under-ground biomass and the ratio of above-ground biomass to under-ground biomass. Lolium perenne monoculture had the highest soil water content, water utilization efficiency, above-ground biomass and the ratio of above-ground biomass to under-ground biomass, while intercropping of Setaria anceps and Medicago sativa and intercropping of Festuca ovina and Crotalaria pallida had got highest gross cover and under-ground biomass respectively. Planting forages had a remarkably positive effect on vegetation and soil restoration at target region. However, intercropping patterns had not explicit superiority over monoculture, and each pattern acted distinctively.
By analyzing the influence mode and degree of soil organic matter content on grain yield per unit area, the study provides a theoretical reference for the determination of organic matter content in soil testing and formula fertilization of cultivated land, and also provides relevant suggestions for cost reduction and efficiency increase in grain production. This paper took Lancao County of Henan Province as an example, the influence of soil organic matter content on grain yield was assessed by using trend and fitting correlation analysis, based on the existing annual renewal evaluation results of farmland quality of 203 administrative villages (2019). The results showed that grain yield would not increase continuously with the increase of soil organic matter content. There existed a critical value of soil organic matter content that could maximize the grain yield per unit area, so the relationship between the two showed a downward parabolic shape on the fitted curve. According to the three fitting curves, the critical value of soil organic matter content was calculated to be between 12.50-13.00 g/kg in Lankao County. The critical value of soil organic matter content in Lankao County was determined to be 15.00 g/kg by referring to the relevant requirements in the “Well-facilitated farmland construction—General rules” (GB/T 30600—2022). It was recommended that soil improvement should be tailored to the actual conditions. Once the soil organic matter content reached the ideal level, it was advisable to reduce the application of organic amendments in order to improve cost-effectiveness and efficiency in crop production.
As an indispensable microbial group in soil, fungi play a crucial role in apple growth and disease prevention. To compare the effects of soil types on the diversity of fungal communities in aged apple orchards in southwestern China, the experiment was conducted with four soil types: brown soil (BS), sandy soil (SS), yellow soil (YS) and apple replant disease soil (ARDS). The results showed that although there was no difference in α-diversity among the four soil types, SS had the lowest Sobs and Ace, while ARDS had the highest Sobs. ARDS, BS, SS and YS had 326, 301, 265 and 303 Operational Taxonomic Units (OTUs) respectively, and the four soil types shared 178 OTUs. The OTUs by oneself was between 23 and 47 (ARDS>BS>YS>SS). Among the four soil types, Solicoccozyma, Mortierella, Rhodotorula and Vishniacozyma were the top four fungi with the highest relative abundance. At the genus level, the four soil types had significant effects on the relative abundance of 15 fungi, including Bionectria, Cladosporium, Mycoarthris, Cylindrocarpon and Clonostachys (P<0.05). The ARDS soil type had a higher number of species and a relatively high abundance of species indicating replant disease. Although pathogenic fungi were present in all soil types, their relative abundance was relatively low.
To explore the water consumption law of Chinese cabbage under microspray irrigation in Kunming regions, using cloud intelligent soil water meter in Yunnan Irrigation Experiment Center Station, the water consumption law of Chinese cabbage during summer and autumn of 2019 year under microspray irrigation was studied by using local planting experience, and the water saving potential in this regions was revealed under microspray irrigation. The results showed that the evapotranspiration of Chinese cabbage were 119.23 and 102.57 mm during the whole growth period, and the average daily evapotranspiration intensity was 1.66 and 1.27 mm/d, in which the average evapotranspiration was the highest in rosette stage, reaching 47.54 mm, and the average evapotranspiration was the smallest in seedling stage, only 2.36 mm. The evapotranspiration of Chinese cabbage in different growth stages showed heading stage> rosette stage> harvesting stage> group tree stage> seedling stage. The curve of evapotranspiration of typical Chinese cabbage showed a single peak change, and the high value of evapotranspiration mainly concentrated in 11:00-14:00, and there was an obviously ‘lunch break’ phenomenon. The evapotranspiration of Chinese cabbage decreased with the increase of soil depth. The evapotranspiration of Chinese cabbage was the highest at 0-10 cm, the average proportion reached 45.25%, and the lowest at 30-40 cm, the average proportion was 7.74%. According to the suitable range of soil water content in different growth stages of Chinese cabbage, there were two times and three times of over-irrigation respectively in the two crops of Chinese cabbage. Under the condition of avoiding over-irrigation, the two crops of Chinese cabbage could save water by 160.0 m3/hm2 and 180.0 m3/hm2 respectively.
This study predicts the potential suitable areas for Oenothera biennis in Heilongjiang Province and its changing patterns under future climate conditions, providing a basis for further monitoring and control efforts. This study focused on the invasive plant O. biennis and used software such as MaxEnt and ArcGIS to predict the changes in its distribution under three carbon emission scenarios (ssp126, ssp370, ssp585) for the present and two future periods (2021-2040, 2041-2060). The study also analyzed the dominant environmental factors and expansion trends that affected the distribution of O. biennis in Heilongjiang Province. The results showed that: (1) the MaxEnt model predicted an AUC value of 0.864, indicating accurate predictions. (2) The environmental factors with the greatest impact on the habitat of O. biennis were annual average precipitation (26.5%), coldest month minimum temperature (21.3%), and annual average temperature (16.9%). (3) The suitable area for O. biennis in Heilongjiang Province was 231600 km2, with high suitability accounting for 9.11% of the province. (4) Under the future climate change scenario of the 2040s, the suitable area for O. biennis increased by 5.78%, 5.16%, and 8.52% under the ssp126, ssp370, and ssp585 climate conditions, respectively. Under the 2060s scenario, the suitable area increased by 7.51%, 8.95%, and 8.66% under the three climate conditions. Under future climate change, the suitable area for the invasive plant O. biennis showed a trend of spreading from the center to the periphery, with average annual rainfall being the main influencing factors for its distribution.
In order to select the ideal carrier for Bacillus megaterium, grass charcoal, cow manure, sheep manure, chicken manure and enoki mushroom residue were used as carriers for B. megaterium to determine their effects on the adsorption capacity, effective viable bacteria number, exopolysaccharides (EPS) content and germination index of the bacterial solution. Charcoal had the highest bacterial liquid adsorption capacity which was 1.64 mL/g, but with the extension of storage time, the effective viable bacterial number and EPS content in the charcoal inoculum decreased sharply, and the germination index was less than 80% within 38 days, indicating the plant toxicity. Although the bacterial absorption capacity of chicken manure and enoki mushroom residue was smaller than that of grass charcoal, the effective viable bacterial number and EPS content in the chicken manure inoculum showed a trend of increasing. For the enoki mushroom residue inoculum, the EPS content increased gradually, and the effective viable bacteria number decreased slowly. The germination index of the two carrier inoculants was greater than 80% after 7 days of storage, indicating no plant toxicity. On the 38th day, the effective viable bacteria number of the chicken manure and enoki mushroom residue inoculants were 1.29×109 CFU/g and 6.20×108 CFU/g, respectively, the EPS content was 535.29 mg/kg and 559.34 mg/kg, respectively, which were significantly higher than other carrier inoculants. Chicken manure and enoki mushroom residue were the ideal carriers for B. megaterium.
Based on the fertilization management mode of organic fertilizer combined with chemical fertilizer, this study summarized a set of technical methods for fast fertilizing and high yield fertilization in low soil fertility fields under winter wheat-summer maize rotation in Beijing. This model was applied to the experiment in Miyun and Shunyi, and three treatments were set, including single fertilizer treatment, fast fertilizing treatment and high yield fertilizing treatment. The results showed that the yield of fast fertilizing treatment only increased about 1%-2%, but the soil organic carbon content increased about 1.06 g/kg in Miyun and 0.96 g/kg in Shunyi. The yield increase rates of high yield fertilizing treatment reached 9.9% (winter wheat) and 11.5% (summer corn) in Miyun, 10.9% (winter wheat) and 10.1% (summer corn) in Shunyi, respectively, but the soil organic carbon content only increased 0.06 g/kg in Miyun, while it did not increase Shunyi. This study provides a fertilization strategy that can increase crop yield and improve soil quality for low-fertility grain fields in the suburbs of Beijing.
Resources and Environment
