Hydrolysable Nitrogen Research Articles

Alkaline Hydrolyzable Organic Nitrogen as an Index of Nitrogen Mineralization in Soils: Relationship with Activities of Arylamidase and Amidohydrolases

ABSTRACT This study investigated the relationship between a recently proposed alkaline hydrolysis method for estimating the chemical index of nitrogen (N) mineralization potential of soils and the activities of arylamidase and four amidohydrolases involved in hydrolysis of organic N (ON) in soils. Nitrogen mineralization was studied in 13 soils from uncultivated fields in Iowa, USA, by direct steam distillation of 1 g field-most soil treated with 1 M KOH or 1 M NaOH. The distillate was collected in boric acids, which was changed every 5 min for a total of 40 min. The NH4 +-N in the distillate was determined by titration with 0.005 M H2SO4. The cumulative amounts of N hydrolyzed were fitted to the first-order exponential equation to determine the “potentially hydrolyzable N (Nmax )” for the soils. The activities of arylamidase, L-asparaginase, L-glutaminase, amidase, and L-aspartase were assayed at their optimal pH values. Results showed that estimated Nmax values were strongly correlated with the activities of arylamidase and amidohydrolases. The activities of arylamidase and the amidohydrolases were significantly correlated, indicating that the activities of the two groups of enzymes are coupled in mineralization of ON in soils. Based on the specificity of enzyme reactions and the strong relationship between estimated Nmax values and the activities of arylamidase and amidohydrolases, we concluded that similar amide-N bonds were susceptible to enzymatic and alkaline hydrolysis, and that alkaline hydrolyzable ON can be used as an index of N mineralization in soils.

Forms of Nitrogen and Phosphorus in Suspended Solids: A Case Study of Lihu Lake, China

Suspended solids are an important part of lake ecosystems, and their nitrogen and phosphorus contents have a significant effect on water quality. However, information on nitrogen and phosphorus forms in suspended solids remains limited. Therefore, a case study was conducted in Lihu Lake (China), a lake with characteristically high amounts of suspended solids. Nitrogen and phosphorus speciation in suspended solids was analyzed through a sequential extraction method. We also evaluated the sources of various forms of nitrogen and phosphorus and their different effects on eutrophication. The total nitrogen (TN) content was 758.9–3098.1 mg/kg. Moreover, the proportions of various N forms in the suspended solids of the study areas were ranked as follows: Hydrolyzable nitrogen (HN) > residual nitrogen (RN) > exchangeable nitrogen (EN). Total phosphorus (TP) ranged from 294.8 to 1066.4 mg/kg, and 58.6% of this TP was inorganic phosphorus (IP). In turn, calcium (Ca)-bound inorganic phosphorus (Ca-Pi) was the main component of IP. The correlation between various nitrogen and phosphorus forms showed that there were different sources of suspended nitrogen and phosphorus throughout Lihu Lake. Correlation analysis of water quality indices and comparative analysis with surface sediments showed that in Lihu Lake, the dissolved nitrogen and phosphorus contents in water were influenced by sediment through diffusion, while particle phosphorus content in water was influenced by suspended solids through adsorption; however, due to the higher phosphorus contents in suspended solids, we should pay more attention to the impact of suspended solids.

ФОТОСИНТЕТИЧЕСКИЙ ПОТЕНЦИАЛ ПОСЕВОВ НУТА В ПРЕДГОРНОЙ ЗОНЕ РСО – АЛАНИЯ

The article is devoted to the study of the influence of sowing methods, seeding rate and herbicide on the development, yield and photosynthetic activity of chickpea sowing – one of the most controversial issues in chickpea agricultural technology. The influence of sowing methods and seeding rates on the photosynthetic activity of plants has been studied. The selection of effective measures to control chickpea weeds is also part of our research. One of the most significant issues for obtaining high yields of chickpea is the correct sowing method, seeding rate and the use of herbicides. The studies were carried out in 2017–2018. on the experimental field of the North Caucasus Research Institute of Mining and Piedmont Agriculture of the All-Russian Scientific Center of the Russian Academy of Sciences on leached chernozems: arable layer pH salt. 5.8–6, humus content 5.8%, easily hydrolyzable nitrogen – 80 mg/kg, available phosphorus – 118 mg/kg, exchangeable potassium – 120 mg/kg, molybdenum – 0.25 mg/kg, boron – 0,5 mg/kg of soil. In field experiments, the seeding rates, the method of seeding and the effect of herbicides were studied. The aim of the research was: to develop agricultural practices that ensure the collection of grain products and vegetable protein in the foothill zone of RNO-Alania. According to the results of the studies, in the conditions of the foothill zone of the Republic of North Ossetia – Alania, according to the complex of indicators of plant activity, variants were distinguished when applying the herbicide with seeding rates of 0.8 and 1.0 million viable seeds per hectare with a wide-row sowing method and with seeding rates 0.6–0.8 million germinable seeds per hectare with the drill method. Against a herbicide-free background, the best options were with a seeding rate of 1.0 million viable seeds per hectare, both with wide-row and with a row sowing method.

ПРОДУКТИВНОСТЬ ГОРОХА В УСЛОВИЯХ ЛЕСОСТЕПНОЙ ЗОНЫ РСО – АЛАНИЯ

The article is devoted to the study of the influence of sowing methods, seeding rate and herbicide on the development, yield and photosynthetic activity of chickpea sowing – one of the most controversial issues in chickpea agricultural technology. The influence of sowing methods and seeding rates on the photosynthetic activity of plants has been studied. The selection of effective measures to control chickpea weeds is also part of our research. One of the most significant issues for obtaining high yields of chickpea is the correct sowing method, seeding rate and the use of herbicides. The studies were carried out in 2017–2018. on the experimental field of the North Caucasus Research Institute of Mining and Piedmont Agriculture of the All-Russian Scientific Center of the Russian Academy of Sciences on leached chernozems: arable layer pH salt. 5.8–6, humus content 5.8%, easily hydrolyzable nitrogen – 80 mg/kg, available phosphorus – 118 mg/kg, exchangeable potassium – 120 mg/kg, molybdenum – 0.25 mg/kg, boron – 0,5 mg/kg of soil. In field experiments, the seeding rates, the method of seeding and the effect of herbicides were studied. The aim of the research was: to develop agricultural practices that ensure the collection of grain products and vegetable protein in the foothill zone of RNO-Alania. According to the results of the studies, in the conditions of the foothill zone of the Republic of North Ossetia – Alania, according to the complex of indicators of plant activity, variants were distinguished when applying the herbicide with seeding rates of 0.8 and 1.0 million viable seeds per hectare with a wide-row sowing method and with seeding rates 0.6–0.8 million germinable seeds per hectare with the drill method. Against a herbicide-free background, the best options were with a seeding rate of 1.0 million viable seeds per hectare, both with wide-row and with a row sowing method.

Prickly Ash Seed Kernel: A New Bio-Fumigation Material Against Tobacco Black Shank

The present study evaluated the fumigant effect and potential mechanisms of Chinese prickly ash seed kernel (PSK) against tobacco black shank caused by Phytophthora nicotianae Breda de Haan. The results showed that PSK fumigant increased the soil organic matter, hydrolysable nitrogen, available potassium, and total phosphorus significantly, while the pH was decreased. Application of 2% PSK promoted plant growth, with higher plant height, root length, and dry weight compared to those in the treatment with no PSK. Both in vitro and in vivo tests indicated that PSK fumigant effectively inhibited mycelial growth of P. nicotianae, and significantly reduced the severity of tobacco black shank. Based on the analysis of volatiles in PSK by headspace solid-phase microextraction (HS-SPME) gas chromatography-mass spectrometry (GC-MS), 28 components were identified, among which monoterpenes were the major components (accounting for 79.46% of peak area). Among the six top components, linalool, piperitone, sabinene, and limonene exhibited strong mycelial inhibition of P. nicotianae. Linalool was the most effective with an IC50 value of 18.03 μL/L. Results of GC-MS revealed that the main components of PSK extract were cis-Vaccenic acid (40.81%), n-Hexadecanoic acid (15.67%), 9,12-Octadecadienoic acid (Z,Z)- (15.25%), Ethanone-1-(2-hydroxy-4,6-dimethoxyphenyl)- (10.32%), cis-9-Hexadecenoic acid (6.21%), and Psilocin (11.75%). Among them, Ethanone-1-(2-hydroxy-4,6-dimethoxyphenyl)- and 9,12-Octadecadienoic acid (Z,Z)- have an obvious inhibitory effect on P. nicotianae. Additionally, changes in soil bacterial and fungal communities were observed. The relative abundance of some microbes, such as Pseudomonas, Azospirillum, Thermomonas, Glutamicibacter, Dyella, and Trichoderma, increased, which have many beneficial microbes in these genera, indicating that microbial community shift could be one of the important outcomes of the PSK fumigant effect. In conclusion, PSK could be a new bio-fumigation material against plant soilborne pathogens, which can function as both a fungicide and fertilizer.

Soil-plant co-stimulation during forest vegetation restoration in a subtropical area of southern China

BackgroundSoil and vegetation have a direct impact on the process and direction of plant community succession, and determine the structure, function, and productivity of ecosystems. However, little is known about the synergistic influence of soil physicochemical properties and vegetation features on vegetation restoration. The aim of this study was to investigate the co-evolution of soil physicochemical properties and vegetation features in the process of vegetation restoration, and to distinguish the primary and secondary relationships between soil and vegetation in their collaborative effects on promoting vegetation restoration in a subtropical area of China.MethodsSoil samples were collected to 40 cm in four distinct plant communities along a restoration gradient from herb (4–5 years), to shrub (11–12 years), to Pinus massoniana coniferous and broadleaved mixed forest (45–46 years), and to evergreen broadleaved forest (old growth forest). Measurements were taken of the soil physicochemical properties and Shannon–Wiener index (SD), diameter at breast height (DBH), height (H), and biomass. Principal component analysis, linear function analysis, and variation partitioning analysis were then performed to prioritize the relative importance of the leading factors affecting vegetation restoration.ResultsSoil physicochemical properties and vegetation features showed a significant trend of improvement across the vegetation restoration gradient, reflected mainly in the high response rates of soil organic carbon (SOC) (140.76%), total nitrogen (TN) (222.48%), total phosphorus (TP) (59.54%), alkaline hydrolysis nitrogen (AN) (544.65%), available phosphorus (AP) (53.28%), species diversity (86.3%), biomass (2906.52%), DBH (128.11%), and H (596.97%). The soil properties (pH, SOC, TN, AN, and TP) and vegetation features (biomass, DBH, and H) had a clear co-evolutionary relationship over the course of restoration. The synergistic interaction between soil properties and vegetation features had the greatest effect on biomass (55.55%–72.37%), and the soil properties contributed secondarily (3.30%–31.44%). The main impact factors of biomass varied with the restoration periods.ConclusionsIn the process of vegetation restoration, soil and vegetation promoted each other. Vegetation restoration was the cumulative result of changes in soil fertility and vegetation features.

Effects of different coated slow-release calcium peroxide on microbial characteristics of gleyed paddy soil

To explore the effects of different coated slow-release calcium peroxide on soil microbial characteristics in gleyed paddy field, we set seven treatments by simulation test in a greenhouse, including CK (none calcium peroxide), calcium peroxide powder, calcium peroxide particle and other four coated slow-release calcium peroxide treatments. Samples were collected in same tillering stage of early season rice. The results showed that all the applications of calcium peroxide could improve the concentrations of active soil organic carbon, soil available nutrients, soil microbial biomass, culturable microorganism population, as well as soil enzyme activity. The coated slow-release calcium peroxide had stronger effects than calcium peroxide particles and calcium peroxide powder. The calcium peroxide coated by ethyl cellulose was the most effective, which enhanced soil active organic carbon, soil microbial biomass carbon, nitrogen, phosphorus by 19.4%, 11.4%, 121.5% and 127.2%, soil alkaline hydrolysis nitrogen and available phosphorus by 4.0% and 45.5%, soil culturable bacteria and culturable microorganism population by 137.3% and 113.7%, fungi and actinomyces number were increased by 33.6% and 44.7%. The enzyme activities of invertase, phosphatase, urease as well as catalase were increased by 92.4%, 91.8%, 112.5% and 17.1%, respectively. The results could provide reference for improving gleyed paddy field with coated calcium peroxide.

Alkaline hydrolyzable nitrogen and properties that dictate its distribution in paddy soil profiles

Nitrogen (N) is a key nutrient for rice production, and its bioavailability in paddy soils is strongly coupled to soil organic matter (SOM) cycling. A better understanding of potentially available N forms in soil, such as alkaline hydrolyzable N (AH-N), and their depth distribution will support the development of best management practices to improve the N use efficiency of rice while minimizing adverse environmental effects. Fifteen rice (Oryza sativa L.) fields from Southern Brazil were selected, and stratified soil samples were taken to a depth of 60 cm before crop establishment. Selected soil physical and chemical properties were analyzed to evaluate their relationships with AH-N contents in the soil profile. The AH-N contents below 20 cm varied extensively (increased, reduced, or constant) compared with that above 20 cm. Although clay and clay + silt contents were highly correlated to AH-N for some soils, the major property dictating AH-N distribution by depth was total N (TN), as the correlation between TN and AH-N was mainly by direct effect. The proportion of TN recovered as AH-N across sites and depths presented high amplitude, and thus AH-N was not a constant N pool across depths, indicating that AH-N can be affected by soil management practices even when TN showed no major changes. The distinct distribution of AH-N across soil sampling sites and depths indicates that depths greater than 20 cm should be considered when calibrating the AH-N index for N fertilizer recommendations for flooded rice in Southern Brazil.

Content of hydrolysable nitrogen in the soils of wet mixed broadleaved forest conditions of aviary keeping of hunting animals on the territories of sanctuaries of Western and Central Polissya

Semi-free maintenance of animals has a considerable impact on an agroecological condition of the soil. The content of hydrolysable nitrogen by Kornfild method (DSTU 7863:2015) in soils of wet mixed broadleaved forest conditions on the territories of sanctuaries of Western and Central Polissya is analyzed in the article. The increase of an indicator on feeding grounds in comparison with control ground was fixed. Thus, the content of hydrolysable nitrogen in soil samples which were taken in sanctuaries of Rys HFC LLC, UTMR LLC (Central Polissya) and Sarnenske HF LLC (Western Polissya) was significantly higher than samples which were selected on the control grounds — for 35.9, 29.5 and 22.3%, respectively. On the other hand on the territories of sanctuaries of Sokil HPF LLC, Bilotserkivske Forestry SOE, Horodnytskey Forestry SOE and Korostyshivskey Forestry SOE the difference between samples in the content of hydrolysable nitrogen was 14.3–17.4%. However, in the inspected sanctuaries the content of hydrolysable nitrogen was low (106.74±18.78 mg/kg, n=16) and was characterized by the considerable level of feature variation — the coefficient of variation was 35.9%. Different levels of accumulation of hydrolysable nitrogen, according to us, are caused by intensity and duration of the use of sanctuaries. During the period of observations the accurate dependence is shown (r=0.84; R2 =0.70) between duration of functioning of sanctuaries and the content of hydrolysable nitrogen in a layer of 0–20 cm. The conducted researches can form a basis for prediction of these key nutrient stocks for forest cenoses on the territories of sanctuaries in different forest site conditions of Western and Central Polissya

Effect of selective logging on soil microbial communities in a Pinus yunnanensis forest

AbstractSelective logging strongly affects forest structure and functions, which has direct and indirect effects on the soil microbial community. However, the effect of selective logging on soil microbial community composition remains unclear. We analyzed the soil microbial diversity and community composition in a pine (Pinus yunnanensis) forest using the Illumina platform for bacterial and fungal sequencing. The results showed that selective logging significantly altered most soil properties and stand attributes. Dominant phyla abundance varied significantly with change of selective logging intensity, affecting soil microbial community composition. The diversity of bacterial community decreased with the increase of selective logging intensity, whereas the diversity of fungi initially decreased and then increased. Soil properties accounted for most of the variation in the soil microbial communities, followed by stand attributes. Stand density (SD), soil pH, and soil moisture directly influenced the diversity of the bacterial communities, and understory species richness (USR), soil organic carbon (SOC), and soil hydrolysable nitrogen (HN) also directly influenced bacterial community composition. However, selective logging intensity affected the diversity and composition of the bacterial communities indirectly via SD, soil pH, HN, SOC, and USR. Similarly, the intensity of selective logging directly affected the diversity of fungal communities and also showed indirect effect on it via SD, soil pH, SOC, HN, C:N ratio, and soil available potassium. Further, selective logging intensity indirectly affected fungal community composition via soil available phosphorus. Our findings could be used to predict the change in the soil microbial community for the management of P. yunnanensis forest.

Cadmium Pollution Impact on the Bacterial Community of Haplic Cambisols in Northeast China and Inference of Resistant Genera

Modern industry and agriculture has aggravated heavy metal pollution of soils, of which cadmium (Cd) is among the common most toxic and widely distributed pollutants. Bacteria are a major group of microorganisms and the most abundantly occurring in soils. In Northeastern China, many mining sites occur whose soils need reclamation and Cd pollution has commonly existed. Haplic Cambisols is the zonal forest soil here. Yet, how Cd contamination may affect the bacterial characteristics and chemical properties of Haplic Cambisols is still unknown. Here, we applied different concentrations of Cd contamination to Haplic Cambisols and monitored the resulting changes to bacterial community structure and diversity, as well as the general soil environments; we then inferred Cd-resistant bacteria to provide theoretical support for microbial remediation of Cd-contaminated Haplic Cambisols in Northeast China. Haplic Cambisols were treated with different concentrations of CdCl2 solutions (0 [CK], 1, 5, 25, 50, 75, 100 mg kg−1, respectively expressed as T1, T2, T3, T4, T5, and T6) and incubated for 50 days, and then bacterial community composition was identified, and the pH, organic matter, hydrolytic nitrogen, available phosphorus, potassium, and cadmium contents of the soils were measured. Adding higher concentrations of Cd usually significantly increased the richness and diversity of the bacterial community in Haplic Cambisols in terms of both species and abundance with the effects of some treatments being not significant, and this effect varied with Cd concentration. Applying Cd significantly influenced the bacterial community’s structure and its metabolic functioning. Cd also influenced bacterial diversity via several key soil environmental factors, namely the pH, organic matter, and hydrolytic nitrogen contents. Pseudolabrys, Ralstonia, Reyranella, Afipia, Pelomonas, Rhizomicrobium, and Bradyrhizobium within Proteobacteria; Rhodanobacter from Bacteroidetes; and Nitrobacter within Nitrospirae were the main resistant bacteria. Higher concentrations of Cd increased the bacterial community richness and diversity of Haplic Cambisols, as well as the relative abundance of their main bacterial populations. The Cd-resistant genera were inferred, and relative abundances of Ralstonia, Bradyrhizobium, Rhizomicrobium, and Afipia were the highest.

The difference of soil properties between pure and mixed Chinese fir (Cunninghamia lanceolata) plantations depends on tree species

Second generation Chinese fir plantation has occurred the problem of site deterioration, which is usually supposed to be solved by mixed plantation. Here, we determined the physicochemical properties of six soil layers in pure and three types of mixed Chinese fir plantation stands (admixed species: Michelia macclurei, Pinus massoniana, and Phyllostachys heterocycla) in southeast China. The Ph. heterocycla is a bamboo. The effects of plantation type and depth on soil properties and variations among different depths were analyzed by two-way ANOVA with Tukey’s test. Non-parametric Wilcoxon rank sum test was used to analyze the soil property differences between pure and mixed plantations. The soil organic matter and alkaline hydrolysis nitrogen of mixture of Chinese fir and Ph. heterocycla were significantly higher than those of other plantation types (p < 0.05). The variations of soil chemical properties in pure plantation were significantly greater than these in mixed plantation. The soil organic matter in 10–20 cm soil layer, alkaline hydrolysis nitrogen in 10–40 cm, total phosphorus in 0–40 cm, available phosphorus and rapidly available potassium in nearly all soil layers were significantly lower in pure plantation than that in mixed plantation. In general, the mixed Chinese fir plantation could improve the soil quality, especially for chemical properties. Further investigations into the effects of mixing proportions of tree species on soil properties are needed to explore the effect of tree species on soil quality.

The role of soil fertility in the management of agricultural bioproductivity

Relevance and methods. The optimal selection of precursors and methods of biologization can increase the return of organic matter to the soil, increase the yield and productivity of crops. Corn was studied on irrigation, and crops (sorghum, oats, winter wheat) in crop rotation were studied on the bogar. To elucidate the general patterns of plant development in the system of forest strips and in experimental fields (bogar), statistical processing of the research results was used in the Exel and Statistica software packages, which is based on the generalization and synthesis of the results, which makes it possible to reach forecasts of plant development during the growing season. The soil is light chestnut, heavy loamy, with a humus content in the arable layer of 1.74%, the pH of the soil solution is 8.1. The content of easily hydro-lyzable nitrogen is low — 3.2–3.9 mg/100 g of soil, average phosphorus mobile — 2.1–3 mg and exchange potassium increased — 30–40 mg/100 g of soil. The amount of average annual rainfall is 339.7 mm.Results. A study of the data showed that regardless of crop rotation the maximum content of nutrients (nitrogen, phosphorus, potassium) was observed in the tillering phase, then decreased. The correlation coefficient on irrigation shows the tightness of communication over the entire array and gives grounds to use the approximation of the multiple regression equation as predictive in the system of forest stripes on irrigation: Y = a + b1 Х1 + b2X2 and on the dry land: Y = a + b1X1 + b2X2 + b3X3. In dry years the yield of grain crops (corn, sorghum, oats, winter wheat) ranges from 0.59 to 1.73 t/ha. In wet years the yield of grain crops increases to 4.95 t/ha. With the help of programs you can calculate the amount of fertilizer for a given yield and manage the bioproductivity of crops in the system of forest belts and on the dry land. The importance of soil fertility in managing bioproductivity is based on the optimal selection of precursors and methods of biologization, which can increase the yield of grain crops. The scope of the recommendations is the Lower Volga soil zone.

Impact of vegetation restoration on soil properties in near-surface fissures located in karst rocky desertification regions

Karst rocky desertification and vegetation restoration have become major environmental and social problems throughout the world. In regions facing rocky karst desertification, any form of residual soil is pivotal to vegetation growth and the restoration of rocky desertification. The goals of this study were to discover the impact of vegetation restoration on soil properties in near-surface fissures of karst rocky desertification regions, and analyses of the physical and chemical properties of soil and stable isotope techniques were used to achieve these goals. We found that the morphological structures of karst near-surface fissures are diverse. Fissures with grass and shrubs exhibit improved soil bulk density and more fine soil particles than those with other vegetation. Fissures with shrubs have higher soil field capacity, an increased capillary water content and a greater field capacity, whereas fissures with grass display greater fertility, particularly with respect to hydrolysable nitrogen, and greater available phosphorus and potassium contents, which create conditions that are superior to those found in areas with other crops, shrubs and even trees. Karst near-surface fissures are the optimal locations for vegetation restoration in areas of karst rocky desertification. Fissures with grass have a better soil structure, a higher water content and improved fertility compared with other fissure with growing crops, shrub grasses and forests with certain soil degradation. The use of grasses should be prioritized to improve soil conditions and to advance sustainable land use during the implementation of vegetation restoration projects in karst rocky desertification regions, particularly in highly fissured areas.

Influence of the Fertilization System on Fertility Indicators of Sod-Podzolic Heavy Loamy Soil in the Pre-Urals

The effect of long-term usage of various fertilization systems (organic, mineral, and organic-mineral) on the agrochemical indicators of sod-podzolic heavy loamy soil and the productivity of crops of eight-field crop rotation has been studied. Fertilization systems with high saturation (manure 20 t/ha per year, NPK in equivalents of manure 20 t/ha per year, and manure 10 t/ha per year + NPK in equivalents of manure) provided a significant increase in soil humus content (from 1.97 to 2.23–2.50%), mobile phosphorus (by 120–145 mg/kg), and exchangeable potassium (by 105–163 mg/kg) as well as increase in total, mineral, and hydrolyzable nitrogen content (by 200–360, 1.3–2.3, and 53–65 mg/kg, respectively). Cattle manure contributes to a decrease in hydrolytic acidity from 2.3 to 1.5–1.8 and to an increase in the amount of exchange bases from 18.2 to 20.8–21.9 mmol/100 g of soil. NPK treatment (in equivalents of manure 20 t/ha per year) leads to an increase in the hydrolytic acidity by 1.0 and to a decrease in the total exchangeable bases by 1.1 mmol/100 g. The maximum productivity of arable land (3800 fodder units per ha) has been obtained under fertilization systems NPK equivalent to manure 20 t/ha per year and manure 10 t/ha per year + NPK in equivalents of manure.

Effects of Graphene on Larix olgensis Seedlings and Soil Properties of Haplic Cambisols in Northeast China

We investigated the impacts of graphene application at different concentrations on the growth and physiological characteristics of Changbai larch (Larix olgensis A. Henry) seedlings and the chemical properties and enzyme activities of Haplic Cambisols under these seedlings. The aim is to evaluate the environmental effects of graphene on the afforestation species and the zonal forest soils of Northeast China. Seedlings receiving 0 (CK), 25, 50, 100, 250, or 500 mg L−1 graphene were incubated for 30, 40, or 50 days. Low concentrations (25–50 mg L−1) of graphene increased the dry masses of root, stem, and leaf; however, high concentrations (100–500 mg L−1) inhibited them. Compared with those under 0 mg L−1 graphene, the root length, surface area, volume, and average diameter all increased during the early stages of incubation (i.e., 30 and 40 days) under low concentration of graphene (&lt;50 or 100 mg L−1) and decreased at higher graphene concentration (&gt;100 mg L−1); at 50 days, they were significantly inhibited. At 30 days, graphene decreased superoxide dismutase (SOD) and peroxidase (POD) activities, as well as pigment, soluble protein, and proline contents, and the decline increased with increasing graphene concentration; at 40 and 50 days, the above parameters increased initially and then decreased, reaching a maximum at 50 mg L−1. The changes in relative conductivity and malondialdehyde (MDA), superoxide anion and hydrogen peroxide contents were the opposite of those in the physiological indexes mentioned above. Therefore, graphene caused different degrees of oxidative stress in L. olgensis seedlings. At 30 days, graphene generally increased the organic matter, hydrolytic nitrogen, and available phosphorus and potassium contents of Haplic Cambisols, but these parameters decreased at 40 and 50 days. Graphene generally decreased acid phosphatase, urease, dehydrogenase, and catalase activities. Therefore, when graphene reaches a certain content level in this soil, it may also affect nitrogen and phosphorus cycling.

Effect of Pennisetum giganteum z.x.lin mixed nitrogen-fixing bacterial fertilizer on the growth, quality, soil fertility and bacterial community of pakchoi (Brassica chinensis L.).

Biofertilizer plays a significant role in crop cultivation that had reduced its inorganic fertilizer use. The effects of inorganic fertilizer reduction combined with Pennisetum giganteum z.x.lin mixed nitrogen-fixing biofertilizer on the growth, quality, soil nutrients and diversity of the soil bacterial community in the rhizosphere soil of pakchoi were studied. The experiment composed of 6 treatments, including CK (no fertilization), DL (10% inorganic fertilizer reduction combined with Pennisetum giganteum z.x.lin mixed nitrogen-fixing biofertilizer), ZL (25% inorganic fertilizer reduction combined with Pennisetum giganteum z.x.lin mixed nitrogen-fixing biofertilizer), SL (50% inorganic fertilizer reduction combined with Pennisetum giganteum z.x.lin mixed nitrogen-fixing biofertilizer), FHF (100% inorganic fertilizer) and JZ (100% inorganic fertilizer combined with sterilized Pennisetum giganteum z.x.lin mixed nitrogen-fixing biofertilizer). Compared with conventional fertilization, the 25% reduction in chemical fertilizer applied with the Pennisetum giganteum mixed nitrogen-fixing biofertilizer resulted in higher plant height, plant weight, chlorophyll content, soluble protein content, soluble sugar content, vitamin C content, alkali hydrolyzed nitrogen content, available phosphorus content, available potassium content and organic matter content in pakchoi, and these variables increased by 11.81%, 8.54%, 7.37%, 16.88%, 17.05%, 23.70%, 24.24%, 36.56%, 21.09% and 19.72%, respectively. In addition, the 25% reduction in chemical fertilizer applied with the Pennisetum giganteum mixed nitrogen-fixing biofertilizer also had the lowest nitrate content, which was 53.86% lower than that with conventional fertilization. Different fertilizer treatments had a significant effect on the soil bacterial community structure. Compared with conventional fertilization, the coapplication of Pennisetum giganteum z.x.lin mixed nitrogen-fixing biofertilizer and inorganic fertilizer significantly increased the relative abundance of Proteobacteria and Actinobacteria in the soil. The results of the redundancy analysis (RDA) showed that soil organic matter, alkali-hydrolyzed nitrogen, available phosphorus, available potassium, pH and water content had a specific impact on the soil bacterial community. Among the factors, soil water content was the main factor affecting the soil bacterial community, followed by soil organic matter, soil pH, available potassium, soil available phosphorus and soil alkali-hydrolyzed nitrogen.

ПРОДУКТИВНОСТЬ КАРТОФЕЛЯ В ЗАВИСИМОСТИ ОТ СПОСОБА ПРИМЕНЕНИЯ РЕГУЛЯТОРА РОСТА И РАСЧЕТНОМ ФОНЕ МИНЕРАЛЬНОГО ПИТАНИЯ НА СЕРОЙ ЛЕСНОЙ ПОЧВЕ ЛЕСОСТЕПИ СРЕДНЕГО ПОВОЛЖЬЯ

The reaction of the early ripening potato of Vineta variety to different methods of using growth regulators against the calculated background of mineral nutrition on the gray forest-steppe soil of middle Volga was studied. The effectiveness of processing planting tubers and foliar treatment of plants during their vegetation has been established. The experiments were carried out on the control without the introduction of NPK and on a fertilized background, designed to obtain a tuber crop of 40 tons per hectare. The studies were conducted on gray forest medium loam granulometric composition soil of “Zemlyaki” farm in Nizhnekamsk district of the Republic of Tatarstan. Field experiments were carried out in 2019 by employees of Plant Growing and Horticulture Department of Kazan State Agrarian University. The humus content in the arable layer of soil according to Tyurin is 3.35%, pH is 5.7, easily hydrolyzable nitrogen is 112 mg/kg of soil, mobile phosphorus is 156 mg/kg, exchange potassium is 136 mg/kg of soil, molybdenum is 0.07, copper is 0.52, boron - 0.7, zinc - 4.82 mg/kg. The effectiveness of the integrated use of growth regulators (treatment of planting tubers and foliar application of the drug during the growing season) has been established. The yield increase to control against the background without applying basic fertilizers amounted to 4.82 tons per hectare, and against the background of their application - 4.80 tons per hectare.

Mapping spatiotemporal decisions for sustainable productivity of bamboo forest land

AbstractProperly mapping the sustainability of bamboo forest production plays an important role in providing basic strategies for decision makers to ensure sustainable use of bamboo resources. Understanding the response pattern of drought, poor management, elevation, and barren soil to bamboo forest ecosystem productivity is critical to formulating appropriate improvement strategies of sustainable management of bamboo forest productivity for addressing growing challenges of bamboo forest land degradation. The objectives of this study were to quantify differences in productivity, meteorological, topographical, soil, and bamboo distribution and structure factors under different sustainable management levels of bamboo forest ecosystem productivity in order to support management decision making in a spatiotemporally explicit context. We constructed an innovative three‐layer index system for the sustainable management of bamboo forest productivity by integrating productivity, meteorological, soil, topographic, bamboo distribution, and structure factors to promote sustainable management and spatiotemporal decision making, particularly in bamboo forest areas with low productivity. The partial least squares (PLS) path model was used to analyze the spatiotemporal effects of different factors on bamboo forest productivity and to create sustainable management maps that could be used for spatially informed decision making regarding bamboo forest production. The results showed the spatial and temporal variations in gross primary productivity (GPP), net primary productivity (NPP), and net ecosystem exchange (NEE) in bamboo forests. The sustainable management index was also mapped each year throughout the study area. We divided the index value range into five management‐friendly classes, which were shown to be directly related to GPP, NPP, NEE, Slope, Aspect, soil texture, hydrolytic nitrogen, and Abundance. We found that the areas with relatively high sustainable management levels (I and II) occupied only 18.94% of the bamboo forest area and exhibited a highly clustered distribution. Most of the other areas (78.67%) had relatively low levels of sustainable management (III and IV), and their distribution was rather scattered. The remaining 2.39% of the bamboo forest area that had the lowest sustainable management level (V) was small in area, fragmented, and not conducive to intensive management. The results of the present study can serve as a useful reference for bamboo forest management, which is of great importance for bamboo‐based ecosystems and economies.

Removal of heavy metals from industrial sludge with new plant–based washing agents

Washing is one of the techniques for permanent removal of heavy metals from industrial sludge, for which washing agents are a key influence factor. However, high–efficiency, eco–friendly, and inexpensive agents are still lacking. In this study, the solutions derived from the three plant materials including Fatsia japonica, Hovenia acerba and Pterocarya stenoptera were employed to remove Cd, Cu, Pb, and Ni from industrial sludge. The effects of washing solution concentration, pH, washing time and temperature on metal removal were investigated. The metal removal efficiencies were found to increase with increasing solution concentrations or washing temperatures, decline with increasing pH, and presented various trends with increasing washing time. Among the three agents that derived from H. acerba showed relatively high removal for Cu (75.81%), Pb (63.42%), Ni (27.52%), and Cd (56.99%). After washing, environmental risks of residual metals were markedly diminished in sludge, attributable to decrease in their exchangeable forms. Furthermore, the applications of the plant washing agents increased sludge organic carbon, alkali–hydrolysable nitrogen, available phosphorus, and available potassium. Fourier transform infrared spectroscopy analysis suggested that the hydroxyl, carboxyl, ether, and amide may be the main functional groups in the three plant materials binding the heavy metals. Overall, the agent derived from H. acerba appears to be a feasible washing material for heavy metals removal from sludge.