Alkaline Hydrolysis Nitrogen Research Articles

Effect of Compound Fertilizer on Foxtail Millet Productivity and Soil Environment

The effects of balanced fertilization with nitrogen, phosphorus, and potassium (NPK) on foxtail millet productivity and the soil environment under the same conditions of total nutrients have received limited research attention. Therefore, in this study, three balanced fertilization patterns of 27-14-10 (T1), 27-17-7 (T2), and 30-10-11 (T3), and one no fertilization treatment (CK), a total of four treatments, were set up through a two-year field experiment to study the effects of balanced fertilization patterns on foxtail millet yield and soil environment. Mantel analysis was conducted to reveal the correlation between soil environmental factors and the community and their contribution to productivity. The results showed that: (1) all balanced fertilization treatments significantly increased foxtail millet yield, with the highest yield in the T1 treatment. (2) The contents of EC, available K, available P, and alkaline-hydrolyzable nitrogen in the soil of the two-year TI treatments were higher than those of the other treatments and increased by 7.20–9.36%, 24.87–52.35%, 55.83–56.38%, and 21.05–43.95%, respectively, compared with CK. (3) Soil urease activity in the T1 treatment increased significantly by 26.67% and 9.00% compared with the control over the two years. Sucrase activity increased by 36.27% and 23.88% in the T1 treatment compared to CK, and glutaminase activity increased by 33.33% and 19.23% in the T1 treatment compared to CK. (4) T1 treatment significantly increased the OUT number and diversity index of the soil bacterial community. (5) Mantel analysis and principal component analysis showed that available soil nutrients and soil enzymes were positively correlated, and soil enzymes and soil nutrients contributed more to foxtail millet productivity. In this study, the 27-14-10 balanced fertilization pattern was more effective, providing a theoretical basis for the research and development of special fertilizers for foxtail millet and offering technical guidance for realizing the light simplified cultivation of foxtail millet and sustainable development of cost–saving and increased efficiency.

Soil Biocrusts May Exert a Legacy Impact on the Rhizosphere Microbial Community of Plant Crops

Biological soil crusts (biocrusts) play important ecological roles in many ecosystems, but their legacy effects in subtropical agricultural systems are poorly understood. This study investigated how biocrusts impact soil properties and subsequent crop rhizosphere microbiomes. Soil with (+BC) and without (−BC) biocrusts was cultivated and used to grow pepper plants in a greenhouse experiment. Soil physicochemical properties and microbial communities in the pre-planting soils, and microbial communities in crop rhizosphere were analyzed. The results showed that soils with biocrust had significantly higher organic matter, total nitrogen, alkaline hydrolyzable nitrogen, total phosphorus, and total potassium content. Microbial community structures differed significantly among treatments, with −BC soils exhibiting higher microbial diversity in pre-planting conditions, while +BC soils showed higher diversity in crop rhizosphere soils. Soil properties, especially extractable potassium, total nitrogen, and organic matter content, were significantly correlated with rhizosphere microbial community structure. Additionally, our results showed that the first principal coordinate (PCoA1) of soil microbial community structure was significantly correlated with rhizosphere microbiota. Multiple regression analysis revealed that pre-planting soil microbial diversity indices and certain soil physicochemical properties could predict crop rhizosphere soil microbial diversity. Our results demonstrate that biocrusts can enhance soil fertility and alter microbial communities in subtropical agricultural soils, with persistent effects on the crop rhizosphere microbiome. This study provides new insights into the ecological legacy of biocrusts in managed subtropical ecosystems and their potential agricultural implications.

Effects of decomposed and undecomposed straw of three crops on clubroot disease of Chinese cabbage and soil nutrients

Aims: Straw turnover plays an important role in reducing soil diseases, improving the ecological environment of plowland and realizing the effective ecological utilization of straw. Methods: Pot and field experiments were carried out to investigate the effects of maize, rice and wheat straws on the growth, clubroot disease of Chinese cabbage and soil nutrients. Undecomposed and decomposed maize, rice and wheat straws were quantitatively added to the monocultural soil of Chinese cabbage, and the crops without straw were taken as the control. Results: The results showed that the addition of maize, wheat and rice straws could promote the growth of monocultural Chinese cabbage, inhibit the occurrence of clubroot disease, increase soil pH value, the content of soil organic matter, alkaline hydrolyzable nitrogen and available potassium in pot experiment. Exogenous straw application could reduce the incidence rate by 22.54 ~ 47.85%, increase the plot yield of field 95.15 ~ 365.81%. Conclusions: In terms of inhibiting clubroot disease and improving soil properties, undecomposed rice straw is superior to maize and wheat straw, while decomposed maize straw is superior to rice and wheat straw.

Effects of Continuous Cropping on the Physiochemical Properties, Pesticide Residues, and Microbial Community in the Root Zone Soil of Lycium barbarum

Continuous cropping is a common obstacle limiting the high quality and yield of Lycium barbarum （wolfberry）. To clarify the response of soil characteristics of the wolfberry root zone to continuous cropping years, we systematically determined the physicochemical properties and pesticide residues of soils in the wolfberry root zone with different continuous cropping years. In addition, soil bacterial and fungal communities were characterized using high-throughput sequencing technology. The results were as follows： The content of total salt and imidacloprid in the root zone of wolfberry increased with increasing years of continuous cropping. Compared to that with 2 and 9 years, the total salt content in the root zone of wolfberry with 15 years of continuous cropping increased by 51.97% and 54.33%, respectively, and the imidacloprid content increased by 39.58% and 36.61%, respectively. Alkaline nitrogen and available potassium showed an increasing and then decreasing trend. Compared to that with 2 and 15 years, alkaline nitrogen and available potassium in the root-soil of wolfberry with 9 years of continuous cropping increased by 16.94%-28.09% and 18.31%-18.34%, respectively. The diversity and abundance of bacterial communities and the abundance of fungal communities were higher in the root-soil of wolfberry with 9 years of continuous cropping compared to that with 15 years of continuous cropping. In addition, the increase in continuous cropping years also increased the accumulation of harmful plant pathogens such as Pseudomonas, Arthrobacter, Actinomucor, and Trichoderma in the root zone of L. barbarum. Soil total salinity, organic matter, alkaline hydrolyzable nitrogen, and available potassium were the main factors influencing the distribution of bacterial communities. Soil alkaline hydrolyzable nitrogen, available potassium, and ammonium nitrogen were the main factors influencing the distribution of fungal communities. In addition, the soil bacteria in the root zone of L. barbarum were dominated by metabolic functions； in particular, amino acid metabolism, energy metabolism, and nucleotide metabolism were most abundant in the root soil of wolfberry with 9 years of continuous cropping, whereas the highest abundance of functional genes related to membrane translocation was found in the root-soil of wolfberry with 15 years of continuous cropping. The soil fungi were all dominated by saprophytic trophic types, followed by pathogenic cross-nutrients in the root zone of L. barbarum. In conclusion, long-term continuous cropping induced changes in the soil microenvironment in the root zone of L. barbarum, increased soil residues of harmful pesticides and the enrichment of plant pathogens, and reduced the diversity of soil bacterial and fungal communities. Therefore, it is necessary to control the rate of application of soil nutrients and pesticides in the management of L. barbarum and to carry out deep ploughing and deep tilling in good time, and the turnover of old plants in the cultivation of L. barbarum.

The advantage of afforestation using native tree species to enhance soil quality in degraded forest ecosystems

Different vegetation restoration methods have improved soil quality to varying degrees. This study, focused on the forest–grassland–desert transition zone in the Hebei–Inner Mongolia border region, and employed a systematic grid sampling method to establish fixed monitoring plots in the Saihanba Mechanized Forest Farm and the Ulan Buh Grassland. The differences in soil quality evolution across various vegetation restoration methods under the same climatic and soil historical conditions were analyzed, elucidating the roles of these vegetation restoration methods in degraded forest ecosystems, with the aim of providing a reference for ecological restoration under similar land conditions. This study used a grid method to establish sample points in the forest–grassland–desert transitional zone and assessed five methods of vegetation restoration sites: artificial forest composed of native species of Larix principis-rupprechtii (FL), artificial forest composed of exotic Pinus sylvestris var. mongolica (FP), natural secondary broad-leaved forest (FN), open grassland (GO), and enclosed grassland (GC). The differences in soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), alkaline hydrolysis nitrogen (AN), rapidly available phosphorus (AP) and rapidly available potassium (AK) among the different vegetation restoration sites were compared via variance analysis, and the soil quality index (SQI) was calculated to assess the soil quality at the sample points. The SOC, TN, and AN contents of forest soil were significantly greater than those of grassland, and the TN, TP, AN, AK, and SOC contents of FL, FN, and GC were significantly greater than those of FP and GO. Among them, the TN, TP, and SOC contents were the highest in the FL, reaching 2.74, 0.39, and 47.27 g kg−1, respectively. In terms of ecological stoichiometric characteristics, the average N:P ratio in the study area was 6.68, indicating a serious lack of N in the study area. Among the different types of restoration sites, the effect was stronger in the FP than in the FL, and the TN and AN contents were only 1.48 g kg−1 and 116.69 mg kg−1, respectively. The SQI in the FL was not significantly different from that in the FN or GC, but it was significantly greater than that in the FP and GO. These findings indicate that native tree species restoration in degraded forest ecosystems significantly improved soil quality, while the introduction of exotic tree species for afforestation had a minimal effect on improving soil quality.

Co-application of biochars and Piriformospora indica improved the quality of coastal saline soil and promoted the growth of forage.

Soil quality is defined as the ability of soil to maintain the soil environment and the biosphere. Due to the limitation of salt and alkali stress, soil quality can be reduced, which in turn affects agricultural production. Biochar is widely used in saline-alkali land improvement because of its special pore structure and strong ion exchange ability, while Piriformospora indica is widely used in saline-alkali land improvement because it can symbiose with plants and improve plant stress resistance. However, the synergistic effect of combined biochar application and inoculation of P. indica on the quality of saline-alkali soil and plant development is uncertain. Hence, we investigated the combined influences of biochar and P. indica on the soil physicochemical characteristics, as well as the growth and chlorophyll florescence of sorghum-sudangrass hybrids (Sorghum bicolor × Sorghum sudane) in our study. The results indicated that after applying biochar and P. indica together, there was a considerable drop in soil pH, conductivity, Na+, and Cl- concentrations. Meanwhile, the soil organic matter (SOM), available phosphorus (AP), and alkaline hydrolyzable nitrogen (AN) increased by 151.81%, 50.84%, and 103.50%, respectively, when the Bamboo biochar was combined with 120 ml/pot of P. indica. Eventually, sorghum-sudangrass hybrid biomass, transpiration rate, and chlorophyll content increased by 111.69%, 204.98%, and 118.54%, respectively. According to our findings, using P. indica and biochar together can enhance soil quality and plant growth. The results also provide insights to enhance the quality of saline-alkali soils and the role of microorganisms in nutrient cycling.

Synergistic enhancement of cadmium immobilization and soil fertility through biochar and artificial humic acid-assisted microbial-induced calcium carbonate precipitation

Microbially induced carbonate precipitation (MICP) is emerging as a favorable alternative to traditional soil remediation techniques for heavy metals, primarily due to its environmental friendliness. However, a significant challenge in using MICP for farmland is not only to immobilize heavy metals but also to concurrently enhance soil fertility. This study explores the innovative combination of artificial humic acid (A-HA), biochar (BC), and Sporosarcina pasteurii (S. pasteurii) to mitigate the bioavailability of cadmium (Cd) in contaminated agricultural soils through MICP. X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses revealed that the integration of BC and A-HA significantly enhances Cd immobilization efficiency by co-precipitating with CaCO3. Moreover, this treatment also improved soil fertility and ecological functions, as evidenced by increases in total nitrogen (TN, 9.0–78.2 %), alkaline hydrolysis nitrogen (AN, 259.7–635.5 %), soil organic matter (SOM, 18.1–27.9 %), total organic carbon (TOC, 43.8–48.8 %), dissolved organic carbon (DOC, 36.0–88.4 %) and available potassium (AK, 176.2–193.3 %). Additionally, the relative abundance of dominant phyla such as Proteobacteria and Firmicutes significantly increased with the introduction of BC and A-HA in MICP. Consequently, the integration of BC and A-HA with MICP offers a promising solution for remediating Cd-contaminated agricultural soil and synergistically enhancing soil fertility.

Bacterial community in the buckwheat rhizosphere responds more sensitively to single microplastics in lead-contaminated soil compared to the arbuscular mycorrhizal fungi community

Soil pollution by microplastics (MPs), defined as plastic particles <5 mm, and heavy metals is a significant environmental issue. However, studies on the co-contamination effects of MPs and heavy metals on buckwheat rhizosphere microorganisms, especially on the arbuscular mycorrhizal fungi (AMF) community, are limited. We introduced low (0.01 g kg−1) and high doses of lead (Pb) (2 g kg−1) along with polyethylene (PE) and polylactic acid (PLA) MPs, both individually and in combination, into soil and assessed soil properties, buckwheat growth, and rhizosphere bacterial and AMF communities in a 40-day pot experiment. Notable alterations were observed in soil properties such as pH, alkaline hydrolyzable nitrogen (AN), and the available Pb (APb). High-dose Pb combined with PLA-MPs hindered buckwheat growth. Compared to the control, bacterial Chao1 richness and Shannon diversity were lower in the high dose Pb with PLA treatment, and differentially abundant bacteria were mainly detected in the high Pb dose treatments. Variations in bacterial communities correlated with APb, pH and AN. Overall, the AMF community composition remained largely consistent across all treatments. This phenomenon may be due to fungi having lower nutritional demands than bacteria. Stochastic processes played a relatively important role in the assembly of both bacterial and AMF communities. In summary, MPs appeared to amplify both the positive and negative effects of high Pb doses on the buckwheat rhizosphere bacteria.

Mn-modified bamboo biochar improves soil quality and immobilizes heavy metals in contaminated soils

Soil contamination by heavy metals is becoming increasingly serious and needs to be solved urgently. Modified biochar is an effective strategy to solve this problem, and previous studies have only focused on the remediation of single heavy metal contaminated soils through biochar. However, the effects of metal-modified bamboo biochar on soil improvement and the passivation of heavy metals are still unknown. In this study, the Mn-modified bamboo biochar was prepared and the effects of Mn-modified bamboo biochar on soil improvement and the passivation of heavy metals were investigated. The results showed that Mn-modified bamboo biochar can improve the physical and chemical properties of soil, and immobilize heavy metals (i.e., Pb, As, Cd, and Cu). After adding Mn-modified bamboo biochar, soil pH decreased by 0.08–0.70, organic matter content increased by 8.00–45.13%, and alkaline hydrolysis nitrogen content increased by 1.84–5.78%. The diethylene triamine penta-acetic acid (DTPA)-extractable Pb, As, Cd, and Cu decreased by 21.25–58.65%, 7.76–34.02%, 36.44–46.50%, and 3.13–35.21%, respectively, while the acid-extractable Pb, As, Cd, and Cu decreased by 27.81–43.31%, 23.91–26.01%, 17.56–50.60%, and 7.94–18.09% respectively. These results indicated that Mn-modified bamboo biochar can improve the physicochemical properties of the soil and effectively inactivate multi-heavy metals in contaminated soil, Mn-modified bamboo biochar is a potential alternative agent for the management of multi-heavy metal contaminated soils.

Differential effects of winter cold stress on soil bacterial communities, metabolites, and physicochemical properties in two varieties of Tetrastigma hemsleyanum Diels & Gilg in reclaimed land.

Tetrastigma hemsleyanum Diels & Gilg (TDG) has been recently planted in reclaimed lands in Zhejiang Province, China, to increase reclaimed land use. Winter cold stress seriously limits the growth and development of TDG and has become the bottleneck limiting the TDG planting industry. To investigate the defense mechanisms of TDG toward winter cold stress when grown on reclaimed land, a combined analysis of soil bacterial communities, metabolites, and physicochemical properties was conducted in this study. Significant differences were observed in the composition of soil bacterial communities, metabolites, and properties in soils of a cold-tolerant variety (A201201) compared with a cold-intolerant variety (B201810). The fresh weight (75.8% of tubers) and dry weight (73.6%) of A201201 were significantly higher than those of B201810. The 16S rRNA gene amplicon sequencing of soil bacteria showed that Gp5 (25.3%), Gemmatimonas (19.6%), Subdivision3 (16.7%), Lacibacterium (11.9%), Gp4 (11.8%), Gp3 (10.4%), Gp6 (7.0%), and WPS-1 (1.2%) were less common, while Chryseolinea (10.6%) were more common in A201201 soils than B201810 soils. Furthermore, linear discriminant analysis of effect size identified 35 bacterial biomarker taxa for both treatments. Co-occurrence network analyses also showed that the structures of the bacterial communities were more complex and stable in A201201 soils compared to B201810 soils. In addition, ultra-high-performance liquid chromatography coupled to mass spectrometry analysis indicated the presence of significantly different metabolites in the two soil treatments, with 10 differentially expressed metabolites (DEMs) (8 significantly upregulated by 9.2%-391.3% and 2 significantly downregulated by 25.1%-73.4%) that belonged to lipids and lipid-like molecules, organic acids and derivatives, and benzenoids. The levels of those DEMs were significantly correlated with the relative abundances of nine bacterial genera. Also, redundancy discriminant analysis revealed that the main factors affecting changes in the bacterial community composition were available potassium (AK), microbial biomass nitrogen (MBN), microbial biomass carbon (MBC), alkaline hydrolysis nitrogen (AHN), total nitrogen (TN), available phosphorus (AP), and soil organic matter (SOM). The main factors affecting changes in the metabolite profiles were AK, MBC, MBN, AHN, pH, SOM, TN, and AP. Overall, this study provides new insights into the TDG defense mechanisms involved in winter cold stress responses when grown on reclaimed land and practical guidelines for achieving optimal TDG production.IMPORTANCEChina has been undergoing rapid urbanization, and land reclamation is regarded as a viable option to balance occupation and compensation. In general, the quality of reclaimed land cannot meet plant or even cultivation requirements due to poor soil fertility and high gravel content. However, Tetrastigma hemsleyanum Diels & Gilg (TDG), extensively used in Chinese herbal medicine, can grow well in stony soils with few nutrients. So, to increase reclaimed land use, TDG has been cultivated on reclaimed lands in Zhejiang Province, China, recently. However, the artificial cultivation of TDG is often limited by winter cold stress. The aim of this study was to find out how TDG on reclaimed land deal with winter cold stress by looking at the bacterial communities, metabolites, and physicochemical properties of the soil, thereby guiding production in practice.

Soil fungal community is more sensitive than bacterial community to modified materials application in saline-alkali land of Hetao Plain.

Soil salinization has become a major challenge that severely threatens crop growth and influences the productivity of agriculture. It is urgent to develop effective management measures to improve saline-alkali soil. Thus, in this study, soil properties, microbial communities, and function under desulfurization gypsum (DE), soil amendment (SA), farm manure (FA), and co-application of desulfurization gypsum, soil amendment, and farm manure (TA) in a field experiment were examined by high-throughput sequencing. The results showed that the application of modified materials is an effective approach in improving saline-alkali soil, especially TA treatment significantly increased the content of available phosphorus (AP), available potassium (AK), soil organic matter (SOM), and alkaline hydrolysis nitrogen (AHN) and decreased pH, bulk density (BD), and electrical conductivity (EC). The application of modified materials resulted in notable enhancement in fungal diversity and altered the composition and structure of the fungal community. Conversely, the effect on the bacterial community was comparatively minor, with changes limited to the structure of the community. Regarding the fungal community composition, Ascomycota, Mortierellomycota, and Basidiomycota emerged as the dominant phyla across all treatments. At each taxonomic level, the community composition exhibited significant variations in response to different modified materials, resulting in divergent soil quality. The TA treatment led to a decrease in Mortierellomycota and an increase in Ascomycota, potentially enhancing the ability to decompose organic matter and facilitate soil nutrient cycling. Additionally, the sensitivity of fungal biomarkers to modified materials surpassed that of the bacterial community. The impact of modified materials on soil microbial communities primarily stemmed from alterations in soil EC, AP, AK, and SOM. FUNGuild analysis indicated that the saprotroph trophic mode group was the dominant component, and the application of modified materials notably increased the symbiotroph group. PICRUSt analysis revealed that metabolism was the most prevalent functional module observed at pathway level 1. Overall, the application of modified materials led to a decrease in soil EC and an increase in nutrient levels, resulting in more significant alterations in the soil fungal community, but it did not dramatically change the soil bacterial community. Our study provides new insights into the application of modified materials in increasing soil nutrients and altering soil microbial communities and functions and provides a better approach for improving saline-alkali soil of Hetao Plain.

Response of the rhizosphere soil microbial diversity to different nitrogen and phosphorus application rates in a hulless barley and pea mixed-cropping system

The mixed-cropping mode of hulless barley (Hordeum vulgare L) and peas (Pisum sativum L) can optimize the planting system, effectively enhancing crop nitrogen and phosphorus utilization and increasing yield. This mode has been widely applied in Qinghai Province, China. In this study, a split-plot experimental design was employed to investigate the bacterial and fungal communities in the rhizosphere soil of monocropping and mixed-cropping treatments under different fertilization levels. The Illumina MiSeq sequencing technology was used for the research, and the physicochemical properties of the soil were measured. The results indicated that with the increase in the application of nitrogen and phosphorus, the bacterial α-diversity in the rhizosphere of the mixed-cropping system initially increased and then decreased after reaching a peak. The α-diversity index of soil bacteria was higher under the mixed-cropping mode than under the monocropping mode. For the rhizosphere soil fungi in the mixed-cropping system, the Shannon index initially increased and then decreased, while the Chao1 and ACE indices decreased initially and then increased. Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Sphingomonas, and Pseudomonas comprised the predominant bacterial genera in the rhizosphere soil of the hulless barley–pea intercropping treatment, whereas Fusarium, Metarhizium, and Cladosporium dominated among the fungal genera across the 12 treatments. Under the same fertilization levels, the relative abundances of Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium in the rhizosphere soil of the mixed-cropping treatment increased by 8.4 %, 7.1 %, 5.7 %, and 5.6 %, respectively, compared to the monoculture of hulless barley, with a decreasing trend as nitrogen and phosphorus levels increased. Compared to the monoculture of hulless barley, the relative abundance of Fusarium in the mixed-cropping treatment decreased by 37.3 %, 43.8 %, 56.8 %, and 40.3 %, respectively. Redundancy and correlation analyses suggested that the variation in bacterial and fungal diversity and community composition in the mixed-cropping zone due to the interaction between hulless barley and peas under different nitrogen and phosphorus fertilizer application levels was significantly correlated with changes in soil organic matter, available phosphorus, and alkaline hydrolyzable nitrogen.

Современное состояние почв лесных питомников таежной зоны Европейской части России

When producing planting material in the taiga zone, it is extremely important to assess problematic sites in forest nurseries. Attention should be paid to poor soil quality, which can significantly affect the growth rate of seedlings and the yield of standard planting material. The article considers a comprehensive assessment of soil conditions in forest nurseries of the taiga zone of the European part of Russia. The research was conducted in six forest nurseries. Agrochemical and physical properties of soils were determined. The content of organic matter in the soils of forest nurseries is low, mobile forms of phosphorus, exchangeable potassium and alkaline hydrolyzable nitrogen are insufficient for optimal growth and development of coniferous seedlings. The level of acidity in the soils of nurseries in the taiga zone of the European part of Russia turned out to be favorable. Half of the studied forest nurseries have increased density of soil composition, which can lead to the formation of soils with low pore volume, limiting air intake and moisture retention in the soil. A decrease in the intensity of seedling growth and yield of standard seedlings may occur due to the lack of technological measures such as weed control, lack of irrigation, etc., but one of the most important reasons is the insufficient supply of soils with mineral and organic substances. Equalization of soil fertility parameters in forest nurseries can be achieved by application of necessary fertilizers and by means of cultivation. The results of the presented work will make it possible to draw the attention of specialists engaged in the cultivation of planting material in the taiga zone of the European part of Russia to the problem of low soil fertility.

Оценка биологического ресурса базовых компонентов агроценоза с бинарными посевами подсолнечника и галеги восточной

The article provides an analysis of binary sunflower crops with eastern galega and typical chernozems as basic components of the agrocenosis from the point of view of soil conservation as a natural resource, as well as increasing the biological productivity of cultivated agricultural plants in the Buturlinovsky district of the Voronezh region. The sunflower yield is significantly influenced by the sowing of a perennial legume crop – eastern galega. Perennial leguminous grasses have an impact on the economic value of the soil cover, which is expressed in such indicators as the thickness of the humus horizon, the percentage of humus, the amount of alkaline hydrolyzable nitrogen. There was no significant effect of eastern galega on the amount of exchangeable potassium and phosphorus. Binary crops contribute to the preservation of soil moisture, due to a denser covering of the soil cover, which prevents the physical evaporation of moisture from the surface. Therefore, the introduction of binary crops leads not only to the stabilization of the soil component, the integrity of the agroecosystem is preserved, the productivity of the agrocenosis increases. Keywords: AGROECOSYSTEMS, BINARY CROPS, EASTERN GALEGA, SUNFLOWER, ALKALINE HYDROLYZABLE NITROGEN, EXCHANGEABLE PHOSPHORUS, EXCHANGEABLE POTASSIUM, HUMUS

Characteristics of rhizosphere and bulk soil microbial community of Chinese cabbage (Brassica campestris) grown in Karst area.

Understanding the rhizosphere soil microbial community and its relationship with the bulk soil microbial community is critical for maintaining soil health and fertility and improving crop yields in Karst regions. The microbial communities in the rhizosphere and bulk soils of a Chinese cabbage (Brassica campestris) plantation in a Karst region, as well as their relationships with soil nutrients, were examined in this study using high-throughput sequencing technologies of 16S and ITS amplicons. The aim was to provide theoretical insights into the healthy cultivation of Chinese cabbage in a Karst area. The findings revealed that the rhizosphere soil showed higher contents of organic matter (OM), alkaline hydrolyzable nitrogen (AN), available phosphorus (AP), total phosphorus (TP), available potassium (AK), total potassium (TK), total nitrogen (TN), catalase (CA), urease (UR), sucrase (SU), and phosphatase (PHO), in comparison with bulk soil, while the pH value showed the opposite trend. The diversity of bacterial and fungal communities in the bulk soil was higher than that in the rhizosphere soil, and their compositions differed between the two types of soil. In the rhizosphere soil, Proteobacteria, Acidobacteriota, Actinobacteriota, and Bacteroidota were the dominant bacterial phyla, while Olpidiomycota, Ascomycota, Mortierellomycota, and Basidiomycota were the predominant fungal phyla. In contrast, the bulk soil was characterized by bacterial dominance of Proteobacteria, Acidobacteriota, Chloroflexi, and Actinobacteriota and fungal dominance of Ascomycota, Olpidiomycota, Mortierellomycota, and Basidiomycota. The fungal network was simpler than the bacterial network, and both networks exhibited less complexity in the rhizosphere soil compared with the bulk soil. Moreover, the rhizosphere soil harbored a higher proportion of beneficial Rhizobiales. The rhizosphere soil network was less complicated than the network in bulk soil by building a bacterial-fungal co-occurrence network. Furthermore, a network of relationships between soil properties and network keystone taxa revealed that the rhizosphere soil keystone taxa were more strongly correlated with soil properties than those in the bulk soil; despite its lower complexity, the rhizosphere soil contains a higher abundance of bacteria which are beneficial for cabbage growth compared with the bulk soil.

Effects of different grassland use patterns on soil bacterial communities in the karst desertification areas.

Soil bacteria are closely related to soil environmental factors, and their community structure is an important indicator of ecosystem health and sustainability. A large number of artificial grasslands have been established to control rocky desertification in the karst areas of southern China, but the influence of different use patterns on the soil bacterial community in artificial grasslands is not clear. In this study, three grassland use patterns [i.e., grazing (GG), mowing (MG), and enclosure (EG)] were used to investigate the effects of different use patterns on the soil bacterial community in artificial grassland by using 16S rDNA Illumina sequencing and 12 soil environmental indicators. It was found that, compared with EG, GG significantly changed soil pH, increased alkaline hydrolyzable nitrogen (AN) content (P < 0.05), and decreased soil total phosphorus (TP) content (P < 0.05). However, MG significantly decreased the contents of soil organic carbon (SOC), total phosphorus (TP), available nitrogen (AN), ammonium nitrogen (NH4+-N), β-1,4-glucosidase (BG), and N-acetyl-β-D-glucamosonidase (NAG) (P < 0.05). The relative abundance of chemoheterotrophy was significantly decreased by GG and MG (P < 0.05). GG significantly increased the relative abundance of Acidobacteria and Gemmatimonadota (P < 0.05) and significantly decreased the relative abundance of Proteobacteria (P < 0.05), but the richness index (Chao 1) and diversity index (Shannon) of the bacterial community in GG, MG, and EG were not significantly different (P > 0.05). The pH (R2 = 0.79, P = 0.029) was the main factor affecting the bacterial community structure. This finding can provide a scientific reference for ecological restoration and sustainable utilization of grasslands in the karst desertification areas.

Effects of Microbial Fertilizer on Physicochemical Properties and Bacterial Communities of Saline Soil Under Brackish Water Irrigation

The improvement of saline soil with microbial fertilizer has numerous advantages including high efficiency, green environmental protection, etc. At the same time, applying microbial fertilizer is an effective way to safely use brackish water. Based on the moderately saline soil in the Hetao irrigation area, four treatments of F1 (4500 kg·km-2), F2 (7500 kg·km-2), F3 (10500 kg·km-2), and CK without microbial fertilizer were applied under brackish water irrigation using Lycium barbarum as the indicator plants. The aim was to study the effects of different microbial fertilizer application rates on soil ions, soil moisture content, pH value, nutrients, and bacterial community in four key growth stages of L. barbarum (flowering stage, fruit expansion stage, full fruit stage, and deciduous stage). The results showed that, compared with that in CK, F1 only significantly decreased Na+ content in the first two growth stages (P<0.05), whereas F2 and F3 significantly decreased Na+ content in the whole growth period (P<0.05), with an average reduction of 33.66% and 57.98%, respectively, and F3 significantly increased soil moisture content (MC), organic matter (OM), alkaline hydrolysis nitrogen (AN), and available phosphorus (AP) contents (P<0.05) during the whole growth period. In the flourishing period of L. barbarum, the Shannon index of F3 increased by 4.41% compared with that of CK. The dominant bacterial phyla in the soil were Proteobacteria, Bacteroidetes, and Actinobacteria, and the dominant bacterial genera were Sphingomonas and Pseudomonas. The most abundant functions of bacterial communities in the study area were chemoheterotrophy and aerobic chemoheterotrophy, with an average relative abundance of 15.07% and 13.16%, respectively. The application of microbial fertilizer increased the chitinolysis function and chloroplast functions of soil bacteria, which F2 increased to the highest degree. Canonical correlation analysis (CCA) showed that MC, Na+, and OM were important factors affecting the composition of the bacterial community. The correlation heat map showed that MC was positively correlated with Planctomycetes (P<0.01), and Gp6 was positively correlated with AN (P<0.01). Compared with that in CK, the F3 treatment increased the relative abundance of Gp6 and optimized the community structure during the growth period. In conclusion, the application of 10500 kg·km-2 microbial fertilizer (F3 treatment) under brackish water irrigation could significantly reduce soil salinity, increase nutrients, and improve the diversity of the soil bacterial community structure, which is conducive to the safe utilization of brackish water and the maintenance of soil ecological health.

Effect of Nano Carbon and Nano Calcium Carbonate Application on Soil Nutrient Dynamics in Winter Wheat (Triticum aestivum L.)

ABSTRACT The application of nanomaterials in agriculture has considerable advantages, but its impact on the dynamic change of soil nutrients is still unclear. In the two-year experiment, the effects of nanocarbon (NC) and nano calcium carbonate (NCC) on the dynamic changes of soil nutrients in the wheat field were studied by setting the ratio of different nanomaterials and fertilizers. All treatments with NC and NCC applications positively affected soil nutrient effectiveness at 0–35 d after wheat anthesis, and the effect of NC+NCC was more significant. At 35 days after anthesis, soil available phosphorus (P), available potassium (K), organic matter (OM), and alkaline hydrolysis nitrogen (N) were elevated by 77.9%, 21.9%, 11.7%, and 7.0%, respectively, in the first year and 44.3%, 10.2%, 9.0%, and 7.6%, respectively, in the second year of treatment with 100% CF (complex fertilizer) + 50% NC + 50% NCC compared with control. The treatment with reduced fertilizer application also demonstrated a greater advantage. At 35 d after anthesis, 70% CF + 35% NC + 35% NCC had 54.3%, 11.5%, 8.4%, and 5.8% higher soil available P, available K, OM, and alkaline hydrolysis N, respectively, compared with the control, and 41.05%, 6.4%, 7.8%, and 5.4% higher the following year, respectively. In acidic soils, positively charged NC and NCC have a lasting effect on maintaining soil nutrients by adsorbing acid ions. Therefore, NC and NCC with compound fertilizer have favorable effects in maintaining soil nutrient content and improving fertilizer utilization.

Agricultural Land Quality Evaluation and Utilization Zoning Based on the Production–Ecology–Health Dimension: A Case Study of Huanghua City

Clarifying the constituent elements of agricultural land quality, carrying out multi-dimensional quality evaluation of agricultural land, and implementing precise land consolidation and utilization zoning all have important guiding significance for achieving efficient utilization of agricultural land in China. This work analyzed the multi-dimensional evaluation framework of agricultural land based on its comprehensive quality elements and the production, ecological, and health functions. This paper constructed a multi-dimensional agricultural land “production–ecology–health” quality evaluation index system and evaluation criteria, and carried out a multi-dimensional quality evaluation of agricultural land in Huanghua City, Hebei Province, China. The spatial superposition of each dimension′s evaluation results, combined with the logical relationship between agricultural land use and each dimension′s quality, realized the renovation and utilization zoning of agricultural land. The results are as follows: (1) The production, ecological, and health qualities of agricultural land in Huanghua City were below the average and there is spatial variability, whose proportions of grade III and below were 63.12, 66.23, and 69.32%, respectively. In addition, low score areas are mainly located in the south and northwest of the study area. (2) The obstacle factors to quality in different dimensions were different: The obstacle factors to production quality were matter content, soil pH, irrigation guarantee rate, and alkaline hydrolysis nitrogen; groundwater salinity and depth, soil pH, and chemical fertilizers consumption for ecological quality; and groundwater salinity and depth and soil pH for health quality. (3) Agricultural land in Huanghua city is divided into five types of remediation, including 30,277.34 hm2 for high efficiency utilization area, 10,576.54 hm2 for production quality cultivation area, 34,387.86 hm2 for health quality cultivation area, and 56,311.22 hm2 for comprehensive consolidation and restoration area; special remediation measures are proposed for different types of zones. The work improves the multi-objective quality evaluation index system for agricultural land and implements differentiated land remediation strategies by identifying obstacle factors through zoning. It provides methodological ideas to improve the efficiency of land remediation and utilization.

Long‐term rice cultivation improved coastal saline soil properties and multifunctionality of subsoil layers

AbstractRice cultivation has been found to be an effective and feasible approach for improving saline soils and increasing food production. Most studies on the improvement of rice cultivation on saline soil have focused on the several individual soil properties in the topsoil, and we know little about the importance of rice cultivation for improving multifunctionality in coastal saline soils. We investigated basic soil properties (soil physical sand content, soil physical clay content, pH, EC, soil organic carbon, total nitrogen, alkaline hydrolysis nitrogen, available potassium, available phosphorus), enzyme activities (urease, catalase, protease) and soil multifunctionality (SMF) in 0–20 cm, 20–40 cm, 40–60 cm, 60–80 cm and 80–100 cm soil layers with rice cultivated for 0 (tidal flat; CK), 20 (R20), 44 (R44) and 70 years (R70). We found that soil EC was alleviated markedly in the first 20 years after rice cultivation. Soil physical sand content, pH, EC and available potassium (AK) decreased while total nitrogen (TN), alkaline hydrolysis nitrogen (AN), urease (URE), catalase (CAT) activities and SMF increased with the increase in rice cultivation years. The highest soil total organic carbon (SOC) was shown in R44. Soil pH, EC, AK and physical sand content increased while SOC, TN, AN, enzyme activities decreased with the increase in soil depth. Redundancy (RDA) analysis showed soil physicochemical properties explained 97.53% of the variation in soil enzyme activities. Soil CAT, URE and protease (PRO) had a positive correlation with soil physical clay content, SOC, TN, AN and AP while negatively correlated with pH and AK. The increased SOC and clay content by rice cultivation might be the main reasons stimulating soil enzyme activities. In summary, long‐term rice cultivation could alleviate soil salinity, increased SMF down to 1 m, implying that rice cultivation effectively improved coastal saline soil, and the improvement could last for 70 years.