Total Potassium Content Research Articles

Characteristics of water distribution and preferential flow processes and nutrient response on dolomite slopes in the southwestern karst region

Understanding the characteristics of the soil water content and preferential flow is critical for a thorough comprehension of soil nutrient loss in Karst slopes/ecosystems. We monitored the soil water content and soil temperature at 0–20, 20–40, and 40–60 cm depths on a typical Karst dolomite slope at a high frequency to determine the water distribution characteristics and confirm the occurrence of preferential flow from 2018 to 2021. The soil properties and nutrients in different soil layers during the rainy and dry seasons were determined along the slope (from upper to lower slope positions, with a total of 9 sampling sites). The results revealed that the saturated hydraulic conductivity of the soil at the upper slope position was significantly (p < 0.05) greater than that at the middle and lower slope positions. The soil water content at the down slope position was greater than that at the middle and upper slope positions, further more, coupling monitoring of the soil water content and temperature revealed obvious preferential flow in the Karst dolomite slope. In addition to the spatial variability in the water content, the soil nutrients exhibited regular spatial variations. The dissolved organic carbon (DOC), dissolved organic nitrogen (DON), total nitrogen (TN), total phosphorus (TP) and total potassium (TK) contents were the lowest at the upper slope position and the highest at the down slope position, whereas the difference in nutrients between the rainy and dry seasons was the greatest at the upper slope position. Our results demonstrated that the patterns of the soil water content and surface nutrient loss are consistent along the Karst dolomite slope and are related to the occurrence of preferential flow. Furthermore, the results suggested that, compared with those in previous studies, which focused only on soil properties in the Karst regions of Southwest China, the variation in the soil water content and occurrence of preferential flow may be more important than previously assumed.

The Influence of the Farming System and Forecrop on the Yield and Chemical and Health-promoting Composition of Spring Wheat Grain

Spring wheat was grown on a loess-derived Luvisol under the conditions of two farming systems (conventional and organic) and five forecrops (sugar beet, spring barley, red clover, winter wheat, and oat) over the period 2021–2023. In the conventional system, mineral NPK fertilization and pesticides (herbicides, fungicide, insecticide, and retardant) were applied at the recommended rates for wheat. Mechanical weed control was also used (double harrowing). In the organic system, the organic fertilizer Humac Agro was applied and the fields under the wheat were harrowed twice. No plant protection products were used under organic farming conditions. The organic system was proven to have an effect on reducing spring wheat yield, on average by 23%, compared to the conventional system (the grain yield was, respectively, 4.59 t ha−1 compared to 5.96 t ha−1). In spite of the lower yield potential, the organic cultivation of spring wheat significantly improved the quality and health-promoting parameters of this cereal grain. Except for the total nitrogen and potassium content, the organic system contributed to a significant increase in the grain content of total dietary fiber (by 0.89 p.p.), o-dihydroxyphenols (by about 19%), and polyphenols (by about 12%), and increased the content of the following elements: Se, Mg, Ca, Cu, Mn, Fe, and Zn. Among the forecrops, red clover and sugar beet had the most beneficial effect on grain quality (including the amino acid composition and EAAI index), followed by oat (especially under organic farming conditions). The other wheat forecrops (spring barley and winter wheat) clearly deteriorated the yield and quality of spring wheat grain. To sum up the obtained research results, appropriate management of organic spring wheat cultivation (forecrop sugar beet or red clover, Humac Agro fertilizer) contributes to high grain nutritional quality relative to the conventional system and also reduces the yield gap relative to conventional farming.

Enhancing chickpea growth through arbuscular mycorrhizal fungus inoculation: facilitating nutrient uptake and shifting potential pathogenic fungal communities.

Arbuscular mycorrhizal fungi (AMF) are the most widespread plant symbionts associated with plant roots, and theyperform numerous functions that contribute to plants' health and physiology. However, there are many knowledge gaps in how the interactions between AMF and root mycobiomes influence the performance of the host plants. To this end, we inoculated a local chickpea cultivar grown in agricultural soil under semi-controlled conditions with Rhizophagus irregularis. In addition to examining mycorrhizal colonization, plant biomass, and mineral nutrition, we sequenced the ITS region of the rDNA to assess the chickpea mycobiome and identify key fungal taxa potentially responding to R. irregularis inoculation. Our results showed that inoculation had a positive effect on chickpea biomass and mineral nutrition, especially the total aboveground phosphorus, potassium and sodium contents. Fusarium, Sporomia, Alternaria, and unknown Pleosporales were the most abundant taxa in the roots, while Stachybotris, Penicillum, Fusarium, Ascobolus, an unknown Pleosporales and Acrophialophora were the most abundant in the rhizosphere. Among the ASVs that either were enriched or depleted in the rhizosphere and roots are potential plant pathogens from the genera Didymella, Fusarium, Neocosmospora, and Stagonosporopsis. This study highlights the relevance of AMF inoculation not only for enhancing chickpea growth and mineral nutrition in semi-arid conditions but also for influencing the composition of the plants' fungal community which contributes to improved plant performance and resilience against biotic and abiotic stress.

Enhancing Soil Health and Tea Plant Quality Through Integrated Organic and Chemical Fertilization Strategies

As the global demand for high-quality tea increases, adopting sustainable agricultural practices is crucial to maintaining environmental health and improving crop productivity. Employing organic fertilizers has the potential to boost agricultural output and improve soil health, as well as curb the spread of pests and diseases. The purpose of this survey was to determine the impact of a range of organic fertilizer mixtures on both tea plants and rhizosphere soil characteristics in tea plantations. This study investigated the response of Jin Guanyin tea (Camellia sinensis L.) plants to various organic fertilizer ratios: 2/3 chemical fertilizer + 1/3 organic fertilizer (JTC), 1/2 chemical fertilizer + 1/2 organic fertilizer (JHOC), 1/3 chemical fertilizer + 2/3 organic fertilizer (JTO), and organic fertilizer only (JOF), with chemical fertilizer alone (JCF) as the control. The experiment was conducted in Xingcun Town, Wuyishan, Fujian Province, China, on 13 October 2021. Key metrics measured included tea plant growth indicators, soil physicochemical properties, enzyme activities, and microbial functional diversity. Results show that JTC and JTO produce the largest leaf area and bud weight, significantly surpassing those in JCF. JCF demonstrated the longest new tip length and highest bud density, while JHOC achieved the highest chlorophyll content, significantly exceeding JCF. Soil analysis revealed that total nitrogen, available nitrogen, organic matter, and pH were highest in JOF, significantly overtaking JCF. Conversely, total phosphorus, available potassium, and available phosphorus levels were highest in JCF. JHOC also had the highest total potassium content compared to JCF. Soil enzyme activity assessments showed that polyphenol oxidase and urease activities peaked in JTC, significantly exceeding those in JCF. JHOC exhibited the highest acid phosphatase activity, while JTO exhibited the highest protease activity. Catalase activity was highest in JOF, both significantly surpassing JCF. Microbial functional diversity analysis indicated that combined organic fertilization improved soil microorganisms’ utilization of carbon sources, significantly enhancing the Shannon diversity index and evenness. Key carbon sources identified included α-cyclodextrin, D-galacturonic acid, and 4-hydroxy benzoic acid. Overall, JHOC emerged as the optimal fertilization strategy, yielding superior growth indicators, enhanced soil physicochemical properties, increased enzyme activity, and improved microbial functional diversity compared to JCF. This study has important value for guiding the rational application of fertilizers in tea gardens, improving the soil environment of tea gardens, enhancing the quality of tea leaves, and achieving sustainable tea production.

Impact of Organic Fertilizer Substitution and Chemical Nitrogen Fertilizer Reduction on Soil Enzyme Activity and Microbial Communities in an Apple Orchard

To mitigate the issues of soil quality degradation and environmental pollution caused by excessive fertilizer use in apple orchards, the present study investigated the effects of organic fertilizer substitution combined with chemical nitrogen (N) fertilizer reduction on soil nutrient status, enzyme activity, and microbial communities (bacteria, fungi and archaea) over one year in an apple orchard. Five fertilization treatments were implemented, including 100% chemical fertilizer (CK), 80% chemical fertilizer + 20% liquid humic fertilizer (S1), 60% chemical fertilizer + 40% liquid humic fertilizer (S2), 60% chemical fertilizer + 20% liquid humic fertilizer (S3), and 40% chemical fertilizer + 40% liquid humic fertilizer (S4). Substituting chemical fertilizers with liquid humic fertilizers effectively enhanced the soil organic matter (SOM) content in the topsoil (0–20 cm) for all treatments. Compared to CK, the amounts of available N (NO3−-N and NH4+-N) were decreased in the topsoil and the amounts of total N, total phosphorous and available phosphorous were increased in the subsoil (20–40 cm) for all treatments. The β-diversity of bacterial communities exhibited the highest sensitivity to soil environmental changes, followed by that of archaea, whereas fungi demonstrated the least susceptibility. The higher soil carbon/nitrogen ratio and SOM content in S2 altered the abundance of microorganisms (Proteobacteria, Ascomycota, and Crenarchaeota) that were closely related to the decomposition and mineralization of SOM and N, enhancing the efficiency of SOM decomposition. The activities of sucrase (SUC), urease (UE), and phosphatase were increased, also promoting the conversion efficiency of SOM and improving N fixation and soil fertility. In the organic fertilizer substitution treatments (S1 and S2), the abundance of dominant Actinobacteriota, Ascomycota and Crenarchaeota phyla were increased, as well as the activities of SUC and UE, accelerating the decomposition and mineralization of SOM and improving soil fertility. In the top, organic fertilizer substitution combined with reduced chemical N fertilizer (S3 and S4) treatments increased the abundance of bacteria and fungi. In addition, RDA showed that total potassium content could significantly affect changes in the bacterial and fungal community structure in subsoil. Overall, organic fertilizer substitution enhanced the content of soil available nutrients and improved soil nutrient retention. It is recommended to promote organic fertilizer substitution + chemical N fertilizer reduction (S4) with the supplementation of potassium fertilizer in the subsoil. The findings provide a theoretical basis and practical guidance for improving orchard soil management and achieving sustainable development in the apple industry.

Climate, soil, and viticultural factors differentially affect the sub-regional variations in biochemical compositions of grape berries

Terroir leaves its influence on the flavor build-up in grape berries by triggering biochemical reactions that ultimately shape the typicality of the produced wines. However, the complex relationship between terroir, carbon stable isotopic composition, and the biochemical composition of grapes remains poorly understood. To fill these gaps, grape berries were harvested at maturity from two grape cultivars, Cabernet Sauvignon and Merlot (Vitis vinifera L.), across 32 sites within the Eastern Foothills of the Helan Mountains region over two vintages. The climate and soil data for these sites were collected, and cultivation practices were surveyed. In parallel, the grape quality indicators were measured at maturity to explore their variations among sub-regions and the correlations between terroir factors and grape quality. Moreover, the carbon stable isotopes (δ¹³C) were measured to evaluate the water status of vines at different sites. Results indicated that organic acids and anthocyanins exhibited a strong vintage effect, with the cooler vintage exhibiting higher levels of these compounds relative to the warmer vintage. Specifically, the Hongsipu sub-region, with a cooler climate, consistently demonstrated higher anthocyanin concentrations than other sub-regions in both vintages of the study. Further analysis revealed that the cultivar Cabernet Sauvignon displayed a higher ratio of di-hydroxylated to tri-hydroxylated anthocyanins in the cooler year, whereas Merlot exhibited the opposite trend. The Mantel test identified several critical factors influencing anthocyanin concentration, including total soil phosphorus (Tp), total soil potassium (Tk), soil thickness (Thickness), precipitation (April-September precipitation, Pre4–9), April-September average temperature (4–9 Tave), April-September active accumulated temperature (4–9 Aa), April-June active accumulated temperature (4–6 Aa), July-September active accumulated temperature (7–9 Aa), temperature diurnal range (May, July, August, September, DR-5 and DR 7–9), trellis system, vine density, and δ13C. Finally, structural equation modeling (SEM) was used to analyze and summarize the relationships between terroir factors, anthocyanin concentration, and δ¹³C. The results indicated that June and September precipitation had a positive impact on anthocyanin concentrations, while soil total potassium content had a negative impact. On the other hand, the July to September temperature diurnal range, trellis system, vine perimeter, and canopy height were the main drivers of δ¹³C, which further influenced grape anthocyanin concentrations. This research contributes to a scientific foundation for grape cultivation in the Eastern Foothills of the Helan Mountains and provides valuable insights for practices in other regions.

Influence of increasing doses of nitrogen fertilizers on the productivity of field crops and the potassium regime of sod-podzolic soil

In a long-term experiment launched in 1972 on sod-podzolic heavy loamy soil, the effect of increasing doses of nitrogen fertilizers on the productivity of field crops and the potash regime of the soil was studied. The scheme of the experiment included the following options: without fertilizers, P60K60 (background), background + N30, background + N60, background + N90, background + N120. The analysis of crop yields in the 6th rotation of the crop rotation (2013–2019) showed that the most effective application for spring crops (wheat, barley, oats) was N30P60K60, for potatoes – N60P60K60. The highest yield of clover hay was noted in the P60K60 and N30P60K60 variants. The maximum productivity of an 8-field crop rotation (4.19 tons of grain/ha/year) and a payback of 1 kg of mineral fertilizers (8.7 kg of grain) was obtained by applying N30P60K60. Studies of the total potassium content, its easily exchangeable, mobile and non-exchangeable compounds in the soil were carried out at the end of the 6th rotation of the crop rotation in a layer of 0–60 cm. It was revealed that the long-term use of nitrogen fertilizers led to an increase in the mobility of potassium compounds in the soil. A significant increase in the content of easily exchangeable and mobile potassium compounds was found by 1.2–1.9 times relative to the background in layers 0–20 and 40–60 cm of soil when N60–120 was applied. With prolonged use of the N30 dose, only trends towards an increase in the content of these forms of potassium were noted, which could be the result of using a low dose or due to the maximum potassium removal by plants per rotation in this variant. The application of the maximum dose of fertilizers (N120P60K60) led to an increase in non-exchangeable potassium compounds (by 1.1 times), which may have been due to the destruction of the mineral part of the soil. A comparison of the P60K60 and N60P60K60 variants showed that the maintenance of the content of mobile potassium compounds at the initial level (1972) with the use of a complete mineral fertilizer was largely due to the influence of nitrogen fertilizers on the solubility and availability of potassium compounds. The effect of prolonged use of phosphorus-potassium fertilizers P60K60 and increasing doses of nitrogen fertilizers on the total content of potassium in sod-podzolic heavy loamy soil has not been revealed.

Impact Mechanisms of Different Ecological Forest Restoration Modes on Soil Microbial Diversity and Community Structure in Loess Hilly Areas

The Loess Plateau, with a fragile ecological environment, is one of the most serious water- and soil-eroded regions in the world, which has been improved by large-scale projects involving returning farmland to forest and grassland. This work is mainly aimed at exploring a more reasonable and efficient ecological forest restoration mode and revealing synergistic restoration mechanisms. This study sampled typical Loess Plateau areas and designed the restoration modes for pure forests of Armeniaca sibirica L. (AR), Amygdalus davidiana (Carrière) de Vos ex Henry. (AM), Medicago sativa L. (MS), and mixed forests of apricot–peach–alfalfa (AR&AM&MS), using abandoned land (AL) as a control treatment. The effects of these modes on the physical and chemical properties and enzyme activities of various soils were investigated in detail. Moreover, the soil microbial diversity and community structure, functional gene diversity, and differences in the restoration modes were deeply analyzed by meta-genomic sequencing technology, and the inherent driving correlation and mechanisms among these indicators were discussed. The results showed that the soil water content and porosity of the AR, AM, and AR&AM&MS treatments increased significantly, while the bulk density decreased significantly, compared with AL. Moreover, the total carbon, total nitrogen, nitrate nitrogen, total phosphorus, available phosphorus, total potassium, and available potassium contents of the AR&AM&MS restoration mode increased significantly. Compared to CK, there was no significant change in the catalase content of pure forest and mixed forest; however, the contents of urease, phosphatase, sucrase, B-glycanase, and N-acetylglucosaminidase in the restoration mode of the mixed forest all increased significantly. The species diversity index of the restoration modes is similar, and the dominant bacteria in soil microorganisms include Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, and Gemmatimonadetes. The mixed forest restoration mode had the highest microbial abundance. The functional gene diversity of the different restoration modes was also similar, including kegg genes, eggNOG genes, and carbohydrate enzymes. The functional genes of the mixed forest restoration mode were the most abundant, and their restoration mechanism was related to the coupling effect of soil–forest grass. After evaluation, the restoration mode of mixed forest was superior to that of pure forest or pure grass. This is attributed to the fact that the mode can improve soil structure, retain soil moisture, enhance soil enzyme activity, optimize soil microbial community structure, and improve microbial diversity and functional gene activity. This provides key data for the restoration of fragile ecological areas, and the promotion of sustainable management of forests and grass in hilly areas of the Loess Plateau.

Soil Nutrient Profiles in Three Types of Rocky Fissure Network Habitats of Typical Karst Formations in China: A Maolan World Heritage Perspective

Amid global desertification, this study investigates karst ecosystems; analyzing soil’s physiological and ecological properties within intricate fissure networks supporting plant root growth. This study investigates soil nutrients in three types of rocky fissure network habitats in Maolan, through field surveys and experimental measurements. Significant variability was found across habitats. The quantities of organic carbon, total nitrogen, available nitrogen, available phosphorus, and available potassium were highest in Type I soil, followed by Type III; and were lowest in Type II. Total phosphorus was highest in Type III, intermediate in Type I, and lowest in Type II; while total potassium content was highest in Type III, moderate in Type II, and lowest in Type I. Based on nutrient participation in C, N, P, and K cycles, Type I habitats had the highest levels, Type III had moderate levels, and Type II had the lowest levels; while potassium-related nutrients were highest in Type III. The nutrient ratios C/K, N/K, P/K, and N/P were highest in Type I, moderate in Type II, and lowest in Type III. C/N was highest in Type II, moderate in Type III, and lowest in Type I; while C/P was highest in Type II, moderate in Type I, and lowest in Type III. A comprehensive nutrient evaluation ranked Type I as the best, Type III as moderate, and Type II as the worst. Key factors such as average trace length, areal density, and integration significantly influence soil nutrients by impacting humus and soil storage, and the growth space for plant roots within rocky habitats. Additionally, the orientation of fissures primarily impacts nutrient cycling, while both the angles and lacunarity significantly affect the stoichiometric ratios of nutrients. Rocky habitat networks characterize soil quality. A comparison of existing studies reveals stoichiometric differences between karst and non-karst regions. Effective ecological restoration in karst areas requires targeted strategies that consider the specific attributes of different rocky habitats. This study enhances understanding of soil nutrients in karst forest ecosystems and proposes new approaches for soil’s ecological restoration and combating global desertification.

Plant Diversity, Productivity, and Soil Nutrient Responses to Different Grassland Degradation Levels in Hulunbuir, China

Grassland degradation could affect the composition, structure, and ecological function of plant communities and threaten the stability of their ecosystems. It is essential to accurately evaluate grassland degradation and elucidate its impacts on the vegetation–soil relationship. In this study, remote sensing data based on vegetation coverage were used to assess the degradation status of Hulunbuir grassland, and five different grassland degradation degrees were classified. Vegetation community composition, diversity, biomass, soil nutrient status, and their relationships in different degraded grasslands were investigated using field survey data. The results showed that grassland degradation significantly affected the species composition of the vegetation community. As degradation intensified, species richness declined, with the proportion of Gramineae and Legume species decreasing and Asteraceae species increasing. Additionally, the proportion of annual species initially increased and then decreased. Degradation also markedly reduced aboveground, belowground, and litter biomass within the communities. Soil moisture, electrical conductivity, organic carbon, total carbon, total potassium, and hydrolyzable nitrogen contents in non-degraded areas were higher than those in severely degraded areas. Conversely, soil total phosphorus content and bulk density gradually increased with degradation. Nitrate nitrogen and ammonium nitrogen levels in severely degraded soils were significantly higher than those in non-degraded soils. Plant diversity in the study area was significantly positively correlated with aboveground biomass and belowground biomass, and it positively correlated with soil nutrient total carbon and available carbon but negatively correlated with soil bulk density. Results of the partial least squares path model showed that grassland degradation had significant negative effects on plant diversity, soil nutrients, and biomass. Soil nutrients were the main factors affecting ecosystem productivity. The direct effect of plant diversity on biomass was not significant, suggesting that soil nutrients may play a more important role than plant diversity in determining biomass during grassland degradation. The results illustrated the relationships among soil nutrients, plant diversity, and biomass in degraded grasslands and emphasized the importance of an integrated approach in the effective management and restoration of degraded grasslands.

Effects of Rubber Plantation Restoration in National Parks on Plant Diversity and Soil Chemical Properties

Plantations left for natural succession play a significant role in Tropical Rainforest National Parks. Studying the succession and restoration of plantations is crucial for achieving a park’s authenticity and integrity, as well as for maximizing its ecological functions. However, the changes in vegetation and soil properties during the natural succession of these decommissioned plantations remain unclear. In this study, we examined rubber [(Hevea brasiliensis (Willd. Ex A. Juss.) Muell. Arg] plantations in the Yinggeling area of the National Park of Hainan Tropical Rainforest. We used community surveys, field sampling, and soil property analyses to investigate the species richness, diversity, and species composition of the aboveground plant communities during three succession periods of rubber plantations left for natural succession, including 0 years (ZY), 3 years (TY), and 7 years (SY). The soil pH, total organic carbon, total nitrogen, total phosphorus, available phosphorus, nitrate nitrogen, ammonium nitrogen, and total potassium contents in the three succession periods were analyzed. These results showed that there were 92 species of understory plants in the decommissioned rubber plantations, belonging to 72 genera in 39 families. The highest number of understory plant species was found in the plantations with 3 years of natural succession, totaling 66 species from 49 genera in 29 families. The number of families, genera, and species followed the pattern TY > SY > ZY. The Margalef richness index (F), Simpson index (D), and Shannon–Wiener index (H) of understory plants in the 0-year succession plantations were significantly lower than those in the 3-year and 7-year succession plantations. However, there was no significant difference in the Pielou (EH) index among the succession gradients. The soil pH, nitrate nitrogen (NO3--N), and available phosphorus (AP) in the 0-year succession plantations were significantly higher than those in the 3-year and 7-year succession plantations. There were no significant differences in soil total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), and ammonium nitrogen (NH4+-N) across the three succession gradients. The soil total potassium (TK) in the 3-year succession plantations was significantly higher than that in the 0-year and 7-year succession plantations. Soil available phosphorus and total phosphorus (TP) were positively correlated with the Margalef index, Simpson index, Shannon–Wiener index, and Pielou index. The recovery rate of understory vegetation in decommissioned rubber plantations was faster than that of the soil. This indicates that the construction of the National Park of Hainan Tropical Rainforest has significantly promoted the recovery of the number of plant species and plant species diversity that have been left from rubber plantation operations. These findings not only deepen our understanding of soil property changes during the vegetation succession of artificial forests, particularly rubber plantations, but they also hold significant implications for guiding tropical forest management and sustainable development.

Effects of cotton peanut rotation on crop yield soil nutrients and microbial diversity

Background and Aims Cotton-peanut rotation is a sustainable farming practice that enhances land utilization and promotes the sustainable development of agriculture. Crop rotation can reduce the occurrence of pests and diseases, as different crops have varying levels of resistance to such threats. Additionally, by alternating the types of crops grown, the soil environment is changed, which can lead to the elimination of favorable conditions for pathogens and pests, thereby alleviating the impact of these issues. Furthermore, cotton-peanut rotation can improve soil fertility.To investigate the effects of different crop rotation systems on crop yield, soil nutrients, and soil microbial communities. Methods: Using high-throughput sequencing technology, investigate the soil microbial diversity in the root zone after cotton-peanut rotation.Various planting patterns, including cotton continuous cropping (MC), peanut continuous cropping (HC), peanut-cotton-peanut rotation (HR), and fallow (X), were established to assess variations in crop yield, soil nutrients, and soil microbial diversity. Results: Significant differences were observed in crop yield, soil nutrients, and soil microbial community structure among different planting patterns. The HR system significantly increased the output compared with the HC and MC systems. Additionally, HR exhibited significantly lower total nitrogen (N) and basic nitrogen (BN) contents than HC and MC, whereas MC showed lower total potassium (K) and available potassium (AK) contents. HR led to a decrease in soil bacterial diversity but an increase in fungal diversity, with Ascomycota and Mortierellomycota being dominant. Various bacteria (Chloroflexi, Bacteroidota, and Actinobacteriota) associated with organic matter degradation and nutrient cycling were found across different planting systems, enhancing material cycling efficiency. Furthermore, Planctomycetota bacteria related to crop nutrient synthesis and Glomeromycota bacteria aiding plant nutrient absorption were significantly higher in the MC system than in the HR or HC systems. Redundancy analysis indicated a significant negative correlation between crop rotation and soil fungal community, whereas Ascomycota exhibited a significant negative correlation with organic matter.Conclusion: Peanut-cotton rotation can mitigate soil nutrient loss, enhance beneficial microorganism diversity, suppress harmful bacterial populations, stabilize ecosystems, and boost crop yield.

Morphological adaptation strategy of invasive plant Ambrosia trifida seed distributed along rivers is closely related to soil nutrients

Rivers are crucial in the spread of invasive plants. Invasive plants alter their seed traits to adapt to environmental changes and promote invasion. Studying the trait changes in invasive plant seeds may improve the understanding of their propagation mechanisms along the river and provide appropriate control measures. In this study, seven Ambrosia trifida populations along the Liaohe River were used as study subjects. The results showed that the seven A. trifida populations were closely related and exhibited a certain gene exchange, but the absence of evidence of directed gene flow among populations did not confirm that rivers were the medium of seed dispersal of A. trifida. Along the Liaohe River, from top to bottom, the positive view area, length, width, perimeter, and thousand seed weight of A. trifida seeds showed an increasing trend. The total nitrogen and phosphorus contents in the river water of the A. trifida population in the lower reaches of the Liaohe River were higher than those at the other sites. Furthermore, along the river, from top to bottom, the available nitrogen, total nitrogen, total potassium, available potassium, and organic matter contents in the soil in which A. trifida populations grew showed significant increasing trends. River structure, water quality, and soil nutrients had direct and indirect effects on seed morphology. Soil total nitrogen, available potassium, and organic matter had significant positive effects on seed positive view area and perimeter, suggesting that the maternal effect played a critical role in shaping seed morphology. Our analysis showed that soil nutrients along the river may be the primary driver that governs changes in A. trifida seed traits.

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.

Fiber morphological characteristics of bamboo Ferrocalamus strictus culms from different geographical distribution regions

The fiber index including fiber length, width, wall thickness and lumen diameter of Ferrocalamus strictus culms (1, 2, and ≥ 3 years) from Jinping, Mojiang and Lvchun counties of Yunnan Province was determined and the elemental content of the soil was also determined to analyze the fiber characteristics. The average relative fiber index measured for F. strictus culms were fiber length (1.30 mm), width (21.57 μm), slenderness ratio (60.79 μm), wall thickness (4.21 μm), lumen diameter (7.22 μm), and runkel ratio (1.22 μm), which belonged to the range of middle and long fibers. The fiber length increased with the culm age. The proportion of long fiber increased while short fibers decreased along with culm maturing. The fiber morphology did not show a specific trend with the culm height. Fiber length reached the maximum in the bottom portions of the culms. There is a correlation between fiber morphology and soil elements, the content of organic matter, total potassium, total sulfur, total aluminum, total zinc, total iron, total boron, alkali-hydrolyzed nitrogen and available silicon in the soil affects fiber morphology. The content of organic matter, total boron and alkali-hydrolyzed nitrogen in the soil from Mojiang County was largest. Comparatively, the culm fiber in Mojiang County had the best fiber index performance for utilization, since the greatest proportion of medium and long fibers and the optimal distribution of fiber length frequency was obtained from the culms in Mojiang County. This study can provide a theoretical basis for large-scale bamboo forest cultivation and the development and utilization of bamboo culm fiber.

An integrated dataset of ground hydrothermal regimes and soil nutrients monitored in some previously burned areas in hemiboreal forests in Northeast China during 2016–2022

Abstract. Under a warming climate, the occurrence of wildfires has been becoming increasingly more frequent in boreal forests and Arctic tundra over the last few decades. Wildfires can cause radical changes in forest ecosystems and the permafrost environment, such as the irreversible degradation of permafrost, succession of boreal forests, rapid and massive losses of soil carbon stock, and increased periglacial geohazards. Since 2016, we have gradually and more systematically established a network for studying soil nutrients and monitoring the hydrothermal state of the active layer and near-surface permafrost in the northern Da Xing'anling Mountains in Northeast China. Soil moisture content (depth of 0–9.4 m), soil organic carbon content (0–3.6 m), total nitrogen content (0–3.6 m), and total phosphorus and potassium content (0–3.6 m) datasets were obtained in 2016 via field sampling and subsequent laboratory tests. Ground temperature (0–20 m) and active layer thickness (2017–2022) datasets were obtained using thermistor cables that were permanently installed in boreholes or interpolated with these temperatures. The present data can be used to simulate changes in permafrost features under a changing climate and wildfire disturbances and to explore the changing interactive mechanisms of the fire–permafrost–carbon system in hemiboreal forests. Furthermore, they can provide baseline data for studies and action plans to support the carbon neutralization initiative and assessment of the ecological safety and management of the permafrost environment. These datasets can be easily accessed via the National Tibetan Plateau/Third Pole Environment Data Center (https://doi.org/10.11888/Cryos.tpdc.300933, Li and Jin, 2024).

Effects of Cover Measures on Soil Organic Nitrogen Fractions and Total Soluble Nitrogen Pools in Citrus Orchards of the Red Soil Hilly Region of Southern China

Soil organic nitrogen fractions and total soluble nitrogen (TSN) pools are crucial for assessing orchard soil fertility and tree nutrient requirements. Here, we studied the effects of grass cover (GC), plastic mulch (PM), and clean tillage (CK) on the physicochemical properties, organic nitrogen fractions, and TSN content of soil from a 0–60 cm depth in a 7-year-old orchard in the red soil hilly region of southern China. The results showed that GC and PM significantly increased the content of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK), as well as the C/N and N/P ratios. The mean total organic nitrogen (TON) content in the 0–60 cm soil profile was 1219.21 and 895.15 mg·kg−1 in the GC and PM treatments, and it was 67.36% and 22.88% higher in the GC and PM treatments than in the CK, respectively. In the 0–20 cm soil horizon, the active organic nitrogen (AN, AAN, ASN) content was 52.67% and 17.15% higher in the GC and PM treatments than in the CK, respectively. In the 20–60 cm soil horizon, the stable organic nitrogen (UN, NHN) content was 97.13% and 21.69% greater under the GC and PM treatments compared to the CK, respectively. Different ground cover methods increased the total soluble nitrogen (TSN) concentration in the 0–20 cm soil horizon while reducing it in the deeper 20–60 cm layer. Correlation analysis revealed significant positive correlations of SOC, TN, TP, TSN, and TON with acid-hydrolyzable nitrogen fractions (AN, AAN, ASN, UN) and significant negative correlations with bulk density (BD). Stepwise linear regression analysis, using the regression equation TSN = 0.372AN − 0.053NHN + 18.473 (p < 0.01, R2 = 0.925), identified AN as a critical indicator for TSN among the active organic nitrogen fractions.

Foliar Nourishment with Different Potassium Sources to Maximize Yield Through Improving Nutrient Uptake in Citrus Aurantifolia Trees Grown in Potassium-Deficient Soil

AbstractPurpose: Based on its crucial regulatory role in several biochemical processes, potassium (K) is considered to greatly influence fruit yield and quality. Methods: Two field experiments were carried out in two seasons (2021 and 2022) to explore the response of lemon (Baladi cv.) trees grown in K-deficient soil to four different K fertilizer sources applied individually as a foliar spray. K citrate (KC1 = 1.3 vs. KC2 = 2.6 g L− 1), K nitrate (KN1 = 1.5 vs. KN2 = 3.0 g L− 1), K tartrate (KT1 = 1.5 vs. KT2 = 3.0 g L− 1), and K thiosulfate (KS1 = 1.25 vs. KS2 = 2.5 g L− 1) were applied three times, and the treated trees were compared with untreated trees. This study was established with a randomized complete block design (RCBD) using four replicates. Results: The findings revealed that the KC treatment, regardless of dosage, showed clear superiority in terms of the values for the leaf phosphorus (%), manganese, and zinc contents (mg kg− 1), as well as fruit firmness, fruit dry matter, and total soluble solids in both seasons. In second place was the KT treatment, which yielded the best values for fruit length and width in 2021, the best values for leaf nitrogen and iron contents and fruit weight and volume in 2022, and the best values regarding variable fluorescence by maximum fluorescence, relative chlorophyll content (SPAD readings), the photosynthetic performance index, total acidity, and vitamin C in both seasons. Furthermore, the highest total lemon yield and leaf potassium contents were achieved with the KN treatment in both seasons. The heat map illustrating that most of the studied characteristics were positively and significantly correlated with total lemon yield (TLY). Conclusions: The KN treatment, closely followed by the KC treatment, is regarded to be the best treatment for most of the studied trails.

Biochar addition influences C and N dynamics during biochar co-composting and the nutrient content of the biochar co-compost

This study investigated the effects of corn cob biochar (CCB) and rice husk biochar (RHB) additions (at 0%, 5%, and 10% w/w) on nitrogen and carbon dynamics during co-composting with poultry litter, rice straw, and domestic bio-waste. The study further assessed the temperature, moisture, pH, and nutrient contents of the mature biochar co-composts, and their potential phytotoxicity effects on amaranth, cucumber, cowpea, and tomato. Biochar additions decreased NH4+-N and NO3- contents, but bacteria and fungi populations increased during the composting process. The mature biochar co-composts showed higher pH (9.0–9.7), and increased total carbon (24.7–37.6%), nitrogen (1.8–2.4%), phosphorus (6.5–8.1 g kg−1), potassium (26.8–42.5 g kg−1), calcium (25.1–49.5 g kg−1), and magnesium (4.8–7.2 g kg−1) contents compared to the compost without biochar. Germination indices (GI) recorded in all the plants tested with the different composts were greater than 60%. Regardless of the biochar additions, all composts treatments showed no or very minimal phytotoxic effects on cucumber, amaranth and cowpea seeds. We conclude that rice husk and corn cob biochar co-composts are nutrient-rich and safe soil amendment for crop production.

Performance of Hybrid and Inbred Rice Varieties under Vermicast Application

This study aimed to evaluate the performance of hybrid and inbred rice varieties using vermicast as fertilizer. Soil chemical properties, plant growth, and yield performance were observed and tested for significant differences. The experiment employed a Randomized, Completely Design-Factorial layout with three replications of 30 plots. Six check plots were also prepared as farmers fertilization practices for rice production. The total experimental area is 468 m², with a planting distance of 20m x 20m and a total plant population of 5,376. Factor A involved six rice varieties, and Factor B included varying vermicast levels. Growth parameters and yield components were assessed, and data were analyzed using two-factor ANOVA and LSD test. Results indicated significant differences among rice varieties in days to flowering, days to maturity, plant height, and grain yield per hectare. However, no significant differences were observed in productive tillers, filled grains, and thousand-grain weight. No interactions were observed between rice varieties and vermicast levels. Soil analysis revealed an increase in available phosphorus but a decrease in total nitrogen and potassium content in the soil after the experimental study. Based on the observed results, the study recommends utilizing the NSIC Rc314H variety in rice production with a vermicast application rate of 5 tons per hectare for better crop yield. Future research on vermicast application in lowland rice is highly recommended for more conclusive findings and valuable insights into optimizing rice cultivation with specific varieties and application for improved yield and sustainable agricultural practices.