Soil Nutrient Responses Research Articles

Responses of soil nutrients and microbial communities to the application of spent mushroom substrates

Responses of soil nutrients and microbial communities to the application of spent mushroom substrates

Response of soil nutrients to terracing and environmental factors in the Loess Plateau of China

Terracing is a widely adopted agricultural practice in mountainous regions around the world that aims to conserve soil and water resources. Soil nutrients play a crucial role in determining soil quality, particularly in landscapes prone to drought. They are influenced by factors such as land-use type, slope aspect, and altitude. In this study, we sought to examine the impact of terracing on soil nutrients (soil organic content (SOC), total nitrogen (TN), nitrate-nitrogen (NO3–-N), ammonium nitrogen (NH4+-N), total phosphorus (TP), available phosphorus (AP), total potassium (TK), and available potassium (AK)) and how they vary with environmental factors in the Chinese Loess Plateau. During the growing season, we collected 540 soil samples from the 0 to 100 cm soil layer across five major land-use types, different slope aspects, and varying altitudes. Additionally, a meta-analysis of literature data further corroborated the effective accumulation of soil nutrients through terracing in the Loess Plateau. Our findings are as follows: (1) Terraced fields, regardless of land-use type, showed a significant improvement in SOC and TN content. (2) Soil nutrient contents within terraced fields were predominantly higher on sunny slopes. (3) Terraces at lower altitudes are characterized by elevated SOC concentrations. (4) A meta-analysis of literature data pertaining to terracing and soil nutrients in this region confirmed the effective accumulation of soil nutrients through terracing. The elucidated outcomes of this study offer a profound theoretical underpinning for the accurate planning and management of terraces, the scientific utilization of land resources, and the enhancement of land productivity.

Response of soil nutrients and erodibility to slope aspect in the northern agro-pastoral ecotone, China

Abstract. Soil erosion, considered a major environmental and social problem, leads to the loss of soil nutrients and the degradation of soil structure and impacts plant growth. However, data on the effects of land use changes caused by vegetation restoration on soil nutrients and erodibility for different slope aspects are limited. This study was conducted to detect the response of soil nutrients and erodibility to slope aspect in a typical watershed in the northern agro-pastoral ecotone in China. The following indexes were used to determine the improvement in soil nutrients and erodibility through a weighted summation method: the comprehensive soil nutrient index and the comprehensive soil erodibility index. The results showed that the vegetation types with the highest comprehensive soil quality index (CSQI) values on western, northern, southern, and eastern slopes were Pinus sylvestris and Astragalus melilotoides (1.45), Caragana korshinskii and Capillipedium parviflorum (2.35), Astragalus melilotoides (4.78), and Caragana korshinskii and Lespedeza bicolor (5.00), respectively. Slope aspect had a significant effect on understory vegetation characteristics, soil nutrients, and soil erodibility. Understory vegetation and soil characteristics explained 50.86 %–74.56 % of the total variance in soil nutrients and the erodibility. Mean weight diameter and total phosphorus were the main factors that affected the CSQI for different slope aspects. Our study suggests that the combinations of species, such as C. korshinskii and L. bicolor, were the optimal selection to improve soil nutrients and soil erodibility for any slope aspect.

Responses of soil nutrients, enzyme activities, and maize yield to straw and plastic film mulching in coastal saline-alkaline

Responses of soil nutrients, enzyme activities, and maize yield to straw and plastic film mulching in coastal saline-alkaline

Spatial Distribution Characteristics of Soil Carbon and Nitrogen in Citrus Orchards on the Slope of Purple Soil Hilly Area

Since the 1990s, a large area of sloping farmland in a purple soil hilly region of southwest China was converted into an orchard to prevent soil erosion, increase soil fertility, and elevate economic benefits for farmers. In order to explore the spatial distribution of soil carbon (C) and nitrogen (N) fractions on the slope of returning arable lands to citrus orchards in purple soil hilly areas, a soil sampling event was carried out in a citrus orchard at the Yanting Agro-ecological Experimental Station of Purple Soil, Chinese Academy of Sciences, to examine the differences in soil C and N fractions and their influencing factors. The results showed that the slope position had significant effects on the contents of soil total nitrogen (TN), nitrate nitrogen (NO3--N), and dissolved organic carbon (DOC) (P < 0.05), but the effects were not obvious regarding the total organic carbon (SOC) and ammonia nitrogen (NH4+-N) of the soil (P > 0.05). For topsoil (0-30 cm), the variation trend of soil NO3--N content along the slope was upper slope < middle slope < lower slope, whereas the TN and DOC contents along the slope exhibited the trend of upper slope > middle slope > lower slope. The contents of soil C and N in each slope position generally showed a downward trend with increasing soil depth (0-30 cm). The contents of soil TN, SOC, NO3--N, and DOC were significantly affected by soil depth (P < 0.05). The TN storage (0-30 cm) significantly decreased from the top to the bottom within the soil slope, with a value of 2.37, 1.89, and 1.62 t·hm-2 (reported as N) for the upper slope, middle slope, and lower slope, respectively. There was no significant difference in SOC reserves along the slope, with a range from 56.12 to 58.48 t·hm-2 (reported as C). Our results provide scientific basis for understanding the spatial distribution of soil nutrients of the restored farmland in purple soil hilly areas. Our research suggests that the spatial distribution of soil carbon and nitrogen storage should not be ignored when predicting the response of soil nutrients to land use change.

Soil bacterial communities are more sensitive to short-term nitrogen deposition than fungal communities in subtropical Chinese fir forests

The increasing rate of atmospheric nitrogen (N) deposition seriously affects the structure and function of ecosystems. Although soil microorganisms play a crucial role in ecosystem carbon (C) and nutrient cycling, the impact of N deposition on soil microbial communities in subtropical forest ecosystems is unclear. Here, we selected the subtropical Chinese fir (Cunninghamia lanceolata) forest as the research object and conducted simulated N deposition experiments with different levels of N deposition (0 kg N ha−1 yr−1,50 kg N ha−1 yr−1, 100 kg N ha−1 yr−1, and 200 kg N ha−1 yr−1, respectively) to explore the response of soil nutrients, soil microbial community structure, and potential ecological functions to short-term N deposition. We found that the bacterial richness Chao1 index and phylogenetic diversity PD_whole_tree decreased with the N deposition level approximately 13 % −16 % under MN and HN treatment. N deposition significantly altered the composition of soil bacterial communities (P < 0.05), but the responses of different taxa to N deposition were inconsistent at different stages of growing season. N deposition treatment significantly increased the relative abundance of Actinobacteria at both beginning of growing season (BGS) and end of growing season (EGS), decreased the relative abundances of Planctomycetes at BGS, and decreased the relative abundances of Elusimicrobia and Cyanobacteria at both BGS and EGS. Non-metric multidimensional scaling (NMDS) and Anosim (Analysis of similarities) analyses showed that the bacterial communities were clearly distinguished among treatments at both BGS and EGS. However, N deposition had a relatively small impact on fungal communities, only altering the fungal community structure at BGS. The impact of N deposition on soil microbial communities was mainly induced by the alteration in soil water content (SWC), pH, NO3–-N, and available nitrogen (AN). Both bacterial and fungal communities exhibit seasonal community dynamics, while the interaction of N deposition and season was mainly reflected in the impact on bacterial communities. Our research not only provides research ideas for the potential impact of nitrogen deposition on subtropical forest ecosystems in the short term, but also provides a theoretical basis for future scientific management and regulation of forestry, microorganisms, and sustainable management of Chinese fir plantations.

Post-Fire Soil Nutrient Dynamics in Seriphium plumosum L. Encroached Semi-Arid Grassland of Gauteng Province, South Africa

Seriphium plumosum L. is an indigenous unpalatable shrub that occurs in fire-prone semi-arid South African grassland areas, yet research proposes the use of fire to control its encroachment of rangelands. This study investigated the interaction effects of burning and soil depth on components of soil fertility. Soil samples were collected from the surface (&lt;10 cm) and subsurface (&gt;10 ≤ 20 cm) soil, before and after burning in randomly selected paired subplots (25 m × 25 m), with six replicates. Data was analysed as a randomised complete block design, with repeated measures (before and after burning) in a 2 × 2 factorial analysis of variance (ANOVA) using generalised linear model (GLM) procedures. Components of soil fertility measured (K, Ca, Mg, Org C, P, pH and TN) showed a significant decrease with increasing soil depth both before and after burning, except for K and P, which were significantly higher in surface soils after burning. The results showed that the response of soil nutrients to fire depends on the temperature tolerance threshold of individual soil nutrient elements. Increasing surface soil available K and P concentrations after burning may improve the conditions for S. plumosum encroachment, with implications for similar environments and species worldwide.

Responses of soil nutrients and rhizosphere microbial communities of a medicinal plant Pinelliaternata to vermicompost.

Vermicomposting is an important strategy for restoring soil function and fertility. However, information on the effects of vermicompost application in intensive Pinellia ternata planting systems has rarely been reported. Here, we focus on the effects of different vermicompost levels and chemical fertilizer (CF) strategies on soil chemical properties, soil enzymes, and soil rhizosphere microbial communities (bacteria and fungi) in a field experiment. Compared to no added fertilizers (CK), vermicompost was more effective than the CF treatment in increasing P. ternata yield. We found that the 5 t ha-1 vermicompost treatment (VC2) significantly increased the tuber yield by 44.43% and 6.55% compared to the CK and CF treatment, respectively, and water-soluble exudates by 6.56% and 9.63% (P < 0.05). The vermicompost and CF treatments significantly increased the total phosphorus (TP), urease (Ure), and soil catalase (Cat) contents (P < 0.05). Compared to the vermicompost and CK treatments, the CF treatment significantly decreased soil organic carbon (SOC), C/N ratio, and soil acid phosphatase (Pac) (P < 0.05). Redundancy analysis (RDA) showed that Ure and total potassium (TK) were the major drivers in the bacterial community, whereas TP, total nitrogen (TN), Pac, and TK were the major drivers in the fungal community. We also found a positive correlation between soil enzyme activities, including between Ure and bacterial genera (Clostridium, Pseudoclavibacter, Stella, Hyphomicrobium, Mesorhizobium, and Adlercreutzia). In summary, vermicompost application promotes P. ternata soil microecosystems and improves soil fertility, soil enzyme activities, and rhizosphere microbial structure and function. Vermicomposting is a novel and promising approach to sustainable ecological cultivation of Chinese herbs via the promotion of soil properties and beneficial organisms.

Potential Mechanism of Optimal Tillage Layer Structure for Improving Maize Yield and Enhancing Root Growth in Northeast China

A field experiment was conducted to evaluate the effect of different tillage structures on soil physical properties, soil chemical properties, maize root morphological and physiological characteristics, and yield. Four tillage structures were designed. Soil tillage plays a prominent role in agricultural sustainability. The different tillage layer structures affected soil physical properties. An enhancement in the optimal tillage layer structure improved soil structure. The MJ tillage layer structure created an improved soil structure by regulating the soil physical properties so that the soil compaction and soil bulk density would be beneficial for crop growth, increase soil water content, and adjust the soil phrase R value and GSSI. Soil nutrients are significantly affected by soil depth, with the exception of available potassium. However, soil nutrients are influenced by different tillage layer structures with soil depth. Soil nutrient responses with depth are different for MJ layer treatment compared with other tillage layer structures. Soil organic matter (SOM) is affected with an increase in depth and is significantly influenced by different tillage layer structures, except at 20–30 cm soil depth. MJ treatment increased by 10–20% compared with other tillage layer structures. In addition, QS treatment enhanced the increased pH value in soil profile compared to others. The root morphology characteristics, including root length, root ProjArea, root SurfArea, root AvgDiam, and root volume, were affected by years, depth, and the tillage layer structures. The MJ tillage layer structure enhanced root growth by improving tillage soil structure and increasing soil air and water compared with other tillage layer treatments. Specifically, the MJ layer structure significantly increased root length and root volume via deep tillage. However, the differences in root physiological properties were not significant among treatments. The root dry weight decreased with an increase in soil depth. Most of the roots were mainly distributed in a 0–40 cm soil layer. The MJ treatment enhanced the increase in root dry weight compared with others by breaking the tillage pan layer. Among the different tillage layer structures, the difference in root dry weight was smaller with an increase in soil depth. Moreover, the MJ treatment significantly improved maize yield compared with others. The yield was increased by 14.2% compared to others under MJ treatment via improvements in the soil environment. In addition, the correlation relationship was different among yield and root morphology traits, root physiology traits, soil nutrients, and soil physical traits. So, our results showed that the MJ tillage layer structure is the best tillage structure for increasing maize yield by enhancing soil nutrients, improving the soil environment and root qualities.

Effects of Changing Restoration Years on Soil Nutrient Traits and Plant Community Diversity in a Phosphate Mining Area

The thinning vegetation and soil erosion problems left behind by extractive mining have caused serious environmental pollution, and vegetation restoration is one of the effective strategies to counter them. To study the effects of vegetation restoration on plant community species diversity, soil carbon, nitrogen and phosphorus, and the response of their plant community succession, four communities of different ages (1, 7, 10, 40) and one natural forest (&gt;50 years) in the Kunyang phosphate mine were selected, and the analysis was carried out using the methods and protocols for plant community inventory. The species composition was recorded, and soil was collected from 0–60 cm in each community to determine the response of soil nutrients and plant diversity to the restoration process. The results show that the species richness of the community increases with the restoration year, the species composition at 40 years of restoration is similar to that of the natural forest, and the Shannon–Wiener diversity index in the tree layer at 40 years of restoration is greater than in the natural forest. Soil pH showed a decreasing trend with restoration year, and TP and AP increased with increasing time series. And the linear stepwise regression analysis showed that soil pH, soil organic carbon (SOC), total phosphorous (TP), available phosphorous (AP), and restoration year were the main factors of plant diversity. Compared to restoration of 10 years, TP and AP at the restoration of 40 years increased to 11.9–20.0 g∙kg−1 and 33.4–75.5 mg∙kg−1. The SOC of the community reached a maximum at 40 years of restoration, 1.5, 2.8, and 2.4 times higher at 0–20 cm, 20–40, and 40–60 cm, respectively, than at 1 year. The organic carbon fraction increased with the restoration year in an ‘N’ pattern, and mineral-associated organic carbon (MOC) and unstable organic carbon fraction decreased at 10 years and 40 years of restoration. The SOC of natural forests decreased, but stable organic carbon increased. The soil pH, SOC, and organic carbon fraction of the communities decreased with increasing soil depth, while TP and AP increased with increasing soil depth at the later period of restoration. In general, with extended restoration years, 40 years plant of restoration in phosphate mines can be expected to allow for plant community succession to climax community, and the key influence on plant diversity are the phosphorus and stable carbon fractions. These results are expected to facilitate the future basis for vegetation succession and restore systems during mining area restoration.

Sedges on the edge: new agronomic and research opportunities?

BackgroundThe paper by Tan and co-authors in this issue of Plant and Soil explores feedback mechanisms between functional traits and soil nutrient responses in tiger nut (Cyperus esculentus L.), with emphasis on their growth in marginal agricultural lands.ScopeMany of the world’s top food species belong to the order Poales, specifically the family Poaceae. Cyperaceae, also Poales, are recognised for their ecological importance, yet currently provide only minor contributions to global food security.ConclusionsWide ecological tolerance and naturally weedy tendencies may provide a unique niche for a significant increase in the production of tiger nuts as a global food resource. Further research on the ecology and agronomic potential of Cyperaceae is advocated.

Positive responses of soil nutrients and enzyme activities to AM fungus under interspecific and intraspecific competitions when associated with litter addition

Arbuscular mycorrhizal fungi mediated-litter decomposition is essential for soil carbon and nutrient cycling. Plant competition profoundly influences soil C, nutrients, glomalin-related soil protein, and enzymes. However, it is unclear how a combined AM fungus and litter addition affects soil properties under interspecific and intraspecific competitions. With 170-day-old Broussonetia papyrifera and Carpinus pubescens seedlings, three treatments of intraspecific or interspecific plant competition, AMF Claroideoglomus etunicatum inoculation or not, and leaf litter addition to soil substrate or not were examined to address differences in plant biomass production, soil organic carbon, total nitrogen and total phosphorus, EE-GRSP, DE-GRSP and T-GRSP, and activity of alkaline phosphatase, catalase and urease. The results were as follows: Root, shoot and total biomass increased in B. papyrifera but decreased in C. pubescens under AM mycorrhization in both intraspecific and interspecific competitions. Under mycorrhization, intraspecific, not interspecific, competition increased SOC and ratios of C/N, C/P, DE-GRSP and T-GRSP. Mycorrhization plus litter addition increased SOC, ratios of C/N, C/P and N/P, EE-GRSP, DE-GRSP, T-GRSP, and alkaline phosphatase activity under intraspecific competition, while soil TN, TP, and catalase and urease activities. Soil C, N, P, EE-GRSP or T-GRSP positively associated with catalase, urease or alkaline phosphatase activities. These results showed that alterations in intra- and interspecific competition induced by AM fungus positively respond to soil C, nutrient, GRSP, and enzyme activities, thus plant competition is a key factor in regulating soil properties. Overall, we suggest that interspecific competition enables AMF to increase soil N and P accumulations and related enzyme activities, while intraspecific competition confers more significant benefits than interspecific competition in improving soil C and GRSP accumulations under a combined AMF and litter addition. The findings highlight the importance of plant competition in improving soil function through AM fungus, which is conducive to understand the mechanisms of plant restoration and nutrient cycling in degraded ecosystems.

Responses of soil nutrient and enzyme activities to long-term mulched drip irrigation (MDI) after the conversion of wasteland to cropland

Soil nutrients and enzymes are essential indicators of ecological functions in terrestrial ecosystem and are also sensitive to land-use change. However, the response of soil nutrients and enzymes to long-term mulched drip irrigation (MDI) in the conversion of agroecosystems is still limited. In this study, we analyzed soil nutrient concentrations and enzyme activities at a soil depth of 0–40 cm in four typical cotton fields with different durations of MDI (8, 12, 16, and 22 years) and a wasteland (CK) as control. After the conversion of saline-alkali wasteland into cotton fields, we found that soil electrical conductivity (EC) and pH significantly decreased, but the concentrations of available soil phosphorus (AP), total carbon (TC), soil organic carbon (SOC) and total nitrogen (TN) significantly increased with increasing years of MDI application. Soil enzymes, such as polyphenol oxidase, catalase, urease, alkaline phosphatase, and cellulase were more active in the subsoil than in the topsoil. Compared to the wasteland, a significant reduction of soil enzyme activities (polyphenol oxidase, catalase, and cellulase) appeared in the young cotton field, which gradually reestablished after practicing long-term MDI. Based on redundancy analysis, the variations of the enzyme activities were obtained by pH (38.7 %), C/N (27.6 %), EC (20.9 %), TN (4.9 %), and NO3−-N (3.1 %) at 0–20 cm depth; and by AP (43.7 %), SWC (18.4 %), pH (12.6 %), and TN (12.5 %) at 20–40 cm depth. Long-term MDI has a positive effect on reducing soil salinity, increasing nutrient content in cotton fields, and can accelerate the activities of nutrient-releasing enzymes, which partly confirm the sustainability of MDI in oasis agroecosystems.

Response of soil nutrients, enzyme activities, and fungal communities to biochar availability in the rhizosphere of mountainous apple trees

Response of soil nutrients, enzyme activities, and fungal communities to biochar availability in the rhizosphere of mountainous apple trees

Response of Soil and Plant Nutrients to Planting Years in Precious Ancient Camellia tetracocca Plantations

In order to explore the response of soil nutrient supply capacity and tea plant nutrient utilization capacity to tea-planting years in precious ancient tea garden, field investigation and indoor analysis methods were employed to research the soil and plant nutrient content, eco-stoichiometric characteristics and the correlation between them, with artificially bred Camellia tetracocca at different time periods (5 years, 15 years, 25 years and 40 years). The results showed that: (1) the contents of soil organic carbon and total nitrogen were higher in the 25- and 40-year teas than in 5- and 15-year teas. The soil pH and total phosphorus were the highest in the 40-year tea, and the available nutrient content was the lowest in the 40-year tea. (2) The contents of nitrogen, phosphorus and potassium in tea shoots were the highest in 15-year tea. The nutrient content of tea trees were highest according to the following order: new shoots &gt; leaves &gt; branches. (3) The N: P of soil and leaves was 4.11–7.55 and 6.37–11.76, respectively. Available nutrients and soil pH were the main factors affecting the contents of nitrogen, phosphorus and potassium in new shoots. In conclusion, the soil nutrient supply capacity and the nutrient utilization capacity of tea plants in the Camellia tetracocca garden were significantly different under different tea-planting years. The growth of the tea plants was restricted by the soil nitrogen supply. The nutrient absorption and utilization capacity of precious Camellia tetracocca were higher in the 15- and 25-year teas, respectively. The study provides the basis for the rational development and sustainable utilization of precious ancient tea plants, and the scientific management of tea gardens.

Short-term responses of soil nutrients and enzyme activities to nitrogen addition in a Larix principis-rupprechtii plantation in North China

Atmospheric nitrogen (N) deposition is among the main manifestations of global change and has profoundly affected forest biogeochemical cycles. However, the threshold of N deposition to soil nutrient contents and enzyme activities has rarely been studied in a forest. In this study, we explored the effects of N deposition on soil nutrients and enzyme activities in a Larix principis-rupprechtii plantation on the northern Yanshan Mountain through multigradient N addition experiments (0, 5, 10, 20, 40, 80, and 160 kg N ha−1 year−1) after fertilization for 2 years. Compared with the controls, N addition first led to a decrease in soil NH4+-N and NO3--N, which then increased significantly. N addition had no significant effects on other soil nutrients. N addition overall elevated soil β-glucosidase activity. N application of &amp;gt;40 kg N ha−1 year−1 significantly reduced soil leucine aminopeptidase activity but had no significant effects on soil acid phosphatase, N-acetyl-β-D-glucosidase, and urease activities. N addition increased the overall stoichiometry ratio of EEA C:N and EEA C:P, but EEA N:P started decreasing after N application of 40 kg N ha−1 year−1. The ratios of C, N, and P acquisition activities changed from 1:1.2:1 under the control conditions to 1:1.1:1 under the N application of 160 kg N ha−1 year−1. N addition increased the overall vector length and had no significant effects on the vector angle. Correlation and redundancy analyses revealed that N addition-induced change in available soil N was the main factor affecting soil enzyme activity and stoichiometry. In general, different enzyme activities had different sensitivities to N addition. Moderate N addition or atmospheric N deposition (e.g., &amp;lt;40 kg N ha−1 year−1) had beneficial effects on soil nutrient cycling and microorganisms in a Larix principis-rupprechtii plantation.

Differential responses of soil nutrients to edaphic properties and microbial attributes following reclamation of abandoned salinized farmland

Salinization is a global threat to the sustainability of farmland in arid areas. However, the mechanisms by which soil physicochemical and microbial properties affect soil nutrients in salinized farmlands are not completely understood. Here, the direct and indirect responses of edaphic properties (bulk density [BD], saturated hydraulic conductivity [SC], field capacity [FC], alkalinity[pH], microbial biomass carbon [MBC], and microbial biomass nitrogen [MBN]) and soil microbial properties (denitrifying genes [nirS], nitrogen-fixing genes [nifH], catalase [CAT] and urease [UR] activities, and species richness [Chao1]) to the total soil N content (TN), soil organic carbon (SOC), alkali hydrolyzable N (AN), potassium (K+), and calcium (Ca2+) ions at low-salinity (2–4 dS m−1), mid-salinity (4–8 dS m−1), high-salinity (8–15 dS m−1) sites, and non-salinity (Control, 0–2 dS m−1) farmland in arid areas of northwest China were examined. Soil UR activity (range: 703.5–956.6 U UR L-1 ) and nifH, AN, SOC, and MBN content were higher at the low-salinity than at the medium- and high-salinity sites. Furthermore, FC was indirectly affected by the soil nutrients due to their effects on nifH and CAT activities. The relative contribution of soil TN, SOC, and AN content on the direct responses of the microbial attributes (52–70%) was higher than that of the soil physicochemical properties (27–45%) in different reclamation types. The reclamation process on abandoned salinized farmland promoted the activity of microorganisms, further improving the soil's physical properties and nutrient status. This study has found that improving microbial metabolic activity in combined with reclamation measures will be crucial for future salinity management.

Net primary productivity exhibits a stronger climatic response in planted versus natural forests

Compared to planted forest ecosystems (PFE), natural forest ecosystems (NFE) generally have a longer history and theoretically have stronger environmental adaptability. Changes in net primary productivity (NPP) due to global change have been studied for many forest types, yet the underlying mechanism remain poorly understood. Using 926 forest plots (including both PFE and NFE) established between 2005 and 2020 in China, we found that NPP exhibited stronger climate and soil nutrient responses, with greater environmental plasticity, in PFE versus NFE. Several functional traits (e.g., leaf area, leaf nitrogen and phosphorus content) differed between NFE and PFE, but only weakly predicted spatial variation in NPP, as compared to the environmental factors. Overall, NPP in both NFE and PFE showed consistent responses to climate and soil nutrient changes. These environmental responses were weaker in coniferousforests than broadleaved forests. Direct effects of climatic factors on NPP were stronger than indirect effects. Overall, the effects of functional traits on NPP were mediated by climatic and edaphic factors. These findings provide guidance for more reliable predictions of NPP and succession in NFE and PFE in the context of global warming.

Effects of Irrigation and Nitrogen Application on Soil Nutrients in Triploid Populus tomentosa Stands

Irrigation and nitrogen application directly affect the availability and distribution of soil nutrients. Understanding the response of soil nutrients to long-term water–fertilizer coupling conditions is helpful to improve the management and use efficiency. Irrigation was divided into three gradient levels, which accounted for 45%, 60%, and 75% (W1, W2, and W3) of the field water holding capacity. Based on pure nitrogen, four levels of nitrogen application were set: 0.0, 101.6, 203.2, and 304.8 kg·hm−2 (N0, N1, N2, and N3). We measured tree height and diameter at breast height (DBH), and we analyzed the chemical properties of the soil at 0–40 cm depth, from 2007 to 2020. The ranges of DBH, tree height, individual volume, and stand volume were 5.80–25.25 cm, 6.10–16.47 m, 0.01–0.37 m3, and 11.76–481.47 m3·hm−2, respectively. The contents of organic matter, total nitrogen, available phosphorus, and available potassium in the soil ranged from 8.60 g·kg−1 to 18.72 g·kg−1, from 0.21 g·kg−1 to 0.79 g·kg−1, from 8.09 mg·kg−1 to 47.05 mg·kg−1, and from 90 mg·kg−1 to 322 mg·kg−1, respectively. Soil pH value decreased rapidly at a rate of 0.31 units per year for the first five years. Irrigation and nitrogen application, and their interaction, had significant (p &lt; 0.01) effects on soil total nitrogen, available phosphorus, available potassium, and nitrate-nitrogen. We suggest maintaining the field water holding capacity above 60%, with a nitrogen application rate of 203.2 kg·hm−2, to save water, maintain soil fertility, and optimize soil nitrogen supply. Our study aimed to achieve scientific and accurate fertilization of Populus tomentosa stands over different periods, to alleviate the decline of soil fertility, and to improve the utilization rate of water and fertilizer through long-term nutrient monitoring.

Short-term responses of soil nutrients, heavy metals and microbial community to partial substitution of chemical fertilizer with spent mushroom substrates (SMS)

Currently, many spent mushroom substrates (SMS) are produced each year, which have the great potential to replace partial chemical fertilizer in agricultural production due to the high content of organic matter in SMS. However, how the replacement of chemical fertilizer by different SMS affected soil nutrients and contamination was less reported. Therefore, this study applied Enoki mushroom substrates (EMR), Agaricus bisporus substrates (ABR), or Auricularia auricula substrates (AAR) to replace 25 % chemical fertilizers (based on N fertilizer) with understanding the role of SMS replacement in affecting soil nutrients, heavy metals, and microbial community via the short-term field study, respectively. Compared to chemical fertilizer (CF), the contents of organic matter (OM), total P (TP), and K (TK) in SMS replaced soils were significantly increased by 1.96–4.22, 0.08–0.12, and 0.03–0.53 g kg−1, respectively. Among three SMS replacements, AAR demonstrated the highest increment of soil nutrients. On the other hand, EMR and ABR replacements reduced the contents of total and acid-soluble Cd, Pb, and As by 7.94–30.32 % and 0–31.61 % in soils relative to CF, respectively. Unlike EMR and ABR, AAR reduced 11.08–16.04 % of total Cd, Pb, and As but increased 62.58 % acid-soluble As in soils. Furthermore, it was found that all SMS replacements increased the relative abundance of Proteobacteria, while ABR also increased the relative abundance of Actinobacteria in soils compared to CF. Besides, EMR and ABR replacements increased the relative abundance of Mortierellomycota relative to CF. Finally, it can be known that partial replacement of chemical fertilizer by SMS could elevate soil nutrients (especially AAR) and reduce heavy metals (especially EMR), which further improved microbial diversity and community composition. This study provides information on applying SMS to replace partial chemical fertilizer to elevate nutrients and reduce heavy metals contamination.