Spatial-Temporal Variation of N, P, and K Stoichiometry in Cropland of Hainan Island

Elemental stoichiometry reflects the interaction between plants, soil, and microorganisms, and links biogeochemical patterns with physiological limitations. The stoichiometry of elements in farmland soil is an important part of the function of the agroecosystem. Soil nitrogen (N), phosphorus (P), and potassium (K) are the main macronutrients in terrestrial ecosystems, which are closely related to biogeochemical cycles. Studying the temporal and spatial variability of soil nutrients in tropical farmland is of great significance for exploring the variation of soil nutrients and promoting the sustainable development of tropical agriculture. In this study, soil samples in the farmland of Hainan Island were collected at three different stages for exploring temporal and spatial variations of N, P, and K stoichiometry. Results showed that soil concentrations of available N, P, and K changed markedly with the temporal and spatial variability. The highest available N, P, and K concentrations appeared at the stage of 2016–2020 with values of 110.40 mg/kg, 51.91 mg/kg, and 82.76 mg/kg, respectively, while their lowest values were observed in 2010–2015 with 66.34 mg/kg, 11.27 mg/kg, and 45.77 mg/kg, respectively. The available nitrogen content in the three time periods first increased and then decreased with the increase of available potassium content, an opposite trend was observed between available nitrogen and phosphorus. The content of N increased in Haikou, Lingao, Ding’an, and P increased in Wengchang, and Lingshui and K increased in Danzhou and Wanning as time increased.

Wood Burial is Currently the Only Fast and Effective Method of Carbon Neutrality

In this study, we analyzed the feasibility of various carbon neutral methods based on the first principles of biogeochemistry, namely energy use efficiency and elemental stoichiometry. We believe that wood burial is the only currently feasible carbon neutrality method because this method has no theoretical uncertainties, can be implemented immediately, is large scale, low cost, has low technical requirements, and has a relatively low impact on agriculture.

Climatic Rather than Edaphic Variables Determine Leaf C, N, P Stoichiometry of Deciduous Quercus Species

Purpose Leaf elemental stoichiometry is indicative of plant nutrient limitation, community composition, ecosystem function. Understanding the variations of leaf carbon (C), nitrogen (N), and phosphorus (P) stoichiometry at genus-level across large geographic regions and identifying their driving factors are important to predict species’ distribution range shifts affected by climate change.MethodsHere, we determined the patterns of leaf concentrations ([ ]) and ratios ( / ) of C, N, P of five deciduous oaks species (Quercus) across China covering ~ 20 latitude (~21–41˚ N) and longitude (~99–119˚ E) degrees, and detected their relationships with climatic, edaphic variables. ResultsLeaf [C], [N] and N/P, C/P significantly increased, while leaf [P] and C/N decreased with the increasing latitude. Leaf stoichiometry except for leaf [C] had no significant trends along the longitude. Climatic variables, i.e. mean annual temperature, mean annual precipitation, the maximum temperature of the warmest month, temperature seasonality, aridity index, and the potential evapo-transpiration were the determinants of the geographic patterns of leaf C, N, P stoichiometry. The mean annual precipitation and the maximum temperature of the warmest month indirectly regulated leaf C/N, C/P and N/P via altering leaf [P]. Edaphic variables had non-significant effects on leaf C, N, and P stoichiometry at the broad geographic range.ConclusionsClimatic variables have more important effects than edaphic properties on leaf C, N, P stoichiometry of the studied deciduous Quercus species, which imply the ongoing climate change will alter nutrient strategies and potentially shift the distribution range of this eurytopic species.

The importance of allochthonous organic matter quality when investigating pulse disturbance events in freshwater lakes: a mesocosm experiment

Extreme precipitation is occurring with greater frequency and intensity as a result of climate change. Such events boost the transport of allochthonous organic matter (allo-OM) to freshwater ecosystems, yet little is known about the impacts on dissolved organic matter (DOM) quality and seston elemental stoichiometry, especially for lakes in warm climates. A mesocosm experiment located in a Turkish freshwater lake was designed to simulate a pulse event leading to increased inputs of allo-OM by examining the individual effects of increasing water colour (HuminFeed®, HF), the direct effects of the extra energetic inputs (alder tree leaf leachate, L), and the interactions of the single treatment effects (combination of both sources, HFL), along with a comparison with unmanipulated controls. Changes in the DOM quality and nutrient stoichiometry of the allo-OM treatment additions was examined over the course of the experiments. Results indicated that there was an increase of high recalcitrant DOM components in the HF treatment, in contrast to an increase in less aromatic microbially derived molecules for the L treatment. Unexpectedly, seston C:P ratios remained below a severe P-limiting threshold for plankton growth and showed the same temporal pattern in all mesocosms. In contrast, seston N:P ratios differed significantly between treatments, with the L treatment reducing P-limiting conditions, whilst the HF treatment increased them. The effects of the combined HFL treatment indicated an additive type of interaction and chlorophyll-a was highest in the HFL treatment. Our results demonstrate that accounting for the optical and stoichiometric properties of experimental allo-OM treatments is crucial to improve the capacity to explain extrapolated conclusions regarding the effects of climate driven flooding on freshwater ecosystems in response to global climate change. Graphical abstract

Decoupling of P from C, N, and K Elements in Cucumber Leaves Caused by Nutrient Imbalance under a Greenhouse Continuous Cropping System

There is insufficient information regarding the stoichiometric variation and coupling status of carbon (C), nitrogen (N), phosphorus (P), and potassium (K) in the leaves of nutrient-enriched greenhouse agroecosystems with increasing planting time. Therefore, we assessed the variation in elemental stoichiometry ratios in soil and cucumber (Cucumis sativus L.) leaves, and the coupling status of elemental utilization in the leaves under continuous cropping systems using natural (only soil; i.e., control soil, CO) and artificial (soil + straw + chicken + urea; i.e., straw mixture soil, ST) soil via monitoring studies for 11 years in a solar greenhouse. Soil organic C, total N, and total P concentrations increased by 63.4%, 72.7%, and 144.3% in the CO, respectively, after 11 years of cultivation (compared to the first year), and by 18.1%, 24.3%, and 117.7% in the ST under continuous cropping conditions, respectively. Total K concentrations remained unchanged in both soils. Moreover, the availability of these soil elements increased to different degrees in both soils after 11 years of planting. Additionally, the leaf P concentration increased by 9.8% in the CO, while leaf N and K concentrations did not change, suggesting decoupling of P utilization from that of N and K in leaves under a continuous cropping system. These findings suggest that imbalanced soil nutrients under continuous cropping conditions results in decoupling of P from N and K in the utilization of leaf nutrients.

Characterizations of Spray Deposited CdTe Thin Film

The spray pyrolysis is promising technique for deposition of CdTe thin film. We deposited CdTe thin film on glass substrate by homemade spray pyrolysis technique at substrate temperature 3000C. The CdTe thin film was characterized through Field scanning electron microscopy (FSEM), Energy dispersive X-ray analysis (EDAX), Uv-Visible spectroscopy. The SEM micrograph shows the film was uniform coverage, large number of densely packed grain whosesizes ranging from 474nm to 1.64µm. From EDAX analysis conform that the presenceof Cd and Te in prepared film with elemental stoichiometry of Cd and Se was 50.28% and 49.72% respectively. The optical absorption coefficient of the film of order of 106 and band gap of the film 1.45eV.

Silicon Changes C:N:P Stoichiometry and Favors Pre-Sprouted Seedling Growth, Yield and the Technological Quality of Sugarcane.

The importance of silicon (Si) in sugarcane is well known, but its effects on changing C:N:P stoichiometry enough to increase pre-sprouted seedling (PSS) and sugarcane development in the field remains unknown. To that end, the present study aimed to assess whether Si fertigation favors its absorption enough to change elemental stoichiometry (C:N:P), physiological attributes and PSS growth, as well as the growth, stem yield and juice quality of sugarcane. Two field experiments were conducted in the PSS formation stage and another in the sugarcane plant development phase. Experiment 1 was carried out in a greenhouse with PSSs under two treatments: in the absence and presence of Si (2 mmol L−1) fertigation. Experiment 2 was performed in the field in red-yellow argisol with the sugarcane plant undergoing the following treatments: absence of Si (No Si); Si supplied by fertigation during the PSS formation and sugarcane plant development phases (Si–C); and Si supplied during the PSS formation and sugarcane plant development phases (Si–M+C). The following were assessed in experiment I: growth, leaf green color index (GCI), chlorophyll fluorescence, C, N, P, and Si content, and C:Si, C:N and C:P stoichiometric ratios. In experiment II, the same stoichiometric ratios were assessed, as well as sugarcane growth, stem yield and juice quality. Si reduced the C:Si, C:N and C:P stoichiometric ratios in PSS. The C:Si ratio in the leaves and stems declined with the supply of Si, while the C:N and C:P ratio in the leaves and stem was higher in plants that received Si in the Si-M+C treatment. Applying Si fertigation in PSS formation to promote changes in C:N:P stoichiometry favored photosynthetic efficiency and growth. The Si–M+C treatment stood out, since it also caused enough C:N:P stoichiometric changes to increase sugarcane growth, yield and juice quality.

Leaf Elemental Stoichiometry of Stellera Chamaejasme L. in Response to Environmental Factors in Degraded Grasslands Across Northern China

Plant leaf stoichiometry reflect its adaptations to environments. Leaf stoichiometry variations across different environments have been extensively studied among grassland plants, but little is known about intraspecific leaf stoichiometry, especially for widely distributed species, such as Stellera chamaejasme L. In order to evaluate the biogeographical drivers for leaf elemental stoichiometry in S. chamaejasme, leaf and soil samples were collected from 29 invaded sites in the two plateaus of distinct environments [the Inner Mongolian Plateau (IM) and Qinghai-Tibet Plateau (QT)] in Northern China. Leaf C, N, P, and K and their stoichiometric ratios, and soil physicochemical properties were determined. Results showed that mean leaf C, N, P, and K concentrations were 498.60, 19.95, 2.15, and 6.57 g kg-1, respectively; the C/N, C/P, and N/P ratios were 25.46, 246.22, and 9.84, respectively. Only leaf K was significantly different between the two environments studied. Soil physicochemical properties of S. chamaejasme invaded area varied wildly, suggesting this wide ranging species tend to be insensitive to variation in soil nutrient availability. C and N content of S. chamaejasme leaves were unaffected by any environmental factors. However, the stoichiometric homeostasis of P and K was observed. The correlation between leaf P and climate factors was significant only in IM, while leaf K was significantly related to climate factors only in QT. Partial least squares path modeling suggested that soil exerted a significant effect on LP and climate affected leaf P and K both directly and indirectly in QT, while LP appeared to be limited mainly by climatic factors via direct ways and LK was not affected significantly by any environmental factors in IM. This study evaluated the S. chamaejasme leaf elemental stoichiometry and their relationships with environmental variables, which can help understand the plant biogeographic patterns and adaption strategy in degraded grasslands in China.