Soil Chemical Properties Research Articles

Effects of aerial liming on soil chemical and biological properties in metal contaminated and inaccessible lands in Ontario (Canada).

The manual addition of lime to soil, in addition to tree planting and fertilization have been the dominant strategy described in restoration protocols for ecosystems damaged by acid rain and metal contamination. Investigations on aerial-limed soils in inaccessible lands are limited. The objective of this study was to assess the effects of aerial liming on soil pH, organic matter, microbial biomass, and enzymatic activities, and aboveground plant population quality in metal-contaminated lands in northern Ontario, Canada. Soil samples were collected from three sites around the City of Greater Sudbury with each pair being composed of a reclaimed (areal-limed) site and an adjacent undisturbed (unlimed) area. Soil physico-chemistry, microbial biomass (assessed by Phospholipid fatty acid analysis) and enzymatic activities were analyzed. Soil pH was higher in limed sites compared to unlimed at recently restored sites (Baby Lake and Wahnapitae) but not at the oldest reclaimed site (HWY 80 N). Organic matter was higher in limed areas compared to the unlimed reference site only at most recently reclaimed site at Baby Lake. Aboveground plant population health was visibly improved in limed sites compared to unlimed areas. Metal concentrations of iron (Fe) and arsenic (As), total microbial biomasses, gram-negative bacterial, fungal, and eukaryotic biomasses were all significantly increased in the limed soils compared to the unlimed samples. The same trend was observed for the activities of three of the enzymes tested, β-N-acetylglucosaminidase (BG), aryl sulfatase (AS), and glycine aminopeptidase (GAP). Interestingly, strong positive correlations between the levels of soil organic matter, microbial biomasses, and NAGase and ALP activities were observed. Although expensive, aerial liming is effective in restoring inaccessible sites impacted by smelting operations where other methods cannot easily be used.

Carbon Sequestration and Soil Fertility Management in Sandy and Clayey Soils Revealed by Over Four Decades of Long‐Term Field Experiments in Thailand

ABSTRACTWe investigated the impact of organic matter (OM) application on soil organic carbon (SOC) sequestration and cassava yield in sandy (sand content > 72% and > 62%) and clayey (sand content > 47%) soils through three long‐term experiments conducted from 1975 to 1976 in Thailand. Eight treatments—nitrogen (N), phosphorus (P), and potassium (K) fertilization, cassava residue (CR), and compost application (COM)—were assigned to the control (CT), N, NP, NK, NPK, CR, NPK + CR, and NPK + COM groups. Changes in SOC, cassava yield, and soil chemical properties, were recorded. Interactions of these parameters were visualized using structural equation modeling (SEM). SOC concentrations were determined at five different depths in 2021. A significant treatment effect was observed in the initial stage of the experiment in sandy soils. Conversely, in clayey soil, a significant effect was observed only in the later stage. SOC sequestration rates (mean ± SD of the three sites, Mg C ha−1 0.2 m−1) were in the order of NPK + COM (10.1 ± 6.5), NPK + CR (5.6 ± 3.1), CR (2.8 ± 2.0), NPK (2.0 ± 2.1), NK (1.9 ± 1.3), NP (1.8 ± 2.0), and N (1.2 ± 1.1). SEM highlighted the effect of OM application on SOC sequestration across the three sites. Furthermore, SOC increases positively influenced cassava yield in sandy but not in clayey soils. Vertical distribution of SOC showed consistent treatment effects in deeper soil layers, especially in sandy soils, underscoring the importance of considering deep soil layers for carbon sequestration.

Exploring the Potential of Macroalgae for Sustainable Crop Production in Agriculture.

Marine macroalgae, which typically colonize coastal areas, are simple plant organisms. They live on rocks in coastal regions and are classified into red, brown, and green macroalgae. These algae are an important natural resource in agriculture due to their ability to enhance the structural, chemical, and biological properties of soil. Marine macroalgae can be used to produce various biocidal molecules that are effective in controlling plant pathogens. Much of the literature on marine macroalgae and their derivatives focuses primarily on the pharmaceutical field, while their use in agriculture is still considered secondary. However, various studies and experiments have demonstrated their potential to play a significant role in crop protection and enhancement. This review aims to highlight the various applications of macroalgae in plant production. It also emphasizes the biotechnological importance of marine macroalgae derivatives as biofertilizers, molecules for controlling insects and microorganisms, and as plant growth conditioners. Compounds from macroalgae, such as fatty acids, carotenoids, polyphenols, and carbohydrates, are being investigated for their fungicidal, antimicrobial, and antiviral effects against various plant pathogens. Beyond enhancing crop production, macroalgae can also be considered multifunctional bioinoculants suitable for use in organic farming.

Closing the gap: examining the impact of source habitat proximity on plant and soil microbial communities in post-mining spoil heap succession.

Revegetation of barren substrates is often determined by the composition and distance of the nearest plant community, serving as a source of colonizing propagules. Whether such dispersal effect can be observed during the development of soil microbial communities, is not clear. In this study, we aimed to elucidate which factors structure plant and soil bacterial and fungal communities during primary succession on a limestone quarry spoil heap, focusing on the effect of distance to the adjoining xerophilous grassland. We established a grid of 35 plots covering three successional stages - initial barren substrate, early successional community and late successional grassland ecosystem, the latter serving as the primary source of soil colonization. On these plots, we performed vegetation surveys of plant community composition and collected soil cores to analyze soil chemical properties and bacterial and fungal community composition. The composition of early successional plant community was significantly affected by the proximity of the source late successional community, however, the effect weakened when the distance exceeded 20 m. Early successional microbial communities were structured mainly by the local plant community composition and soil chemical properties, with minimal contribution of the source community proximity. These results show that on small spatial scales, species migration is an important determinant of plant community composition during primary succession while the establishment of soil microbial communities is not limited by dispersal and is primarily driven by local biotic and abiotic conditions.

Mechanical property and microstructure of fly ash-based geopolymer by calcium activators

Geopolymer is a green and environmentally friendly new type of gel material generated from the reaction of activators with silica-alumina raw materials, possessing extensive research and application value. Fly ash can be used as reaction material, enabling the industrial solid waste to be recycled and reused. In this paper, unconfined compressive strength test, X-ray diffraction analysis, Fourier transform infrared light, 29Si nuclear magnetic resonance, scanning electron microscope and energy disperse spectroscopy, and physisorption experiment were carried out to study the effects of the type and dosage on the mechanical property and microstructure of fly ash-based geopolymer activated by calcium hydroxide, calcium sulfate and their compound. The results indicated that calcium hydroxide and calcium sulfate can promote the dissolution of fly ash crystals, providing adequate Ca2+ for the formation of gel products. The products of calcium hydroxide and calcium sulfate activation are hydrated calcium aluminate, hydrated calcium sulfate, and ettringite, respectively. The effect of the compound activator is superior to that of single activators. With the increase of the proportion of calcium hydroxide, the reorganization and polymerization of gel products were accelerated so that the integrity and continuity of the microstructure of geopolymer were improved, and then the strength increased. When the ratio of calcium hydroxide to calcium sulfate was 3:1 and the total dosage was 20 %, the unconfined compressive strength reached the maximum value. According to this study, it was investigated that type and dosage of calcium activators had evident influence on the geopolymerization of fly ash. And the reutilization and resource utilization of fly ash waste can be achieved, which can provide an engineering theoretical basis for using fly ash-based geopolymer to alter the physical and chemical properties of special soils and achieve solidification effect.

Effects of alpine meadow degradation on the soil physical and chemical properties in Maqu, China

While alpine meadow degradation presents a significant ecological challenge, research on the complex patterns of soil property changes induced by degradation has been somewhat limited. In this study, we investigated the Maqu alpine meadow, meticulously categorizing it into different grassland types exhibiting varying degrees of degradation based on factors such as vegetation coverage and community, soil characteristics, and landscape features. These classifications included typical grassland, degraded grassland, desertified grassland, and sandy land. In August 2018, we established three quadrats at each sample point and collected soil samples at five depths (surface [0–2 ​cm], 2–5 ​cm, 5–10 ​cm, 10–20 ​cm, and 20–40 ​cm) to analyze soil particle size distribution (PSD) and nutrients content. The results revealed a discernible trend: alpine meadow degradation led to selective loss of nutrient-rich soil fine particles, resulting in significant alterations in soil PSD and nutrients, particularly pronounced in grasslands with low degrees of degradation. Moreover, within a specific range of degradation degree, the clay content in the shallow soil of alpine meadow increased with the degradation degree, but it declined when the degradation degree exceeded a certain threshold. Degradation also disrupted the intricate relationship between soil nutrients, with notable variations in their coupling. This difference was also reflected in the influence of soil physical and chemical properties on soil nutrients, with the explanatory power of each environmental indicator on soil nutrients decreasing significantly with increasing degradation. This study systematically analyzed the variation in soil physical and chemical properties throughout the degradation process, revealing the mechanism of soil nutrient imbalance and decline caused by the degradation process. It provides crucial theoretical foundations and reference points for the preservation and rejuvenation of alpine meadows, enriching the methodology for assessing the impact of grassland degradation.

Unveiling the impact of organically activated biochar on physiological, biochemical, and yield attributes of maize under varied field moisture conditions.

Water deficiency in semiarid regions is a limiting factor that affects crop quality and yield. In Punjab, Pakistan, a 27% decline in maize yield was detected over the past two decades just because of water scarcity. Currently, no studies have reported the effects of organically activated biochar (AB) on crop productivity under natural field conditions. For this purpose, a field experiment in a split-split-plot design was conducted with three amendment levels (0, 2, and 4 tonnes ac-1), and three maize hybrids (DK-9108, DK-6321, and Sarhaab) under 100%, 70%, and 50% irrigation water (IW) of crop evapotranspiration (ETc). The AB significantly improved the soil's physical and chemical properties, and maximum improvement was recorded in 4 tonnes ac-1 AB amendment in organic matter (16.6%), total organic carbon (17%), phosphorus (11.43%), and available potassium (29.27%). The 4 tonnes ac-1AB amendment in soil had a significant impact on total chlorophyll content (0.3-1-fold in DK-6321), carotenoid content (3.9-4.4-fold in Sarhaab), and relative water content (30% and 21% in Sarhaab) under 50% irrigation water (IW) of ETc at V14th and R3 stages, respectively. Moreover, a significant decline in stress markers (proline content and sugar content) was detected at both growth stages in all maize hybrids in AB amended soil. The analysis of plant metabolites indicated increased intensities of phenolics, alkyl esters, and carbohydrates by 2.5-7%, 17-80%, and 40-43% in DK-6321 under 50% IW in 2-4 tonnes ac-1 AB amended soil, respectively. The highest improvement in growth and yield attributes among maize hybrids was detected in the order DK-6321¿DK-9108¿Sarhaab in 2-4 tonnes ac-1AB amended soil under 70% and 50% IW of ETc, respectively. Hence, this research might help to develop an effective soil amendment to restore degraded soils and improve maize growth under arid climatic conditions.

Model for Estimating Soil Chemical Properties with RGB Drone Images

Precision agriculture optimizes crop management by providing accurate data on soil chemical properties, thereby improving agricultural productivity and sustainability. This study aims to develop models to estimate soil chemical properties, such as pH, electrical conductivity (EC), and organic matter (OM), by analyzing drone-captured RGB images. The methodology included photogrammetric flights with a DJI Phantom 4 Pro drone equipped with a 20 Mpx camera and simultaneous sampling, laboratory analysis and on-site measurements, with Royal Eijkelkamp EC meter set voor grond multiparameter sensors and pH meter set for soil and water. The aerial images were processed with the PIX4Dmapper software, to generate the orthophoto and spectral bands. With the resulting orthophoto of 1.6 cm/pixel, eight spectral indices were calculated, using the spatial analysis tools of ArcGIS software. The in situ results showed an average pH value of 5.83, indicating a slightly acidic soil, and an EC of 1.09 dS/m, suggesting a soil with a low concentration of dissolved salts. Laboratory analyses showed a medium-high content of OM, with an average of 5.19 %. A strong correlation was found between OM and pH_index with coefficients of determination R2=0.55, while moderate correlations were also observed between pH with pH_index and EC with sal_index6 with coefficients of determination R2=-0.39 and R2=0.42 respectively. The aforementioned results allowed the generation of two models for the estimation of these variables from RGB images.

Variability of soil chemical properties and rice productivity in salt-affected soil in the north coastal rice field of Central Java, Indonesia

A coastal rice field is generally characterized by salt-affected soil and low soil quality for rice cultivation. Identifying soil chemical properties in these areas is necessary to determine soil management options for rice production. Therefore, soil samples were collected from 33 sampling points in the Wedung Sub-district of Demak Regency in the late dry season of 2021 to evaluate the variation among soil chemical characteristics in a coastline rice field. Soil samples were obtained beneath the topsoil (0-20 cm soil depth) and observed for electrical conductivity, exchangeable potassium, sodium, calcium, magnesium, and cation exchange capacity. Soils in the research field were categorized as slightly salty (0.75-2 dS m-1) to lightly salty (2.0-4.0 dS m-1) with very high sodium (>2 cmol(+) kg-1). Exchangeable potassium was dominated by moderate (0.3-0.7 cmol(+) kg-1) and low categories (0.2-0.3 cmol(+) kg-1). Based on soil calcium-to-magnesium ratios, around 6% of all samples were classified as calcium-deficient. The range of soil cation exchange capacity was 22-30 cmol(+) kg-1 and classified as high soil cation exchange capacity. Rice productivity in the salt-affected soil was around 4 t ha-1. Strategies for soil and controlling plants, such as soil amelioration and salt-tolerant rice cultivars, should be pursued to support plant growth and enhance rice productivity in the salt-affected soil, particularly in the coastal area.

Application of oil palm and cacao waste biochar to improve the chemical properties of an Ultisol of Langsa, Aceh

Ultisols, including those of Langsa, Aceh, are known to have low fertility due to low pH, low available nutrients, low base saturation, high pH and exchangeable Al, and low cation exchange capacity. These problems can be alleviated by applying organic amendments to the soil. One of the soil amendments is biochar. This study aimed to elucidate the potential of oil palm and cacao waste biochar for improving the chemical properties of an Ultisol of Langsa, Aceh. Biochars generated from oil palm kernel shell (PKS), oil palm empty fruit bunch (PEFB), and cacao pod husk (CPH) were applied to the soil and incubated in the laboratory for 16 weeks. At 4, 8, 12, and 16 weeks after incubation, the changes in soil chemical properties were measured. The results showed that applying different types of biochar significantly improved the chemical properties of the Ultisol of Langsa. Specifically, PEFB biochar caused significant increases in soil pH (H2O and KCl), total phosphorus, available phosphorus, organic C, and cation exchange capacity. These increases became more pronounced with longer incubation times. In addition, using PEFB biochar resulted in the lowest levels of exchangeable Al and Fe in the soil. These levels decreased further with longer incubation times. In general, PEFB biochar produced at a pyrolysis temperature of 450oC for 4 hours is the most effective biochar for improving the chemical properties of the Ultisol of Langsa.

Improving sugarcane productivity on marginal soil in Takalar, Indonesia, through the application of sugarcane factory waste

Marginal soil with low nutrient content is a crucial problem in reducing crop productivity, including sugarcane. This study aimed to elucidate the possible improvement of the physical and chemical properties of marginal soil through the application of organic waste from sugar factories, namely kettle ash and press mud. Nine treatment combinations of 0, 10, and 20 t ha-1 of each kettle ash and press mud were arranged in a two-factor randomized factorial design with three replications. Soil organic matter, N, P, and K, soil aggregate stability, and sugarcane productivity were measured after planting sugarcane for five months. The results showed that the application of kettle ash and press mud, especially with a ratio of 20 t ha-1 kettle ash and 10 t ha-1 press mud, was able to reduce the leaching of organic matter and improve sugarcane growth, particularly increasing the number of tillers by 16%, stem height by 14%, and diameter by 16%. The sugarcane productivity obtained was 58.02 t ha-1. Other portions of kettle ash and press mud did not have a favorable effect on sugarcane productivity. This study provided practical insights for increasing agricultural productivity, especially in sugarcane plantations.

Changes in Soil Bacterial and Fungal Community Composition and Functional Groups During the Artificial Restoration of Degraded Grassland of "Black-Soil Mountain".

About 35% of grassland in Sanjiangyuan area of China has degenerated into black-soil mountain. Artificial grassland is considered to be an effective measure to alleviate the severely degraded grassland in the alpine region of the three rivers and has been widely used. However, the pattern, potential function, and changes of carbon and nitrogen contents of soil microorganisms in degraded grassland in Heimushan by planting artificial grassland are still unclear. In this study, mixed-sown artificial alpine grassland (AG) was the focus of our study, whereas degraded black-soil mountain grassland (BG) and natural alpine grassland (NG) served as controls. Illumina 16S and ITS gene sequence analyses were used to analyze the community structure of the soil bacteria and fungi. The functional groups of NG, AG, and BG were predicted using the FAPROTAX and FUNGuild databases. In addition, the levels of soil carbon, nitrogen, and soil enzyme activities were evaluated. The results indicated a significant increase in the aboveground biomass of BG due to the planting artificial grassland. Moreover, the contents of total carbon (TC), total nitrogen (TN), ammonium nitrogen ( ), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and leucine aminopeptidase (LAP) increased in the soil. Planting artificial grasslands changed the composition of bacterial and fungal communities. Among these, the bacterial community was more sensitive to planting artificial grasslands. The relative abundance of bacterial functional groups involved in carbon and nitrogen cycling changed significantly, suggesting that bacteria may play a role in regulating nutrient cycling during artificial grassland planting. Soil TC, TN, LAP, and affected the microbial community structure related to carbon and nitrogen. and β-1,4-glucosidase were carbon and nitrogen factors, respectively, that affected functional changes in fungi. These results indicate that planting artificial grasslands can effectively enhance the productivity of degraded black-soil mountain and regulate soil microbial communities and soil physical and chemical properties.

Effects of land use types on the soil physicochemical characteristics of Inyi community, Enugu State, Nigeria: Application of multivariate statistical, and eco-toxicological and human risk model approaches

The constant and increased use of arable lands for cultivation has led to its degradation; hence the impacts of different land-use patterns on the soil physical and chemical properties were investigated. Soil samples (n = 36) were collected from the oil palm plantation (OPP), cashew plantation (CP) and untampered forest (UF), in Inyi community, Enugu State, Nigeria. They were air-dried, sieved, and analyzed for their physicochemical properties. The results revealed that the average soil pH ranged from 5.9 to 8.2. Moisture and carbon contents ranged from 6.3 to 35.4, and 3.5 to 6.7 % respectively. Low CEC values were recorded for all the soil samples. The total mean soil textural fractions decreased as follows: sand > clay > silt. Also, the total mean concentrations of N, P, K, and Mg in the study area decreased in the order: OPP>UF>CP, OPP>UF>CP, UF>OPP>CP, and OPP>UF>CP respectively while the S, NO3-, NO2-, and HCO3- followed the order; OPP>UF>CP, UF>OPP>CP, OPP>CP>UF, and CP>OPP>UF respectively. The soil ecological risk index was < 40 in all sample locations, indicating slight contamination of the study area. Therefore, regular monitoring and soil nutrient management practices should be maintained and encouraged.

Effects of different fertilization formulas on fruit quality and soil physical and chemical properties of oil peony in abandoned mining areas

Effects of different fertilization formulas on fruit quality and soil physical and chemical properties of oil peony in abandoned mining areas

Effect of biochar on soil chemical properties of tidal wetland in Jambi, Indonesia, and growth and yield of various rice varieties

The study aimed to determine the effect of biochar on the growth and yield of several rice varieties in a tidal wetland agroecosystem. This research used a split-plot design with the main plot was biochar application, consisting of three levels (no biochar, rice husk biochar, and coconut shell biochar), and the subplot was rice variety consisting of ten varieties (Inpara, Inpari 30, Kuning, Karya Rendah, Bujang Pelawah, Pandan Wangi, Bujang Berinai, Kwatek Tinggi, Candu, and Serai). Plant parameters observed were plant height, number of tillers, productive tillers, panicle length, number of grains per panicle, number of empty grains per panicle, milled rice weight, and weight of 1,000 grains. Results of this study showed that the application of biochar improved soil fertility by increasing organic carbon, available phosphorus and potassium, cation exchange capacity, and reducing the soluble iron in the soil. However, the application of biochar did not significantly affect the height of rice plants. The application of coconut shell biochar yielded the best results in increasing the number of productive tillers, the number of grains per panicle, grain dry weight, and reducing the number of empty grains per panicle.

Effect of zeolite application on soil enzyme activity of potted sandy soil cultivated with Swiss chard and cabbage

A zeolite pot experiment was conducted at the Agricultural Research Council Infruitec-Nietvoorbij in Stellenbosch, South Africa, under greenhouse conditions. The experiment aimed to investigate the impact of zeolite application on soil enzyme activities in sandy soils cultivated with Swiss chard (Beta vulgaris Var. cicla) and cabbage (Brassica oleracea Var. capitata L.) over two years (2018-2019). Different zeolite-to-soil ratios (0:1, 1:9, 2:8, and 3:7 w/w) were used, with each pot containing 12 kg of soil. The experiment involved 72 pots for each vegetable, arranged in a randomized complete block design (RCBD). Soil enzyme activities, including acid phosphatase, β-glucosidase, and urease, as well as soil chemical properties (pH, total plant-available nitrogen, organic carbon, and phosphorus), were analyzed. Key findings indicate that the effect of zeolite application on enzyme activities varied between the vegetable species. Zeolite application significantly increased (P

Effects of Trichoderma harzianum Fertilizer on Growth and Rhizosphere Microbial Community of Continuous Cropping Lagenaria siceraria

This study analyzed the effects of Trichoderma harzianum fertilizer on the growth of continuous cropping Lagenaria siceraria and the physical and chemical properties of rhizosphere soil and microbial community structure, using Illumina Miseq (PE300) high-throughput sequencing technology along with physiological and biochemical detection. The results indicated that after applying T. harzianum fertilizer, the growth of L. siceraria was significantly promoted, with increases in plant height, fresh weight, and dry weight of 21.42%, 24.5%, and 4.5%, respectively. The pH of the rhizosphere soil decreased from 7.78 to 7.51, while the electrical conductivity (EC), the available phosphorus (AP), the available potassium (AK), and the total nitrogen (TN) were markedly higher compared to the CC group and increased by 13.95%, 22.54%, 21.37%, and 16.41%, respectively. The activities of catalase and sucrase in the rhizosphere increased by 18.33% and 61.47%, and the content of Soil Organic Carbon (SOC) elevated by 27.39%, which indicated that T. harzianum fertilizer could enhance soil enzyme activity and promotes the transformation of organic matter. Among them, the relative abundance of beneficial bacteria such as Pseudomonas increased, while the relative abundance of harmful fungi such as Fusarium and Podosphaera decreased significantly. This study clarified that T. harzianum fertilizer promoted the growth of continuously planted L. siceraria plants by improving soil physical and chemical properties and microbial community structure and was an effective microbial agent to alleviate the adverse effects of continuous cropping of L. siceraria.

Impact of petroleum contamination on soil properties in Absheron Peninsula, Azerbaijan

This study aims to assess the extent of hydrocarbon and heavy metal contamination in soils from specific areas on Azerbaijan's Absheron Peninsula, including Absheron, Suraxanı, and Baku, and to evaluate the impact of this contamination on soil properties. Soil samples were analyzed for Total Petroleum Hydrocarbons (TPH) and heavy metals, including aluminum, arsenic, cadmium, lead, and iron, alongside assessments of soil physical, chemical and biological properties. The results revealed significant contamination across all studied areas, particularly in Suraxanı, where TPH levels reached 190 ± 20 mg/kg, exceeding the environmental standard of 100 mg/kg. Similarly, Suraxanı soils exhibited alarmingly high concentrations of heavy metals, with aluminum at 30,128 ± 1,500 mg/kg, arsenic at 50.94 ± 2.5 mg/kg, and cadmium at 0.153 ± 0.01 mg/kg, all surpassing acceptable limits. These contaminants severely degraded soil health, evidenced by increased bulk density (1.7 g/cm³ in Suraxanı) and reduced soil porosity. Microbial activity, a key indicator of soil fertility, was also markedly lower in contaminated regions, with the total bacterial count in Suraxanı being less than half that of the uncontaminated area. The findings underscore the urgent need for comprehensive soil management practices and stricter environmental regulations to mitigate contamination's adverse effects and protect both ecosystems and public health in Azerbaijan’s petroleum contaminated areas.

Patterns and controls of leaf litter nitrogen and phosphorus of broad-leaved tree species across and within the tropics and the extra-tropics

Leaf litter nitrogen (N) and phosphorus (P), as the final products reflecting the foliar nutrient status after resorption, strongly influence forest production and nutrient cycling. However, our nuanced understanding of their general patterns and controls is still lacking, and whether differential regulatory mechanisms exist between climatic zones remains largely incomplete, which introduces substantial uncertainty in the comprehension of net ecosystem productivity and nutrient cycling. Here, we aimed to evaluate patterns of leaf litter N and P concentrations of broad-leaved tree species, and further quantify their controls from climatic, soil physical, soil chemical, and green foliar nutrient factors across and within the tropics and extra-tropics by updating a global dataset comprising 1171 records from 159 studies. We found that tropical tree species exhibited higher leaf litter N concentrations but lower leaf litter P concentrations than extra-tropical tree species. In contrast to previous findings, the effects of climatic and edaphic variables on leaf litter N and P concentrations are more pronounced in the tropics than in the extra-tropics. Different from past bivariate analyses of climate-nutrient relationships for leaf litter, climate exerted more indirect effects on leaf litter N and P concentrations through soil texture, hydrology, nutrient availability, and green foliar nutrients. We also observed direct effects of green foliar N and P concentrations on leaf litter N and P concentrations enhanced from tropical to extra-tropical zones. Overall, this study refines our understanding of differential controls over leaf litter N and P concentrations across climatic zones and highlights the crucial yet often overlooked role of soil physical and chemical properties. These insights further underscore the urgent need to integrate multiple climatic, edaphic, and green foliar nutrient variables into geographically explicit biogeochemical models to improve our understanding of leaf litter-driven forest nutrient cycling in response to future environmental changes for different climatic zones.

Impact of fertility levels and rice genotypes on yield, quality, and chemical properties of soil under tarai region of Uttarakhand

A field experiment was conducted during kharif season of 2019 at Crop Research Centre of G.B. Pant University of Agriculture and Technology, Pantnagar (Uttarakhand) for evaluation of six rice genotypes (IET-27263, IET-26418, IET-26420, NDR-359, PD-19 and PD-26) under varying fertility levels (Control, 100% RDF, 150% RDF). Treatments were tested in Split Plot Design with three replications keeping fertilizer levels in main plots and genotypes in sub plots. Application of fertilizer at 150% RDF resulted in significantly higher grain and straw yield over all other fertilizer levels. The rice genotype IET-27263 produced highest grain, straw and biological yield over other genotypes. Similarly, total nitrogen, phosphorus and potassium content and uptake were also found to be increased significantly up to 150% RDF. Similarly, maximum uptake of N and K in grain and straw was also recorded in genotype IET-27263. It can be concluded that application of fertilizers at higher dose up to 150% RDF is essential for obtaining higher yield of rice. The new rice genotype IET27263 was found superior to all other tested genotypes.