Distribution Of Soil Nutrients Research Articles

Storage and Distribution of Organic Carbon and Nutrients in Acidic Soils Developed on Sulfidic Sediments: The Roles of Reactive Iron and Macropores.

In a boreal acidic sulfate-rich subsoil (pH 3-4) developing on sulfidic and organic-rich sediments over the past 70 years, extensive brownish-to-yellowish layers have formed on macropores. Our data reveal that these layers ("macropore surfaces") are strongly enriched in 1 M HCl-extractable reactive iron (2-7% dry weight), largely bound to schwertmannite and 2-line ferrihydrite. These reactive iron phases trap large pools of labile organic matter (OM) and HCl-extractable phosphorus, possibly derived from the cultivated layer. Within soil aggregates, the OM is of a different nature from that on the macropore surfaces but similar to that in the underlying sulfidic sediments (C-horizon). This provides evidence that the sedimentary OM in the bulk subsoil has been largely preserved without significant decomposition and/or fractionation, likely due to physiochemical stabilization by the reactive iron phases that also existed abundantly within the aggregates. These findings not only highlight the important yet underappreciated roles of iron oxyhydroxysulfates in OM/nutrient storage and distribution in acidic sulfate-rich and other similar environments but also suggest that boreal acidic sulfate-rich subsoils and other similar soil systems (existing widely on coastal plains worldwide and being increasingly formed in thawing permafrost) may act as global sinks for OM and nutrients in the short run.

Organic Phosphorus Fractions in Relation to Soil Aggregate Fractions of Black Soil

Knowledge of long-term phosphorus behavior is essential to improve soil structure, nutrient supply potential, and the sustainability of cropping systems. A 45-year long-term experimental trial was used to observe organic phosphorus fractionation and its effects on soil aggregation and nutrient distribution at three depths (0–20, 20–40, and 40–60 cm) in Vojvodina Province, Serbia, under maize monoculture and maize/barley rotation. Five fertilizing systems were studied, including Control, NPK, NPK + maize remains, NPK + manure, and NPK + manure in rotation. Soil aggregates were fractionated into four size categories (>2000, 2000–250, 250–53, and <53 μm) using a wet sieving method. The samples were analyzed for main indicators, including different forms of phosphorus, total and available (PT and PA), as well as its organic forms (Labile Po, Biomass Po, Mod. Labile Po, Fulvic acid Po, Humic acid Po, and Resistant Po), and other fertility parameters. Significant differences in total and available phosphorus as well as all observed organic phosphorus fractions were evident between treatments with and without organic amendments, particularly in the 0–20 and 20–40 cm soil layers. Moderately labile P forms were dominant across all treatments, while labile forms constituted a smaller proportion. The most notable differences between treatments were observed in the labile and moderately labile forms, as well as in the resistant form of organic phosphorus. Manure application led to increased nutrient content in macroaggregates (>250 μm) compared to microaggregates. Microaggregates (<250 μm) were predominant across all depths, while stable structural aggregates did not show a significant increase after manure application. PCA highlighted significant correlations between soil characteristics, including total and available P, total organic carbon, clay content, and enzyme activity, across different aggregate sizes and organic P fractions. Overall, long-term mineral fertilization combined with organic amendment application induced variations in phosphorus fractions and the content of carbon, nitrogen, and phosphorus associated with aggregates in the first two soil layers, except for aggregate size classes.

Tillage and Straw Management Practices Influences Soil Nutrient Distribution: A Case Study from North-Eastern Romania

Tillage practices govern crop quality and quantity through soil nutrient availability and crop root systems. A deeper knowledge of the impact of conservation tillage on soil chemical characteristics (such as pH, soil organic carbon, macro and micronutrient storage and distribution) is required for both the promotion of agricultural sustainability and environmental preservation. This study assesses the changes in soil features and properties in the context of a long-field experiment with different tillage systems and straw management practices. Research findings revealed that compared with conventional tillage (CT) conservative tillage with partial straw retention (MT) and no-tillage with straw mulching (NT) substantially boosted the organic carbon (OC) (by 6–19%), total nitrogen (TN) (by 2–12%), and available potassium content (AK) (by 2–5%), in 0–30 cm soil depth. However, the stratification trend was observed for available macro and micronutrient content (Zn, Fe, Mn) in both conservative management practices. The concentration of Cu indicates a constant pattern through a 0–30 cm soil profile with a higher concentration under MT (1.41 mg kg−1) compared to NT (1.10 mg kg−1). In particular, the results failed to establish if conservation tillage can increase the total phosphorus (TP) and potassium content (TK), where only in surface 0–10 cm an increase was observed. This research also suggested that the X-ray fluorescence analysis (XRF) of total micronutrient content (Zn, Cu, Fe, Mn) is minimal or unpredictable with no substantial differences between the tillage systems and straw return management practices. These findings suggest that conservation tillage in north-eastern Romania might be optimal to maintain soil quality status and sustain high yields.

Soil properties of thickets and adjacent land use types in coastal savanna landscape of Ghana

Thicket vegetation may be of great importance in soil carbon (C) storage and in provision of other ecosystem services such as soil erosion control and biodiversity conservation. However, it is less studied in tropical ecosystems due to limited understanding of its ecological importance. This study reports soil C pools and nutrient concentrations [nitrogen (N), available phosphorus (P), exchangeable calcium (Ca), magnesium (Mg) and potassium (K)] of unique thicket formations on Vertisol in comparison with adjacent land use types viz. rangeland, dry forest, and farmland at Kpong in the coastal Accra plains of Ghana. We also examined soil particle and nutrient distributions of termitarium associated with the thicket clumps on the Vertisols. Soils were sampled from each land use at 0–30 cm depth in addition to deep coring up to 100 cm. In the rangeland, forest and farmland, we demarcated 1600 m2 area each and established 4 subplots measuring 20 × 20 m (400 m2) and selected for the thicket vegetation, 4 thicket clumps each of approximately 400 m2 for soil sampling. The thicket clumps had greater soil total N, available P, exchangeable Ca and Mg concentrations than the rangeland and farmland but the levels in the thicket were similar (p > 0.05) to that of the adjacent dry forest. Soil C stock varied from 59 Mg ha−1 in the rangeland to 111 Mg ha−1 in the thicket clumps. The C stored in the silt + clay (S + C) fraction did not differ significantly (p > 0.05) in both the thicket and the dry forest, indicating similar C sequestration abilities. The S + C fraction contributed 89.6, 82.8, 81.3, and 73.7% to total soil organic C content in the rangeland, farmland, dry forest, and thickets, respectively. Soils of the termite mounds in the thickets were more clayey (ca. 38–41% clay) than the surrounding thicket soils (ca. 32% clay). We conclude that Vertisols in thicket areas store soil C and nutrients comparably as tropical dry forest, underscoring their ecological importance and the need for their conservation to enhance soil quality in the Anthropocene.

Does soil nutrient heterogeneity affect the competition and adaptation of Vernicia montana?

Plants respond to variations in soil nutrient distribution and the presence of neighboring plants, yet consensus is lacking on the impact of naturally heterogeneous soil nutrient environments on plant competition. This study employs pot experiments to simulate homogeneous and heterogeneous forest soil nutrient environments and designs neighbor competition experiments for Vernicia montana, Cunninghamia lanceolata, and Phoebe bournei, to assess the impact of neighbor competition on these seedlings from the perspective of root morphology and foraging ability in different nutrient environments. The results reveal that when faced with heterogeneous nutrient environments or competitive settings, V. montana primarily utilized morphological and physiological plasticity, such as increasing root morphological indicators and concentrating more nutrients in the underground part, to enhance its adaptability and achieve competitive advantages. C. lanceolata and P. bournei mainly depended on physiological plasticity, like increased root nutrient concentration, when they were co-planted with other species. Compared to interspecific competition, intraspecific competition had a significant inhibitory effect on V. montana, especially under heterogeneous nutrient conditions, with notable reductions in root morphological indicators and root N, P concentration in mono-culture. Nutrient heterogeneity also altered the effects of interspecific competition on C. lanceolata and P. bournei. When mixed-planted with C. lanceolata or P. bournei, V. montana exhibited stronger competitive ability in both nutrient environments. The effects of mixed planting on C. lanceolata and P. bournei were significantly different between the two nutrient environments, in that homogeneous nutrient environment favored the growth and nutrient absorption of C. lanceolata, while heterogeneous nutrients generally benefited P. bournei. Most research on seedling competition is conducted under homogenous nutrient environments, and the results may not accurately reflect in-situ competition, potentially obscuring the scientific implementation of forestry management. Taking into account competition under unevenly distributed soil resources will help in optimizing tree species selection and cultivation methods, thereby improving the adaptability and ecological benefits of forests.

Water and nitrogen supply at spatially distinct locations improves cotton water productivity and nitrogen use efficiency and yield under drip irrigation

The location of water and fertilizer supply directly affects the distribution of soil moisture and nutrients, thereby affecting crop yield and fertilizer use efficiency. However, the impact of water and nitrogen (N) supply location on cotton water and N use efficiency and yield is not yet clear, especially under drip irrigation conditions. A field experiment was conducted in 2022 and 2023. Four water and N supply patterns were set as: water and N supply at the same location (narrow row (PN) or wide row (PW)), water and N supply at spatially distinct (SD) and spatially and temporally distinct locations (STD). Soil water and N leaching, cotton root growth, water productivity (WP) and recovery efficiency of N (REN), and yield were quantified. The soil moisture and NO3--N vertical distribution range (0–60 cm) were deeper at the same location for water and N supply than at spatially distinct locations for water and N supply (0–40 cm). Compared to water and N supply at the same location, supply at spatially distinct locations significantly increased cotton root weight, root length density, and root surface area. In addition, water and NO3--N leaching of water and N supply at spatially distinct (SD and STD) were 12%-50% and 32%-59% lower, respectively, than those from the same location (PN and PW), while the yield and WP increased significantly by 7%-11% and 7%-10%, respectively. The REN of water and N supply at spatially and temporally distinct locations was the highest. Therefore, water and N supply at spatially distinct or spatially and temporally distinct locations can improve water productivity, recovery efficiency of N, and yield of cotton, and reduce soil water and N leaching loss under drip irrigation.

土壤施肥处 方 图 的建立和 应 用

Precision soil fertilization is an important aspect of smart precision agriculture development, and the fertilization prescription map is a prerequisite for precision fertilization. Taking grapevine soil information as an example, this study explores the impact of different sampling densities on the accuracy of soil nutrient distribution. Experimental trials were conducted using sampling densities of 1m x 1m, 3m x 3m, 6m x 6m, 9m x 9m, and 12m x 12m, with the optimal sampling density determined to be 6m x 6m. Nutrient distribution maps were created using Bigemap and ArcGIS software, and based on nutrient balance calculations using ArcGIS software, fertilization prescription maps were developed. Furthermore, precise fertilization schemes for nitrogen, phosphorus, and potassium fertilizers were formulated based on the prescription maps. This study provides methodological and data support for research on precision soil fertilization.

Geographic Information System (GIS) Application in Soil Fertility Management: A Review

As the global population expected to reach 10 billion by 2050 and arable land decreases, innovative soil management strategies are required to maximize agricultural productivity while preserving natural resources. GIS, as a powerful technology, offers a comprehensive solution by enabling the collection, storage, analysis, and visualization of spatial data for agricultural purposes. By integrating GIS with sensors, communication technologies, and data analytics, precision agriculture is possible, allowing for efficient use of agricultural inputs and reduced environmental impact. GIS technology facilitates the simulation and modeling of biological ecosystems, providing valuable insights for sustainable soil management. It has diverse applications in agriculture, ranging from soil nutrient mapping to yield estimations and runoff detection. GIS works by overlaying various layers of information onto digital maps, allowing for the identification of relationships and patterns that are crucial for optimizing soil fertility. Detailed maps created through GIS highlight the distribution of soil nutrients, pH levels, and moisture content, enabling informed decision-making on fertilizer use, irrigation techniques, and land management practices. By harnessing the power of GIS, farmers and land managers can make data-driven decisions that maximize agricultural productivity, conserve resources, and protect soil health for future generations. The integration of GIS with other technologies further enhances its effectiveness in soil fertility management. Overall, GIS is a valuable tool for understanding and managing soil fertility, contributing to sustainable agriculture and food security.

Assessing Shrub Patch Characteristics and Soil Nutrient Distribution Patterns of Four Typical Alpine Shrub Plants in the Eastern Qilian Mountains

Shrub patches have an impact on soil fertility and vegetation, influencing species composition and diversity. The unique context of the Eastern Qilian Mountains provides insights into alpine ecosystems’ responses to environmental challenges. This study aimed to evaluate the physical characteristics and soil nutrient contents of shrub patches for four different shrub species (Salix oritrepha (SO), Spiraea alpina (SA), Rhododendron capitatum (RC), and Potentilla fruticosa (PF)). We assessed their patch characteristics and soil nutrients at different depths within three patch microsites (the center (CS), the edge (ES), and the midpoint between the center and the edge of the shrub patch (BC)). Soil samples were collected and analyzed for organic matter, nitrogen, phosphorus, and potassium content. Statistical analyses were conducted to evaluate differences among shrub species and locations within the shrub patches. Our results showed that the shrub species exhibited variations in patch characteristics and soil nutrient distribution. Soil nutrient content varied by depth and location within the shrub patches, with higher concentrations at the center. The relative interaction intensity (RII) revealed nutrient aggregation or dispersion trends. The study highlighted the complex interactions between shrub characteristics and soil nutrients, emphasizing their influence on nutrient cycling, vegetation dynamics, and soil properties. These findings contribute to our understanding of alpine ecosystem dynamics and inform conservation, sustainability, and management strategies.

Distribution of Macro Nutrients in Surface and Subsurface Soils under Saffron Growing Areas of Pulwama District of Jammu & Kashmir, India

One hundred eighty (180) composite soil samples were collected from surface and subsurface layers from 18 saffron growing villages of Pulwama district to study the available primary and secondary nutrient status of the soils. None of the soil were found to be deficient in available nitrogen, phosphorous, potassium, calcium, magnesium and sulphur. The soils were medium in available nitrogen and phosphorous and medium to high in potassium with mean values of 338.46, 21.25 and 258.83 kg ha-1 respectively in surface soils (0-15 cm) and mean values of 318.07, 18.82 and 232.03 kg ha-1 respectively in sub-surface soils (15-30 cm). All the soils were high in available calcium and magnesium with average values of 1677.1, 317.7 mg kg-1 and 1692.5 and 352.3 mg kg-1 in surface and subsurface soils respectively. The soils were low to medium in available sulphur content with surface and subsurface sulphur content of 10.51 and 8.70 mg kg-1 respectively.

Impact of manure injection on spatial variability in soil nitrate, carbon, and small grain growth

AbstractManure injection alters the spatial distribution of manure by concentrating it in a subsurface band which can lead to differential soil nutrient distribution and growth in small grains. This study assessed the effects of fall manure applications on soil NO3‐N, active carbon, and small grain growth compared to broadcasting and a no manure control. Soil samples were taken to represent whole plot soil means for all treatments, while in‐band (IB) and between‐band (BB) soil samples were taken in injected plots to assess nutrient spatial distribution after injection. Small grain forage samples were also taken IB and BB to assess the effects of manure injection on small grain growth. Soil samples were analyzed for NO3‐N, permanganate oxidizable carbon (POXC), and carbon mineralization (C‐min), while small grain dry matter (DM) yield and forage quality parameters were measured from plant samples. Manure injection did not result in any differences between whole plot injection and broadcast soil NO3‐N concentrations. However, injection resulted in initially elevated soil NO3‐N concentrations IB compared to BB. There were no differences in soil POXC or C‐min under manured versus unmanured soils, nor between IB and BB samples. Manure injection did not increase small grain DM yield or forage quality compared to broadcasting, nor were these measurements altered IB and BB. Even though manure injection altered the spatial distribution of soil NO3‐N, it did not affect soil C‐min, POXC, or small grain growth under the conditions seen in this study. Therefore, differential small grain growth and quality is likely not a concern under injection.

Distribution of Soil Chemical Properties of Smallholder Farms on Derelict Mined-Sites of Jos South LGA, Jos Plateau, Nigeria

Tin mining environments have constituted a degrading challenge to smallholder farmers whose lands have been overtaken. Attempts by smallholder farmers to restore the lands to farming are faced with soil productivity constraints. Yet, these farmers struggle to cultivate farms in-between the mined lands to meet up with subsistence food requirements. To date, the farmers have identified areas with low and high potentials due to years of continuous cultivation. This study was conducted in an environment that had undergone mining on a larger scale and is now undergoing surface mining on a small scale. Thirty-one (31) soil samples were taken at a depth of 0-20cm to investigate the spread of soil chemical properties on smallholder farms. Coordinates of the samples were acquired using GPS to create georeferenced continuous surfaces. The results indicated that the majority of the soil's chemical properties varied moderately. Organic matter (0.89-1.74%) and nitrogen (0.045 - 0.096%) needed mostly by crops were very low due to uninformed distribution of soil chemical properties. Geostatistics was used to generate continuous surfaces through Kriging. The small nugget effect showed spatial continuity between the neighboring points. Strong spatial dependence occurred for all soil nutrients tested, due to intrinsic soil properties such as soil parent material, topography, texture, and mineralogy. Generally, the spread of soil nutrients on the smallholder farm coincides with the smallholder farmers' identified potential areas. The study suggests that for proper nutrient interventions on the farms, distribution of soil nutrients on the farms should be done to avoid excesses and shortages of inorganic and organic interventions.

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.

Predation and Biophysical Context Control Long-Term Carcass Nutrient Inputs in an Andean Ecosystem

Animal carcass decomposition is an often-overlooked component of nutrient cycles. The importance of carcass decomposition for increasing nutrient availability has been demonstrated in several ecosystems, but impacts in arid lands are poorly understood. In a protected high desert landscape in Argentina, puma predation of vicuñas is a main driver of carcass distribution. Here, we sampled puma kill sites across three habitats (plains, canyons, and meadows) to evaluate the impacts of vicuña carcass and stomach decomposition on soil and plant nutrients up to 5 years after carcass deposition. Soil beneath both carcasses and stomachs had significantly higher soil nutrient content than adjacent reference sites in arid, nutrient-poor plains and canyons, but not in moist, nutrient-rich meadows. Stomachs had greater effects on soil nutrients than carcasses. However, we did not detect higher plant N concentrations at kill sites. The biogeochemical effects of puma kills persisted for several years and increased over time, indicating that kills do not create ephemeral nutrient pulses, but can have lasting effects on the distribution of soil nutrients. Comparison to broader spatial patterns of predation risk reveals that puma predation of vicuñas is more likely in nutrient-rich sites, but carcasses have the greatest effects on soil nutrients in nutrient-poor environments, such that carcasses increase localized heterogeneity by generating nutrient hotspots in less productive environments. Predation and carcass decomposition may thus be important overlooked factors influencing ecosystem functioning in arid environments.

Spatial differentiation of soil nutrients and their ecological chemometrics based on geographic detector in National Agricultural Park of Tangchang, Southwest China.

In order to analyze the spatial variability of soil nutrients and their ecological chemometrics in Tangchang Town, National Agricultural Park, 20 influencing factors were selected: soil pH, Cd, Hg, As, Cu, Pb, Cr, Zn, Ni, Se, elevation, slope, aspect, land use type, distance from industrial land, distance from commercial land, distance from railway, distance from residential area, distance from highway and distance from river. The effects of various influencing factors on the spatial variability of total organic carbon (TOC), total nitrogen (N), total phosphorus (P), total potassium (K) and ecological stoichiometry were analyzed by means of geographic detector. The results showed that average contents of soil TOC, N, P and K in the study area are 10.24 g kg-1, 1.33 g kg-1, 1.14 g kg-1 and 23.60 g kg-1, respectively, and there were significant differences in the spatial distribution of soil nutrients and their eco-stoichiometry in the study area, and TOC, N, P, K, C/N, C/P, C/K, N/P, N/K and P/K has a significant correlation with each other and most correlation coefficients are above 0.5 or below -0.5. Factor detection showed that soil properties, distance from railway and distance from residential area had the most significant explanatory power to the spatial heterogeneity of soil nutrients and eco-stoichiometry. Interaction detection showed that the interaction between soil properties with other factors was the most important factor affecting the spatial differentiation of soil nutrients and their ecological chemometrics, and elevation, distance from railway and distance from residential area were also important factors. Risk detection showed that the differences of soil nutrients and their ecological stoichiometry were most significant in the subregions of soil properties (pH, Cd, Hg, As, Cu, Pb, Cr, Zn, Ni and Se).

The Median Isn’t the Message: soil nutrient hot spots have a disproportionate influence on biogeochemical structure across years, seasons, and depths

Soil nutrient distribution is heterogeneous in space and time, potentially altering nutrient acquisition by trees and microorganisms. Ecologists have distinguished “hot spots” (HSs) as areas with enhanced and sustained rates of nutrient fluxes relative to the surrounding soil matrix. We evaluated the spatial and temporal patterns in nutrient flux HSs in two mixed-conifer forest soils by repeatedly sampling the soil solution at the same spatial locations (horizontally and vertically) over multiple seasons and years using ion exchange resins incubated in situ. The climate of these forests is Mediterranean, with intense fall rains occurring following summers with little precipitation, and highly variable winter snowfall. Hot spots formed most often for NO3− and Na+. Although nutrient HSs often occurred in the same spatial location multiple times, HSs persisted more often for PO43− NH4+, and NO3−, and were more transient for Ca2+, Mg2+, and Na+. Sampling year (annual precipitation ranged from 558 to 1223 mm) impacted the occurrence of HSs for most nutrients, but season was only significant for PO43−, NH4+, NO3−, and Na+, with HSs forming more often after fall rains than after spring snowmelt. The frequency of HSs significantly decreased with soil depth for all nutrients, forming most commonly immediately below the surficial organic horizon. Although HSs accounted for less than 17% of the sampling volume, they were responsible for 56–88% of PO43−, NH4+, and NO3− resin fluxes. Our results suggest that macronutrient HSs have a disproportional contribution to soil biogeochemical structure, with implications for vegetation nutrient acquisition strategies and biogeochemical models.Graphical abstract

Variations in soil physico-chemical properties, soil stocks, and soil stoichiometry under different soil layers, the major forest region Liupan Mountains of Northwest China.

Liupan Mountains are an important region in China in the context of forest cover and vegetation due to huge afforestation and plantation practices, which brought changes in soil physio-chemical properties, soil stocks, and soil stoichiometries are rarely been understood. The study aims to explore the distribution of soil nutrients at 1-m soil depth in the plantation forest region. The soil samples at five depth increments (0-20, 20-40, 40-60, 60-80, and 80-100 cm) were collected and analyzed for different soil physio-chemical characteristics. The results showed a significant variation in soil bulk density (BD), soil porosity, pH, cation exchange capacity (CEC), and electric conductivity (EC) values. More soil BD (1.41 g cm-3) and pH (6.97) were noticed in the deep soil layer (80-100 cm), while the highest values of porosity (60.6%), EC (0.09 mS cm-1), and CEC (32.9 c mol kg-1) were reflected in the uppermost soil layer (0-20 cm). Similarly, the highest contents of soil organic carbon (SOC), total phosphorus (TP), available phosphorus (AP), total nitrogen (TN), and available potassium (AK) were calculated in the surface soil layer (0-20 cm). With increasing soil depth increment a decreasing trend in the SOC and other nutrient concentration were found, whereas the soil total potassium (TK) produced a negative correlation with soil layer depth. The entire results produced the distribution of SOCs and TNs (stocks) at various soil depths in forestland patterns were 0→20cm > 20→40cm > 40→60cm ≥ 60→80cm ≥ 80→100 cm. Furthermore, the stoichiometric ratios of C, N, and P, the C/P, and N/P ratios showed maximum values (66.49 and 5.46) in 0-20 cm and lowest values (23.78 and 1.91) in 80-100 cm soil layer depth. Though the C/N ratio was statistically similar across the whole soil profile (0-100 cm). These results highlighted that the soil depth increments might largely be attributed to fluctuations in soil physio-chemical properties, soil stocks, and soil stoichiometries. Further study is needed to draw more conclusions on nutrient dynamics, soil stocks, and soil stoichiometry in these forests.

A mosaic pattern of apple orchards and farmland affects the distribution of soil water and nutrients in their adjacent areas on the Chinese Loess Plateau

With the vigorous promotion of apple tree planting on the Chinese Loess Plateau (CLP), a mosaic pattern of apple orchards and traditional farmland has emerged in the region. However, the interaction between adjacent farmland and apple orchards in terms of soil water and nutrient migration remains unclear. This study aimed to investigate the spatial distribution of the soil water content (SWC) and soil nutrients, as well as their interactions, in 0–10 m soil layers of apple orchards of different stand ages and adjacent farmland under the orchard-farmland land use pattern. The results revealed a significant decrease in average-depth SWC in the orchards in the 0–10 m soil profile (R2 = 0.90) with increasing orchard age, accompanied by a significant increase in soil water deficit (SWD, R2 = 0.94). The annual growth rate of SWD was found to be as high as 5.94 mm·m−1·y−1. Deep soil and surrounding farmland were identified as important sources of soil water for apple tree growth, particularly in older orchards; a 25-year-old orchard absorbed approximately 10.8 % of soil water towards farmland with a horizontal distance of 7 m. The distribution of soil organic carbon (SOC) and total nitrogen (TN) in the 0–10 m soil profile exhibited a similar pattern, decreasing and then stabilizing with increasing depth. However, the peak depth and accumulation of soil nitrate (NO3–-N) significantly increased with orchard age. The migration and accumulation of NO3–-N in the soil provided a scientific basis for the transport of soil water, with NO3–-N accumulation (405.32 mg kg−1) observed in the deep soil (3–6 m) of farmland located 5 m away from a 30-year-old orchard, confirming the exchange of soil water and nutrients between the orchard and the farmland. The stand age of the orchards was identified as the main environmental factor influencing soil water transport under the orchard-farmland land use pattern. Overall, our findings provide valuable insights into the interaction between apple orchards and farmland under the mosaic pattern, which can contribute to a more rational layout of apple orchards and farmland in the future, promoting the efficient utilization of soil water and nutrients on the CLP.

Investigation into the Effects of Different Restoration Techniques on the Soil Nutrient Status in Degraded Stipa grandis Grassland

The degradation and desertification of grassland ecosystems have garnered significant attention both domestically and internationally. Grassland restoration techniques are widely considered a principal measure to promote the sustainable utilization of grasslands, with soil nutrient content being a core indicator for assessing the effectiveness of restoration in degraded grasslands. This study aims to explore the differential impacts of various grassland restoration methods on soil nutrient distribution in degraded Stipa grandis grasslands. Three major restoration methods, i.e., root cutting, enclosure, and fertilization, were applied in the study area. The soil nutrient content was measured and analyzed under the different restoration methods and at varying depths. The results revealed that under all three restoration methods and at different soil depths (0–10 cm, 10–20 cm, 20–30 cm), the organic matter, total nitrogen, total phosphorus, alkali-hydrolyzable nitrogen, alkali-hydrolyzable phosphorus, and available potassium contents were significantly higher than those in the control group (p < 0.05). Furthermore, as soil depth increased, the contents of organic matter and all nutrients gradually decreased. Specifically, regarding the contents of different nutrients, the order of organic matter, total nitrogen, total phosphorus, alkali-hydrolyzable nitrogen, and available phosphorus was as follows: fertilization > enclosure > root cutting > control, while the contents of total potassium and available potassium followed the sequence: fertilization > enclosure > control > root cutting. Additionally, based on the canonical correlation analysis (R2 = 0.88), the total phosphorus content in soil had the greatest impact on soil nutrients, while vegetation cover and plant height contributed the most to vegetation characteristics. In grassland restoration, the increase in soil total phosphorus led to higher vegetation cover and height, mildly influenced plant diversity and density, and simultaneously promoted biomass accumulation. These research findings provide a solid theoretical foundation for the application of grassland restoration techniques, contributing to the sustainable development of grassland ecosystems.

Vertical Distribution of Available Plant Nutrients in Soils of Mid-Central Tableland Agro-climatic Zone of Odisha, India

Study on the vertical distribution of plant nutrients is very essential for improving crop production and productivity rather than studying the nutrient characteristics of the surface soil only. It is because many plants absorb nutrients from the subsoil. Moreover, the vertical distribution of nutrients is much more complex because of the many simultaneous processes going on in the soils such as recycling of the plant residues, leaching of nutrients, and weathering of parent materials. In this context, two pedons located in pedons in two different land types(upland and low land) of Dhenkanal district of the Mid-Central Tableland argo-climatic zone of Odisha were selected for studying the depth-wise vertical distribution of plant nutrients. Genetic horizon-wise soil samples were collected, processed, and analyzed for different soil properties viz., textural class (sand, silt, clay), pH, electrical conductivity (EC), soil organic carbon (SOC), available nitrogen (N), phosphorus (P), potassium (K), sulfur (S) and boron (B) content. The results indicated that there was a gradual decrease in the concentration of SOC, available N, P and S with soil depth. Whereas soil reaction (pH), EC and available K content increased with soil depth. Therefore, surface soils were observed to be more fertile but acidic, whereas the sub-soils were of higher pH. The findings of this study will be helpful for the scientific as well as the farming community for suggesting and uptaking suitable crop and land use plans for sustainable agricultural and land use management.