Nutrient Stocks Research Articles

Changes in Soil Chemistry and Soil Nutrient Stocks after 30 Years of Treated Municipal Wastewater Land Disposal: A Natural Experiment

The benefits and risks of irrigation with treated municipal wastewater (TMW) on soil quality and crop production have been largely investigated. However, there is a lack of knowledge on the effect of plant species on the interaction between soil quality and TMW. We leveraged a natural experiment investigating the effect of 30 years of TMW irrigation at a rate of 4 m y−1 (eq. 1860 kg N ha−1 y−1, and 264 kg P ha−1 y−1) on a sandy soil under pine plantation and pasture, compared with soil under New Zealand native Kunzea robusta. There was a consistent increase in soil P with irrigation under both pasture (Olsen P in topsoil 40 mg kg−1 vs. 74 mg kg−1) and pine (18 mg kg−1 vs. 87 mg kg−1), which was significant down to 2 m deep. The pH, electrical conductivity, total organic C and N, inorganic N and Na were affected by both irrigation and vegetation type. Beyond P soil accumulation, there was no evidence of soil degradation by Na or trace element accumulation. Estimations of nutrient mass balance indicated that 80% and 60% of the total applied P was lost under pine and pasture, respectively. This percentage increased to 96% and 83% for N, respectively. Although plant species had a significant effect on soil quality and N and P losses from TMW-irrigated areas, adjusting irrigation rates to levels that can be managed by plants is the only way to design sustainable TMW irrigation schemes.

Chronic anthropogenic disturbance alters litter decomposition and nutrient concentrations and stocks across a Caatinga dry forest chronosequence

Litter decomposition plays a key role in the cycling and storage of nutrients in terrestrial ecosystems. However, very little is known about decomposition processes and their underlying drivers in tropical dry forests, particularly in human-modified landscapes. Here, we evaluate decomposition rates and nutrient concentrations and stocks in the litter of a Caatinga dry forest chronosequence, in northeast Brazil. Litter decomposition was monitored for a year across forest stands of varying ages and old-growth forests. The litter decomposition rate was highly variable across forest stands, although on average decomposition occurred slowly, with approximately 50% of the initial litter mass still present after one year. The decomposition rate is responsive to forest type and negatively affected by chronic disturbance. Litter nutrient concentration decreased along the decomposition process, exhibiting a nutrient-specific mineralization rate. Response to drivers was also nutrient specific, with precipitation and chronic disturbances playing prominent roles. Nutrient stocks in the remaining litter were higher in old-growth forests, and final stocks of certain nutrients also responded to multiple drivers. Our results suggest that the Caatinga dry forest experiences a slow rate of litter decomposition and mineralization, although rates exhibit considerable variability across forest stands and environmental conditions. Thus, chronic disturbance plays a role by either facilitating or reducing litter decomposition, mineralization rate, and the stocks transferred to the soil. Consequently, these factors have implications for nutrient availability, including goat consumption and subsequent loss of nutrients.

Fifty years after deep‐ploughing: Effects on yield, roots, nutrient stocks and soil structure

AbstractDeep‐ploughing far beyond the common depth of 30 cm was used more than 50 years ago in Northern Germany with the aim to break root‐restricting layers and thereby improve access to subsoil water and nutrient resources. We hypothesized that effects of this earlier intervention on soil properties and yields prevailed after 50 years. Hence, we sampled two sandy soils and one silty soil (Cambisols and a Luvisol) of which half of the field had been deep‐ploughed 50 years ago (soils then re‐classified as Treposols). The adjacent other half was not deep‐ploughed and thus served as the control. At all the three sites, both deep‐ploughed and control parts were then conventionally managed over the last 50 years. We assessed yields during the dry year 2019 and additionally in 2020, and rooting intensity at the year of sampling (2019), as well as changes in soil structure, carbon and nutrient stocks in that year. We found that deep‐ploughing improved yields in the dry spell of 2019 at the sandy sites, which was supported by a more general pattern of higher NDVI indices in deep‐ploughed parts for the period from 2016 to 2021 across varying weather conditions. Subsoil stocks of soil organic carbon and total plant‐available phosphorus were enhanced by 21%–199% in the different sites. Root biomass in the subsoil was reduced due to deep‐ploughing at the silty site and was increased or unaffected at the sandy sites. Overall, the effects of deep‐ploughing were site‐specific, with reduced bulk density in the buried topsoil stripes in the subsoil of the sandy sites, but with elevated subsoil density in the silty site. Hence, even 50 years after deep‐ploughing, changes in soil properties are still detectable, although effect size differed among sites.

Short-term effects of subsoil management by strip-wise loosening and incorporation of organic material

Agricultural production in Central Europe increasingly suffers from extreme drought events. Improving root access to nutrient and water resources in the subsoil below the plow layer is a potential option to maintain productivity during dry summers. Here, we tested a strip-wise subsoil amelioration method that combines subsoil loosening with organic matter incorporation into the subsoil (biowaste or green waste compost) and compared it with a treatment of only subsoil loosening and a non-ameliorated control. A field experiment with randomized block design was conducted on a Luvisol with an argic horizon (Bt), with a rotation of spring barley and winter wheat. In the first two years after amelioration, we monitored soil physico-chemical parameters, microbial biomass, and shoot and root growth at anthesis as well as harvested grain yield and quality. Subsoil loosening with organic matter incorporation significantly decreased soil bulk density at the depth of compost incorporation when biowaste compost was used, but not when green waste compost had been incorporated. Nutrient stocks, nutrient availability and microbial biomass were not consistently affected by the subsoil amelioration. Nevertheless, the incorporation of organic material, especially biowaste compost, significantly increased root growth into the subsoil and subsequently significantly enhanced crop nutrient uptake, biomass and grain yield production. Green waste compost incorporation had less pronounced effects, with an increase in grain yield only in the second year after amelioration. Differences in crop development could not be explained by any single soil parameter, suggesting that it was rather a combined effect of loosened subsoil and better supply of subsoil resources that resulted in an increase in subsoil root length density and subsequently led to better crop performance.

Above- and belowground composition and diversity of subtropical plantations and their relationships with soil nutrient stocks

Above- and belowground composition and diversity of subtropical plantations and their relationships with soil nutrient stocks

Effects of species mixture on understory vegetation, soil properties and bacterial diversity of Acacia cincinnata, Eucalyptus robusta and Acacia mangium plantations in Southeastern China

The establishment of mixed forests is gaining increasing attention as a way to optimize forest production, improve ecological benefits, and serve as a safety net for impacts of future climate uncertainties. However, practical knowledge about which species and what proportion of them should be mixed is still lacking. Thus, this study was conducted to identify suitable species for a mixture with Acacia cincinnata. The mixtures tested in this study were A. cincinnata and Eucalyptus robusta (6:4), A. cincinnata and Acacia mangium (3:1), and monoculture plantation of A. cincinnata established in 2014. After seven years of growth, we analyzed the effects of species mixing on tree species growth, understory vegetation, and soil physicochemical properties as well as bacterial community structure and diversity. The results showed that species mixing had no significant effect on the diameter and individual volume of A. cincinnata. However, mixed planting increased the total stocking volume compared to monoculture plantation of A. cincinnata. The species diversity, biomass and nutrient stocks in the understory vegetation were significantly increased by stand mixing. The soil of mixed stand of A. cincinnata and A. mangium had the highest C and N contents, whereas the soil of monoculture A. cincinnata stands had the highest P content. The diversity of soil bacterial community was highest in the mixing stand of A. cincinnata and E. robusta, followed by monoculture A. cincinnata stand and mixed stand of A. cincinnata and A. mangium. The relative abundance of Proteobacteria and Actinobacteria was highest in mixed stand soil of A. cincinnata and E. robusta. Furthermore, the relative abundance of Firmicutes was high in the mixed stand soils of A. cincinnata and A. mangium while the relative abundance of Verrucomicrobia was high in the mixed stand of A. cincinnata and E. robusta stand. In general, the study revealed that the establishment of mixed-species forest enhances the diversity and composition of understory vegetation, soil physicochemical and soils bacterial community; thereby increasing biodiversity, nutrient cycling and carbon sequestration in the biomass and soil. From the viewpoints of forest productivity and ecological benefits, it is advisable to establish a mixed forest of A. cincinnata and A. mangium in southern China. Overall, our work revealed that the sustainability of mixed-species plantations relies on the interactions between soil attributes, vegetation, and bacterial community.

Untangling the impact of plantation type and functional traits on ecosystem nutrient stocks in an experimentally restored forest ecosystem

The primary objective of ecological restoration is recovering biodiversity and ecosystem functioning. While a functional trait-based approach can help understand community assembly and ecosystem function recovery during ecological restoration, there still exists a knowledge gap in assessing how functional traits indicate the mediating roles of the plant community in response to forest restoration effects on ecosystem functions. This study applied the “response-effect trait” framework to investigate experimentally whether the treatment of plantation type has an impact on community trait compositions, which in turn could affect forest ecosystem nutrient stocks – here, carbon (C) and nitrogen (N) and phosphorus (P) stocks in tree, understory, litter and soil pools at an experimental station in subtropical China. We used structural equation models (SEMs) to examine the relationships among plantation type, community weighted mean of traits, and nutrient stocks in each pool. Our results show that most of the tree and understory traits studied were response traits to plantation type. Moreover, certain traits played a significant role in mediating plantation-type effects on C, N and P stocks for understory pool (e.g., understory stem specific density and specific leaf area, tree leaf phosphorus content), and for litter and soil pools (e.g., tree leaf carbon or phosphorus content, understory specific leaf area, leaf nitrogen or phosphorus content), known as “response-effect traits”. For the tree pool, only effect traits, and no “response-effect” tree traits, were found for the N stock. Total effects of SEMs indicated that, understory or tree traits can have a greater impact than plantation type on understory or litter C, N or P stocks. After approximately 35 years of natural restoration, exotic plantations exhibited a different community trait characteristic from native plantations. The important roles of traits in mediating the effects of plantation type on non-tree pool C, N and P stocks were highlighted.

Role of plastids and mitochondria in the early development of seedlings in dark growth conditions.

Establishment of the seedlings is a crucial stage of the plant life cycle. The success of this process is essential for the growth of the mature plant. In Nature, when seeds germinate under the soil, seedlings follow a dark-specific program called skotomorphogenesis, which is characterized by small, non-green cotyledons, long hypocotyl, and an apical hook-protecting meristematic cells. These developmental structures are required for the seedlings to emerge quickly and safely through the soil and gain autotrophy before the complete depletion of seed resources. Due to the lack of photosynthesis during this period, the seed nutrient stocks are the primary energy source for seedling development. The energy is provided by the bioenergetic organelles, mitochondria, and etioplast (plastid in the dark), to the cell in the form of ATP through mitochondrial respiration and etio-respiration processes, respectively. Recent studies suggest that the limitation of the plastidial or mitochondrial gene expression induces a drastic reprogramming of the seedling morphology in the dark. Here, we discuss the dark signaling mechanisms involved during a regular skotomorphogenesis and how the dysfunction of the bioenergetic organelles is perceived by the nucleus leading to developmental changes. We also describe the probable involvement of several plastid retrograde pathways and the interconnection between plastid and mitochondria during seedling development. Understanding the integration mechanisms of organellar signals in the developmental program of seedlings can be utilized in the future for better emergence of crops through the soil.

Effect of land use on carbon-, nitrogen- and silica soil stocks in the South African bushveld

Anthropogenic land use alters soil properties and influences biological transformations in the root zone, thereby affecting the distribution and supply of soil nutrients. It is generally acknowledged that human land-use activities such as intensive cattle farming and cultivation of citrus products lead to a homogenization of soil nutrients. This research aims at investigating the heterogeneity in soil nutrient stocks and BSi stocks (a beneficial plant element) within the Savannah biome of South Africa. In this study, C-N-Si stocks and their ratios were quantified in the soil of five different land use types, common in South Africa. The five different land use types are i) bush savannahs, ii) mopane-dominated woodlands, iii) annually burned land, iv) communal grazing land and v) citrus orchards. Empirical research however could not fully validate this hypothesis. In particular fire management and game farming (natural land use type) led to more variability in nutrient pools, with occasional occurrences of C-N-Si hotspots. Our results suggest that when ecosystem analysis of soil nutrient and carbon stocks is handled as a homogeneous unit potentially large mistakes are made, even in anthropogenic landscapes previously hypothesized with uniform nutrient distributions.

Effect of nutrient solution concentrations on the growth and yield of potato (Solanum tuberosum L.) varieties grown from apical rooted cutting in a hydroponic system

This study evaluated the effects of nutrient stock solution concentrations on the growth and yield of potato varieties grown from apical rooted cuttings (ARCs). A greenhouse experiment was conducted at the Climate and Water Smart Agriculture Center at Egerton University, Kenya. The experiment was laid out in a split-plot arrangement in randomized complete block design, where the main plot comprised three nutrient concentrations, i.e., 75% (N75), 100% (N100) and 125% (N125) of the ADC-Molo’ nutrient formulation. The subplots were allocated to four potato varieties (Shangi, Wanjiku, Nyota and Unica). The results showed that there were no significant (p<0.05) interaction effects of the nutrient stock solution concentrations application rates on the growth attributes of ARCs. The main effects of N125 gave the tallest plants (32.29cm) at 60 days after planting (DAP), highest normalised difference vegetation index (NDVI) (0.60) at 75 DAP, plant survival rate (82.15%) at 75 DAP, and fresh weight (79.04g) and dry matter (31.26%) of aboveground biomass (AGB). Nyota variety produced taller plants (26.90cm) at 60 DAP, gave higher NDVI values (0.53) at 75 DAP, and higher fresh weight (64.87g) and dry matter (27.60%) of the AGB. Significant (p<0.05) interactions were observed in the yield parameters. The interaction between N125 and Nyota (11.33) and Wanjiku (10.67) gave the highest number of minitubers, the highest yields were obtained between the interaction of N125 and Unica (16.38t/ha). Therefore, to achieve high growth and yields of ARCs under hydroponic system, seed potato producers should use 125% of the ADC Molo nutrient formulation.

Nutrient pools and loss due to the removal of harvesting residue in cedar plantations (a case study from Türkiye).

Determining the nutrient stocks and revealing the extent to which these stocks will be affected by the interventions in forest ecosystems are crucial for sustainable forest management. This study aimed to determine the nutrient stock of cedar (Cedrus libani A. Rich.) plantations at different stands with various diameter classes and estimate the nutrient stock to be removed from the forest due to harvesting. Soil and plant samples were collected from 40 plots in Eskişehir and Afyonkarahisar provinces in Turkey. The variation in the nutrient concentrations and stocks of different components of the ecosystem were evaluated by analysis of variance and the decrease via harvesting by regression analysis. The results showed that the concentrations of N, P, K, Mg, S, Fe, Zn, and Mn were highest in the needles, Ca in the bark, Cu in the needles, dead branches, and root. In the large-diameter forest (LDF), dbh=20.0-35.9 cm, the highest P stock was found in the trees, Fe stock in the forest floor, and S stock in the soil and trees. As a result, the forest floor should be protected as it is the crucial component of both the nutrient cycle and the Fe stock in the ecosystem. In LDF, 28.4-37.3% of the nutrient stored in the trees would be removed from the ecosystem in the case of moderate thinning with whole-tree harvesting, while only 5.9-14.1% of the nutrient stock in the case of stem-only harvesting. For these reasons, leaving logging residues after harvesting in the forest would minimize nutrient loss. The study results showed that improved nutrient management in a forest ecosystem will make a significant contribution to the sustainability of forests.

Sink or carbon source? how the Opuntia cactus agroecosystem interacts in the use of carbon, nutrients and radiation in the Brazilian semi-arid region

Anthropogenic disturbances directly influence environmental processes and increase the concentration of carbon (C) in the atmosphere. Here, we compare the differences in the seasonality of the balance of carbon, energy, and radiation, as well as seek to identify the interrelationships between these environmental variables and their impact on the growth of Opuntia cactus. Data were acquired from an eddy covariance flux tower over a cactus crop agroecosystem (2019–2021) in the Brazilian semi-arid region. In addition, we use plant growth rates, carbon and nutrient stocks, evapotranspiration (ET) and water use efficiency (WUE), and radiation (RUE). We show that the closure of the surface energy balance was 71%, although there are minimal fluxes of available energy lost (29%) by unquantified processes. At all seasons, the highest net ecosystem CO2 exchange (NEE) rate was between 11:00–13:00 (−5.75 μmol m−2 s−1). During the dry and wet-dry season, there was the lowest daily gross primary productivity (GPP) (2.5 μmol m−2 s−1) and net radiation—Rn (217.97 W m−2). Ecosystem respiration was more expressive during the wet season (2.41 μmol m−2 s−1), and maximum diurnal value of 2.65 μmol m−2 s−1. Furthermore, the latent heat flux was higher during the wet season (114.68 W m−2) and lowered in the dry season (9.39 W m−2). The net assimilation rate showed higher values during the dry-wet transition. The dry season presented higher nutrient use efficiency and WUE (14.77 g m−2 mm−1). The highest ET occurred during the wet season (227 mm), and RUE was 81.48% higher than in the dry season. Overall, the cactus was a potential C sink during the three years of assessment (NEE: −377 g C m−2 year−1; GPP: 881 g C m−2 year−1). The results help us to understand that most of the Rn energy is used in the sensible heat flux (58% ratio).

Variation in Soil Properties and Nutrient Stocks Under Different Forest Tree Species with Altitude, Aspect and Soil Depths

Çalışma toprak makro (C, N, P, K, Ca, Mg) ve mikro (Fe, Mn, Na, Cu, Zn, Al) besin stoklarına, yükselti, bakı ve ağaç türlerinin etkisini araştırmak için Kastamonu ili Daday ilçesi ormanlarında gerçekleştirilmiştir. Çalışmada, dört ağaç türünde (sarıçam, karaçam, kayın ve meşe) ve üç toprak derinliğinden (0-10, 10-20, 20-30 cm) olmak üzere iki bakı (güneşli ve gölgeli) ve iki yükselti basamağında (1189 m ve 871 m) örnek alanlar seçilmiştir. Sonuçlara göre, türler arasında en yüksek C (57.7 ton/ha), N (3.32 ton/ha) ve P (0.181 ton/ha) stoku kayın, en düşük meşede (39.7-ton C ha-1; 2.37-ton N ha-1, 0.115-ton P ha-1) bulunmuştur. Ağaç türleri arasında ortalama değerlere göre en yüksek kalsiyum stoku karaçamda (3.64 ton/ha) ve meşede (2.41 ton/ha), en düşük sarıçam (0.73 ton/ha) ve kayında (0.67 ton/ha) tespit edilirken, en yüksek potasyum stoku sarıçamda (3.60 ton/ha), sonrasında kayında (2.92 ton/ha), karaçamda (2.16 ton/ha) ve en düşük meşede (1.03 ton/ha) tespit edilmiştir. Makro besin stoklarının yükselti ile bakıya bağlı olarak önemli değişiklik gösterdiği, fakat değişikliğin yönünün ağaç türü ve besin elementine göre farklılık gösterdiği belirlenmiştir. Mikro besin stoklarında farklılıklar genel olarak aynı yönde değişim göstermiştir. Mikro besin stokları üst rakım ve güneşli bakılarda daha yüksek, türler arasında ise sarıçam ve kayında, karaçam ve meşeden daha fazla bulunmuştur.

The Status and Stock of Soil Nutrients under Different Land Ownership Management of Rice Fields in Kuranji District Padang West Sumatra

This study aims to determine the status and stock of soil nutrients in three types of land ownership management. This research was conducted on smallholder farmers (SF), tenant farmers (TF), and owner farmers (OF) in Kuranji District, Padang, West Sumatra, and at the Soil Laboratory of the Faculty of Agriculture, Andalas University from March to September 2022. The range of nutrient status in the three types of land ownership is 0.06-0.35% C-organic and 0.06-0.13% N. The concentration ranges of Ca, Mg, K, Na, P, and Si, respectively, were 0.52-0.79; 0.58-1.34; 0.07-0.12; 0.03-0.09 cmol.kg-1and 2.52-12.7; 31.73- 49.33 ppm. The results showed that each management type’s status of organic carbon in soil was deficient. This result was presumably due to miss management of straws. The highest concentrations of Ca, Mg, K, and Na were found in smallholder farmers’ fields (SF), while the lowest concentrations were found in tenant farmers’ fields (TF). The stock of soil nutrients shows a similar trend to the nutrient status of the soil. The dose of fertilizer by SF and TF was 129.5 kg/ha N; 37.5 kg/ha P2O5; 37.7 kg/ha K2O, while OF is 176 kg/ha N, 65 kg/ha P2O5, 45 kg/ha K2O. The soil nutrient status among the farmer groups is not significantly related to the amount of fertilizer application. It is recommended to give a dose of fertilizer following the recommendations that have been set and balanced with the proper management of remaining straw after harvest for sustainable soil fertility and agriculture production.

Decomposition and nutrient dynamics of stumps and coarse roots of Eucalyptus plantations in southern China

Key messagePrimary remains of Eucalyptus (E. urophylla × E. grandis) plantations following clear-cutting are the stumps and coarse roots. A chrono-sequence approach revealed that the biomass of coarse roots is higher than that of stumps, while they have a smaller rate of biomass loss than stumps. This implies that coarse roots serve as long-term stock for nutrients (carbon, nitrogen, and phosphorus).ContextA significant quantity of stumps and coarse roots persist in the forest floor following the clear-cutting of Eucalyptus plantations in China. The decomposition of these stumps and coarse roots is a crucial aspect of the nutrient stocks in plantation ecosystems.AimsWe described the stock and decomposition dynamics of stumps and coarse roots on Eucalyptus plantations, as well as the nutrient loss rate associated with them.MethodsWe used a chrono-sequence of 0–6-year-old clear-cutting stands of Eucalyptus plantations in southern China. The biomass and nutrient stocks of these samples were assessed at different times of decomposition.ResultsThe highest biomass of stump-root system was 33.8 Mg·ha−1, with nutrient stocks were 16.3 Mg·ha−1, and 63.0 kg·ha−1, and 6710.9 g·ha−1, for C, N, and P. The coarse roots accounted for 81–96% of the biomass of the stump-root system. The loss rate of biomass and nutrients from stumps was higher than that of coarse roots. This suggests that the decomposition of coarse roots could serve as a long-term source of nutrients, thereby improving the nutrient status of the plantations.ConclusionStumps and coarse roots serve as significant nutrient stocks that decay at varying rates. The loss of nutrients must be considered while analyzing the decomposition dynamics following clear-cutting in Eucalyptus plantations.

Effects of fragmentation and shifting cultivation on soil carbon and nutrients: A case study in Sitapahar forest, Bangladesh

The consequences of converting primary forests to agriculture and pasture on soil carbon (C) and nutrient stocks are important, although they are little known in tropical forests. In the Sitapahar forest of Bangladesh, we evaluated soil C and nutrient concentrations and stocks among intact, fragmented, and shifting cultivation sites. We also investigated whether there are any correlations between nutrient stocks and tree species diversity or soil C stock. We measured and identified the trees in 30 main plots (20 m × 20 m), 10 in each of the three sites. Four subplots (1 m × 1 m each) were used to measure the physical and chemical characteristics of the soil at depths of 0–10, 10–20, and 20–30 cm. Results show that during shifting cultivation as compared to intact sites, soil C stock was 50% lower whereas soil P stock was 26% greater. When compared to the other two sites, the soil N and K stocks under the shifting cultivation site were 57% and 27% greater, respectively. Soil Mg stock in the intact site was up to 155% higher compared to the other two sites. In all sites, soil C stock was positively correlated with N stock, but negatively correlated with the P stock. Tree species diversity was positively correlated with K stock, but negatively correlated with N stock in the shifting cultivation site. Sustainable management of the sites should focus on the understanding of soil-plant interactions and the protection of soil C, nutrients, and species diversity.

Aboveground Biomass Productivity and Nutrient Use Dynamics of Clumping Tropical Bamboos in Northern Thailand

Bamboo has great potential in restoring degraded lands while providing multiple environmental benefits and harvestable products at regular intervals due to its unique characteristics of rapid growth. However, a comprehensive and species-specific knowledge of biomass productivity, nutrient dynamics, and potential harvest-induced nutrient losses is lacking. This study compared the biomass and nutrient dynamics of four bamboo species Bambusa oldhamii Munro, Dendrocalamus latiflorus Munro, Bambusa tulda Roxburgh, and Dendrocalamus brandisii (Munro) Kurz in Northern Thailand. Field measurements, laboratory analyses, and statistical modeling were used to estimate their aboveground biomass (AGB), nutrient use efficiency (NUE), and nutrient stocks. Culm diameter at breast height (DBH) and age were identified as the most reliable predictors of AGB. The study revealed that D. brandisii had superior productivity and NUE compared to the other species, particularly the introduced non-native bamboo species. These findings emphasize the need for species-specific strategies that consider both biomass productivity and nutrient dynamics. Furthermore, D. brandisii can be suggested as a native candidate for bamboo plantations in Northern Thailand and similar environments, given its high productivity and efficient nutrient use, underpinning its potential contribution to environmental rehabilitation and rural livelihoods. However, more research is required to minimize nutrient losses and maintain a productive age structure.

Fine earth soil bulk density at 0.2 m depth from Land Use and Coverage Area Frame Survey (LUCAS) soil 2018

AbstractSoil Bulk Density (BD) is an extremely important variable because it is an important site characterization parameter, and it is highly relevant for policy development because it is mandatory for calculating soil nutrient stocks. BD can influence soil chemical properties, land‐use planning and agronomic management. The 2018 Land Use and Coverage Area Frame Survey (LUCAS) saw the unprecedented collection of BD core analysis in a subset of the locations in Europe and the United Kingdom where soil physical and chemical properties were analysed in the 2009 and the 2015 sampling campaigns. Here, we integrated the LUCAS 2018 BD sampling campaign with the mass fraction of coarse fragments previously determined in LUCAS 2009–2015 in order to provide a dataset of the volume fraction of coarse fragments and the BD of the fine earth and improve soil organic carbon (SOC) stock estimation accuracy for topsoil. BD data sampled at 0–10 and 10–20 cm were averaged to harmonize the BD with the mass fraction of coarse fragments measured in 2009, 2012 and 2015. Samples were from cropland, grassland and woodland soils, which accounted for 41%, 21% and 30%, respectively, of the total number of selected sites (n = 6059); ‘bareland’, and ‘shrubland’ accounted for 3% of the sites each, whereas ‘artificial land’ accounted for <1%. Only six samples were classified as ‘wetland’. The dataset was produced assuming the mass density of the coarse fraction to be constant across all LUCAS soil samples. We also estimated the SOC stocks associated with LUCAS 2018 BD and SOC content measurements and showed that correcting the BD by the coarse mass fraction instead of the coarse volume fraction generates SOC stock underestimation. We found the highest deviations in woodlands and shrublands. We showed that, when SOC stock is computed with coarse mass fraction, the error compared with the computation by volume may vary depending on the SOC and coarse mass fraction. This may imply a SOC stock underestimation for European soils. This dataset fits into the big framework of LUCAS soil properties monitoring and contributes both to soil awareness and soil research and assessments, which are two important objectives of the Soil Strategy and the European Soil Observatory (EUSO).

Changes in soil organic carbon and nutrient pools in aggregate‐sized fractions along a chronosequence of wolfberry (Lycium barbarum L.) plantations in arid areas of Northwest China

AbstractDifferent land use and management actions can affect soil aggregates (SAs) and nutrient stocks, which are crucial for sustainable agriculture. The impacts of various chrono‐sequences on the soil aggregate structure, soil organic carbon (SOC) and nutrients associated with aggregate fractions in wolfberry (Lycium barbarum L.) plantations are still not fully understood. This study examined the composition and stability of SAs, SOC, total nitrogen (TN), available phosphorus (AP) and exchangeable cations (K+, Na+, Ca2+ and Mg2+) in bulk soil and various aggregate‐size fractions from five wolfberry plantations with varying ages (1, 4, 6, 10 and 13 years) and a corn field (0 years) in the arid region of northwest Ningxia in China. The results indicated that silt–clay (<53 μm) fractions were dominant in the soil, accounting for 51%–66%, under different plantation ages. The proportion of the macro‐aggregates (>250 μm) increased significantly, by 40%–47%, over the 4 years of wolfberry plantation. Likewise, the soil aggregate stability was improved, and total exchangeable bases (TEB) along with numerous cations concentrations (K+, Na+, Ca2+ and Mg2+) in SAs were significantly reduced as the wolfberry plantings became older. Both concentrations of SOC and TN in the soil aggregates peaked in the 13th year. The silt–clay fractions stored a considerable amount of SOC and nutrients. However, short‐term (under 6 years) cultivation of wolfberry reduced the stocks of SOC, TN and AP in the soil, while long‐term (over 10 years) cultivation increased them, particularly in macro‐aggregates. These findings indicated that long‐term wolfberry farming had several advantages, such as enhancing soil structure, accumulating SOC and nutrients and ameliorating alkaline soils, especially after 10 years, in the arid northwest of China.

Long-Term Grazing Exclusion Increases Ecosystem Carbon Stock but Decreases Nitrogen Stock in the Karst Alpine Grassland of China

Grazing management practices are a major factor regulating nutrient cycling and plant growth in grasslands. However, the response of long-term grazing regimes to ecosystem carbon and nitrogen accumulation and plant productivity remains uncertain in karst landscapes. The purpose of this research is to assess the effects of long-term management measures on plant biomass and ecosystem organic carbon (EOCS), total nitrogen (ETNS), and phosphorus (ETPS) stocks in a karst alpine grassland. A 17 year-long field experiment, constituting the methods of grazing exclusion (GE), continuous grazing (CG), mowing and grazing (MG), and rotational grazing (RG) was established in 2001. Plant and soil samples were collected in 2017. Grazing treatments significantly reduced the aboveground and root biomass (MG and RG) compared to GE. SOC of GE was higher than that of CG, MG, and RG in each soil layer. Grazing promoted the mean TN content with a significant increase in CG and RG. GE significantly increased the EOCS and decreased the ETNS and ETPS. The EOCS increased by 22.29% (MG) and 16.31% (RG) and ETNS increased by 7.76% (RG), and MG significantly decreased ETNS compared to CG. EOCS were positively related to SOC, stoichiometry, and aboveground biomass, while being negatively correlated with TP; ETNS were positively related to TN and TP, while being negatively correlated with C/N, C/P, aboveground biomass, and root biomass; ETPS were positively correlated with TN and TP and negatively correlated with NH4+-N and stoichiometry. GE can provide significant improvements in plant recovery and ecosystem carbon stock, whereas RG is beneficial for promoting ecosystem nutrient stock under the condition of pasturing utilisation in the karst grasslands.