Shelterbelts as a factor of soil formation in agrolandscapes of the southern part of the central Russian upland

The purpose of the research was to establish the specifics of humus formation in sod-carbonate soils of the Dnister region (typical rendzinas) under natural and anthropogenically transformed areas (forest, meadow grasses, and arable land). The group and fractional composition of humus reflects the entire complex of soil formation conditions, differs significantly between soils of different genetic nature, depends on the lithological and hydrothermal conditions of the area and other environmental factors and is characterized by the corresponding parameters of the indicators, which are important in the context of crop yield and ecosystem productivity. The study of groups and fractions of soil humus under natural and anthropogenically transformed lands allows to find out the regional peculiarities of the passage and direction of transformation of humus formation under the conditions of anthropogenic influence. The processes of humus formation in turf-carbonate soil on limestone eluvium under the forest canopy, meadows, and arable land were monitored. Close parameters of indicators of the fractional-group composition of humus of the studied soils and typical chernozems, which almost did not remain in their natural state on the territory of the "Podilski Tovtry" nature park, make it possible to understand the specifics of humus formation in them at different intensities of anthropogenic influence. Identified differences in the group and fractional composition of humus of turf-carbonate soil under ecologically stabilizing lands and arable land will allow to expand the understanding of the course of humus-forming processes with different types of plant remains entering the soil. It has been proven that during the long-term use of rendzinas in typical arable lands, some indicators of their humus condition deteriorate, in particular, the total humus content decreases and the ratio between humus groups and fractions changes. Under more arid conditions, humicity and the content of fractions HA-3 and FA-3, connected in stable complexes with sesquioxides and clay minerals, can increase in sod-carbonate soils. With intensive use of the soil (meadows and arable land), the proportion of humic acids in the composition of humus increases compared to fulvic acids and fractions HA-2 and FA-2 associated with calcium. In arable soil, a decrease in the content of humus and an increase in its humus content are noted. Key words: rendzinas, Dnister region, humus, group composition of humus, fractional composition of humus, environmental factors, humic acids, fulvic acids, productivity of ecosystems, sod process

Clearing natural vegetation to establish arable agriculture (cropland) almost invariably causes a loss of soil organic carbon (SOC). Is it possible to restore soil that continues in arable agriculture to the pre-clearance SOC level through modified management practices? To address this question we reviewed evidence from long-term experiments at Rothamsted Research, UK, Bad Lauchstädt, Germany, Sanborn Field, USA and Brazil and both experiments and surveys of farmers’ fields in Ethiopia, Australia, Zimbabwe, UK and Chile. In most cases SOC content in soil under arable cropping was in the range 38–67% of pre-clearance values. Returning crop residues, adding manures or including periods of pasture within arable rotations increased this, often to 60–70% of initial values. Under tropical climatic conditions SOC loss after clearance was particularly rapid, e.g. a loss of >50% in less than 10 years in smallholder farmers’ fields in Zimbabwe. If larger yielding crops were grown, using fertilizers, and maize stover returned instead of being grazed by cattle, the loss was reduced. An important exception to the general trend of SOC loss after clearance was clearing Cerrado vegetation on highly weathered acidic soils in Brazil and conversion to cropping with maize and soybean. Other exceptions were unrealistically large annual applications of manure and including long periods of pasture in a highly SOC-retentive volcanic soil. Also, introducing irrigated agriculture in a low rainfall region can increase SOC beyond the natural value due to increased plant biomass production. For reasons of sustainability and soil health it is important to maintain SOC as high as practically possible in arable soils, but we conclude that in the vast majority of situations it is unrealistic to expect to maintain pre-clearance values. To maintain global SOC stocks at we consider it is more important to reduce current rates of land clearance and sustainably produce necessary food on existing agricultural land.

Forest Landscape Restoration and Ecosystem Services in A Luoi District, Thua Thien Hue Province, Vietnam

Soil organic carbon (SOC) is a primary constituent of soil organic matter and plays an important role in the regulation of many soil processes, including greenhouse gas emissions. Recently, SOC also became an indicator for monitoring climate change mitigation policies in the agricultural sector. The availability of up-to-date SOC inventories is thus crucial in terms of supporting SOC–related actions at country or sub-country scales. Currently, the National Monitoring System of the Agricultural Soils of Slovakia (CMS-P), whose network of 318 monitoring sites was last surveyed in 2018, is the only available source of up-to-date topsoil SOC data for agricultural land in Slovakia. Although very useful at the national scale, the number of CMS-P observations it contains is too limited for much needed sub-national SOC inventories. We hypothesized that with the aid of well-chosen macro-scale drivers of topsoil SOC accumulation in agricultural land in Slovakia, and by mapping those drivers geographically, we could upscale the CMS-P observations and produce a regional estimate of topsoil SOC. Altitude, land cover, topsoil texture, and soil type were assumed to be the key factors controlling topsoil SOC accumulation in Slovakia, and based on these, the country was classified into 14 macro-scale geographical regions. Typical ranges and mid-class values of 0–30cm topsoil SOC concentrations (%) and stocks (t ha−1) were calculated for each macro-scale region from CMS-P data. The average topsoil SOC content in agricultural land was estimated to be 2.13% (72.9 t ha−1). The highest topsoil SOC stock (> 90 t ha−1) was estimated for the lowlands of Slovakia, and the lowest (< 50 t ha−1) for the shallow and stony soils of mountain regions. When aggregated to 78 administrative regions at LAU1 level, the area-weighted averages ranged between 39.20 t ha−1 and 80.0 t ha−1, with the highest values (> 65 t ha−1) being in LAU1 regions in the south-west, south-east, and north of Slovakia where arable land is most prevalent. Total SOC storage in 0–30cm topsoil of agricultural land in Slovakia was estimated at 118.39 Mt, with two-thirds of this amount stored in arable soils in 33 south-west, south-east, and south LAU1 administrative regions. As there is no alternative and up-to-date dataset on topsoil SOC content in Slovakia, the upscaling algorithm presented in this study is an important step toward utilizing CMS-P data for sub-national SOC inventories. It may also offer a new way of providing inputs to help predict future or alternative regional topsoil SOC accumulation trajectories in Slovakian agricultural land using process-based or statistical models.

Low soil organic carbon (SOC) levels in dry areas can affect soil functions and may thus indicate soil degradation. This study assesses the significance of SOC content in Mediterranean arable soils based on the analysis of a broad data set of 2613 soils sampled from Mediterranean grasslands and agricultural land. The distribution in values of SOC, pH, clay and carbonates was analysed according to different climatic areas (semi‐arid, Mediterranean temperate, Mediterranean continental and Atlantic) and with respect to six different land uses (grassland, cereal crops, olives and nuts, vineyards, fruit trees and vegetable gardens). The general trend was for low SOC in arable land and decreased with aridity. In wet areas (Atlantic and Mediterranean continental), acidic soils had a higher SOC content than did calcareous soils, whereas in the Mediterranean temperate area SOC had little relationship to soil pH. In low SOC arable soils, the SOC content was related to clay content. In calcareous arable soils of the Mediterranean temperate zone, SOC content was more closely related to carbonates than to clay. In contrast to the Atlantic area, Mediterranean grassland soils had much lower amounts of SOC than forest soils. Mediterranean calcareous and temperate acidic soils under grassland had SOC‐to‐clay ratios similar to or only slightly greater than that under a crop regime. In contrast, Mediterranean continental acidic soils under grassland had a much higher SOC‐to‐clay ratio than arable soils. This suggests a low resilience of the Mediterranean temperate and calcareous arable soils in terms of SOC recovery after the secession of ploughing, which may be a result of intensive use of these soils over many centuries. Consequently, we hypothesize that the Mediterranean calcareous soils have undergone significant changes that are not readily reversed after ploughing ceases. Such changes may be related to alterations in soil aggregation and porosity which, in turn, are associated with soil carbonate dynamics. Decarbonation processes (the depletion of active carbonates) may therefore be relevant to the reclamation of highly calcareous arable soils through fostering soil re‐aggregation. The article concludes by discussing the suitability of zero tillage, manuring or the introduction of woody species to increase SOC in calcareous arable soils that are highly depleted of organic matter.

Europe currently faces a decline in soil organic carbon (SOC) content under arable cropping irrespective of improved management practices. In this study we used more than 32 000 SOC data from the entire North Rhine–Westphalia (NRW) area to elucidate the temporal development and current state of SOC content in arable soil from 1979 to 2015 and, in addition, to identify potential causal factors of changes in SOC content. The dataset comprised 7401 data points for 1979–2003 from FIS StoBo, the branched information system on soil contamination in NRW, and 24 930 data points for 2007–2015 from the Agricultural Investigation and Research Institute NRW (LUFA NRW); all data considered refer to soil sampled at 0–30 cm. We found that topsoil carbon contents in arable soil increased over the entire NRW area during the 1980s (from 1.87% in 1979 to 2.82% in 1987), and that this increase was followed by an exponential decrease from 1988 to 2015 (1.42% SOC in 2015) without a new equilibrium being reached. Livestock‐poor regions showed a more rapid gain and a more rapid loss of SOC contents than regions with large livestock densities. The data correlated with changes in grassland area, which was reduced in NRW by about 360 000 ha mainly between 1970 and 1990; that is, recently ploughed grassland probably contributed to increasing averages of SOC contents in arable land during this period, but not thereafter. We conclude that past changes in land use controlled the evolution in SOC from 1979 to 2015, and there is little opportunity for changed management practices to prevent ongoing loss of SOC from the topsoil.HighlightsThe SOC contents in arable soil in North Rhine–Westphalia (NRW) show temporal trend. The SOC contents increased during the 1980s, but decreased thereafter. Data from the entire NRW area indicate that new SOC equilibria have not yet been reached. Past changes in land use still control current SOC evolution.

湖南省森林土壤有机碳密度及碳库储量的动态

Carbon sequestration in arable soils is gaining increasing attention in global policymaking initiatives for climate-change mitigation. Large-scale assessments of soil organic carbon development in arable land are affected by the scarcity of reliable time series of soil organic carbon monitoring data and often fail to replicate observed trends or appreciate any effects induced by changes in soil management.&amp;#xD;This study quantifies C loss from contemporary soil management on specialist crop farms in the EU and the potential societal benefits from C sequestration potential and avoided C loss due to improved management. Our analysis is based on an evidence pool of 214 independent long-term time series of soil organic carbon measurements spanning a wide range of climatic conditions and soil types, and considers the implementation of reduced tillage, organic amendments, soil cover during winter, and crop rotations.&amp;#xD;Overall, we estimate the potential for C sequestration from improved soil management on specialist crop farms, representing 40 % of all the arable land in the EU, to be 48 (±15) million tonnes CO2 equivalents yearly, which corresponds to 17 % (±8) of the target for additional carbon removals in the soil and forest sinks under the Fit for 55 package. In addition, our results show high spatial variability in C losses due to current soil management practices and potential C sequestration from improvements. The annual climate-change mitigation value per unit of land with improved management shows a four-fold variation across countries, with Finland exhibiting the highest value and Cyprus the lowest. This demonstrates that a C payment eco-scheme should be adjusted spatially to achieve cost-effective soil organic carbon sequestration in arable soils in the EU.

The article analyzes the results of research on the impact of anthropogenic factors on the changes in the content and composition of humus in chernozems . The studies showed that the amount of humus in arable soils consistently decreases. It was found that its content in the “A” horizon of virgin soil averages from 6.1 to 9.9%. It was determined that with prolonged plowing, the humus content in the arable layer decreased to 5.6% (to an average level). In a consistent pattern, there is also a decrease in the content of total carbon and nitrogen in arable variants. Research shows that as the humus content decreases, the amount of humic acids (HA) also decreases. It was found that with the depth of the profile, the relative content of HA (% of total C) decreases, while fulvic acids (FA) increase, and the type of humus transitions from fulvate-humate in the “A” and “B” horizons to humate-fulvate in the “BC” and “C” horizons. It was established that prolonged and unsystematic agricultural use of chernozems led to a decrease in humus content and a change in the qualitative composition of humus. Throughout the profile, these changes are expressed in a decrease in the total amount of humic acids, fulvic acids, and non-hydrolyzable residue.

Soil organic carbon (SOC) constitutes the largest terrestrial biological carbon pool globally. SOC in croplands has declined by approximately 50% since the intensification of agriculture. In light of climate change due to rising greenhouse gas concentrations in the atmosphere, the 4p1000 initiative was launched, suggesting that anthropogenic CO2 emissions could be offset by increasing SOC stocks in arable land by 0.4% per year by implementing more sustainable agronomic measures. In order to estimate the potential effect of different measures on SOC at the national scale, modelling approaches are required. In the last decades, a wide array of SOC models have been developed and validated for different soils, climate conditions and land uses across the globe. These models all have their own advantages, disadvantages, and sources of uncertainty. Carbon inputs into soil, a major driver of SOC dynamics, are an estimated quantity in all modelling procedures and represent an additional, large source of uncertainty. To reduce uncertainties, multi-model ensembles are suggested to outperform single model runs. The objective of this study is to determine the optimal SOC model ensemble to reduce estimation errors in future studies.Therefore, a combination of four carbon turnover models (RothC, Yasso07, ICBM, and C-TOOL) and five published carbon input estimation methods was evaluated by comparing simulations to experimental data from six long-term experiments with 56 treatments on arable land in Austria, with durations from 10 to 32 years to obtain a possible optimal combination for future SOC modelling studies in Austria. Evaluation of model prediction was performed by calculating the absolute mean error (AME), Root Square Mean Error (RMSE) and coefficient of determination on yearly SOC changes to eliminate the effect of different experimental durations on model evaluation.We show that obtained models strongly differ in their stock estimates, and our selected ensemble strongly improved the estimations of SOC against single model runs with significantly lower absolute mean errors and root mean square error. This is in accordance with literature results and presents a way forward towards a more accurate modelling. We thus argue that multi-model ensembles to estimate SOC stocks in arable soils in Austria should be preferred over single-model approaches due to improved accuracy.

Background. Organic carbon, which is part of humic substances, is the basis for the fertility of arable soils. The intensity of agriculture has led to an increase in the use of mineral fertilizers, which have a significant impact on soil formation processes. This leads to a disruption of the natural dynamic balance of organic carbon reserves, the process of mineralization of organic matter intensifies, which leads to an increase in carbon dioxide emissions. The accepted concept of “4 ppm” calls on the world society to develop a farming system aimed at increasing the reserves of organic carbon in arable soils. Based on this, studying the influence of various elements of crop cultivation technology on the supply and fixation of organic carbon in arable soils can be considered one of the tasks of modern agricultural science. The purpose of the work is to study the effect of mineral fertilizers on the supply of plant residues and reserves of organic carbon in grain-fallow crop rotation in the conditions of the forest-steppe zone of the Trans-Urals. The novelty of the work lies in the fact that for the first time long-term stationary studies have been carried out on the effect of mineral fertilizers on the supply and reserves of organic carbon in arable soils. In the future, it will be possible to theoretically substantiate the required doses of mineral fertilizers to obtain a positive balance of organic carbon in arable soils of Western Siberia. Materials and methods. The study was carried out in grain-fallow crop rotation (full fallow, spring wheat, oats) from 1995 to 2023 on leached, thin, heavy loamy chernozem. Every year, calculated doses of mineral fertilizers were applied to spring wheat and oats for a planned yield of 3.0; 4.0; 5.0 and 6.0 t/ha of grain, taking into account the actual nutrient content in the soil. Every year, the mass of straw, stubble and root residues was determined for all crop rotation options. In which the content of organic carbon was determined annually and the mass of carbon entering the soil was determined. Before the foundation of experience in 1995, as well as in 2005; 2015 and 2023 soil samples were taken from a depth of 0-10; 10-20; 20-30; 30-40; 40-60; 60-80; 80-100 cm. In which the content of organic carbon was subsequently determined. The reserves of organic carbon in a meter layer of soil were determined using the recalculation method taking into account the equilibrium density. Statistical data processing was carried out using Microsoft Excel. Results. In the option without the use of mineral fertilizers, 117.3 t/ha of plant residues entered the soil during 28 studies. Refusal to use fertilizers led to a negative balance of organic carbon in the soil, where the decrease in reserves was 6.7% relative to the initial values. The application of mineral fertilizers for a planned yield of 3.0 and 4.0 t/ha of grain led to an increase in the flow of by-products into the soil by 25-48% relative to the natural nutrition level. This ensured a positive carbon balance, where the increase in reserves in the meter layer of soil was 4.2-5.1% relative to the initial values. The application of NP to a planned yield of 5.0 and 6.0 t/ha of grain increased the input of plant residues during the study period by 69-75% relative to the control. Despite this, there was a decrease in organic carbon reserves in the meter layer of soil by 4.7-6.4% relative to the initial value. Conclusion. Refusal to use mineral fertilizers when cultivating grain crops leads to a negative balance of organic carbon, where annual carbon losses reach 0.44-0.78 t/ha. Stable application of fertilizers to obtain 3.0 and 4.0 t/ha of grain ensures a positive carbon balance in the soil, the annual increase in reserves ranges from 0.23 to 0.58 t/ha. High doses of fertilizers to obtain a yield of 5.0 to 6.0 t/ha lead to a negative carbon balance in the soil; annual losses range from 0.30 to 0.55 t/ha.

Using both historic records and CORINE land cover maps, we assessed the impact of land cover change on the stock of soil organic carbon (SOC) in the Republic of Ireland from 1851 to 2000. We identified ten principal land cover classes: arable land, forest, grassland, heterogeneous agricultural areas/other, nonvegetated semi-natural areas, peatland, suburban, urban, water bodies, and wetland. For each land cover class, the SOC stock was estimated as the product of SOC density and land cover area. These were summed to calculate a national SOC budget for the Republic of Ireland. The Republic of Ireland’s 6.94 million hectares of land have undergone considerable change over the past 150 years. The most striking feature is the decrease in arable land from 1.44 million ha in 1851 to 0.55 million ha in 2000. Over the same time period, forested land increased by 0.53 million ha. As of 2000, agricultural lands including arable land (7.85%), grassland (54.33%), and the heterogeneous agricultural areas/other class (7.91%) account for 70.09% of Irish land cover. We estimate that the SOC stock in the Republic of Ireland, to 1 m depth, has increased from 1,391 Tg in 1851 to 1,469 Tg in 2000 despite soil loss due to urbanization. This increase is largely due to the increase of forested land with its higher SOC stocks when compared to agricultural lands. Peatlands contain a disproportionate quantity of the SOC stock. Although peatlands only occupy 17.36% of the land area, as of 2000, they represented 36% of the SOC stock (to 1 m depth).

Soil aggregates may protect organic matter from mineralization; however, there is a lack of knowledge about the stability and structural features of soil organic carbon (SOC) in aggregate external layers and the internal layers. The amount and characteristics of SOC in external and internal layers of soil dry-sieved aggregates from three land use systems (woodlot, grassland, and arable land) were studied using an aerobic incubation. Structural features of SOC and hot water-extractable C, prior- and post-incubations, were investigated using Fourier transform mid-infrared spectroscopy. Soil organic C concentrations were 11.1 and 6.8% greater in the internal layers than in external layers of soil aggregates in woodlot and grassland systems, respectively, while there was no difference between the aggregate layers in arable soil. The CO2–C evolved during the aerobic incubation was significantly greater from aggregate external layers than from internal layers under all three land use systems. The content of aliphatic-C was significantly greater in aggregate external layers than in internal layers under all three land use systems, while the content of aromatic-C was greater in aggregate internal layers than in external layers for the woodlot and grassland systems only. The SOC in aggregate internal layers had a longer half-life, a greater slow-C pool and a smaller active-C pool than the SOC in aggregate external layers. The SOC is characterized with higher aromatization and stability in aggregate internal layers than in aggregate external layers. The aggregates are better developed and provide strong protection for SOC in the native woodlot and grassland systems but this protection was not evolved in arable land.

Soil Organic Carbon (SOC) is considered a proxy of soil health, contributing to food production, mitigation, and adaptation to climate change and other ecosystem services. Implementing Recommended Management Practices (RMPs) may increase SOC stocks, contributing to achieve the United Nations Framework Convention on Climate Change 21st Conference of the Parties agreements reached in Paris, France. In this framework, the “4 per 1000” initiative invites partners implementing practical actions to reach a SOC stock annual growth of 4‰. For the first time, we assessed the achievement of 4‰ objective in Mediterranean agricultural soils, aiming at (i) analyzing a representative data collection assessing edaphoclimatic variables and SOC stocks from field experiments under different managements in arable and woody crops, (ii) providing evidence on SOC storage potential, (iii) identifying the biophysical and management variables associated with SOC storage, and (iv) recommending a set of mitigation strategies for global change. Average storage rates amounted to 15 and 80 Mg C ha−1 year−1 × 1000 in arable and woody crops, respectively. Results show that application of organic amendments led to significantly higher SOC storage rates than conventional management, with average values about 1.5 times higher in woody than in arable crops (93 vs. 63 Mg C ha−1 year−1 × 1000). Results were influenced by the initial SOC content, experiment duration, soil texture, and climate regime. The relatively lower levels of SOC in Mediterranean soils, and the high surface covered by woody crops, may reflect the high potential of these regions to achieving significant increases in SOC storage at the global scale.

&amp;lt;p&amp;gt;Rivers receive large amounts of terrestrial soil organic carbon (SOC) and transport them from land to the ocean. Mounting evidence indicates that a large fraction of the eroded SOC, which is often very old, is quickly decomposed upon entering the river and never reaches the ocean. The mechanisms explaining this rapid decomposition of previously stable SOC remain unclear. In this study, we investigated the relative importance of two mechanisms possibly explaining this rapid SOC decomposition: (i) in the river water SOC is exposed to a different microbial community which is able to metabolise SOC much more quickly than the soil microbial community and (ii) SOC decomposition in rivers is facilitated due to the hydrodynamic disturbance of sediment. We performed different series of short-term (168h) incubations quantifying the rates of SOC decomposition in an aquatic system under controlled conditions. Organic carbon decomposition was measured continuously through monitoring dissolved O&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; concentration using a fiber-optic meter (FirestingO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;, PyroScience). In the control treatment, bottles of 320 ml of river water sampled from Dijle river (Leuven, Belgium) were used, without headspace, under dark conditions in a temperature-controlled room (20&amp;amp;#8451;). In a second treatment, soil material was added to river water filtered at 0.2 um to remove aquatic micro-organisms (MO) (SOC-MO treatment). The effect of the presence of an aquatic microbial community on SOC decomposition was simulated by adding an inoculum of unfiltered river water to a bottle containing the same soil material (SOC+MO treatment). Secondly, we investigated the effect of water motion on respiration rates by simulating the hydrodynamic disturbance of soil particles using a swing system to keep particles suspended in the water. All treatments described above were conducted under both standing- and shaking conditions. Each experiment was repeated six times and two types of soil were tested: one from arable land (sandy loam, 2.4%OC), and the other from a temperate forest site (sandy loam, 5.0%OC). Our result show that SOC indeed further mineralized in a riverine environment. Under both shaking and standing conditions, we found a significant difference between SOC-MO and SOC+MO treatments (paired t-tests, p&amp;lt;0.05), indicating that the presence of an aquatic microbial community enhanced the SOC decomposition process by 94%-131% depending on the soil type and shaking/standing conditions. In contrast, the effect of hydrodynamic disturbance was much less evident. When comparing SOC+MO at shaking vs. standing conditions for soil from arable land, &amp;amp;#160;SOC decomposition was increased by 13% at shaking condition (p&amp;lt;0.05) while no significant effect was found for forest soil (p&amp;gt;0.05). While some recent studies suggested that aquatic respiration rates may have been substantially underestimated by performing measurement under stationary conditions, our results indicate that this effect is relatively minor, at least under the temperature conditions and for the suspended matter concentration range (500 mg/L arable land soil; 200 mg/L forest soil) used in our experiments.&amp;lt;/p&amp;gt;