Incorporation Of Organic Matter Research Articles

The role of bromelain extraction waste product application for intensive land management practice

An intensive land management practice, especially, when related to long-live perennial crops such as pineapples, may lead to acute soil organic matter content depletion. However, incorporation of organic matter into soil in the middle of the planting season is not possible due to massive plant density. The application of bromelain extraction waste product as resistant organic matter resources might answer the problem. A set of experiments consisting of 0, 20, 40, 60, and 80 tons/ha of bromelain waste, based on a case study at PT Great Giant Pineapple Plantation, Lampung, has been done to indicate its role in increasing soil physical quality. After being incubated for 5 months, the application of bromelain showed more stable soil particle aggregation through the slake test. Soil aggregate stability is getting better with the higher rate of bromelain waste application. Soil shear strength is negatively correlated to the rate of bromelain waste, where the higher rate of bromelain waste application, the lower the soil shear strength. Soil sensitivity is carried out to determine the potential loss of soil strength because of remoulding. It indicates a decrease in shear sensitivity following the increasing rate of bromelain waste.

Is biochar a promising soil amendment to enhance perennial crop yield and soil quality in the tropics?

Soil quality improvement is crucial in tropical soils to enhance crop productivity. Organic matter incorporation is not a viable approach regarding perennials as it completely degrades within a year. Hence, biochar is a sustainable solution to boost crop productivity in the tropics. Biochar has been utilized in agriculture for decades due to its inherent properties that enhance the soil-mediated properties associated with soil fertility. The impact of biochar on tropical perennial intensive cropping systems has been understudied, possibly because of the high initial input demand. This paper highlights the facts related to soil chemical, physical, and biological property enhancement upon biochar incorporation relating to long-term impacts on perennial crops.

A multi‐proxy study of Umbric Ferralsols genesis in a high‐mountain environment in Rio de Janeiro state

AbstractThe formation of strongly weathered soils of the tropics (Ferralsols) with high carbon stocks (thick A‐horizon/umbric horizon) is still not understood. In order to contribute to the understanding of the formation of Umbric Ferralsols, we studied these soils in the highlands of Rio de Janeiro state (Brazil) from various perspectives. We analysed soil morphology, micromorphology, physical and chemical soil attributes, soil phytolith assemblages, and δ13C isotopic composition in a multi‐proxy study. The profiles presented ferralic horizons with SiO2/Al2O3 ratio (ki index) < 1.0, low silt/clay ratio values, predominance of kaolinite and presence of gibbsite, and low cation exchange capacity. These characteristics indicate a high degree of weathering and ferralitization. The isotopic and phytolithic variations indicate climatic modifications during the Late Holocene (approximately 2300 years ago), with a predominance of mixed vegetation composed of plants of the C3 and C4 photosynthetic cycles. This condition favoured the accumulation of organic matter in the Umbric Ferralsols. The accumulation of organic matter in subsurface B horizons occurred under drier past climatic conditions in a savanna environment, which may have favoured the occurrence of fires, thereby explaining the charcoal fragments identified in the micromorphological analyses. In contrast, the development of the umbric horizon in the profiles was favoured under wetter environmental conditions than the present environmental conditions, and favoured the development of vegetation and intense accumulation of organic material on the surface and at depths close to 100 cm. The pedogenesis of umbric horizons in Ferralsols reinforces the importance of bioturbation in the incorporation of organic matter, intensifying the humification and resulting in a strong darkening of the soil (melanization).

SUITABILITY EVALUATION OF RAINFED RICE (ORYZA SATIVA) IN FLOOD PLAIN OF SOUTHERN GUINEA SAVANNAH ZONE OF NIGERIA

The flood plain of Awe in Southern Guinea Savannah Zone of Nigeria was studied for rice production. The physical, morphological and chemical properties of the soils were matched with the requirements of the rice production and the overall suitability rating of the soils was obtained using limitation method. The soils were deep (101cm – 170cm) and well drained, poorly to very poorly drained. The soils were fine textured and strongly to moderately acidic and slightly alkaline in reaction (pH 5.10 – 7.15). The percentage sand fraction ranged from 44.8% to 83.1%; silt 5.4% to 9.4% and clay 9.4% to 46.7%. They had low to moderate organic carbon (0.41% to 3.52%); total N (0.04% to 0.11%); available P (1.64mglkg-1 to 3.72mg/kg-1), total exchangeable bases (2.85cmol/kg-1 to 7.97cmol/kg-1), CEC (4.10cmol/kg-1 to 7.98cmol/kg-1), base saturation (65% to 97.5%) and Fe2+ (1.10 to 2.11). Soils of the three flood levels (toeslope or deep swamp, medium or lower slope, levee or shallow swamp) were rated highly to suitable (S1) because of the soils ability to retain water during the growth period with the favourable physical and chemical characteristics such as climate, slope, water levels, pH and texture. Management practices such as organic matter incorporation, liming to increase soil pH, fertilizer application and appropriate time of planting are hereby recommended for increased rice production in the mapping units that are not highly suitable for rice production in the study area.

The significance of cherts as markers of Ocean Plate Stratigraphy and paleoenvironmental conditions: New insights from the Neoproterozoic–Cambrian Blovice accretionary wedge, Bohemian Massif

The Ediacaran to early Cambrian Blovice accretionary complex, Bohemian Massif, hosts abundant chert bodies that formed on an oceanic plate and were involved in subduction beneath the northern margin of Gondwana. Field relationships of cherts to their host, their microstructure and elemental as well as isotopic compositions revealed diverse processes of chert petrogenesis reflecting depositional environment and position on the oceanic plate. The deep-water cherts formed through a hydrothermal precipitation of silica-rich gels on outer trench swell of the subducted slab with none or only minor addition of terrigenous material. On the contrary, the shallow-water cherts formed in lagoons on seamount slopes, and at least some of them represent a product of hydrothermal replacement of former carbonate and/or evaporite precursors. For both chert types, the hydrothermal fluids were of low temperature and continuous pervasive hydrothermal alteration of oceanic crust, together with an elevated Si content in Neoproterozoic seawater, served as the major source of silica. On the other hand, minor carbon enrichment in chert is mostly linked to variable incorporation of organic matter that was deposited on the seafloor. Rare earth element (REE) systematics of the cherts indicate predominantly oxygenated environment for the shallow-water cherts whereas the deep-water cherts were deposited in diverse redox conditions, depending on their distance from hydrothermal vent. Using these data, we demonstrate that the cherts once formed a part of Ocean Plate Stratigraphy (OPS) now dismembered and mixed with terrigenous siliciclastic material to form OPS mélanges. Combining our data with those from the existing literature, we show that cherts can serve as significant markers of OPS since the Archean, recording a complex interplay between seafloor-related volcanic (production of MORB- and OIB-like magmas) and sedimentary processes, hydrothermal activity at mid-ocean ridges and seamount chains as well as at outer slopes of subducting slabs. However, the cherts also exhibit a secular change in composition and petrogenesis most profoundly affected by an overturn in seawater silica cycle across the Precambrian–Phanerozoic boundary.

How can leaf-litter from different species growing in short rotation coppice contribute to the soil nutrient pool?

Quantifying leaf-litter and the potential contribution of essential nutrients to the soil is key to guaranteeing the sustainability of forest systems, especially in plantations under short rotation coppice, insofar as it can condition crop management such as the requirement for nutritional amendments. Nutrient cycling is dependent on production as well as litter decomposition, so to compare the different strategies of the species in nutrient recycling it is important not only to determine the quality and quantity of leaf litter, but also the decomposition rate dynamics and the consequent potential incorporation of organic matter and nutrients into the soil. Therefore, this work aims to quantify and analyze the dynamics of leaf-litter as well as the retranslocation rate, to assess the decomposition rate of the foliar biomass and its nutrient concentrations, and finally, to assess the evolution of leaf-litter quality.For these purposes, eight genotypes were considered in this study: Populus deltoides (‘Baldo’), Populus × canadensis (‘Ballottino’, ‘I-214′, ‘Orion’ and ‘Oudenberg’); Platanus × hispanica (‘Girona’), Salix matsudana × Salix spp. (‘Levante’) and Robinia pseudoacacia (‘Nyirsegi’). The plantation was established in central Spain with a density of 10,000 cuttings ha−1. Three rotations of 3 years each were applied, this study being carried out during the first growing season of the second rotation.Although the leaf fall dynamics were similar among the different species, the production and quality of the leaf-litter were highly species specific. Different strategies were identified; greater retranslocation of N and P being found in poplar, plane tree or only of P in the case of black locust as a conservation strategy, although lower retranslocation of all nutrients was observed in willow, which means that the leaf litter of the latter is very rich in nutrients. While willow, black locust or even some genotypes of poplar are capable of releasing many of the nutrients to the soil during decomposition, plane tree released a smaller variety of nutrients, N, P and Mg being immobilized in the leaf-litter.From the perspective of conserving the soil fertility resulting from the decomposition of leaf-litter, the plantations of species with the highest decomposition rates, such as black locust and willow, were found to be the most recommendable. However, the immobilization of some nutrients in the leaf-litter during the decomposition process could satisfy the nutritional requirements of these species in the medium and long term, thus an advantageous strategy could be to mix species with different decomposition dynamics.

Divergent Response of the Supply Capacity and Turnover of Inorganic Nitrogen to Pitaya Cultivation in the Subtropical Karst Region of Southwest China

Determining the availability and supply capacity of soil inorganic nitrogen (N) can effectively guide the appropriate application of N fertilizers during crop cultivation. However, the mechanism underlying soil inorganic N production remains unknown for cash crops in karst regions. In this study, the rates of organic N mineralization to ammonium (NH4+) and NH4+ nitrification to nitrate (NO3−) were determined using a 15N tracing technique to evaluate the supply capacity of inorganic N in soils from woodland and pitaya plantations with different cultivation years (3, 9, and 15 years) in the subtropical karst region of China. The conversion of woodland to pitaya plantations significantly decreased the content of soil organic carbon (SOC), total N, calcium (Ca), and magnesium (Mg), along with the soil pH and cation-exchange capacity (CEC), but significantly increased the content of available potassium, available phosphorus, iron, and aluminum, in a more pronounced fashion with the increasing length of pitaya cultivation. The conversion of woodland to pitaya plantations has not significantly changed soil NH4+ and NO3− content, but this land use has resulted in divergent effects on mineralization and nitrification rates. Compared to woodland (5.49 mg N kg−1 d−1), pitaya cultivation significantly reduced the mineralization rate to 0.62–2.38 mg N kg−1 d−1. Conversely, the nitrification rate significantly increased from 4.71 mg N kg−1 d−1 in soil under woodland to 9.32 mg N kg−1 d−1 in soil under 3-year pitaya cultivation, but this rate decreased to 1.74 mg N kg−1 d−1 under 15-year cultivation. Furthermore, the mean residence time of inorganic N was significantly higher in long-term than in short-term pitaya plantations, indicating the decline in inorganic N turnover with the increasing length of pitaya cultivation. Taken together, long-term pitaya cultivation could significantly decrease the supply capacity and turnover of inorganic N in soil. The Ca, Mg, SOC, and total N content, as well as CEC, were significantly and positively related to the mineralization rate, but negatively related to the mean residence time of NH4+ and NO3−, suggesting that the incorporation of organic matter can accelerate the soil inorganic N supply and turnover for long-term pitaya plantation in subtropical regions.

Palaeogene glendonites from Denmark

Pristinely preserved mineral pseudomorphs called glendonites, up to 1.6 m long, from the Palaeogene strata of Denmark allow detailed crystallographic characterisation and add to the understanding of the transformation of the precursor mineral, ikaite (CaCO3·6H2O), to calcite, which constitutes the glendonite. We describe Danish pseudomorphs after ikaite from two localities and formations: the Early Eocene Fur Formation and the Late Oligocene Brejning Formation. This detailed study highlights that key aspects such as morphology and mode of occurrence of these ancient glendonites are identical to those of their parent mineral ikaite, when it grows in marine sediments. Systematic distortion of the angles in glendonite and marine sedimentary ikaite relative to the ideal ikaite symmetry may arise due to the incorporation of organic matter into the crystal structure, and we demonstrate the similarity between modern and ancient ikaite formation zones in the marine sedimentary realm with respect to organic matter.

Impact of anaerobic soil disinfestation on seasonal N2O emissions and N leaching in greenhouse vegetable production system depends on amount and quality of organic matter additions

Greenhouse vegetable production (GVP) systems in China receive excessive amounts of fertilizers (>1500 kg N ha−1 yr−1) and irrigation (>1200 mm yr−1), which results in severe soil degradation. Moreover, soil borne diseases are common as the same crop is planted continuously over years. Anaerobic soil disinfestation (ASD) is a method carried out every 3–4 years during the summer fallow period to combat soil-borne diseases and to improve soil health. The standard ASD practice, which is carried out before the cropping season, involves incorporation of organic matter (i.e. rice shells or straw) into the soil, covering of the soil with plastic films and soil irrigation until saturation. However, many farmers incorporate large amounts of organic nitrogen fertilizer for priming ASD. In this study, we investigated if incorporation of rice shells plus chicken manure (ASD+RM; farmers practice) provokes higher environmental N losses (N2O emissions and N leaching) during the ASD and the following tomato crop growing period as compared to the standard ASD practice (ASD+R: only rice shells) or a Control (fallow, but with incorporation of organic manure, standard in non-ASD years). Results showed that ASD+RM increased seasonal (ASD/fallow period plus tomato crop growing period) soil N2O emissions by a factor of 3 (ASD+RM: 14.1 kg N2O-N ha−1; ASD+R: 4.7 kg N2O-N ha−1), with 2/3 of emissions occurring during the 25 days long ASD period. Across all treatments, nitrate (NO3−) leaching dominated total N leaching (75%), with significantly lower rates observed for ASD+R as compared to ASD+RM. For both ASD treatments, total dissolved organic nitrogen (DON) leaching was a factor of two higher than for the Control. Crop productivity was not affected by ASD. Our findings imply that ASD+RM should be abandoned as the additional supply of manure N results in high environmental N losses without further increasing yields.

Positive contribution of macrofaunal biodiversity to secondary production and seagrass carbon metabolism.

Coastal vegetated habitats such as seagrasses are known to play a critical role in carbon cycling and the potential to mitigate climate change, as blue carbon habitats have been repeatedly highlighted. However, little information is known about the role of associated macrofauna communities on the dynamics of critical processes of seagrass carbon metabolism (e.g., respiration, turnover, and production). We conducted a field study across a spatial gradient of seagrass meadows involving variable environmental conditions and macrobenthic diversity to investigate (1) the relationship between macrofauna biodiversity and secondary production (i.e., consumer incorporation of organic matter per time unit), and (2) the role of macrofauna communities in seagrass organic carbon metabolism (i.e., respiration and primary production). We show that, although several environmental factors influence secondary production, macrofauna biodiversity controls the range of local seagrass secondary production. We demonstrate that macrofauna respiration rates were responsible for almost 40% of the overall seafloor community respiration. Macrofauna represented on average >25% of the total benthic organic C stocks, high secondary production that is likely to become available to upper trophic levels of the coastal food web. Our findings support the role of macrofauna biodiversity in maintaining productive ecosystems, implying that biodiversity loss due to ongoing environmental change yields less productive seagrass ecosystems. Therefore, the assessment of carbon dynamics in coastal habitats should include associated macrofauna biodiversity elements if we aim to obtain robust estimates of global carbon budgets required to implement management actions for the sustainable functioning of the world's coasts.

Incorporation of marine organic matter by terrestrial detrital food webs: abiotic vs. biotic vectors

Marine organic matter can potentially enter terrestrial ecosystems via abiotic or biotic vectors. The former is facilitated by e.g. waves, tides, winds, etc.; the latter – by the activity of organisms, e.g. seabird migration. However, differences in its assimilation rate in detrital food webs at different distance from water remain generally unexplored. To fill this gap, we compared the consumption of marine organics by terrestrial invertebrates within coastal ecosystems of the Black sea using stable isotope analyses of carbon and nitrogen. We focused on relatively inland (100 m from the coast) forested areas with the recently established overwintering colonies of the great cormorant (Phalacrocorax carbo) and control ecosystems isolated from any marine organic matter input. Guano and cormorant food leftover input led to the significant increase of δ15N values of soil, litter and all trophic groups of soil invertebrates. However, δ13C values changed to a smaller extent. The importance of marine resources (in a form of guano) as a carbon source for soil arthropods was relatively low: approximately 15% of their diet. In contrast, coastal soil invertebrates were significantly enriched with 13C compared to control and cormorant-influenced ecosystems as they were greatly dependent on the seaweed and other marine resources (on average 45% of coastal invertebrate diet). We conclude that marine resources delivered by an abiotic vector may form the basis of the soil food web diets in a 15 m zone from the water edge. Alternatively, the biotic transfer further inland (forest on a cliff 100 m away from the water edge) with e.g. nitrogen-rich seabird guano or food remains may geographically extend proliferation of marine nutrients into terrestrial ecosystems. As far as we know, our results are among the first to demonstrate the spatial zoning of mechanisms securing bottom-up subsidy of biogenic elements to soil ecosystems having originated from the sea.

Acidified Biochar Confers Improvement in Quality and Yield Attributes of Sufaid Chaunsa Mango in Saline Soil

Mango fruit quality plays a significant role in fruit storage. It also directly affects the economic value of fruit in the national and international markets. However, deterioration of soil health due to low organic matter is a major hurdle for mango growers. Scientists suggest incorporation of organic matter. However, high temperature and low precipitation lead to oxidation of organic residues in soil. On the other hand, biochar is gaining the attention of growers due to its resistance against decomposition. It can improve soil physicochemical attributes. Limited literature is available regarding biochar effects on the quality attributes of mango. Therefore, the current study was planned to investigate the effects of acidified biochar on mango quality and yield attributes in alkaline soil. Five levels of biochar, i.e., 0, 5, 10, 20 and 40 Mg/ha, were applied in a randomized complete block design (RCBD). Results showed that 20 and 40 Mg/ha acidified biochar significantly enhanced fruit retention, sugar contents, ash contents and TSS of mango compared to control. A significant increase in mango fruit weight and yield per plant validated the efficacious role of 40 Mg/ha acidified biochar over control. Furthermore, the maximum significant decrease in fruit juice acidity signified the imperative functioning of 40 Mg/ha acidified biochar in alkaline soil. In conclusion, 40 Mg/ha acidified biochar application can improve mango quality and yield attributes in alkaline soil. More investigations on different soil types, climatic zones and mango varieties are recommended to declare 40 Mg/ha acidified biochar as the best treatment for improvement in the quality and yield of mango fruit in alkaline soils.

Coupling Water Resources and Agricultural Practices for Sorghum in a Semiarid Environment

Water scarcity and changing rainfall distribution have caused uncertainties in relation to agricultural production in semiarid areas. In this context, water reuse for irrigation is a promising alternative, although requiring irrigation and agricultural management. Production of forage plants is strategic for semiarid areas due to their high tolerance to stresses and use as animal fodder. The objective of this work was to evaluate the combined performance of treated wastewater irrigation and mulching on forage sorghum and on soil attributes in Northeast Brazil. Sorghum was cropped in November 2018, three months before the beginning of the hydrologic year, and cultivated over three cycles until April 2019. The experiment was designed with five irrigation depths (60%, 80%, 100%, 120%, and 140% of crop evapotranspiration), and with four soil cover conditions (0% (witness), soil covered with native vegetation, with coconut coir, and with macerated moringa seeds), adopting four replications. Irrigation with treated wastewater promoted linear increases in forage sorghum yield at irrigation depths of up to 140% of crop evapotranspiration. Mulch promoted a 24% increase in productivity in relation to the area where conservation was not practiced, being able to control salinity while also contributing to the higher incorporation of organic matter. Irrigation with treated wastewater had no negative agronomic impacts on soil, once natural rainfall events typical of the Brazilian semiarid region allowed effective salt leaching from shallow sandy soils.

Rehabilitation of a Riparian Site Contaminated by Tailings from the Fundão Dam, Brazil, Using Different Remediation Strategies.

The tailings spilled by the Fundão Dam rupture in the Doce River basin (Brazil) had a high pH, elevated sodium (Na) and ether amine, and low soil organic matter. With the aim of decreasing the toxic compounds, we established 2 remediation strategies: treatment 1, phytoremediation with tolerant native species of the Atlantic Forest cultivated on scraped sediment plus the incorporation of organic matter; and treatment 2, phytoremediation with native species plus superficial deposition of organic matter. The experimental site was compared with a degraded site that the dam tailings had reached and with a preserved site, a fragment of preserved Atlantic Forest. After 12 mo, plants showed an outstanding growth, especially after treatment 1 (~4 m), and the remediation procedures resulted in significant decreases in pH (from 8.0 to ~ 6.0), Na (from 154 to 22-35 mg/kg), electrical conductivity, and ether amine (from 6.0 to 0.5 mg/kg) in both treatments. By contrast, ammonium, a product of ether amine degradation, showed a significant increase in the experimental site, along with a significant increase in nitrate and improvement of soil microbial populations assessed by phospholipid fatty acid analysis. The treatments also improved soil fertility in the experimental site, as estimated by soil nutrients, cation exchange capacity, and soil aggregation. Based on the parameters analyzed, a principal component analysis showed that samples from the degraded site and the preserved site clustered in an opposite position and those from the experimental site clustered in an intermediate position but closer to the samples from the preserved site. Overall, our results demonstrated that the remediation procedures adopted were effective and resulted in rehabilitation of a riparian forest contaminated with dam tailings that included Na and ether amine. Environ Toxicol Chem 2021;40:2359-2373. © 2021 SETAC.

Study of the permeability of tubular mineral membranes: application to wastewater treatment

This research work opens up the possibility of developing tubular mineral membranes from Moroccan clay powders and their use in water permeability tests and wastewater treatment. The aim is to show the possibility of using clay as a low-cost raw material for the production of ceramic membranes with high mechanical and chemical performances.In a first step, we developed ceramic membranes by extruding a prepared plastic paste with the addition of an optimized amount of wood powder as organic matter (OM) to improve the porosity characteristics of the final products after firing. Several parameters are controlled such as the chemical and mineralogical composition of the starting clay powder, the granulometry and the final sintering temperature.The effect of sintering temperature in the range from 800 to 1000 °C, and OM addition (5, 10, 15wt%) on tubular membrane properties such as mechanical and chemical resistance, porosity and permeability were investigated. It was found that the incorporation of OM in the raw clay enhance the pore volume and the permeate flux but it was also accompanied by a decrease in mechanical strength. The membrane sintered at 1000 °C with 15wt% of OM is considered as optimized membrane and it was applied for the second stage of this work. This stage concerns the treatment of wastewater from a thermal complex located 12 km south of the city of Meknes, Morocco, through a treatment by a biological disk microstation. The filtrate obtained then undergoes tangential filtration by the membranes elaborated and optimized following the evolution of the pollution parameters. Based on physicochemical and biological analyses of wastewater after treatment by the coupled system, the membranes obtained have a good permeability and an excellent pollution removal performance.

Metal Speciation in Water of the Flooded Mine “Arsenic” (Karelia, Russia): Equilibrium-Kinetic Modeling with a Focus on the Influence of Humic Substances

Equilibrium-kinetic modeling allows investigating metal behavior in the water–rock-organic matter system with time to evaluate anthropogenic effects on the environment. In the article, the interactions of stagnant mine drainage water of the flooded mine “Arsenic” with ore and gangue minerals were simulated using different organic matter incorporation approaches. If the model is closed to humic substances (no additional organic matter input), most fulvic acids are bound in the Fe fulvate complex. While under the removal of Fe fulvate from the model, the Cu fulvate becomes prevalent, the contribution of the fulvate complexes with Zn, Mg, and Ca also increases. This scenario simulates the organo-mineral complexes behavior well and allows identifying the sequence of metal binding to organic ligands as follows Fe > Cu > Zn > Mg > Ca. The second scenario imitates the constant input of organic matter to the model (open system regarding humic substances). The dissolved metal concentrations in the model solution are extremely high in comparison to the mine drainage water. This scenario demonstrates that excessive input of organic matter leads to the accumulation of the metals in a dissolved form and blocks the secondary mineral formation despite the faster dissolution of the primary minerals under a more acidic pH than in the first scenario. However, despite the differences between the model solution and the mine drainage water, this scenario is useful to address specific issues associated with changes in natural and anthropogenic conditions. Both scenarios show the importance of organic matter incorporation to the equilibrium-kinetic models.

Soil conditioners as candidates to mitigate salt/water stress effects on sorghum growth and soil properties

In arid and semiarid regions the use of saline water is common in agricultural irrigation, due to the scarcity of high-quality irrigation water. Thus, agriculture faces a challenge in developing strategies to grow crops under such adverse conditions in these regions. The objectives of this research are to study soil chemical properties and sorghum growth response to saline irrigation levels and application of soil conditioners. A greenhouse experiment (4x5) was carried out using a Cambisol cultivated with sorghum and irrigated with five saline water levels: 100%, 80%, 60%, 40% and 20% of soil field capacity (FC). Soils were treated with no soil conditioner (control), organic matter, elemental sulfur (S0) + organic matter and gypsum + organic matter, applied to the soils 30 days before sorghum planting. At 60 days after plant emergence, measurements were recorded for: leaf water potential, plant dry weight, soil P availability, and soil chemical properties. Increasing saline water levels reduced exchangeable and soluble cations and saline variables. Organic matter + elemental sulfur promoted the highest levels of P in the soil and soil saturation extract. This mixture and the saline irrigation of 60% of field capacity promoted the greatest plant growth. However the organic matter + gypsum mixture promoted higher leaf water potential in relation to the other conditioners tested. The saline irrigation level equivalent to 60% of field capacity and the incorporation of organic matter + S0 were sufficient to reduce soil salinity and sodicity, maintaining P and soluble/exchangeable cations contents to a level that best promoted sorghum growth

三种不同类型亚高山森林凋落物输入对土壤腐殖化的影响

森林凋落物既是土壤腐殖质的主要来源，也可以通过新鲜凋落物中易降解组分的输入激发土壤原有腐殖质的降解，导致其相互关系并不明确。以王朗国家级自然保护区内的典型亚高山针叶林、针阔混交林以及阔叶林为研究对象，开展土壤原位培养试验，设置允许凋落物正常输入和去除凋落物两种处理，分析2017年-2019年期间不同凋落物处理下森林土壤可提取腐殖物质的光密度特征，研究土壤腐殖化程度与凋落物的关系。结果表明，在2年的试验过程中，3种森林土壤的腐殖化程度整体表现为针叶林>混交林>阔叶林，均展现出在冬季降低，生长季增加的动态规律；凋落物对3个森林的土壤腐殖化程度均无显著影响，但凋落物输入明显改变了土壤腐殖化程度的季节性变化趋势，且在冬季的阔叶林和混交林中表现更为突出。冬季凋落物的输入使得阔叶林和混交林土壤的腐殖化程度明显降低，而生长季凋落物输入对3种森林土壤腐殖化程度无显著影响。这些结果表明气候变暖情景下冬季温度的上升可能导致土壤的腐殖化程度增加，但凋落物的存在可以减缓增加的趋势。这些结果对于具有明显季节性冻融且对气候变化敏感的亚高山森林土壤肥力管理及可持续经营具有一定的科学意义。;Humus is the main component of soil organic matter, which is important for soil fertility and nutrient cycling. Forest litterfall as a carrier of nutrients and carbon plays an essential role in the formation of soil humus. The input of litterfall can provide raw materials for the synthesis of soil humus. However, the evidence shows that the incorporation of fresh organic matter into soil can increase microbial activity due to the higher availability of energy released, then stimulate the degradation of soil humus. These conflicted results can lead to a confusing relationship between litterfall and soil humus. Therefore, we carried out a field incubation experiment in three typical subalpine forests (coniferous, mixed and broadleaved forests) on the eastern Qinghai-Tibetan Plateau. There are two treatments in this experiment. One allowed litterfall to enter the soil normally and the other prevented litterfall to enter the soil. Soils were sampled in October (the end of the growing season), March (the end of the winter season), and September (the middle of the growing season) from 2017 to 2019. Litterfall production, and the values of ΔlogK (the ratio of absorbance at 400 to that at 600 nm on a logarithmic scale), E4/E6 (the ratio of absorption at 465 to that at 665 nm), and A600/C ratios of soil extracted humic substances were analyzed in each period. The results showed that, during the two-year experiment, the overall performance of the soil humification degree in the three forests showed the order as coniferous forest>mixed forest>broadleaved forest, and exhibited an obvious dynamic pattern with decreasing in winter and increasing in the growing season. Statistical analysis indicated that litterfall had insignificant effects on the degree of soil humification in the three forests, but the input of litterfall significantly changed the seasonal tendency of soil humification, which was more prominent in broadleaf and mixed forests in winter. The input of litterfall significantly reduced the degree of soil humification in broadleaved and mixed forest in winter, while had no significant effect on the three forest soils in the growing season. These results suggested that the increase of temperature in winter under the condition of climate warming might lead to an increase in the degree of soil humification, and the presence of litterfall could slow the increase proceeding, which are scientifically significant for soil fertility management and sustainable management in subalpine forests due to seasonal frequent freeze-thaw cycles and the sensitivity to climate change.

Особливості трансформації фітопланктону Житомирського водосховища (р. Тетерів, басейн Дніпра, Україна)

Stable functioning of the ecosystem of the Zhytomir reservoir, which is indicated by the absence of directed changes in the primary production over a long period, is pro­bably supported by the alterations of the algae groups at the level of their structure, by the high speed of incorporation of organic matter into the bio-water cycle, and by large areas of water levels. Over the last 10 years, the role of blue-green algae has decreased in the taxonomic composition of the phytoplankton of the Zhytomir reservoir, while the species richness of green, euglenic and golden ones has increased; there were minor alterations to the phytoplankton structure at the class level and more noticeable changes at the order, family, and birth levels. Over a period of almost ten years the species saturation of the genus Chlamydomonas Ehrenb., Euglena Ehrenb., Cyclotella Kützing., Peridinium Ehrenb. Generally, the generic coefficients and the saturation of species with intraspecific taxa increased (which was also observed for the small Denyshivske reservoir), whereas for large reservoirs of the Dnipro and Volga there is a tendency to simplify the taxonomic structure of phytoplankton with their age. Phytoplankton biomass indicators remained unchanged for almost ten years, however, there was a shift in biomass peaks from summer to autumn. The number of algae cells decreased. Phytoplankton alignment decreased. Inadequacy has been established in the trophic status of the Zhytomir Reservoir, determined by biomass and primary phytoplankton production. The higher trophic level, determined by the intensity of photosynthesis, is probably due to the predominance in the dominant complexes of small-cell highly productive species that support the high trophic status of aquatic ecosystems with relatively low phytoplankton biomass. At the present stage, there is a tendency to improve the water quality of the reservoir according to the saprobiological indicators of phytoplankton development in comparison with 2003–2007.

Biogenic structures in soils under a primary Atlantic Rain Forest in SE-Brazil

As minhocas desempenham papeis importantes na formação do solo, contudo pouca atenção é dada à bioturbação pelos pedólogos. A descrição morfológica tradicional, assim como os procedimentos de caracterização física e química do solo, não contemplam as estruturas biogênicas, que nem mesmo são consideradas pelo Sistema Brasileiro de Classificação de Solos. O objetivo deste trabalho foi caracterizar as feições biogênicas como canais, câmaras e dejeções, produzidas pela atividade de minhocas no solo da Estação Biológica de Boracéia, em São Paulo. As bioestruturas foram coletadas, medidas, fotografadas e organizadas por tipo (cilíndricos e blocos irregulares) e tamanho (muito pequeno, pequeno, médio, grande e muito grande). Foram realizadas análises físicas e químicas destes materiais e do solo: granulometria, carbono orgânico, bases trocáveis (Ca2+, Mg2+, K+, P). Alguns canais biogênicos encontravam-se preenchidos por solo revolvido (as crotovinas) e outros não. As características redoximórficas são muito comuns nas paredes dos canais, porque esses dutos biogênicos contribuem para a difusão de O2 do solo e a remoção de CO2 no perfil. As dejeções têm textura arenosa, o conteúdo de carbono orgânico nelas é três vezes superior comparado ao da matriz do solo, indicando a eficiência de certos grupos ecológicos de anelídeos na incorporação de matéria orgânica em subsuperfície. Os coprólitos também apresentaram maiores quantidades de fósforo, cálcio e magnésio do que o solo. As minhocas cumprem funções fundamentais no solo, como aeração, agregação, incorporação de matéria orgânica e aumento de sua fertilidade. Portanto, os agregados biogênicos influenciam fortemente na pedogênese, especialmente na zona tropical.